ibe ay h ste obs $e FF OO ws she . sattass ‘ ¥ Giastineiies Saat: : atissts CREE AS sites ee, Fa5 . o vee te rye 8 Pees 3X7 on = ah ethane SS staRe erthes ke eeeteenas 1 % hae abe eee: pees crecttensrarts Ph velt nes <5 push bh jaa tt. eeerrat tsa tier) seastretinn|csesess 2S ese ee + eeee Staath iis rea #3 eh 4 Sar weve vente ri Gee, ms Here 4 we se peek i letheniaeel Serstiittiey Sore Seabesbbaiie tele Lesa Seg Ya ewes phe Tite ie ~ “ Toat eet eease st oak es tbetrekieatreeteetie » ster tee abeye heey 4 oleaehers tashvetpes te ites: en pat aele bata thks Seo tes webertin Seesyiee bas sons TP hse ee vee ISS) Sees eoreba-y We 4 ves rb TAA >> . wees ve th netabes Sele ebs percents svete bt vheerbeab eaten TSR EAL STALE Soha rpieestaneks Paty fein pat ee Reseed ” tas) ce eives pre Saison posters at a Ege rent :" Mees wabd Sie tetes ree ste coed sorereegeente bias ear Pieces oa riers: Srebiabe ee Sad >> * oe Steen ewe: Shey eahiniy a Tame ¥ eh tS, Thee : e 1354 i : : : peel Srpeseeseaest Sage cetet nee she tedeeatierts Sp : rabebhes tries heaton: n4 peasiesy! eaeks SiGe awe tr reetoagt xr ee Gribatalereer ratpeiie : ig aeeed Arcee aa ttady Rineeroshnlogwe cs tapiesgersstceses “f vie Cees epitetiey S tinthet tabi ta sta thet beriectorerncet Shones gh ae tert pap ; SRAM Ras Fa ea neal Rhelehan nas: eeautel ae esti i Tie Ss ‘ = ‘4 ee = Ser Prt ms Waae a ahead aol Tyra pene As’ ey ae siveterie Sapp ind sen peeqseay cee pina baer 2, i resets Prehs apes , a eeseti Grey Bn Mees Sheuhete mah ary Ts at 5 Mus hake oape 5 ~ orm, tavet ee 0 we hon ts Sek eats ted bp bee se By eres 08 kes beh Vebesyhebveterts teres Patek ots: Geers xs tite hone eee aarye ST7 ee bes) 4a anh ery Peper SS ‘4 Hee a te . a . ean Pile Et toe ba biok bake SF 3 Raine 3 SS Pe =o hats ake TE rhea ke se KE te capa 7 eopercan By 7 ee snap Stier ten tat vin ren assis beLoA hs, Po teehee Saray ee Rissuies kus ae) be | Fe ons patars tarts iat Sibeb aiintece 5 Repteske ote a * da wk het eet ee teeta Wie > Peete rab ats aan se maw sine he é ey eS Vi ee iter eed tive tiuht cite alt wae Faye, we Suny Exes yur Se eeen tess abt fhoty ese ieieel barrecl Lea ear aere eeahe eres ape sei tas hee GS eebbess Sods ye ee Pouce Ries Ronde: eer sere) Beth RAT aaah Seg, tinpedeplden snips Nb fede a 1 beaetass ie 3 : ates hh dds peeskyhtase hice’ Sse ee eee Sass, beatae toes nan) beats " . pei ota rapyss drys mee hee ee beet eens eLeS rates 3 [fore sonst ute 3 2 63 bye wy mt TRAP ETE woe abel vr ceentee suet wa ths ae phi bbe tt ees rt ¢eeua kuetadeae ted Resi sur bee esl e bet Pd pests ors : ‘ prey ehe coos ? bers tone Fs —e pe a eh doy Ce Vibebs & se ges s) Calwetivat uses Tab Pred Dppeting ne th foi ed Yanavas Phebe i ies sera ts ‘ zat lat ¢ si ree eva re we nal iver Sat p¥a tet beast man Ab bois eda tee Os Gta Dif ech A sehg it Soh 4 tel Ba puted Ty eabecen rel em top tant dosh F los Spina date ea SP PO Sepa 2. abe Ao gota seca bara? ante Ing eg Saeed Les garry wah ans Tadd to nye Reve ions ayaa Scheitawiient bene tae tate a ~ of. pe ileeetn Det etine:s yup Ts DAE te hT phi tite £F Db ma} 8 aay ee ty by Med be ros Sdanhltetad. Broce hee aa Us Seah gin y uM teh an ceitetrory thle * letavy ned eiy 9 tad ‘ site RS aE Try Pye FRANKLIN INSTITUTE LIBRARY PHILADELPHIA Class... 7.. Book..26.6. Accession ZA2 3F The book may be borrowed for a period of two weeks and re- newed only for an additional period of two weeks. LIBRARIAN. =a) t FACTORY PRACTICE IN MANUFACTURE OF ~AZO DYES BY “W. B 'OBRIEN,: BEB. 13 ae: Chemist for the Flash Chemical Company Formerly wit ' the 45 tasselli: Chém: ‘ca! Company’ aud? the Synfeur Scientific Labovatorfes « *° EASTON, PA. THE CHEMICAL PUBLISHING COMPANY 1924 LONDON, ENGLAND: TOKYO, JAPAN: WILLIAMS & NORGATE ' MARUZEN COMPANY. LTD. 14 HENRIETTA STREET, COVENT GARDEN, W. C. 11-16 NIHONBASH!I TORI-SANCHOME. ereerce PRON ce Canoe cence COPYRIGHT 1924, BY EDWaRD HAR o faeooenr € PREFACE The purpose of this volume is to afford basis for a view point on azo dye manufacturing, in so far as actual factory procedure is concerned, for the general chemist and for those who look forward to the dye industry as a possible field for their pro- fessional activity. Informative discussion upon the manipula- tion and working conditions in the dye factory is not easily avail- able to the student. For presenting the elements essential to standardized produc- tion of azo dyes, the simplest members of that class are to be herein discussed, covering chiefly the mono azo group, by out- lining in detail specific methods for preparation of individual dyes with explanation of technical principles involved. In deal- ing with the subject of factory practice some attention must be given to necessary theoretical and research matters, but it is not intended in this volume to present the more abstract chemistry of the azo dyes as aclass. A factory process is merely a routine based upon theoretical and experimental considerations. The soundness of chemistry indispensable in theoretical and research work must be inherent in factory processes, but, apart from chemistry, economy in regard to labor and materials and con- formation to the limitations of the short working day becomes of paramount importance. A lay belief somewhat generally ac- cepted attributes an indefinable, mysterious elusiveness to the work of dyestuff production. Such belief, while serious enough in the stubbornness with which it persists, is in no way justified. Similarly to other large industries, success in dyestuff manu- facturing depends upon capital, organization and hard work. The advantage possessed, elsewhere than in America, due to earlier participation in the industry, has been largely compensated by economic and circumstantial factors affecting the industry here. It is hoped that the student of the subject will realize that alternative methods of procedure are always possible and that statement of fixed methods may serve only as a starting point for an understanding or improvement. Undoubtedly more numer- 1 FES 4- 1V PREFACE ous recipes than given herein would be acceptable, but in the opinion of technologists well versed in the subject, recipes are of value only when accompanied by explanation of the principles involved, and the principles which apply to mono azo dye pro- duction need only stricter observation for application to produc- tion of other, more complicated, azo dyes. The author is indebted to Mr. John Eliot Foster of Boston for his cordial help in preparing the illustrations, and to Dr. E.. von Salis of Albany, N. Y., for his valued direction in the production of dyestuffs. Boston, Mass., April, 1924. CONTENTS CHAPTER 1 Te Pe a aN tae! eee ac Ne eg ad oe a be I Importance of the azo dyes as_a class. Chemical theory and nomenclature of the dyes. Outline of the factory routine of manufacturing. CLAP ER old Buripincs, MAjorR EQUIPMENT, OPERATION, MATERIALS ............-- 14 Scale of operations. Buildings for the making, drying, milling and standardizing processes. Tubs, filters, blow-cases, stor- age tanks, mills, mixers, general equipment. Operation, maintenance, chemical materials used. CHAPTER, Il Pe Me trea OM CPP ANILINE | 7.0. 0502s cc cccewed ences Waters a ase tees 46 Manufacture of Orange G. ; CHAPTER IV Fovye ParrAnen FROM DIAZOTIZED ANILINE $i0%...0. coeces cescdvenars 56 Amino Naphthol Red G, Fast Acid Fuchsine B, Croceine Orange, Chromotrope 2B, Chrysoidine Y, Sudan I. CHAPTER V -DIAzoTIzATION oF THE HoMOLOGUES OF ANILINE ........0eeeeeceeee 73 Manufacture of Ponceau 2R, Sudan II, Brilliant Orange O. CHAPTER VI ATO ZATION OF THE NITRO -ANILINES sos e00ccccndscedenc cas nescees 81 Alizarine Yellow R, Paranitraniline Red, Alizarine Yellow GG. CHAPTER VII DIAZOTIZATION OF THE SULFONATED ANILINES .......ccescccceccceves 93 Chrome Yellow AS, AM, Orange J, I], III, 1V, Metanile Yellow. Vi CONTENTS PAGE CHAPTER VIII DIAZOTIZATION OF ACETYL PARA PHENYLENE DIAMINE AND AN- TEHRANILIC ACID. cscs o55.c d5.0's)ele dua bap toticlc eee akc tn aa ahi tina 117 Amino Naphthol Red B, Azo Coralline, Acid Anthracene Red B. CHAPTER IX Mono Azo Dyes FROM OrtTHO AMINO PHENOL DERIVATIVES ......... 129 Chrome Brown R, Peri Wool Black, Palatine Chrome Violet. CHAPTER X Mono Azo Dyrs FRoM ALPHA NAPHTHYLAMINE AND NAPHTHIONIC ACID Lecce ened ecracb elated cu palace e8c cy 00 Nkiehee prea t= ia 137 Fast Red B, Fast Brown N, Fast Red A, Azo Rubin. CHAPTER XI Mono Azo Dyks From AMINO NAPHTHOL SULFoNIC AcIDs .......... 149 Salicine Black U, Sulfon Acid Blue R. CHAPTER XII TETRAZOTIZATION OF BENZIDINE <0. ..052¢¢> os ue sie ess ee eee 157 Diamond Flavine G, Chrysamine G, Diamine Fast Red C. CHAPTER XIII RELATION OF THE CHEMIST TO THE INDUSTRY. EXPERIMENTAL WorRK AND SMALL SCAL® PRODUCTION |.....¢0e.uce bee ue ee 166 LIST OF PLATES PAGE ATS foe gwd de SRA PRs Kuiek SL eRe ig & rad eV bk ale Mew ca eeee 15 Cross section, making building. eee Sc ia ao 3c ona s bpd 6 6 a9 ode tcele sf Mane wale ee oe Be oe 24 Longitudinal section, making building oe Sag a aaiy ble pics ¢c.s civ cies be wae cb ein he We sebues 29 Plan, first floor, making building. SE a tee eos hal Sicrs ie @ as sc «ue vi ab aie *saaieud eahho.b eiaice 6 ve wis 30 Plan, second and third floors. ee eA a) 4 0ha's w FEM POR OES bared ae dele Petal he ah aed eee 35 Plan and elevation, drying department Pete ee ng aioe Sa cig disvos ese vrsvvavenscuscesget vec euve 38 Plan and elevation, milling department. RE ee hogs gels enn-ace a SiG biate.y «'s s.g/aa vivings o MalaRi + 6.4.0 ole we 47 Table of dimensions and content of cylindrical tubs. eer aE PR ET, Oi. Sale a cate el ola ds Se or Lea dew a pps eee coh 169 Plan and elevation, experimental plant. FIGURES PAGE Cylindrical tub: .o0s.0c0 set oa aa nei eve oak ee 17 Tub with slanting sides ...:45.2..%. [00 ales nen 17 Tub with blade agitator, overhead suspension ............. 18 Tub with propeller agitator. ...0 o. 0.» +/s00% 10 selene 18 Agitator with bearing om tub floor .....4.),\).aee eee eee 19 Gate type agitator ..« 05 ck bees us «ose aiie cle ee 19 Bib cock outlet: (00084 62. cee Ale oe ete cree eee 20 Straight type’ outlet. yo. 0200 fe. 0) a ee 21 Location of outlets in tubs’ i..c, opacity een 21 Special. manner of installing outlet; ...: J). ae Renee 22 Top and sectional. views of filter tub 3. /i.2 2 yee eee 26 Detail of filter tub fittings eievawcaw es vee sai) tne ln 27 Sketch of frame and plate 2.2.3... .2.0 us = pee 28 Arrangement of tubs, blow-cases and their corresponding filter -Pr@SS€S ....46se0rioee gas: ope scp ale cient an 3I Front view of drying ovens (2.2/2.7) vss ss scene 34 Vitriol tanks ....5.caccnenvscescce ae Ue eu e's oan ne 40 CHAPTER«I INTRODUCTION Of the dyestuffs that originate in coal tar products, the “Azo” dyes form a highly interesting class, including in number more than 60 per cent of the total dyes manufactured in the United States.? | The chemical name “azo” finds use with manufacturers rather than with distributors and consumers. In a discussion of their manufacture the dyes of this class can be identified only by use of the term, although the finished azo dyestuffs are classified in trade circles as acid, basic, mordant and direct dyes. Such com- mercial classifications relate somewhat to the chemical compo- sition of individual dyes, but do not constitute exact chemical classification of the dyes nor give indication as to the methods employed in their manufacture, and are based mostly upon the manner in which a dye is applied to a fabric or other materials. The commercial classifications include other dyes with the azo and do not differentiate between the simple dyes and the blends, or mixtures of several dyes that are marketed. From a chemical standpoint the azo class of dye is well de- fined, and once the chemical composition of a dye has been de- termined there is seldom any doubt as to whether or not it be- longs in the azo class. The molecular structure of all of its members has a dominating point of similarity due to the presence of the “azo” chromophore, a characteristic grouping of nitrogen atoms, represented by the symbols —N = N—, or —N,—. Further, dyes of this class are all prepared according to a 1In the year of 1920, eighteen classes of dyes were manufactured in the United States, with total production of 88,263,736 pounds, valued at $95,613,749. Of the 240 individual dyes which made up the classes 148 were azo, totaling 36,897,003 pounds, value $46,984,135. The remaining 92 dyes were divided among seventeen classes, of which the most important numerically was the triphenyl methane class, with zo members and total production of 2,482,169 pounds, value $10,130,336. Of synthetic indigo, 18,178,231 pounds were produced, value $13,497,981. The sulfur dyes amounted to 20,034,500 pounds, value $6,936,703. The average price per pound was for azo dyes, $1.27; for triphenyl methane, $4.08; for synthetic indigo, $0.74; sulfur dyes, $0.25. The figures relate to actual production in the United States. During 1920, only 3,402,582 pounds of dyes were imported, value $5,763,437, of which Germany supplied 51 per cent, Switzerland 34 per cent, England 6 per cent, and other countries 9 per cent. (U. S. Census of Dyes and Coal Tar Chemicals for 1920). 2 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES general method which varies but slightly in detail for each member. The raw materials consumed in manufacturing azo dyes are in themselves highly developed products of the chemical industry, known as “intermediates.” They include amines and phenols of the aromatic series of organic chemistry, and derivatives such as the chlorinated, nitrated, and sulfonated, amines and phenols. It is extremely practical to combine the manufacture of the inter- mediates with that of the dyes, into one organization, but the discussions of methods and equipment for manufacturing the products of each of these two industries must be taken up sepa- rately. In this volume it is assumed that the raw materials, or “intermediates,” are furnished, and in a condition suitable for their use in the production of dyes. Manufacture of an azo dye begins with the preparation of a diazonium salt, ordinarily referred to as a “diazo.” The follow- ing structural formulas represent typical diazonium salts: N,Cl N,Cl a Ge WA Nae Benzene diazonium chloride Naphthalene diazonium chloride or Diazo benzene chloride or Diazo naphthalene chloride Preparation of such diazos is effected in the factory by the action of nitrite of soda on the water solution or suspension of an aromatic amine, usually in the presence of an excess of a mineral acid. The amino group is converted into a diazonium group, the reaction being called “diazotization,” and for aniline, is repre- sented as follows: NH, N,Cl fay Mou | | + HNO,+ HCl = | | + 20H,O wy Ny Aniline Diazo benzene chloride INTRODUCTION 3 The diazos as a class react quantitatively in water solution with certain amines and phenols, and derivatives, a reaction termed “coupling” taking place. A compound reacting thus with a diazo is termed a “component.” Coupling produces new compounds, containing the groups of atoms that were formerly diazo and component, united by the azo group, —N = N—, as shown in the equation for the coupling of diazo benzene chloride and beta naphthol : N,Cl N ==== Bee NOX ae | we SLE LASS ETON AG Diazo Beta benzene chloride naphthol Sudan I The product of the above reaction, Sudan I, is a typical azo dye, with a chromogen containing the azo group as a chromophore and the hydroxyl group as an auxochrome. Dyes of greater complexity can also be prepared, containing more than one azo group and therefore of greater dyeing power. The number of auxochromes in an azo dye can be varied by selection of the diazos and components. Only primary amines can be diazotized, but the composition of materials adapted for use as components varies considerably, including primary, secondary and tertiary amino compounds, and phenolic compounds, used in the forms of the acid and basic salts. As a rule, the diazonium salts do not possess much stability and so must be used immediately or at least soon after prepara- tion. Directions for their preparation and use in the factory should include specifications as to the material and construction of the containing vessel and the character of the mechanical agitation applied. The solubility of the amine and concentration of its solution or suspension, the manner of introducing nitrite of soda, the duration of the diazotization, the temperature throughout and the final volume, must be considered for secur- ing the diazo. The diazo results and is used in solution or in a suspension; if sufficiently insoluble, it may be filtered for use. 4 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Difficulties of preparing components for coupling vary with the solubility of their salts in water. It is generally desirable to effect solution in the smallest volume attainable. If heating is necessary to bring the component into solution, the temperature must be brought down again before coupling, with of course due consideration for the form in which the component reprecipitates. A component can be used in solution or in a suspension. Coupling action between diazos and components is promoted by a favorable condition of solution, which may be alkaline, acid or neutral, depending on the nature of the component. The alka- line condition is regarded as that produced by soda ash; the acid condition that from muriatic or sulfuric acids; the neutral con- dition that from acetate of soda or bicarbonate of soda. In gen- . eral, phenols and their sulfonic acids couple well in alkaline solu- tion, amines in acid solution and the amino sulfonic acids best in neutral solution. To effect coupling in either the alkaline or neutral conditions, the prepared diazo is added to the solution of the component containing soda ash or acetate of soda. For coupling in acid condition, the component is added to the solution of the diazo; ordinarily sufficient acid will be present to maintain this condition without further addition of acid. Special cases occur where the diazo is prepared in solution with, and in the presence of, the component; in these cases the components are amines and coupling goes on in acid condition. In calculating the amounts of diazo and component to be pre- pared it is customary to take a slight excess of one of the two, depending upon the influence which the unused excess will have upon the finished dye. Ideal procedure would require that ex- actly equivalent amounts of each reacting material be taken but absolute exactness in control is unattainable in practice and the employment of an excess of one insures complete utilization of the other with advantage to the results. The time required for the completion of a coupling reaction in the factory depends much upon the efficiency of the contact INTRODUCTION 5 obtained between the diazo and component. In case both are completely soluble, reaction may be completed immediately after mixing, or at the most within a few hours. In the cases of slightly soluble diazos and components, used in suspension, as much as forty-eight hours’ agitation of their mixture may be necessary to completely utilize the one present in lesser amount. Efficient agitation and a fine state of division in the reacting ma- terials promotes the contact and is necessary for completing the coupling reaction. The less soluble diazos are to be had in a finely divided condition as result of the method of their prepa- ration, but a process should include directions for producing this state for slightly soluble components used in suspension. The volume or concentration of the coupling mixture influences the progress of the reaction differently for individual cases. Some azo dyes on formation precipitate immediately in a thick slimy state of particles which hinder contact between unreacted por- tions of the diazo and component and completion of such coup- ling is favored by efficient agitation rather than by concentration, but in cases where the resulting dye is very soluble, or else pre- cipitates in a crystalline form, concentration is advantageous. While diazotization and coupling are chemical reactions which ordinarily may proceed smoothly in the manner indicated by their written equations, secondary reactions must nevertheless be anticipated. In the course of its formation a diazo may react with a portion of the undiazotized amine, to form a compound having the nature of a dye but undesirable. In the lesser stable diazos partial decomposition may occur to form phenolic com- pounds which will later couple with the diazo in alkaline solu- tion; the yield, as well as the purity of the dye, is thereby lessened. ‘The necessity for use of pure intermediates is em- phasized by a consideration of the influence of secondary re- actions upon the finished dye; small amounts of alien color formed may alter the shade sufficiently to destroy the value of the product. Completion of the coupling reaction is recognized by testing a portion of the mixture for presence of the material taken in 6 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES excess and absence of the other. In a practicable industrial method the dye is out of solution after completion of the coup- ling, and it is generally filtered in an alkaline condition, after addition of common salt, up to 15 per cent of the total weight of the charge, to the solution to insure complete precipitation. The mechanical work of filtering, drying and pulverizing the dye comprises a large part of the total work of the manufacture. In so far as purely speculative organic chemistry ts concerned, the number of possible azo dyes is almost unlimited. Commer- cial enterprise uses only the simpler compounds, including the mono azo, disazo, trisazo and tetrakisazo dyes. The Greek pre- fixes refer to the number of azo groups contained in a molecule of the dye compound; a mono azo dye is the result of simple union between a diazo and a component, and contains but one azo group, —N = N— or —N,—. Orange II is a mono azo dye, as shown by its structural formula: | N SS et N a . ee Bice: ye eI SO,Na Orange II Of these dyes the disazo type finds use in the industry to a greater extent than the other three types, and is further sub- divided according to the manner of formation, into, (a), pri- mary and secondary disazo dyes, and (b), disazo dyes from diamines. The disazo dyes are prepared from the mono azo dyes by employment of reactions entirely similar to those used to form the mono azo. It is sometimes the case that a com- ponent has the power of coupling with two molecules of diazo; resorcin is such a component. When coupled with one molecule of a diazo, resorcin gives a mono azo dye in which the com- bined resorcin nucleus may again react as a component and INTRODUCTION Fi couple with a second molecule of a diazo. The compound formed by the second diazo contains two azo groups in the molecule and is termed a disazo dye. The two molecules of diazo used may be of the same composition, in which case symmetrical dyes are formed, or of different composition, giving rise to “mixed” or unsymmetrical dyes. In either case a primary disazo dye re- sults from this manner of formation. The first coupling takes place much more readily than does the second and it is neces- sary to couple the lesser stable of two diazos in a first operation, forming the mono azo dye and to then introduce the second and more stable diazo. A longer duration of the coupling period, and adjustment of the conditions of temperature and alkalinity, is required to bring the slower second coupling to completion. The case of Resorcin Brown is illustrative of this type of dye; the slightly stable diazo from meta xylidine is coupled with resorcin and the mono azo dye resulting is then coupled with a molecule of the diazo from sulfanilic acid: OH Meee Ace.) /NCH, GH. (0) 1) oa le | AGE Ry NH, 3 CH, ; Xylene Resorcin OH diazonium N,——7 ee NN oe chloride Je os NEC ET nt a | Ue Ps eh bs Oem te AGH. Bak ee LON Ge N ke CH, | 3 Benzene N diazo sulfonate ~$O,Na Resorcin Brown Secondary disazo dyes differ from the primary only in man- ner of formation; no radical dissimilarity appears in the compo- 2 8 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES sition of the finished dyes; a mono azo dye obtained by coupling a diazo with an amine or amino sulfonic acid will contain a free amino group as auxochrome; the amino group may be diazotized in the conventional manner and the secondary diazo resulting is usually stable, coupling readily with components to form second- ary disazo dyes. Sulfon Cyanine Blue G is an example of the type: N,-—O NH, Nee Ng NE, diazotize TAN Ni NTS AN aR et his | | = aN a with Diazo benzene a-Naphthylamine m-Sulfone | MAN ONE es a NC DN NO eee Ci PNAC : ys J Ns0.Na oe Cone 3 3 CJ soNa ee Sulfon Cyanine Blue G Phenyl peri salt In the case of dyes of this type there is no great difficulty in promoting the second coupling. Primary diamines of the aromatic series give rise to a class of disazo dyes. In some diamines the two amino groups can be “tetrazotized,” or diazotized simultaneously, yielding a “tetrazo” analogous to the diazo. Extensive use is made of meta phenylene diamine, benzidine, and their derivatives, in producing disazo dyes by means of tetrazotization. In the preparation of Bismarck Brown the two amino groups of meta phenylene diamine are tetrazotized in one operation but in the case of this dye the component is also meta phenylene diamine, and tetrazotization is performed in the presence of the component; coupling with two molecules of the component follows immediately to form the disazo dye, it not being possible to limit the reaction of either INTRODUCTION 9 of the diazonium groups and control the introduction of the component: NH, % a + 2NaNO, + 4 HCl => oH, Meta phenylene diamine N,Cl NH, | eu are \/N,CI \/NH, NS cue er DNH, HCl Bismarck Brown This behavior, of simultaneously tetrazotizing and coupling, is peculiar to the meta diamines and constitutes a special case. Ortho and para diamines cannot be tetrazotized and indirect methods must be used to obtain the disazo dyes which theoretic- ally correspond to such diamines. Dyes derived from ortho dia- mines have no commercial importance but this cannot be said of the dyes derived from para diamines, especially para phenylene diamine. Two methods are used for preparing disazo dyes from such diamines. The first method starts with a mono acetyl dia- mine, the free amino group of which is diazotized and coupling made with a component to form a mono azo dye. The acetyl amino group is then split by a process of hydrolysis and the amino group set free for diazotization and a subsequent coupling. Violet Black B is a disazo dye prepared in such manner: IO FACTORY PRACTICE IN MANUFACTURE OF AZO DYES NWHCOCH = ONECOCEH. NHCOCH, C Kn ah A/S om (1) was ii oe A Nhe NH, N,Cl O,H N=N/SV\/S\ Acetyl para —- Diazo N- wr Acid meray | phenylene ee ee diamine SO,Na NH, N,Cl (1), +H SOpte 7 Ne ae aN | (IT) OH ed Baia AaN meme Bs akeae’ Waa ; SO, NH, N=WN Be. LES 7 mr CET) Gch ae cee | | | C Ona a a-Naphthyl pee OH amine N= Bae. SO,Na Violet Blank B The second method uses a nitro amine, which is diazotized and coupled with a component. The nitro group in the resulting mono azo dye is then reduced to an amino group, which is diazo- tized and the second coupling made to form the disazo dye. The above two methods introduce more highly involved chemical operation than is usually met with in the course of azo dye manu- facturing. Added complications in operation need not necessarily be accompanied by a decline in the yield but, increased cost in equipment and operation can be sufficiently heavy to eliminate possible products from a field of competitive production. INTRODUCTION II Diamines of the biphenyl series, benzidine and its homologues and derivatives, can be directly tetrazotized; the tetrazo formed couples with components in a manner which can be controlled for each diazonium group to the extent that one diazonium group may be coupled with a molecule of a component while the other diazonium group is held unchanged, for subsequent coupling with a molecule of a second component: NH, N,Cl OH MAN oes ee OO ON NL) i L | | is) Ler, —COONa ae xX + Salicylic ye Pe: a acid | (I) ee Og MA NH, N,Cl N,Cl Benzidene ‘Tetrazo diphenyl dichloride OH Ne n~. OH Be 7S > Couns ee eae ee ue be Oe NA net Gamma Fhe Diamine . acid ied Fast Red C A Ns N OH ae A ~ cy \/80;Na The disazo dyes of this type are of importance from their prop- erty of dyeing cotton without aid of a mordant. Azo dyes containing three, or four, azo groups in the molecule are prepared by methods similar to those used in forming the mono azo. A simple illustration is in the case of a trisazo dye which can be prepared from phenol as component with three molecules of diazo which may be introduced in steps, forming a compound whose formula is: 12 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES OH X—N=N /\ N=N—Z Leu Peed oa N xX, Y and Z = aromatic radicals. | N Y Of the trisazo dyes which have commercial importance, Benzo Brown 3-GO may be mentioned. In preparing this dye, two mono azo dyes are first formed separately, one by coupling meta phenylene diamine with a molecule of the diazo from sulfanilic acid, the other by tetrazotizing benzidine and coupling one of its diazonium groups with a molecule of salicylic acid as com- ponent; the two mono azo dyes are then mixed and the free diazonium group of the benzidine nucleus couples with the meta phenylene diamine nucleus to form the trisazo dye compound: NH, ap NH, N==N Sn pene os A a OOM Gl pe (I) ee SN Ba SO,H So, - SO,Na NH, NH, N,Cl N==N ine OH LX NH, N,Cl N,Cl VN oe ost (I)+(Ud1D= \/ Benzo Brown 3-GO yom INTRODUCTION 13 Only few tetrakisazo dyes are manufactured. Compounds con- taining more than four azo groups are seldom commercialized. The difficulty of preparation increases with the number of azo groups, due to the difficulty of bringing the slower higher coup- lings to completion and to the accumulative influence of second- ary reactions. The yield of the finished dye should increase with the number of azo groups proportionately to the molecular weight, making it possible to overcome the cost of an expensive intermediate by coupling it with several of low price. The manufacture of azo dyes from intermediates may be out- lined as follows: I. Coupling. vue Preparation of the diazo, including (1), all work necessary in procuring, weighing, acidifying, dis- solving and icing the amine; (2), preparation of the nitrite of soda solution and addition of it to the amine. Preparation of the component, including procuring, weighing, dissolving in acid or alkali, and icing. Combining, or mixing the diazo and component, and observance of the time for completion of the reaction, also neutralization and salting of the finished charge. II. Filtration. By Conveying the charge to suction tubs or to blow- cases for filtration. B. Filtration, washing, removal of the cake. C. Finishing some dyes as paste. III. Drying. A. Entering the paste in proper type of oven and tray. B. Duration of the drying and treatment of the dye. IV. Milling. A. Grinding. B. Standardization, including dye laboratory tests and addition of the proper reduction materials. CHAPTER II BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS In the manufacture of azo dyes the unit quantity of the pro- duction is the batch or charge. For practical work the batches prepared should be of a size sufficient to yield from 500 to I,000 pounds of dye, selling strength, in a single charge. On such a scale the production can be of sufficient volume to carry the manufacturing expense, while the size of the batches is not too great for good control and completion within twenty-four hours. The molecule charge, based on a molecule of the diazo in pounds, such as would be obtained from 93 pounds of aniline, in the case of diazo benzene, is conveniently of the size de- sired, yielding in many cases about 1,000 pounds of dye when the product has been reduced to selling strength. The molecule charge is made the basis for methods of procedure to be taken up later. The coupling equipment should be constructed with capacity to carry such charges and have ample room for excess. In some cases it is necessary to conduct larger charges, of from two to five molecules in size, to maintain the volume of the pro- duction when the molecular weight of the dye compound is low, or when the selling strength of the product is highly concentrated and little or no reduction can be allowed; in such cases the equipment described will serve. For the work of coupling and filtering, an entire building should be allotted, drying and milling to be conducted in a sepa- rate building. In practice such a scheme for operation is fol- lowed rather than one which combines the manufacturing pro- cess entirely within one building. Plates A, B and C show sec- tional views of a building designed for the ‘“‘making” or coupling and filtering of azo dyes, with equipment for conducting eight charges per diem. Points in which the difficulties of the making process can be reduced include the handling of raw materials, providing ready access to the coupling outfits for introduction of raw materials and the transfer of charges from one section Zz SLV7TS L/12 LAS /2 y MENGES IE SVITID FIVIOLS ay A) (CAT man wl = | YU Cope eh L SORYS LFLIS { SSFAS SILVA OL GPITS s FMT FINSSIAS S10 — C=! AYTTTIVI—™ : R SSSESSSSSSSE ELI ESSAI aS SS SSSA SSS AYFTIWVI-Y 16 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES to the next. Plans? of the three floors or working levels are shown in Plates C-1, C-2 and C-3; a raised center portion of each floor, shown in Plate A, allows access to the top line of coupling tubs located on the lower side portions of the floors; on the third floor the sides are left partially open, for transmission of power, and for light. The coupling units are housed within a main section of the building, the first floor being extended with a shed roofing on each side to house the filtration equipment. Elevator space is made near one end, where raw materials are received. Storage bins for salt and ice flank the elevator on the first floor, the corresponding space on the second floor being allotted to laboratories for the chemical control, and on the third floor to space for location of a small plant for experimentation with new methods. The coupling tubs on the lower side floors are placed closely along the raised center floors, and raw ma- terials, handled on the center floor, can be entered in the tubs without the use of chutes or hoists. It is desirable to minimize the installation of fixed chutes as far as possible; much incon- venience attends their use. In general construction the building should be of a steel frame with brick or tile walls, the floors to be of reinforced concrete, supported by steel girders and up- rights. The ventilation afforded in the building designed will ordinarily be adequate for the needs in azo work but ample window space must be allowed for light. Provision should be made, in the form of openings, pits and tunnels, for the pipe lines, water, sewer, steam, vacuum and compressed air, with easy access for inspection and repair as alterations and repairs figure prominently through a period of dyestuff manufacturing. The coupling reactions are conducted in wooden tubs fitted with connections for water and direct steam, and mechanically driven wooden agitators. The materials for diazo and component are dissolved in tubs on the upper levels and the solutions de- livered progressively to lower levels during operation. A charge 2The plans and designs shown do not refer specifically to those of any plant in use at the present time, as far as the author knows, nor are they intended for use other than to illustrate the practical features of the specialized work of azo dye manu- facturing. Buildings in use by manufacturers result from their special needs, for com- bining the manufacture of intermediates and dyes or to adapt buildings constructed for other purposes, to the manufacture of dyes. BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 17 ordinarily flows by gravity but when filtering with pressure the charge flows into a steel blow-case located in a pit sunk in the first floor and is then forced up into the filter press by means of compressed air. For vacuum filtration, filter tubs are placed on the raised portion of the first floor. Batches filtered by vacuum are to be coupled and finished on the second floor and run by gravity to the filter tubs. Greater rapidity may be obtained by using pressure filtration; the steel blow-cases used for alkaline or neutral batches must be specially equipped with an interior lining of lead or acid resistant brick for acid charges filtered by pres- sure. The wooden tubs for this work are built from 3-inch stock, of cypress, redwood or white pine. Sizes of tubs vary with their purpose, ranging from about 200 gallons upwards to 3,000 gallons in capacity. The manner of arrangement of tubs is illustrated in Plate F. Two types of tubs are in use, the first AANA MTT WT eee CKLIVORICAL TUB- STRAIGHT SOLS TUB WITH SLAINTING HIDES Fig. 1 Fig. 2 having vertically straight sides, giving the same diameter at top and bottom, bound with round iron hoops drawn tight with malleable iron draw lugs; the second type has a slanting side giving less diameter at the top, bound with flat iron hoops se- cured in place to prevent slipping unwards. Tubs are cylindrical in shape excepting some of the larger which have an oblong con- struction. 18 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES For rapid calculation of the exact volume occupied by solutions at various depths, required intermittently in azo work, the first type is more desirable; exact measurement of volumes is essen- tial for the control. Greater durability and length of service is claimed for the second type. Tubs should be set in place with the bottom at a slight pitch towards the outlet in order that the contents may be emptied completely without much rinsing and washing. Mechanically-driven agitators are employed in all tubs except those used for dissolving nitrite of soda. The single-blade type SETERHMAA>»yg »yy SSSA W 2 Ee ES a SSS SSS SS SSS 1 LT Ti MASS a Rea y, Y) Y Y Z y Z Z Z Z Y Z Z Z Yj Y) Z Y Z Z Z Y 4 a RSS 108 BLADE AGITATOR WIT WERHEAD PROPELLER AGITATOR SUSPENYS/O/Y Fig. 3 Fig. 4 of agitator shown in Fig. 3 is used and should swing to clear the bottom by not above 3 inches. The propeller type of agi- tator, Fig. 4, is installed for processes requiring very rapid agita- tion and may clear the bottom by 6 or 8 inches. Suspension of the agitator should be from bearings at two points in the upper section of the agitator shaft, as indicated in the figures. BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS I9 The type of agitator resting on a metallic stud in the bottom of the tub is not suitable for azo work as the stud, even if of brass, is eaten out periodically by muriatic acid in conjunction with nitrous acid, causing delay for repairs and mishap to the charge under preparation; the stud also forms a center around which mud, soda ash and debris will cake. Wooden pegs for securing the agitator blade to the bottom of the shaft are more suitable than brass bolts although in this case the matter of re- newing brass bolts is much simpler than the removal of an acid- eaten stud. Fig. 5 illustrates the type of agitator to which ob- jection is made. The gate type of agitator, Fig. 6, is likewise unsatisfactory from its undue splashing of material during agita- tion, but has some use for slow agitation of heavy mixtures. oe i 1 SS SSSSSSS = ESSSSSSSSSSSSSSSSST'ASSSSSSSS SSS = A es a we SMS Le il SS) BLADE AGITATOR BEARING | CATE T¥PE AGITATOR OMY TUB SLOOR Fig. 5 Fig. 6 It is desirable to have the blade of an agitator swing within 3 inches of the tub floor for agitation of small initial and final volumes; thus, in a tub 8 feet in diameter the smallest amount of water that could be agitated would be 784 pints. If the agi- tator cleared the bottom by 5 inches, the corresponding amount would be 1,307 pints, the difference becoming more noticeable in 20 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES larger tubs. For pastes or mixtures running out of tubs it is desirable to agitate as long as possible to prevent settling. In many instances the methods for diazotization and coupling - call for strong agitation. Agitation to comply with this specifi- cation varies in rapidity depending on the diameter of the tub and the density of the mixture to be worked. A tub 6 feet in diameter could not have a blade agitator running at much over forty revolutions per minute, as when filled to any depth prac¢ti- cal for working, the material would flow over during agitation. In a tub of large diameter a blade agitator running slowly will effect as strong agitation as a more rapid agitator in a smaller tub; in a tub 8 feet in diameter, agitation at twenty-four revo- lutions per minute, would suffice for diazotization of a moder- ately thick “H” acid paste where forty revolutions per minute would be required for the same material in a tub 6 feet in diam- eter, the difference being due to the relative sweep of the blades. Studs secured to the sides of the tub are of little advantage, work- ing best below the surface. The propeller types of agitator, hav- BIB COCK TX¥PF OUTLET -LARTHENWARE Fig. 7 ing shorter arms or blades, has little effect on heavy pastes but is used at high speed to produce a smooth rotation of solutions or thin suspensions. In tubs used for dissolving nitrite of soda, large paddles worked by hand are used for agitation as the quan- tity of solution is small; care must be taken to completely dis- solve and use all of the nitrite. Outlets for discharging the contents of tubs are of earthen- ware or hard rubber, especially in cases where acid is to be used. The hard rubber material is affected by heat and should not be used where temperatures of over 50° C. are attained. as is the case when dissolving alpha naphthylamine hydrochloride. Earthen-ware cocks are not entirely satisfactory because of their BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 21 brittleness; the straightway type is more suitable than the bib- cock, cakes of paste, bits of wood and other debris which fre- quently obstructs the channels of cocks being more easily re- moved with a stiff wire. cont Cum STRAIGHT WAY TYPE OUTLET-LAPTHEN WARE Fig. 8 Outlets may be advantageously set in the tubs in two posi- tions, the first by screwing the outlet through the tub bottom at a point adjoining the side wall, as in Fig. 9, the second by screw- ing the outlet through the side wall on a line with the bottom, as in Fig. 10. The first setting is the usual one, with the second as alternative when the tub sits too close to the floor to allow access to a bottom outlet. SS TASS Wy Hy 7UB 7UB et INTERIOR | WYTERIOR | Wh ree Wye Wee Caesar. | We jo LOCATIONS OF OUFLETS MWY TOBS Fig. 9 Fig. 10 22 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Such outlets are simple to install, require no metal retainers, and have no angles in the channels. A system of installation shown in Fig. 11, is one that should not be employed; a block attached to the bottom of the tub by means of bolts or pegs, has a channel bored down from the tub and through from the out- side, meeting at right angles; with a bib-cock for outlet two angles result in the channel to augment difficulty from an obstructed channel. ed 8 Ty waerat (El) 8 2a a, 40; ini ALLL LSS) Pa C422 a? 18 BRO NI aN SPECIAL IIAIVIYER OF LIYSTALLIVYC OUTLET Fig. 11 Attention should be given to providing outlets of sufficiently large size, it being a common error to install a size considerably too small. A suitable size is that of a cock with a channel of 1¥4 inches diameter, so that from an ordinary tub 1,000 gallons may be discharged within thirty minutes. Transfer of contents from one tub to a lower is made through a stout rubber hose 2%4 to 3 inches inside measurement, fitted over the tapered end of the outlet and run to the lower floor through the openings between floors. Such equipment is cheap and easy of replacement; the charges flow from the tubs with no loss from leaks or retention in angles such as can happen with BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 23 a fixed chute; one hose may be used to discharge alternately to any of several tubs below, where a fixed chute can do for only one connection and is costly to install if made compact and last- ing. The construction of the building, (Plate A), allows a man to reach the outlet of a tub on the next floor, with a short step up, and regulate the flow of a charge without the necessity of ascending to the upper floor to halt the charge at a critical moment. Solutions from the nitrite of soda tubs are run down through a i-inch, or larger, iron pipe connected in the bottom of the nitrite tub and running to a diazotization tub below. A valve is placed in the nitrite pipe close to the outlet from the tub; a second valve is placed at the discharging end of the pipe so that once the flow of nitrite solution has been started, it may be regulated at the diazotization tub. Main pipe lines for water and steam are located directly under the raised portion of the third floor; water pipes to the tubs should be of 2-inch size and the open ends should not run far down into the tubs, to avoid contact with acid solutions. For heating alkaline or neutral charges a 11%4-inch steam pipe, secured to the inside wall of the tub and running down to the bottom will give the desired temperatures by passing live steam directly into the solution. The iron steam pipes should be removable and have an elbow attached at the bottom to avoid shooting steam directly at the tub floor. For heating water to obtain a concentrated solution, the nitrite dissolving tubs are also equipped with iron steam pipes. For heating acid solutions, a 4-inch by 4-inch wooden pipe with an 1% bore is used to replace the iron steam pipe; the bottom of the wooden steam pipe should be plugged and exit for the steam made through %-inch holes bored in the sides of the pipe. Wooden pipes used for heating may split after a period and need to be replaced but in general they give satisfactory service. The wooden pipes are also in- stalled to conduct nitrite of soda or other solutions to the bottom of an acid charge, instead of using metal or composition pipes. All pipes used within the tubs should have flanking side boards as protection during agitation. 3 24 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES SS \ SS [ SA) SOS: QS IW, : @ i Ses RK sh q oe y X 4 = 2 lle 16 FX SSH | ELEVATOR || | SHAFT II | | HN NS * i 2S Pe iI Hi My ft 3RO MAIN FLOOR & OISSOLV/IVG TUBS & DIAZOTISAT/OVY TUBS (ST. MALY FLOOR & COUPLIIYG TUES 21ND. MA/IY FLOOR IK i | | ann Be | | f H i — TE NNN NNNONAAARRRARRAARARAARAS LSE Lae 4Afe2z 4AM 4A a : ‘ BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 25 A useful installation is that of a small water faucet at each tub, with a short length of hose attached, for rinsing down tubs after the contents have been discharged and for washing out tubs preparatory to use; in the latter case the washings may be run to the sewer through a 3-inch hose. Sewer holes on each floor should be not more than 15 feet apart and be protected by wooden gratings. For a supply of hot water for washing filter clothes and filter press plates a spare tub, 6 feet in diameter by 4 feet deep, may be located on the first floor in the shed extension, and connected with water and steam. A completed charge contains the dye as a precipitated solid suspended in many volumes of the mother liquor. Separation is . made by a filtration of either the vacuum or the pressure type. Vacuum or suction filtration is done in low wide tubs built from a stock similar to that of the coupling tubs. A standard size for filter tubs is 7 feet in diameter by 3 feet in depth. A set of planks, drilled with perforations, forms a partition or false bottom at 12 inches from the top, Fig. 12. The perfora- tions are Y%4 inch in diameter and spaced 2 inches apart. The surface of the planks is scored with a network of grooves con- necting the perforations, Fig. 13. To prepare a filter, a layer of burlap cloth is laid on the false bottom and a layer of heavy canvas superimposed, the two layers then drawn tight and secured in place by a flat stave nailed to the side of the tub, Fig. 14. The chamber under the false bottom is connected to a vacuum line by a pipe fitted into the side of the tub closely under the false bottom and provided with a valve and vacuum gauge. A bib-cock outlet for discharging the filtrate is fitted into the side, close to the true bottom, and a vent hole for the chamber is bored in the side and closed with a wooden spigot. A filter should be thoroughly wetted and soaked before using for the first time, and may then serve for a number of filtra- tions. ‘To make a filtration, the outlets of the vacuum chamber are left open and as much of the charge as possible is run onto the bed of the filter; the outlet and vent holes are then closed tightly and the vacuum line opened slowly. As filtration pro- 26 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES SHOWING FA WNA FO. VAS ewe SS WEAVE DASA=> DPV BYs =aSe' SS S38 TR RS See BS RS RS ANINN ISS | ISS RIN SPS ISS RS [See a > S45 SIN are RSS ISY bos SINR RY RY NES RIN RS SORES RRS RS STRSTR Be 3 ; 4 14 4 Ala 4 > ) a Re SS ewe mas Teva Sexevicne wees Tires, eeeises - 38.5 s, DETAIL OF FILTER TUB FITTUVES Fig. 14 a wool cloth should be substituted for the cotton; the cloth is to be inspected for holes before filtration. A state of vacuum up to 25 inches is indispensable for good work in the factory, for rapid filtration and a cake low in moisture. Individual dyes vary greatly but the speed of filtration can be judged from a test made in the laboratory by filtering a sample on a Buchner funnel. Suction filtration has the disadvantage that the coupling tub must serve as a reservoir for the charge during the hours of filtration, preventing use of the tub for preparing the next charge, as only a portion of a charge may be filtered at a time; very little gain can be made by forcing the filtration. Pressure filtration of azo dyes utilizes a series of wooden frames and plates held together in a horizontal screw press. A standard size for such frames and plates is 24 inches square by 2 inches thick. The press consists of two parallel steel bars 28 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES 30 inches apart, terminating at ends in fixed sections of steel, one of which acts as a base where the charge is fed into the press; at the opposite end a movable steel section, or head, rests between the bars by means of elbows and is moved by a screw held in the cross piece which unites the bars. The plates and frames also rest between the bars on elbows. ‘The plates are solid and have their two surfaces gouged with a set of close vertically parallel grooves which terminate at the top and bottom in a larger, horizontal groove which is connected to a channel bored through the plate to form a passageway to the exterior. FRAME PLATE Fig. 15 The plates are each covered with a layer of tightly stretched canves. On one side of the plates and frames a 2-inch hole is bored; when the press is made up and tightened, a plate alter- nating with a frame, the concentric 2-inch holes on the side form a channel through which the charge from the blow-case is forced ; the hollow part of the frames is in connection with this channel by means of a slot cut so that material is delivered to the hollow center of the frame where the solid remains while the liquor passes on through the canvas of the adjacent plate and follows the grooves and channel out through a spigot, for removal. The flow of liquor from the spigots diminishes and ceases as the press fills. The solid cake remaining in the press contains some liquor and may be further pressed out by blowing air through BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 29 Gi DIN7HD LSU UALIE thd XS Gi DT RAIO? WOILIE SOW FAWOD DLISIVOD Wee OOTY DSAFMOT : 8 Q ; Q 4 DMI THAD LSM HN LLE ME LTYS ol Sa Sweety WIT Fovsols Chey & OL AMALIA ek oe ek \ a en 2 SSS = SS LE Ex: a G4 = ss IN TA/OD j— = WO LASS Gs IM TSOP WO LSE PLISINOD- SOOTY TFSIMOF UM TA/OD ASHUVLIE FLTAINOD 2007, M/W LJ 0HS eOLATTIF [ penerc a MEG FH 30 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES the press, for which purpose a small channel is located in the upper part of the plates and frames, by a series of concentric 34-inch holes, connected with the air pressure line; this channel is also connected to a water line for washing a cake in the press or for wetting up a press to keep it tight when not in use for a period. To remove or “dump” the cake the air and feed valves are shut, the press unscrewed, the cake removed from the frames by hand with an iron scraper and the press closed up for further use. The cake falls into a trough below the press and is shoveled into barrels for delivery to the drying room. OVAZOTISATIONY TUBS LOWERED SIDE FLOOR, COMCRET PLATE C-2 PLATE C-3 212. FLOOR BRD. FLOOR Plate A shows the location of the filter presses in the side ex- tension of the first floor. The blow-cases are located in a pit between the presses and the main building. A blow-case is essentially a closed cylindrical vessel made from %-inch boiler steel, equipped with an agitator and connected to the air pres- sure line. The dimensions of a blow-case with capacity for hold- BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 31 ing about 1,500 gallons would be a diameter of 6 feet with a nominal height of 6 feet augmented by a convex top and bottom to a total height of 9 feet. To operate, an escape valve is opened and the agitator started; the outlet valve in the connection from the making tub to the blow-case is then opened and the charge transferred from the making tub to the blow-case; all valves are then closed and the air pressure applied, from 25 to 50 pounds pressure per square inch being required; when suf- ficient pressure is indicated, the outlet is opened in the pipe leading from the bottom center of the blow-case to the filter press, gradually until liquor begins to run from the press spigots, when the full stream may be allowed to flow into the press. Filtration of the dye is a slow procedure and frequently holds back production; for this reason it is sometimes necessary to make use of several presses for one charge; a series of connec- tions made between the different units, as shown in Fig. 16, per- mits use of several filters for one tub. = COUFLIIVG FILTER PRESSES i COUPLIYG CASE TUB Fig. 16 Upon completion of a filtration, a small quantity of water may be run from the making tub through the blow-case and press to prevent caking the dye in connecting pipes. The wash out valve in the connection between the making tub and the blow-case in 32 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Plate F may be used for emptying tubs without the necessity of passing the liquid through the blow-case. In a dye factory steam is ordinarily supplied from a central power plant of the factory; vacuum and compressed air may be supplied from a central plant or furnished by pumps located in the azo building. For forcing the charge through a filter press, individual pumps may replace the blow-cases, but are not en- tirely satisfactory, partly from the service which a blow-case gives as reservoir to hold the finished charge, leaving the making tub free for the next charge. Power for agitation is furnished from within; two 10 horse- power electric motors, one for each side of the building serve for agitation of both tubs and blow-cases. The motors can be located on the first floor, with belt drive to the main power shaft on that level, which in turn drives the main shaft for the two upper levels; each tub has individual belt drive from the main shaft and is furnished with fast and loose pulley. A gallery should be constructed within reach of each main shaft to allow access to the driving pulleys for repairs to belts and changing of pulleys, and for use when oiling the shaft bearings; the location of such galleries is indicated in Plate A. Power for other equipment, such as mixing apparatus, ice crusher, elevator and various small pumps, is furnished by individual motors. Mixing equipment is required for reducing pastes to uniformity; dyes sold as pastes are taken directly from the filter to the mixer and either diluted or strengthened in tinctorial power. This procedure is necessary, as the wet filter cake of each charge varies in content of the dye, however closely controlled the process of making may have been, and the marketed product must be of a uniformly standard strength. The mixer should be located in close vicinity to a filter to avoid carrying the paste; after mixing the paste is dumped into barrels for weighing and shipment. Intermediates received in the form of pastes, for use in making the dye, must be put through a mixer before a sample of the intermediate can be taken for analysis, as the paste dries unevenly in barrels and a true sample can be obtained only after mixing thoroughly; the mixer for this work should be located on the working floor of BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 33 the second level where such pastes find most of their use; to fill the mixer the barrels of paste received are taken to the third floor and the contents shoveled into the mixer on the floor below. Intermediates are used in paste form to eliminate the cost of the drying and grinding operations necessary to produce a powder; a paste is more easily dissolved than the corresponding powder, and the advantages attending the use of pastes over- come minor difficulties in their handling. A platform scale may be built into the first floor near the elevator for weighing stores received, especially for large pack- ages such as drums and barrels. Small movable scales with capacities up to 500 pounds are located on the three working floors for weighing out portions of the charges. During full production, over 50 tons of salt may be con- sumed in one month; the storage bin should be large enough to hold an adequate supply. Ice is to be received daily from an outside storage; artificial ice, containing no debris, is preferable to natural ice; the storage for ice within the making building should be large enough to accommodate a minimum amount of fifteen tons per diem. For conveying salt and ice to the tubs, carts may be constructed with capacities for holding accurately 500 pounds of each of these materials, eliminating the need for weighing each load; attention should be given to good construc- tion in the carts so that one man may handle a load without assistance. DRYING, MILLING AND. STANDARDIZING The most of the azo dyes are marketed in a powder form, hence the wet product of the making building must be dried and pulverized. Drying of any batch of dye consumes more time than does the work of coupling and filtering; a charge may be completely coupled in twenty-four hours and filtered within an- other twenty-four hours for each set of tubs and filters, but dry- ing for the same charge will require from four to eight days. Adequacy of facilities for drying permits of speed in production. 34 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES The mechanical character of the work of drying necessitates very little chemical control other than that to indicate the high- est temperature permissible for the various dyes. Drying is done in stoves or ovens containing the wet paste on pans or trays. Space for such ovens is usually allowed on the ground floor of a building. Plate D shows an arrangement of twelve ovens to be used in connection with the scale of operations described for a | ieee ss fSeremESTh pa | | | | | Hi || | | FLA Ht HL a Pof___ sb FROWT VIEW OF DRYUYC OVENS Fig. 17 the making of the dye. The construction of ovens suitable for this work is not restricted to any special style; generally they are box-shaped with brick or steel walls, the front side con- sisting mainly of steel doors, the other sides closed. The dimen- sions of the ovens indicated in Plate D would be 16 feet long by 6 feet wide and 7 feet high, each oven being divided into three compartments of about 4 feet width and each compart- ment divided into two sections, the sections to have shelves 3 inches apart on centers, to hold twenty-five pans in tiers; such an oven would accommodate one hundred and fifty pans. Pans for this style oven are 20 inches wide by 40 inches long and 1% inches in depth, of a steel of No. 20 gauge thickness. Heating is accomplished by means of a current of air which passes over coils of steam pipes contained in a special compartment at one end of the oven; a fan at an aperture in the opposite end causing the circulation; baffle walls constructed within the oven route the air current throughout to give contact to all the pans. In place BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 35 Nena eee A ee FLATE 2 of fixed section, use may be made of movable trucks for holding the pans. Such trucks may be withdrawn from the stove and loaded with pans or withdrawn to allow the pans to cool before handling, thus minimizing the time during which the doors must be kept open. Hydrochloride salts of basic azo dyes, such as Chrysoidine and Bismark Brown, cannot be dried on metal pans, wooden trays being substituted for these. 36 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES The wet paste received from the making building contains from 50 per cent to 60 per cent of moisture on the average; some pastes run as high as 70 per cent in moisture and others as low as 30 per cent, varying with the character of the filtration. The temperatures maintained in the ovens vary from 50° C., up to go° C., depending upon the susceptibility of the dye to decom- position from prolonged heating; some few dyes may not be dried as high as 50° C. Individual dyes vary in their behavior on drying; a Metanile Yellow paste containing much moisture will dissolve in its moisture if entered directly in a hot stove; this does no damage of itself but loss and nuisance can result from warped or unlevel pans and it is necessary to dry at a low temperature until most of the moisture has been driven off, when the full heat of the oven is necessary to obtain a product dry enough to grind. An Azo Rubin may be entered to a hot stove directly but has the peculiarity of forming rocky hard lumps which are difficult to break up and retard the drying. Treatment of the dye is simple in description. The paste is laid out in pans to a depth of about % inch; and entered in the oven; after several days’ drying the pans are withdrawn and the friable cake broken up and turned over by hand, this treatment being repeated several times during the drying; the extent of the drying can be observed by crumbling a specimen in the hands. The dried product is put into barrels for delivery to the milling department. The general run of azo colors is not considered explosive, more dangerous members of the class having become less used, but some azo dyes are known to ignite and burn with a smoldering flame during drying or milling; the Alizarine Yellows, R and GG, are often mixed with 3 per cent ammonium sulfate before enter- ing into the ovens, to prevent possible ignition. Milling procedure includes grinding of the dye to a powder and then mixing to uniformity after addition of salt or other ingredients; the same mill serves both for grinding and mixing. Mills of several sizes and types are in use, the principle employed being that of a revolving steel drum containing loose steel balls or other fragments of steel for abrasion and crumbling of the BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 37 dye. Mills are either cylindrical or spherical in shape; a cylin- drical mill 4 feet long and 3 feet in diameter serving for the amount of dye obtained from a one-molecule charge. The ar- rangement of mills on a floor above the oven room is shown in Plate EF. Large mills, of 8 feet length and 6 feet diameter are located on one side of the floor, for use in mixing together of several charges. Mills are loaded through openings fitted with manhole covers; for loading the larger mills, access is obtained from the third floor. Several hours’ time suffices for pulver- izing a well dried charge in a mill revolving sixty times per minute but mixing may require twenty hours. The materials used for diluting or “reducing” the dye include chiefly common salt and sodium sulfate; these materials must be dry and finely ground. In some cases aniline salt and the cheaper spirit soluble gums are used for mixing with the spirit soluble dyes. When a batch of dye has been thoroughly pulverized, a sample is tested for the tinctorial value by dyeing a small amount of yarn or other suitable material, and comparing the strength and shade produced with that of an equal weight of the standard dye applied under identical conditions; the strength of the standard dye is rated at 100 and the strength of the batch is reported in percentage equivalents; that is, the batch is ordinarily stronger than the standard and is rated as 60/100, 65/100, etc., in reference to the number of parts which are equivalent in strength to 100 parts of the standard. The weight of the batch being known, calculation can be made to determine the amount of salt to be mixed; the standardization is completed by gradu- ated addition of the salt and repeated dyeing tests. Common salt is mixed with direct dyes and dyes which are to be applied in a sulfuric acid bath, including the mordant dyes and acid dyes; also with basic azo dyes. Sodium sulfate is mixed with dyes which are to be applied in a bath acidified with acetic acid, such as the “sulfon” colors. A dyestuff may be marketed in several strengths, such as the “ordinary,” and the “concentrated,” with greater, or less, reduction in the milling. Certain of the “highly concentrated” wares consist of unreduced dye, the manufacture being directed. with a view to obtaining as —_ BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 39 pure a product as possible, with less regard for yield and cost in the production. Reduction of dyes is not considered adulter- ation or falsification but is an operation necessary for obtaining a consistently standard product, due to the fact that no two batches run to similar strengths as first prepared. Discrepancy in the strengths of dyes marketed for the same brand by differ- ent manufacturers comes from a difference in standards adopted, but the products of one factory can be expected to be in accord- ance with the standards announced by that factory. There is nothing, however, to prevent a purchaser from remilling and further reducing the dye for resale; the appearance of dye does not indicate the general extent to which reduction has been made, and only a laboratory test of each package can show the actual strength of the dye. MATERIALS Chemicals used in the manufacture of azo dyes are of two kinds, industrial chemicals and coal tar intermediates. The in- dustrial chemicals, inorganic bases, acids and salts, are of con- siderable bulk and their handling requires regard for convenience and saving of labor as well as for economy of materials. Fused caustic soda, the industrial sodium hydroxide, is marketed in thin sheet iron drums holding about 700 pounds of a grade containing 76 per cent of sodium oxide. For its use, cylindrical iron dissolving kettles 5 feet in diameter by 4 feet deep will hold the solution of 40° Bé. density made from 700 pounds of caustic soda; the proportions for such a solution are roughly two pints of water to one pound of caustic. A dissolv- ing kettle should have water connection and an iron steam pipe running down to the bottom to heat and agitate when dissolv- ing. The main dissolving kettle may be located on the third floor and connected by a 2-inch iron pipe with iron plug cock valve, to a similar kettle on the second floor; the solution made on the third floor can be run to storage and use on the second floor 4 40 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES while another solution is being made up and allowed to cool; a dissolving kettle must contain no liquid when the solid caustic is being thrown in. To make up a solution for factory use, a drum of the caustic soda is pounded on the seams with a sledge hammer, breaking up the caustic within and splitting the cover open. This requires about twenty minutes’ pounding; the workmen must wear goggles SUPPLY PIPE FRO PAI STORAGE STORAGE TANYA FOR VITRIOL CAUSTIC SODA | G = eerecaerprrerces— OURE (Clise; STORAGE Fig. 18 Fig. 19 when handling the solid caustic. The caustic is shoveled into the kettle and 1,000 pints of water run in, a mark being kept in the side to indicate the proper depth, about 17 inches from the bottom; steam is passed slowly through the mixture for an hour to agitate and the batch then allowed to stand until next day, occasionally stirring with an iron bar. The solution made is run down to the storage kettle on the second floor, the gravity taken at room temperature and dilution made to 40° Be. density for use; the connecting pipe between the kettles should be washed down to prevent caking. A 40° Bé. solution contains 35 per cent BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 4I of sodium hydroxide; 115 pounds of such solution contains a pound molecule or 40 pounds of too per cent sodium hydrox- ide and calculation of the proportion to be used in a charge is made on the basis of this figure. One drum of 700 pounds per diem should be sufficient for the needs of this factory during full production. For conveying caustic liquor from the storage kettle to the tubs where used, it is ladled out into an iron weigh- ing bucket large enough to hold a molecular weight, and trans- ferred to the tubs; a set of two-handled 25-gallon iron buckets may be used for this work; one man with a flat cart can handle 115 pounds of caustic liquor unassisted and avoid the splashing that accompanies the use of small pails. A set of similar-sized wooden buckets or half barrels can serve in the same way for handling pastes and salts. Soda ash is handled in bags of 200 and 300 pounds content, the grade used is a practically pure anhydrous sodium carbonate powder containing 58 per cent of sodium oxide; on long standing in damp weather the soda ash takes up moisture from the air and lowers in relative strength. Soda ash is mainly used for neutralizing the acid of the diazo in coupling; the molecule for factory use is taken as 106 pounds, the soda ash being neutralized only to the bicarbonate stage to avoid frothing in the charge. Large amounts of soda ash should be entered slowly into a charge as the powder hydrates immediately in cold water and may form a rocky mass in the tub, stopping agitation and very difficult to break up. Acetate of soda is used in some couplings instead of soda ash to neutralize the mineral acid. The technical crystalline material has three molecules of water present and 138 pounds is taken as a molecule. The material is very soluble and gives no trouble in use. Bicarbonate of soda is used for neutralization in a few special cases; the technical grade may be regarded as pure for factory use. Muriatic acid, the hydrochloric acid of industry, comes on the market in standard strengths of 28.14 per cent, 32.10 per cent and 35.39 per cent, or respectively of 18°, 20° and 22° Bé. density. A2 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES The 20° Bé. acid is used for azo work as it is ordinarily the cheapest, price figured on the net content of hydrogen chloride; 115 pounds of this acid is taken as a pound molecule for factory work. The manner in which muriatic acid is received at any one plant depends largely upon local circumstances; if tank cars are received, the acid is drawn off into standard carboys of uniformly 115 pounds net content. To avoid nuisance and injury from splashing, the carboys should be plugged with large well-fitting wooden stoppers; for short periods of handling these are better than the ordinary glass stoppers used. The average diazotization requires 300 pounds of muriatic acid; two carboys may be dumped directly into the tub, by in- verting the carboy and resting on the side of the tub with the help of a supporting bar laid across the tub; the remaining por- tion, or 70 pounds, is drawn from a carboy by means of a hard rubber band siphon, into an earthen-ware vessel and weighed. A carboy can be carried by two men using long sticks caught under the cleats nailed on the sides of carboy cases for that pur- pose; a better method is to use a flat cart capable of carrying several carboys. Carrying carboys on stevedore trucks result in damage to carboys and accidents; the dumping of a carboy on a block of wood to pour out the acid is undesirable for the same reasons. Sulfuric acid is used to some extent in azo work. A 66° Bé. oil of vitriol with 100 per cent content of hydrogen sulfate is the form sulfuric acid employed; 50 pounds of the vitriol is taken as one molecule for factory use. A heavy iron tank of one ton capacity may be used for storage for use in the azo building; the vitriol is drawn through an iron plug cock outlet, into iron buckets similar to those used for carrying caustic soda solution; the storage tank is connected by pipe line to the main vitriol tank outside the making building and supplied by means of air pres- sure. For most purposes sulfuric acid may be replaced by muriatic acid; vitriol added to solutions creates much heat, requiring extra loads of ice to bring the temperature down sufficiently, off- BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 43 setting economy derived from the difference in price of the two acids. In the case of persons splashed with vitriol, the vitriol should first be wiped off as completely as possible with cotton waste or cloth and the person then deluged with water from a hose or shower, but to use water without removing the vitriol only adds to the injury. Commercial 56 per cent acetic acid is used for some work and is received and stored in wooden barrels; the amounts required are drawn with a hand siphon pump into wooden buckets.’ The commercial material varies somewhat in its content of acetic acid and should be analyzed before use. Technical nitrite of soda, containing about 95 per cent of sodium nitrite is usually marketed in barrels of about 600 pounds content. The molecular weight is taken as 72 for factory pur- poses. For diazotization of a molecule of an amine, 72 pounds of the technical nitrite of soda is weighed into a bucket and trans- ferred to a nitrite dissolving tub, such as shown in Plate F, con- taining 200 pints of hot water or 300 pints of cold water, and the bucket carefully rinsed into the dissolving tub; solution is easily made in this proportion by stirring with a hand paddle; the solu- tion usually contains bits of wood and paper from the nitrite barrels and the tub outlet should be screened to prevent clogging. The coal tar intermediates for use as raw materials are of different forms, liquids, solids and pastes; they are smaller in bulk than the industrial chemicals and relatively more valuable. Liquid intermediates are of two kinds; those which are naturally liquid, and those which are water solutions. Aniline or “aniline oil,” dimethyl aniline, the toluidines and xylidines, are handled in steel drums holding about 700 pounds of each; the drums are stored in the vicinity of the tubs where used and the amounts required, such as 93 pounds of aniline oil, drawn with a hand siphon pump into a weighing bucket for transfer to the tub. Water solutions of the sodium salts of acid intermediates, such 44 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES as metanilic acid or the phenyl peri naphthylamine sulfonic acid, are used in factories where the intermediate has been manu- factured on the grounds and can be delivered to the azo build- ing while yet in solution, to avoid the expense of isolating the in- termediate. For concentrated solutions, large drums holding about 1,000 pounds may be used to transport the liquor, as in the case of metanilic acid, where 975 pounds of a 20 per cent solution of sodium metanilate would contain one molecule, or 195 pounds of the metanilate; to use the solution, a rotary hand pump is fitted into the bunghole and the contents pumped into a large weighing bucket for transfer to the tub. For solutions to be used in large amount, tanks may be installed in the storage space under the first floor, (Plate A), and filled from the inter- mediate factory through a pipe line or by dissolving a large batch of the intermediate in a tub in the azo building and running the solution down to storage; such storage tanks must have con- necting pipe lines for pumping the solution to the tub where used. For dilute solutions, of 3 per cent content or less, measure- ment is made by volume rather than by weight, filling a tub to a depth which corresponds to the volume required. Intermedi- ates very often handled in solution include meta phenylene diamine and acetyl para phenylene diamine, and many special cases; these intermediates are also handled as solids. Solids and pastes are transported in wooden barrels. The volumes occupied by intermediates in the paste or the powder forms are usually similar; the paste form has the disadvantage of extra weight for long transportation, but no dust nuisance accompanies its use in the factory. Some solid intermediates are to be had in the form of almost 100 per cent pure powders or crystals, such as sulfanilic, anthranilic, and salicylic acids, naph- thylamine, diphenylamine, and the nitro anilines, but in general the percentage composition of commercial intermediates varies with each lot produced and used; the materials used in the factory are seldom as pure as those met with in the laboratory, cost of purification on a large scale being prohibitive. Certain impurities, such as moisture and inorganic salts and acids, are not objectionable in intermediates used for azo dyes provided BUILDINGS, MAJOR EQUIPMENT AND OPERATION, MATERIALS 45 the true content of the intermediate is known, but insoluble salts such as calcium sulfate and carbonate are undesirable, and especially so are the organic compounds isomeric with the inter- mediate or similar to it in composition, as they make exact analytical determination difficult and tend to produce off shade in the finished dye. The molecular weight of an intermediate _ must always be stated to give significance to the percentage con- tent of a commercial product; metanilic acid has a molecular weight of 173 but is often sold with analysis based on the con- tent of sodium metanilate, molecular weight of 195; free “H” acid has a molecular weight of 319, but the commercial product is usually the monosodium salt with more or less water of crystal- lization and the percentage may be based on several molecular weights. The purity of materials such as sulfanilic acid, diphenylamine, the nitro anilines and the simpler sulfonic acids, can be readily determined with the technical methods of analysis, either by titrating a weighed sample against standard nitrite of soda solution, or by coupling with a standard solution of diazo benzene chloride, and by the physical tests. Difficulty is met in cases such as a mixture of ““R” and “G” salts, where the isomeric impurity would not be apparent from an ordinary coupling test. In the case of “H” acid, two possibilities of analysis are met, one of titrating its amino group with nitrite of soda solution, the other of coupling with a diazo solution; in a chemically pure “H” acid the two determinations should give results agreeing within the limits of error allowable for analytical procedure. For a paste, discrepancy between these two determinations would actually be greater than is apparent, that is, an “H” acid which analyzed 40 per cent for diazo value and 39 per cent for nitrite value, would be 100 per cent and 97.5 per cent if reduced to the dry basis, with an actual difference of 2.5 per cent in the determinations. Intermediate should be reanalyzed before use, as a routine of operation. CHAPDERMAY ' THE DIAZOTIZATION OF ANILINE AND MANUFACTURE OF ORANGE G In Chapter III and the subsequent chapters, methods for the manufacture of certain monoazo dyes are outlined. The system to be followed includes a standard practical method for the prepa- ration of each diazo, followed by directions for coupling the diazo with various components and treatment of the dye formed. Plate F illustrates the arrangement of equipment necessary for such industrial methods; Plate G is for assistance in calculating the quantities of solutions in tubs from the measurement of the depth. General details of operation have been taken up in Chap- ter II. Diazotization of Aniline.2— Aniline, C,H,N, Molecular Weight = 93. NH, NCI eee ert tS) Aniline Diazo benzene chloride Materials.— 93 lbs. aniline = 1 mol. 285 lbs. muriatic acid, 20° Bé. 2,000 lbs. ice tub No. 6 72 lbs. technical nitrite of soda 300 lbs. water tub No. 4 Method.—A tub 6 feet in diameter and 6 feet deep, fitted with agitator to turn at a speed of thirty revolutions per minute (tub No. 6, Plate F), is used for the diazotization. A nitrite of soda solution is made up in a tub 3 feet in diameter and 3 feet deep (tub No. 4, Plate F), by running in water to a 8’ This preparation is to be referred to as Diazo-1 when its use is directed in the subsequent pages. NOWLVAT TF TUNOLLITS SSOP) _ ZL Vi of ihidds Viti. Ah WEEE cde O79 2076 e O79 = 07640-// PA O79 9 9 ~O79 O78 ¢ OF «OS Ev2 -O7€ vO 23/ WLIAFTD = ASPLIWVWG DN SHIL SO SENOENGIMIG FOS Pe -LN09 WHYALIWMAS QWIGUNG || To. i NOLVASTIS TK TALIINO7T 48 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES depth of 7 inches, to give 300 pounds and dissolving 72 pounds of technical nitrite of soda. One thousand pounds of cracked ice is entered in tub No. 6; 93 pounds of aniline is entered on top of the ice and followed by 285 pounds of muriatic acid (2% mols.). The mixture stiffens at first but begins to liquefy immediately afterwards and the agitator is then carefully started. An additional 1,000 pounds of ice is now added and the nitrite of soda solution in tub No. 4 is started flowing down in a fine stream onto the surface of the agitating mixture in tub No. 6. The flow of the nitrite of soda solution is adjusted so as to take thirty minutes for its addition. The temperature must remain below 2° C., throughout the period of reaction, and will do so under the above conditions except possibly in the hot season when an extra amount of 500 pounds of ice may be required to cool. When all of the nitrite of soda solution has been added and the nitrite dissolving tub also rinsed down, agitation is continued for fifteen minutes, when the diazoti- zation can be considered complete and the solution ready for testing and use in a coupling. The agitation may be stopped, as an aid to maintaining the low temperature. The solution as prepared should have a volume equal to that of approximately 3,000 pounds of water, and should fill the diazotization tub to a depth of 20 inches; the temperature must not be allowed to exceed 5° C., before coupling. A distinctly mineral acid reaction should be obtained when a test is made with Congo Red paper, and a portion of the solution seen through a test-tube should be almost water white and should give the following reactions; a drop of the solution on starch potassium iodide paper should immediately show an intense blue color,* or, if no excess of, free nitrous acid is shown to be present by the above test, 10 cc. of the solution on addition of one drop of tenth normal nitrite of soda solution, should give the blue color- * Solutions containing commercial muriatic acid will gradually develop a blue color when tested on starch potassium iodide paper, even in the absence of free nitrous acid, but the effect is not pronounced, whereas that from free nitrous acid is distinct and immediate. DIAZOTIZATION OF ANILINE AND MANUFACTURE OF ORANGEG 49 ation when tested with starch potassium iodide paper, indicating complete utilization of the aniline; 5 cc. of the solution treated in a test-tube with 2 cc. of a Io per cent solution of sodium acetate should not give the yellowish color of the iminoazo com- pound. The tests should be made immediately and the use of the diazo in a coupling commenced within one hour from the time at which the diazotization was started. Observance of the conditions outlined above assures a small volume in the diazo solution. Aniline undergoes diazotization at a speed proportionate to the concentration of the mineral acid present and unnecessary dilution is to be avoided. The small volume is advantageous for ease in controlling the temperature and obtaining a good yield of the dye to be formed in the sub- sequent coupling operation. Preparation of this diazo should never be commenced until the component has been prepared and held in readiness for coupling. ORANGE G° Orange G is prepared by coupling diazotized aniline with the 2:6:8 naphthol disulfonic acid, or “G” salt, in alkaline solution. NasO, N,Cl EI) 9 ER aN | | be) {iat Na,CO, => NaSO,\/\/ oe irae ‘*G”’ salt Diazo-1 NaSO, N ==== a (to? EeNeHCO! NaCl Orange G Preparation of the Dye.— “G” Salt, C,,H,O,S,Na,, Molecular Weight = 348. 5 Also known as Fast Light Orange, Orange 2G, Crystal Orange, Patent Orange and by other special names. 50 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Materials.— 355 lbs. ““G” salt, 100 per cent 150 lbs. soda ash 2,500 lbs. water 500 lbs. ice tub No. 8 I Ib. mol. Diazo-1 tub No. 6 1,000 lbs. salt Method.—A tub 9 feet in diameter and 6 feet deep, fitted with an agitator to turn at a speed of thirty revolutions per minute (tub No. 8, Plate F), is used for preparing the component and coupling with the diazo. Two thousand five hundred pounds of water is run into tub No. 8, filling to a depth of 8 inches, and the agitator started. A quantity of “G” salt, in powder or paste form, containing 355 pounds of the 100 per cent material (1 mol. plus 2 per cent ex- cess), is entered and dissolved. The material should dissolve easily and the solution should be slightly alkaline; if there is difficulty in obtaining a solution, or if the reaction is acid, caustic soda solution should be added gradually and in small amounts until the reaction shown on Brilliant Yellow test paper indicates slight alkalinity. One hundred and fifty pounds of soda ash is then added and dissolved. ‘The component is now ready for coupling and may be allowed to agitate while Diazo-1 is being prepared as directed above. When the diazo is ready, 500 pounds of cracked ice is entered in tub No. 8, to bring the temperature down to 5° C.; the diazo solution is then run down from tub No. 6 in a moderate stream, the flow of the diazo solution being adjusted so as to complete the addition within forty-five minutes but not so fast as to cause excessive frothing in the coupling tub. As the diazo solution strikes the surface of the component, an orange red precipitate may be observed; most of the precipitate redissolves so that when the diazo has all been added and tub No. 6 rinsed down only a portion of the dye is out of solution. Agitation of the DIAZOTIZATION OF ANILINE AND MANUFACTURE OF ORANGE G 51 charge is continued for fifteen minutes and a test then made to ascertain the completeness of the coupling. The laboratory test upon a sample portion of the charge should show the presence of a slight excess of “G” salt, and absence of the diazo. One thousand pounds of common salt is then added to the charge and agitation continued for one hour to dissolve the salt and pre- cipitate the dye. The charge is tested in the laboratory for com- pleteness of the precipitation and then delivered to a blow-case for pressure filtration. The volume of the finished charge should not be greater than that of 6,000 pounds of water, sufficient to fill the coupling tub to a depth of about 18 inches; the precipitated dye is crystalline in character and has no abnormal bulk to swell the volume. The reaction should be very slightly alkaline, sufficient to slowly redden a Brilliant Yellow test paper in a manner similar to that of a solution of bicarbonate of soda. The laboratory test for presence of “G” salt in slight excess is made by spotting out a drop from a sample of the charge onto a pinch of salt on a piece of filter paper, allowing the liquor to seep away from the spot of dye; a drop of freshly prepared tenth normal diazo benzene chloride solution is streaked along the outer rim of the seepage and the juncture will show a thin red line if “G” salt is pres- ent. The presence of uncombined diazo is shown by spotting a drop of the sample and treating in the same way with a freshly prepared 2 per cent alkaline solution of ‘“H” acid; in this case a violet line shown at the juncture of the seepages would be positive indication for the presence of free diazo. If tests for both diazo and component are positive, the coupling reaction is incomplete. ‘The extent to which the dye has been precipitated by salt is tested by spotting a drop of the charge on filter paper and observing the degree to which the seepage is colored; if there is only slight streaking, or “bleeding,” the salting out may be considered complete, but experience is necessary for properly judging by this test. Filtration of Orange G is rapid and without points of special difficulty; a compact, firm cake is obtained. Because of the small bulk of the cake obtained from a one-molecule charge it 52 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES is best to use only ten of the frames (24 inches square) of a filter press, reversing the eleventh plate so as to block the feed to further frames. Filtration could be made by vacuum with equally satisfactory results, but for that purpose the diazo would need to be prepared on the third floor and the coupling made on the second floor, the finished charge being run to the suction filter shown on the raised center portion of the first floor (Plate F). Drying of this dye is comparatively rapid, only about 35 per cent of moisture being present in the cake; the initial tempera- ture used should be 60° C., and after twenty-four hours’ time the full heat of the oven may be allowed. Statement of the yield to be obtained depends upon the stand- ard of selling strength adopted. Considerable reduction is made in this dye for the market, a typical, strong selling standard be- ing that in which the marketed product contains one part of pure dye and one part of salt. The molecular weight of the dye compound is 452, that is, 452 pounds of pure dye constitutes the yield theoretically possible from a one-molecule charge; reduction with an equal weight of salt makes the theoretically possible yield of standard 904 pounds. With due regard for the purity of the “G” salts used and for exactness of the control in pre- paring the diazo, the yields to be averaged during a twelve months’ period of production depend upon the final volumes obtained in the charges and the completeness of the salting out process. Orange G is taken as a typical azo dye, presenting no variation from the general method of manufacture. It does not rank as one of the most important of the class; for the year of 1920, 120,874 pounds valued at $1.22 per pound were produced in the United States. During the same year 11,143 pounds were im- ported from Germany, the figure undoubtedly relating to a very highly concentrated ware for purpose of competitive sale and minimization of tariff charges.® Orange G is used for dyeing wool in acid bath, dyeing easily and level; the shade produced has excellent fastness to light, steaming and ammonia when applied to either new wool or car- 6 The figures of domestic production and import given above and later are from the United State Census of Dyes and Coal Tar Chemicals for 1919 and 1920. DIAZOTIZATION OF ANILINE AND MANUFACTURE OF ORANGEG 53 bonized wool. Silk, weighted or unweighted, is dyed with good fastness to light. When mixed silk and wool is dyed the silk results in a lighter shade than the wool. PLAte G.—DIMENSIONS AND CONTENTS OF CYLINDRICAL TUBS. When filled to When filled to _ 1 inch depth— s -——1 foot depth—— Bottom Volume Pounds Gallons Pounds Gallons Diameter, area in of of of of inside Sq. it. ene T: water water water water 2'0” 3.14 .262 16.3 1.96 196 23.5 gs 3.41 284 17.7 21% 213 25.5 2'Qh 3.69 .307 19.2 2.30 230 27.6 aa” 3.08 331 20.7 2.48 248 29.7 24" 4.28 350 22.2 2.67 267 32.0 25° 4.59 .382 23.8 2.86 286 34.3 25° 4.91 .409 25.5 3.06 306 36.7 oa 5.24 437 27.3 3.27 327 39.2 2'8” 5.50 465 29.1 3.48 348 41.8 2'9” 5.04 495 30.9 3-70 370 44.4 210" 6.30 525 32.8 3.04 304 46.1 eit” 6.68 557 34.8 4.17 417 50.0 3'0" 7.07 580 36.8 4.41 4AI 52.9 3/1” 7.47 .622 38.8 4.65 465 55.9 aia” 7.88 .656 41.0 4.91 491 58.9 ara 8.30 691 43.2 TF 517 62.1 a4" 8.73 fa7 45.4 5-44 545 65.3 3/5” 9.17 .764 47.7 5.72 572 68.6 3'6" 9.62 802 50.1 6.00 601 72.0 aie* 10.08 .840 52.5 6.29 630 75.4 4/8" 10.56 880 54.9 6.58 659 70.0 39” 11.05 .920 57.5 6.89 690 82.6 TIO" 11.54 .962 60.1 7.20 721 86.3 arr 12.05 1.004 62.7 7.51 752 90.1 40” 12.57 1.047 65.4 7.83 785 94.0 AT 13.10 1.091 68.1 8.16 818 08.0 4/2” 13.64 1.136 70.9 8.50 851 102.0 4'3” 14.19 1.182 73.8 8.84 886 106.1 44” 14.75 1.220 76.7 9.19 921 110.3 4'5” 15.32 1.277 79.7 9.55 957 114.6 46” 15.90 1.325 82.7 9.91 993 119.0 Pid 16.50 1.375 85.8 10.28 1030 123.4 4'8” 7ii1 1.425 89.0 10.66 1008 128.0 54 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES PLraté G.—DIMENSIONS AND CONTENTS oF CYLINDRICAL TuBs.—Continued. When filled to When filled to --——_——1 inch depth —_—_, -——1 foot depth——— Bottom Volume Pounds Gallons Pounds Gallons Diameter area in of of oO fa) inside Sqranc: cit t water water water water 4'9” 1772 1.477 92.2 11.05 1106 132.6 4/10” 18.35 1.529 92.5 11.43 1145 137.3 art 18.99 1.582 98.8 11.84 1185 142.0 oes 19.64 1.636 102.15 12.24 1226 146.9 eu 20.30 1.691 105.58 12.65 1267 151.8 5.2” 20.97 1.748 109.07 13.07 1309 156.8 ce 21.65 1.804 112.64 13.50 1352 161.9 iw ke 22.34 1.862 116.22 13.93 1395 167.1 Cae 23.04 1.920 119.88 14.37 1439 172.4 6.4 23.76 1.980 123.59 14.80 1483 1770 cotig 24.48 2.040 127.37 15.26 1528 183.1 5/8” 25 22 2.102 131.21 15.72 1575 188.7 Rites 25.07 2.164 135.09 16.19 1621 194.3 S104 26.73 2297 139.04 16.66 1669 199.9 Bri” 27.50 2.291 143.04 17.14 1716 205.7 60” 28.26 . 2.356 147.09 17.63 1765 211.5 wig oe 20.07 2.422 151.21 18.12 1814 217.4 O27 29.87 2.489 155.38 18.62 1865 223.4 O45 30.68 2.557 159.61 19.13 1915 220.5 6'4” 31.50 2.626 163.89 19.64 1967 235.7 G50 32.34 2.605 168.23 20.16 2019 241.9 6'6” 33.18 2.765 172.63 20.69 2071 248.2 iy = Ne saa ioe NaSO,;\ 4\/S0,;Na Amino Naphthol Red B Preparation of the Dye.— Preparation of the dye includes the acetylation of “H” acid to form the component. For a detailed method of acetylation reference is made to the preparation of Amino Naphthol Red G, in Chapter IV. 27 Azo Fuchsine B. DIAZOTIZATION OF ACETYL PARA PHENYLENE DIAMINE I2I Materials.— 348 Ibs. “H” acid disodium salt, 100 per cent 120 lbs. caustic soda solution, 40° Bé.. 750 lbs. water 500 lbs. ice 175 lbs. acetic anhydride, 100 per cent 150 lbs. soda ash tub No. 3 I lb. mol. Diazo-13 tub No. 5 250 lbs. soda ash 500 Ibs. salt 2,500 lbs. ice tub No. 7 Method.—The dimensions and locations of tubs No. 3, 5 and 7 for this preparation are according to Plate F. | A quantity of “H” acid paste or powder containing 348 pounds of the 100 per cent material, or one mol. plus 2 per cent excess, is to be acetylated in tub No. 3 and the acetylated mixture then neutralized by adding very carefully 150 pounds of soda ash. The solution of the component is then delivered to the large tub No. 7, for coupling, and 250 pounds of soda ash and 500 pounds of salt are added and the mixture agitated while Diazo-13 is being prepared in tub No. 5. When the diazo is prepared, 2,500 pounds of cracked ice is entered in tub No. 7 to insure a temperature very close to 0° C., for coupling. The diazo solution is then delivered onto the sur- face of the component in a stream adjusted so as to complete the addition in an hour; the charge must be watched for exces- sive frothing during the addition. Agitation is continued until the following day when the dye will be found almost entirely out of solution and a drop of the charge spotted out on a test filter paper will show almost no coloration in the seepage. The charge is delivered to a blow-case for pressure filtration. Dry- ing should be conducted at a low temperature, as for Amino Naphthol Red G. I22 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES The final volume of the charge should be that of about 15,000 pounds of water; the reaction should be alkaline to the bicar- bonate stage and the temperature should not have risen above 10° C., before filtration is commenced. Only a slight excess of the component be shown when a drop of the charge is spotted on filter paper and the rim of the seepage tested with diazo benzene. Coupling takes place only slowly; a low temperature is neces- sary to hold the diazo from decomposition as long as possible and to cause precipitation of the dye on formation. With a diazo solution cooled to 5° C., and a large proportion of ice in coupling, the dye is almost completely precipitated and filters well, yielding a filter cake with 65 per cent moisture. Difficulty in obtaining the yield is met if the final volume is more than 15,000 pounds for a molecule charge; salting is of little assist- ance for remedying a poorly controlled charge the character of the dye being such that salt added is not dissolved in the mother liquor but is included in the suspended dye, causing a low strength and dull shade in the product. If circumstances attend- ing the manufacture were such that Diazo-14 should be used in place of Diazo-13 for this preparation, the ease with which the volume and temperature could be controlled would be extremely favorable to the yield. The molecular weight of Amino Naphthol Red B is 566. The market wares of this dye are to be found greatly reduced, typical selling strengths being those which contain about 25 per cent of the pure dye and 75 per cent of salt; the occurrence of such a weakened standard may be attributed to the character of the factory product to be obtained with other than a systematized method of preparation. On the basis of the above mentioned reduction, a yield of 2,264 pounds of selling strength dye con- stitutes the yield theoretically possible from a molecule charge, and yields of over 2,000 pounds are met with in practice. At the prices prevailing in 1922 the total cost of materials consumed in a molecule charge may be stated at $460, which with a yield of 2,000 pounds and a manufaturing cost of 11 cents per pound brings the total cost of production to 34 cents per pound. The dye is applied to wool and silk in acid bath, the shade produced DIAZOTIZATION OF ACETYL PARA PHENYLENE DIAMINE 123 being fast to light but less satisfactory toward washing treat- ments. Production of the dye in the United States during 1920 amounted to 142,367 pounds, valued at $1.52 per pound. The price may be compared with the average selling price of $1.25 per pound in 1921 and the market quotations of from 75 cents to $1.00 per pound in 1922. AZO CORALLINE* Prepared by coupling diazotized acetyl para phenylene diamine with “R” salt in alkaline solution. N,Cl \/\OH ie | ie ae NaSO, \40,SNa MOA NHCOCH, ‘*R’? salt Diazo-13 N= NS OH | | NasUs Zs 7 Oo Na Leh NHEOCH? Azo Coralline Preparation of the Dye.— Materials.— . 355 lbs. “R” salt, 100 per cent 2,000 lbs. water tub No. 3 150 lbs. soda ash 1,000 lbs. ice tub No. 8 1 lb. mol. Diazo-13 tub No. 5 1,000 lbs. salt Method.—The location and dimensions of the tubs No. 3, 5 and 8 are according to Plate F. 22Azo Crimson L, Azo Grenadine Ll. I24 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Preparation of the component is made according to the direc- tions for its use in manufacture of Ponceau 2R, Chapter V, by dissolving 355 pounds of “R” salt, or one mol. plus 2 per cent excess, in 2,000 pounds of water in tub No. 3. The solution is allowed to cool by agitation until the following day, when it is delivered to tub No. 8 where 150 pounds of soda ash is added. Diazo-13 is prepared in tub No. 5. One thousand pounds of ice is entered in tub No. 8 with the component and the diazo is then delivered into tub No. 8 in as short a time as the frothing permits. Agitation is continued for four hours and the charge then tested to ascertain the completion of the coupling reaction. When a test shows the diazo to be completely utilized, steam is passed in to bring the temperature of the charge to 65° C., and precipitation then made by adding from 500 to 1,000 pounds of salt. The finished charge is delivered to a blow-case for pres- sure filtration. Drying should be conducted at a low temperature. The final volume of the charge is unimportant in this case as the dye is very little soluble under the conditions of its forma- tion. The dye precipitates in a form which filters poorly. Fil- tration is improved by heating to 65° C., to cause partial solution, and then precipitating with salt; heating to 85° C., gives still better filtration but if the high temperature is maintained long enough to bring about complete solution of the dye hydrolysis of the acetylamino group may set in, causing alteration in the shade of the product. An almost neutral condition is favorable to the filtration and lessens the possibility of decomposing the acetylamino group. At the best, a filter cake containing 70 per cent of moisture is obtained. “R” salt couplings filter poorly in general, varying somewhat with the grade of the intermediate used ; usually the dye precipitates in a fine, silty form and retards filtration by filling the interstices of the filter cloth; by employ- ing a pure grade of “R” salt, in the form of a Io per cent solu- tion filtered before use, the dye may be obtained in a more granular condition. “R” salt couplings usually precipitate com- pletely upon formation so that the filtration offers the chief difficulty in the production. DIAZOTIZATION OF ANTHRANILIC ACID 125 Azo Coralline is used on wool and silk in acid bath to give a crimson shade. The molecular weight of the dye compound is 509. As the selling strengths ordinarily contain about 30 per cent pure dye and 70 per cent salt, the yield of marketable dye theoretically possible from a molecule charge amounts to 1,696 pounds and a factory yield of over 1,500 pounds is to be expected. The statistics of the domestic production are not available. Diazotization of Anthranilic Acid.?°— Anthranilic Acid, C,H,O,N, Molecular Weight = 137. NH N, — O By @ CO Anthranilic acid Diazo benzoic acid anhydride Materials.— 137 lbs. anthranilic acid, 100 per cent = one mol. 120 lbs. caustic soda solution, 40° Bé. 72 \bs. nitrite of soda, technical 1,000 lbs. water tub No. 3 500 lbs. water 250 Ibs. muriatic acid, 20° Be. 1,000 lbs. ice tub No. 6 Method.—A tub 6 feet in diameter and 6 feet deep, fitted with an agitator to turn at a speed of thirty revolutions per minute, such as tub No. 6, Plate F, is used for the diazotization. The amine is to be dissolved in a small tub such as No. 3, Plate F. One thousand pounds of water is entered in tub No. 3, filling to a depth of 10 inches. One hundred and thirty-seven pounds of anthranilic acid, 100 per cent, is added and dissolved by ad- dition of caustic soda solution in small excess; solution should 29 Diazo-15. 126 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES occur immediately without heating ; 72 pounds of technical nitrite of soda is then entered and dissolved with the amine. For diazotization, 500 pounds of water is entered in tub No. 6 by filling to a depth of 3 inches. Two hundred and fifty pounds of muriatic acid, or two mols. plus 20 pounds, is added and followed by 500 pounds of ice. Agitation is commenced and the solution in tub No. 3 is delivered into the acid mixture in tub No. 6, taking thirty minutes for the addition; during diazoti- zation 500 pounds of ice is fed into tub No. 6. Diazotization is complete as soon as the solution in tub No. 3 has been discharged and the tub rinsed down. The diazo results in solution and, when prepared from a good grade of anthranilic acid, is almost white in color; small amounts of free nitrous acid and muriatic acid should be shown present by tests. Diazotization of anthranilic acid takes place rapidly and the diazo is fairly stable at ordinary temperatures; the temperature should not exceed 15° C., during diazotization, to avoid loss of nitrous acid through fuming. Preparation of the diazo by precipitating anthranilic acid in a finely divided state and leading in a solution of nitrite of soda gives results equally as satisfactory as the procedure outlined above; the method of dissolving the nitrite with the amine is practical and convenient, especially when the diazo results in solution. Another procedure, sometimes recommended, that of leading diluted acid into the cold alkaline solution of the amine and nitrite, is difficult to control; the acid must be entered very slowly and its handling is disagreeable; the sequence in which the chemical reactions take place in such a diazotization is not fixed but the conditions are very favorable to the formation of imino azo compounds. ACID ALIZARINE RED B” Prepared by coupling diazotized anthranilic acid with “R” salt in alkaline solution. 80 Palatine Chrome Red B, Pigment Scarlet 3B. DIAZOTIZATION OF ANTHRANILIC ACID 127 No ns ase ae eQ® OH COONa Baste ( NaSO, SO, tia NYY NaSO SO, RD **R”’ salt Diazo-15 Acid Alizarine Red B Preparation of the Dye.— Materials. — 355 lbs. “R” salt, 100 per cent, in the form of a 10 per cent solution 125 lbs. soda ash 500 Ibs. ice ; | tub No. 8 1 lb. mol. Diazo-15 tub No. 6 Method.—A tub 9g feet in diameter and 6 feet deep, with an agitator to turn at a speed of thirty revolutions per minute, such as tub No. 8, Plate F, is used for the coupling. A quantity of a filtered stock solution of “R” salt containing 355 pounds of the 100 per cent material, or one mol. plus 2 per cent excess, is entered in tub No. 8. For this purpose the exact percentage composition of the stock solution must be determined ; the solution is pumped from a storage tank, through a pipe termi- nating in a valve at the vicinity of the coupling tub, and measure- ment of the required quantity made by weighing in 100-pound lots. One hundred and twenty-five pounds of soda ash is entered with the “R” salt and allowed to dissolve while Diazo-15 is be- ing prepared in tub No. 6. When the diazo is prepared, the component is cooled by addi- tion of 500 pounds of ice and the diazo solution delivered into tub No. 8 in a stream adjusted so as to complete the addition in thirty minutes. Formation and precipitation of the dye follows immediately and as soon as the diazo has been added the charge may be tested to determine the completion of the coupling re- action and then delivered to a blow-case for pressure filtration. With an adequate air pressure filtration may be completed in 128 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES from fifty to seventy hours, yielding four standard pressfuls of firm cake containing about 60 per cent of moisture. The final volume of the charge is that of about 8,000 pounds of water. Very little dye is dissolved in the mother liquor at this volume and no salt is required to complete the precipitation. An excellent yield is obtained, varying only with the quality of the intermediates employed. For selling purposes the dye is only moderately reduced; typical market wares are to be found with from 30 to 40 per cent of salt. The dye is applied to wool in acid bath and then subjected to an after-chroming treatment ; the shade produced is highly fast to light. Because of its light fastness and insolubility in oils or spirit solvents, the dye is a valuable coloring for pigments. Production of this dye in the United States during 1920 amounted to a total of 67,817 pounds valued at an average price of $1.99 per pound. CHAPTER IX MONO AZO DYES PREPARED FROM ORTHO AMINO PHENOL DERIVATIVES. CHROME BROWN R, PERI WOOL BLACK AND PALATINE CHROME VIOLET Diazotization of Nitro Amino Phenol 4: 2: 1.32— Nitro Amino Phenol, C,H,O,N,, Molecular Weight = 154. OH O-- DN N, rai | nse by NO, NO Nitro amino phenol Diazo oxide of nitro benzene Materials. — 154 lbs. nitro amino phenol, 100 per cent = one mol. 2,000 lbs. water 1,000 lbs. ice 130 lbs. muriatic acid, 20° Bé. tub No. 2 72 |bs. nitrite of soda, technical 300 Ibs. water special container Method.—A tub 5 feet in diameter and 5 feet deep, fitted with _ an agitator to turn at a speed of thirty-five revolutions per min- ute, such as tub No. 2, Plate F, is to be used for preparation of the amine and for the diazotization. A solution of 72 pounds of nitrite of soda in 300 pounds of water is prepared in a barrel located on the deck of tub No. 2; a bottom outlet in the barrel permits discharge of the nitrite solution into tub No. 2 during diazotization. To prepare the amine, 2,000 pounds of water is entered in tub No. 2 by filling to a depth of 20 inches; a quantity of nitro amino phenol containing 154 pounds of the Ioo per cent material is added and steam is then passed in to heat the mixture to 60° C. 31 Diazo-16. 130 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES The material should dissolve upon agitation for thirty minutes at this temperature and the solution is then allowed to cool to 40° C., under agitation. One thousand pounds of ice is added, where- upon the temperature drops to 15° C., or below, and most of the nitro amino phenol precipitates in a finely divided form. One hundred and thirty pounds of muriatic acid, or slightly over one mol., is now added; diazotization is then made by delivering the nitrite of soda solution onto the surface of the agitating mixture in tub No. 2, taking thirty minutes for the addition. The nitrite of soda should be easily taken up and diazotization completed within fifteen minutes after the nitrite has been added. The diazo results as a suspension of yellow crystal and should be tested for presence of muriatic and nitrous acids in slight excess. Diazotization of nitro amino phenol 4:2:1 offers little diff- culty. The diazo is stable and a lowered temperature is desirable only to prevent loss of nitrous acid by fuming; at 5° C., or be- low, the nitrite is only slowly taken up but at 12° to 15° the diazotization goes on rapidly. One molecule of muriatic acid can suffice for the diazotization and the occurrence of secondary reactions need not be anticipated. The diazo is only moderately reactive but couples with some components to form dyes which are used on wool, with after-chroming, to produce the darker shades, such as greens, browns and blacks. CHROME BROWN R Prepared by coupling diazotized nitro amino phenol with: meta phenylene diamine sulfonic acid in neutral solution. O-- NH, OH NH, ¥: N, “a N=N © Bf Tr NH, NH, NO, SO,H NO, SO,Na Diazo-16 Phenylene diamine Chrome Brown R sulfonic acid 1:3:4 Preparation of the Dye.— Phenylene Diamine Sulfonic Acid, C,H,O,N,S, Molecular Weight = 188. MONO AZO DYES FROM ORTHO AMINO PHENOL DERIVATIVES I31 Materials.— 192 lbs. phenylene diamine sulfonic acid, 100 per cent 120 lbs. caustic soda solution, 40° Bé. 1,500 lbs. water tub No. 3 I Ib. mol. Diazo-16 tub No. 2 Method.—A tub 6 feet in diameter and 6 feet deep, such as No. 6, Plate F, fitted with an agitator to turn at a speed of forty revolutions per minute, is to be used for the coupling. The com- ponent is prepared in a tub such as No. 3, Plate F, and delivered to tub No. 6 for coupling. Filtration of the dye is made by vacuum, To prepare the component, 1,500 pounds of water is entered in tub No. 3 by filling to a depth of 15 inches; a quantity of meta phenylene diamine sulfonic acid containing 192 pounds of the 100 per cent material, or one mol. plus 2 per cent excess, is added and followed by sufficient caustic soda to neutralize the free acid; solution is obtained by agitating at 35° C., and any excess caustic soda present should be neutralized by addition of dilute acetic acid; the solution of the component is then deliv- ered to tub No. 6. Diazo-16 is to be prepared according to the directions previ- ously given; the final volume of the diazo suspenion should not be much greater than that of 3,500 pounds of water. Before coupling, the excess muriatic acid of the diazo is to be neutral- ized by addition of soda ash in small amounts but using no ex- cess. The diazo is then delivered into the solution of the com- ponent in tub No. 6 and allowed to couple until the following day, under agitation; the charge should then show absence of the diazo when a drop is spotted on filter paper and the rim of the seepage is tested with a drop of an alkaline beta naphthol solu- tion. The dye should be completely out of solution, in the form of dark brown particles; salting should be unnecessary with a final volume of about 5,000 pounds in the charge. The finished charge is delivered to a suction filter and filtered by vacuum. 132 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES When prepared from pure intermediates, it shows no tendency to ignite and can be dried at the full heat of the ovens. During the above coupling the reaction should be maintained neutral. An alkaline condition is to be avoided as in such case the dye is held partly in solution and salting is necessary to ob- tain the full yield. A charge which has been coupled in the neutral condition should however be made slightly alkaline, with soda ash, previous to filtration; this treatment does not affect the yield and is advantageous to the filtration and the shade of the dye. The molecular weight of Chrome Brown R is 375; standard selling strength for the “Extra” brands usually is based upon a mixture of two parts pure dye and one part salt. The dye is applied to wool in acid bath with after-chroming, to produce deep shades of brown. PERI WOOL BLACK Prepared by coupling diazotized nitro amino phenol with peri phenyl naphthylamine sulfonic acid in neutral solution. O-, (C,H,NHSO,Na N, N= N NHC,H, OE Oe 2 i: Na NO, Diazo-16 Phenyl peri salt ate nine Black Preparation of the Dye.— Phenyl Peri Sodium Salt, C,,H,,O,NSNa, Molecular Weight = 321. Materials.— 321 lbs. phenyl peri salt, 100 per cent in the fone of 6 per cent solution tub No. 6 1 lb. mol. Diazo-16 tub No. 2 MONO AZO DYES FROM ORTHO AMINO PHENOL DERIVATIVES 133 Method.—A tub 6 feet in diameter and 6 feet deep, such as tub No. 6, Plate F, fitted with an agitator to turn at a speed of forty revolutions per minute, is used for preparation of the com- ponent, and for the coupling; filtration of the dye is made by vacuum. Commercial phenyl naphthylamine sulfonic acid is obtained and used in the form of its solution, as isolation of this inter- mediate in the solid form is attended by too much difficulty to be practical. The technical solution produced generally contains from 10 to 15 per cent of the solid intermediate. For use in coupling a stock solution of phenyl naphthylamine sulfonic acid is to be stored in the azo building and as in the case of other stock solutions used similarly the required quantity is delivered to the vicinity of the coupling tub through a feed pipe and pump arrangement. Estimation of the true strength of a phenyl peri salt solution offers some difficulty. If an analysis is made by: titration with a standard solution of nitro diazo benzene, the figure obtained may represent impurities present as well as actual phenyl peri salt. The impurities do not couple with the weakly reactive diazo from nitro amino phenol, and can be discharged in filtration, leaving the dye uninjured, but in order to bring a proper pro- portion of phenyl peri salt into a coupling it is advisable to take an excess or at least 4 per cent over the amount shown by analysis. e To prepare the component a quantity of stock solution con- taining 321 pounds of the phenyl peri salt is weighed and, after entry in tub No. 6, is diluted to a strength of approximately 6 per cent. Any alkalinity in the component due to presence of soda ash should be neutralized with dilute acetic acid, using Brilliant Yellow test paper as indicator. Coupling is to be made at ordinary temperature and in neutral condition. Diazo-16 is prepared in tub No. 2 according to the directions given and the excess muriatic acid present is neutralized with soda ash. ‘The diazo is then delivered into the component in tub No. 6, taking one hour for the addition. Agitation is con- tinued until the day following, when a test made by spotting a 134 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES drop of the charge against an alkaline solution of beta naphthol should show absence of the diazo; a test for the presence of the component in excess is usually positive and of little significance. The dye should be practically all out of solution and no salting necessary. ‘The charge is made slightly alkaline with soda ash and then delivered to a suction filter tub; a practically quantita- tive yield is obtainable. When applied on wool with after-chrom- ing the dye produces a lustrous black. Diazotization of Amino Phenol Sulfonic Acid 2: 1: 4.3?— Amino Phenol Sulfonic Acid, C,H,O,NS, Molecular Weight = 189. OH O--5 NH, N, Oy ae SO,H SO,Na Amino phenol Diazo oxide of benzene sulfonic acid 1:2:4 sodium sulfonate Materials.— 189 lbs. amino phenol sulfonic acid, 100 per cent, = one mol. 120 Ibs. caustic soda solution, 40° Bé. 2,000 lbs. water 72 lbs. nitrite of soda, technical tub No. 2 150 Ibs. muriatic acid, 20° Bé. 500 lbs. ice 500 lbs. water tub No. 6 Method.—A tub 6 feet in diameter and 6 feet deep, such as No. 6, Plate F, fitted with an agitator to turn at a speed of forty revolutions per minute, is used for the diazotization. The amine is prepared in a tub such as No. 2, Plate F. To dissolve the amine, 2,000 pounds of water is entered in tub No. 2, filling to a depth of 20 inches. One hundred and eighty- 82 Diazo-17. MONO AZO DYES FROM ORTHO AMINO PHENOL DERIVATIVES 135 nine pounds of ortho amino phenol para sulfonic acid 100 per cent, corresponding to one mol., is added and followed by 120 pounds of caustic soda solution 40° Bé. density, or a quantity sufficient to make the mixture slightly alkaline to Brilliant Yellow paper. The mixture is agitated for a short time to effect solution and 72 pounds of technical nitrite of soda is then added and allowed to dissolve. For the diazotization, 500 pounds of water is entered in tub No. 6, filling to a depth of 3% inches, and followed by 500 pounds of cracked ice and 150 pounds of muriatic acid 20° Bé. Agitation is commenced and the solution of the amine and nitrite in tub No. 2 is delivered into tub No. 6 in a stream adjusted so as to accupy thirty minutes for the addition. Diazotization should be complete within thirty minutes after the addition. The diazo results in solution with final volume equal to that of about 3,500 pounds of water, and is stable towards most treatments. For coupling with beta naphthol the solution should be treated with sufficient soda ash to insure a neutral condition towards Congo Red test paper. PALATINE CHROME VIOLET Prepared by coupling diazotized amino phenol sulfonic acid with beta naphthol in alkaline solution. oes OH ez aa NaO/\/\ a ail eee a. oe va Wan Ve, ,Na SO,Na Nae Diazo-17 Sodium beta Palatine Chrome Violet naphtholate Preparation of the Dye.— Materials.— 147 lbs. beta naphthol, technical 120 lbs. caustic soda solution, 40° Bé. 1,000 Ibs. water tub No. 3 136 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES 1 lb. mol. Diazo-17 | tub No. 6 100 lbs. muriatic acid 500 lbs. salt Method.—Tub No. 6 is to be used for the coupling. The com- ponent is prepared in a tub such as No. 3, Plate F. One thousand pounds of water is entered in tub No. 3, filling to a depth of 10 inches, and followed by 147 pounds of beta naphthol and 120 pounds of caustic soda solution 40° Bé. Solu- tion is obtained by heating to 65° C. and agitating at that tempera- ture for thirty minutes; the solution is allowed to cool until the following day. When the component is prepared, Diazo-17 is prepared in tub No. 6 according to directions given. The solution of the com- ponent is started flowing into tub No. 6, taking one hour for the addition. The coupling is allowed to agitate for three hours and the excess alkalinity is then destroyed by adding slowly 100 pounds of muriatic acid. Agitation is continued until the follow- ing day, when the charge is salted out with 500 pounds of salt and delivered to a suction filter tub for filtration. - CHAPTER X MONO AZO DYES FROM ALPHA NAPHTHYLAMINE AND NAPHTHIONIC ACID Diazotization of Alpha Naphthylamine.*°— Alpha Naphthylamine, C,,H,N, Molecular Weight = 143. NH, N,Cl | ar | | Alpha naphthylamine Alpha diazo naphthalene chloride Materials.— 143 lbs. 150 lbs. 4,000 lbs. 150 lbs. 250 lbs. 4,500 lbs. 75, Ibs. 300 Ibs. alpha naphthylamine, 100 per cent, = one mol. muriatic acid, 20° Bé. water tub No. 3 oil of vitriol, 66° Bé ice special container ice tub No. 5 nitrite of soda, technical water tub No. 4 Method.—For the diazotization, a tub 8 feet in diameter and 6 feet deep, fitted with an agitator to turn at a speed of thirty revolutions per minute, such as tub No. 5, Plate F, is used. For dissolving the amine, a tub 5 feet in diameter and 5 feet deep, fitted with an agitator to turn at a speed of thirty revolutions per minute, such as tub No. 3, Plate F, located on the floor above tub No. 5, is used; the tub must be provided with a wooden steam pipe suitable for heating an acid mixture. The tub, No. 4, used for dissolving nitrite of soda should have a large outlet and a discharging pipe 2 inches in diameter for rapid delivery of the nitrite of soda solution during diazotization. A lead-lined 33 Diazo-19. 138 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES tub similar to that described for use in the manufacture of Metanile Yellow, is employed to contain a solution of sulfuric acid. In general the set of tubs used for preparing Diazo-19g is the same as for Diazo-7 and the set may be used alternately for each of these diazotizations. To prepare the amine, 4,000 pounds of water is entered in ‘tub No. 3 by filling to a depth of 40 inches. One hundred and fifty pounds of muriatic acid, or 1.3 mols. is added and followed by 143 pounds of technically pure alpha naphthylamine. Steam is passed in to bring the temperature to 70° C., and the mixture is agitated at that temperature for thirty minutes. The naphthyl- amine at first melts and later solidifies partially as contact with the acid goes on; complete solution is obtained by continued heat- ing. The hot solution of alpha naphthylamine hydrochloride is delivered into tub No. 5 as rapidly as the large outlet of the tub permits and allowed to cool in tub No. 5 with agitation, until the temperature has dropped to between 47° C. and 45° C. A solution of sulfuric acid is prepared in the lead-lined tub above No. 5, from 250 pounds of cracked ice and 150 pounds oil of vitriol, and held in readiness. The cooling of the naphthyl- amine hydrochloride solution in tub No. 5 takes about thirty minutes and care must be taken that the temperature does not drop to the point where precipitation of the hydrochloride com- mences. When the desired temperature has been reached, the sulfuric acid solution is delivered rapidly into tub No. 5 and the naphthylamine precipitates completely in the form of its white, crystalline, sulfate. The suspension is allowed to cool to about 30° C., by agitation. A solution of 75 pounds of technical nitrite of soda, or one mol. plus 3 pounds excess, is made in tub No. 4, using 300 pounds of water. For diazotization, the suspension of alpha naphthyl- amine sulfate in tub No. 5 is cooled to 0° C., by addition of 4,500 pounds of cracked ice, and the nitrite of soda solution is then de- livered into the agitating mixture in tub No. 5 by opening the valve in the nitrite delivery pipe so as to perform the addition in one and one-half minutes. The nitrite should be immediately absorbed and no red fumes noticeable. The naphthylamine sul- MONO AZO DYES FROM ALPHA NAPHTHYLAMINE 139 fate is quickly converted into the diazo and goes into solution. The diazo results as a strongly acid solution containing free nitrous acid in excess and, as the stability of the diazo is rela- tively low, its use in a coupling should be undertaken without delay. With the proportion of ice employed in the diazotization, the final temperature should not be much over 2° C., and the agitation may be halted finally as an aid in retaining the low temperature. The diazo solution should not have a greater volume than that of 10,000 pounds of water, filling the tub to a depth of 40 inches. Attempts to reduce the total volume by starting with less than 4,000 pounds of water to dissolve the naphthylamine hydro- chloride are usually followed with unsatisfactory results. One- pound molecule of alpha naphthylamine hydrochloride can be readily dissolved in 4,000 pounds of water at 70° C.; with any appreciable reduction of this volume difficulty is met in obtain- ing complete solution, followed by an undesired reprecipitation of the hydrochloride on slight cooling, in a dense form which is diazotized only on prolonged agitation with nitrite, during which formation of the insoluble imino azo compound can take place. A successful diazotization is to be obtained by careful manipu- lation of the naphthylamine hydrochloride solution until precipi- tation of the sulfate has been effected, when, with a rapid distri- bution of the nitrite solution under good agitation, a minimum formation of the imino azo compound may be had and filtration of the diazo, a difficult operation sometimes recommended is un- necessary. At the low temperature required for diazotization and with the dilution obtained, a large proportion of the less active sulfuric acid is of advantage for promoting the speed of the reaction. The diazo from alpha naphthylamine exhibits a degree of re- activity for coupling somewhat less intense than that shown by diazo benzene but in general Diazo-19 can be coupled with beta naphthol, Schaeffer’s Salt and other salts by following procedures similar to those directed for the coupling of Diazo-1 with the various components. I40 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES FAST RED B* Prepared by coupling diazotized alpha naphthylamine with “R” salt in alkaline solution. ie Gee i /\ /\OH eo NaSO, \/ VO,SNa VV NaSO,\V/ VO,SNa VV eR Salt Diazo-19 Fast Red B Preparation of the Dye.— Materials.— 355 lbs. “R” salt, 100 per cent, in the form of a Io per cent solution . 250 lbs. soda ash 1,000 lbs. ice tub No. 8 I lb. mol. Diazo-19 tub No. 5 1,000 lbs. salt Method.—Coupling is made in a tub g feet in diameter and 6 feet deep, such as tub No. 8, Plate F, fitted with an agitator to turn at a speed of thirty revolutions per minute and an iron steam pipe for heating the finished coupling prior to salting. Filtration is made by pressure and as the filtration of this dye is a difficult procedure, a good grade of “R” salt should be em- ployed, preferably in the form of a filtered 10 per cent stock solution. The necessary quantity of “R” salt solution is pumped from storage and, after analysis, is weighed into tub No. 8. Two hundred and fifty pounds of soda ash is entered and dissolved with the “R” salt solution, and Diazo-19 is then prepared in tub No. 5 as previously directed. For coupling, the component in tub No. 8 is cooled by addition of 1,000 pounds of ice and the diazo solution is delivered into 34 Bordeaux B, etc., Cerasine R, Rouge B, Azo Bordeaux. MONO AZO DYES FROM ALPHA NAPHTHYLAMINE I4I tub No. 8 as rapidly as the frothing will perimit; the addition in such a case can go on rapidly at first, slowing up gradually as the soda ash is converted into bicarbonate, after which stage frothing may become dangerous. The addition can be completed within two hours and the coupling is then allowed to agitate until a test shows completion of the reaction. The dye pre- cipitates completely, but in a poor condition for filtering, and to obtain a form which will filter, steam is passed into the charge and heating carried on to bring the dye completely into solution, a temperature of 85° C. sufficing for the purpose. From 5 per cent to 10 per cent of salt on the weight of the charge is re- quired to precipitate the dye at this temperature; the salt should be added to the hot solution and dissolved completely so that the minimum amount may be used. When precipitation is completed, the charge is delivered to a blow-case, or better, divided between two blow-cases, and filtered. The charge cools down before filtration is even partly completed and filtration usually drags out for a number of days, especially if the diazotization of alpha naphthylamine has not been entirely successful; the yield to be obtained is in accordance with the success attained in diazotiza- tion. A large amount of salt is included in the precipitated dye, so that a reduced factory product is obtained and the strength of the standard to be adopted for selling purposes must be weak in proportion to permit further reduction in the mill room. Standard market wares ordinarily contain over 60 per cent of salt. | For difficult filtrations where the blow-case and press system is not well adapted, such as in the case of Fast Red B, a system of filtration on a revolving suction drum has been recommended, with advantages from removal of the dye as soon as filtered and the feasibility of holding the charge in the making tub at a high temperature until filtration is completed. By reducing the time of filtration and improving the character of the product, such a filtration system can afford much improvement in azo work in ‘cases where filtration offers the greatest difficulty in preparation of the dye. § 142 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Diazotization of Naphthionic Acid.*°— Sodium Naphthionate, C,,H,O,NSNa, Molecular Weight = 245. NH, Naame ae, Koy ee | WA , a ON 1 eC | S0,H S08 Naphthionic acid © Anhydride of diazo naphthalene sulfonic acid Materials. — 490 lbs. sodium naphthionate, 100 per cent, = two mols. 150 lbs. nitrite of soda, technical 2,000 lbs. water tub No. 3 500 Ibs. water 805 lbs. muriatic acid, 20° Bé. 2,000 lbs. ice tub No. 6 Method.—For the diazotization, a tub 6 feet in diameter and 6 feet deep, such as tub No. 6, Plate F, is used and should have an agitator to turn at a speed of forty revolutions per minute. A small tub such as No. 3, Plate F, is used for preparation of the amine. Previous to coupling, the diazo is to be filtered, by vacuum. For preparation of the amine, 2,000 pounds of water is entered in tub No. 3, filling to a depth of 20 inches; a quantity of sodium naphthionate, powder, equivalent to 490 pounds of the 100 per cent material, is added and dissolved by agitating for thirty min- utes. Solution is obtained without heating; 150 pounds of tech- nical nitrite of soda, an excess over two molecules, is then added and allowed to dissolve with the naphthionate. For the diazotization, 500 pounds of water is entered in tub No. 6, filling to a depth of about 3 inches, and 805 pounds of muriatic acid, equivalent to a total of seven molecules, is added 85 Diazo-20, preparation of the diazo in charges of two-pound molecule size. MONO AZO DYES FROM NAPHTHIONIC ACID 143 and followed with 500 pounds of cracked ice. Agitation is com- menced and the naphthionate-nitrite solution in tub No. 3 is started flowing into the acid mixture in tub No. 6 in a stream adjusted so as to occupy one hour for the addition; after the first twenty minutes has elapsed, and one-third of the naphthionate solution has been delivered, the addition is halted while 500 pounds of ice is added to tub No. 6; the diazotization is then continued and another 500 pounds of ice is entered twenty min- utes later; when addition of the naphthionate has been completed, 500 pounds of ice is entered and the agitation continued for an hour to complete the reaction. The diazo results in suspension as a fairly thick paste. A test is made to determine the complete- ness of the conversion of naphthionic acid to diazo and the charge then delivered to a suction filter located on the first floor; after filtration, the cake is washed twice from a shower arranged over the filter tub and finally pressed out with a hand float. The diazo meal is removed from the filter by means of a wooden shovel and placed in barrels for transfer to the tub where used, where it is mixed with 2,500 pounds of water to form a paste. The volume of the diazo suspension in the above two-molecule charge is about that of 6,000 pounds of water before the filtra- tion. At this volume the thickness of the paste obtained neces- sitates strong agitation, otherwise portions of an naphthionic acid remain undiazotized from lack of contact. If the agitation avail- able is less vigorous than that obtained at forty revolutions per minute, in a tub such as No. 6, greater dilution with ice is neces- sary, else the thickness of the paste retards the reaction and a considerable amount of nitrous acid may be lost through fuming. With suitable agitation, a temperature of 10° C., is desirable to prevent loss of nitrous acid during the diazotization. Theoretic- ally only two molecules of muriatic acid should be required for the chemistry of diazotization of sodium naphthionate, as in the case of sodium sulfanilate, but for sodium naphthionate a larger proportion of acid, up to three and one-half mols., is generally employed to prevent occurrence of secondary reaction between 144. FACTORY PRACTICE IN MANUFACTURE OF AZO DYES the diazo and undiazotized naphthionic acid. The completion of diazotization is recognized by treating a 20 cc. sample of the charge in a beaker with 4o cc. of water and making the mixture alkaline with a Io per cent solution of sodium carbonate; the yellow color of the diazo may deepen but should not become red, as would be the case if undiazotized naphthionate were present to react with the diazo. The procedure of dissolving sodium nitrite with the amine and leading the solution into an acid mixture is the most suitable method for diazotizing naphthionic acid when a small final volume is desired. As the first portions of the naphthionate- nitrite solution enter the acid mixture, good distribution is ob- tained and a fairly rapid diazotization becomes possible; as the proportion of naphthionate increases, dilution with ice and the agitation described is sufficient to overcome the caking that occurs when naphthionic acid is precipitated in small volume. If the diazotization were to be conducted by first precipitating the naphthionic acid in tub No. 6 and then leading in a solution of sodium nitrate, the smallest volume at which the precipitation could be made to give a paste sufficiently thin to allow reaction with the nitrite would be 8,o00 pounds for the two-molecule charge; the final volume in such case would not be less than that of 10,000 pounds of water and the time required for diazotization would extend up to five hours. FAST BROWN N Prepared by coupling diazotized naphthionic acid with alpha naphthol in alkaline solution. OH pee HO YN=N SO,Na PC « ONS ue WR NE” | 80-4 Alpha naphthol = Diazo-20 Fast Brown N MONO AZO DYES FROM NAPHTHIONIC ACID 145 Preparation of the Dye.— Maiterials.— 288 lbs. alph naphthol, refined, = two mols. 240 lbs. caustic soda solution, 40° Bé. 25 lbs. soda ash 1,400 lbs. water tub No. 2 1,000 lbs. ice tub No. 6 2 lb. mol. Diazo-20 2,500 lbs. water tub No. 3 1,000 Ibs. salt Method.—For preparation of this dye, tubs with the locations and dimensions of No. 2, 3 and 6, Plate F, are to be used. Coup- ling is made in tub No. 6 and the filtration made by vacuum. To prepare the component, 1,400 pounds of water is entered in tub No. 2, filling to a depth of 14 inches. Two hundred and eighty-eight pounds of alpha naphthol, or two mols., is added and followed by 240 pounds of caustic soda solution of 40° Bé. density and 25 pounds of soda ash. Solution is made by heat- ing to 60° C., and maintaining the temperature for thirty minutes. The solution is then allowed to cool under agitation. The preparation of Diazo-20 commenced simultaneously with _ that of the component, and the diazo, after filtration, is entered in tub No. 3 with 2,500 pounds of water. The partially cooled solution of the component is delivered into tub No. 6 and the temperature brought below 15° C., by addition of 1,000 pounds of cracked ice. The diazo suspension in tub No. 3 is then deliv- ered into tub No. 6, taking one hour for the addition. The re- action of the coupling mixture should remain alkaline, and very little frothing should occur. Agitation of the charge is continued until a test shows the presence of either diazo or component in excess. Precipitation of the dye is then completed by gradu- ally adding salt until a spotting test is satisfactory and the charge then delivered to a suction filter tub on the first floor. 146 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES By use of the proportion stated above a slight excess of alpha naphthol should be present in the finished charge, as some diazo is lost in the filtration and transfer to tub No. 3. Excess of the component has less objectionable influence on the dye than an excess of the diazo. The dye is applied to wool in acid bath, producing a brown orange shade. Statistics as to production in 1920 are not available. FAST RED A* Prepared by coupling diazotized naphthionic acid with beta naphthol in alkaline solution. N.-7 N sseeeeaa ay A AOH AVEO RS \ OEY ia NE teh pire bid lysate od ok ba VV Vie VV VV | so,- SO,Na Beta naphthol Diazo-20 Fast Red A Preparation of the Dye.— Materials.— 294 lbs. beta naphthol, technical 240 lbs. caustic soda solution, 40° Bé. 25 lbs. soda ash 1,500 lbs. water tub No. 2 1,000 Ibs. ice 2 lb. mol. Diazo-20 2,500 lbs. water tub No. 3 1,000 lbs. salt Preparation of this dye follows the same course as that of Fast Brown N and a slight excess of the component should be present in the finished charge. 38 Rocelline. MONO AZO DYES FROM NAPHTHIONIC ACID 147 AZO RUBIN* Prepared by coupling diazotized naphthionic acid with the 1:4 naphthol sulfonic or Nevile-Winther acid, in alkaline solution. OH N.--7 OH /\/\ ihe | AWN N= oo>SO,Na Pere ee ieObe, veriagels liv] sia da VV eee VV SO,H So,- SO,Na Nevile- Diazo-20 Azo Rubin Winther acid Preparation of the Dye.— Nevile-Winther Acid, C,,H,O,S, Molecular Weight = 224. Materials.— 457 lbs. Nevile-Winther acid, 100 per cent 240 lbs. caustic soda solution, 40° Bé. 3,000 lbs. water 200 lbs. soda ash tub No. 2 2 lbs. mol. Diazo-20 2,500 lbs. water tub No. 6 1,500 lbs. ice 1,500 lbs. salt tub No. 8 Method.—Coupling is made in a tub such as No. 8, Plate F, and the dye is filtered by pressure. To prepare the component, 457 pounds of Nevile-Winther acid, 100 per cent, corresponding to two molecules plus 2 per cent ex- cess, is entered in tub No. 2 with 3,000 pounds of water and neutralized with caustic soda solution. Steam is passed in and solution made by heating at 4o° C. for thirty minutes; 200 pounds of soda ash is then added in tub No. 2 and completely dissolved. The solution is delivered to tub No. 8, on the first floor, and allowed to cool under agitation while Diazo-20 is being prepared i in tub No. 6. 37 Carmoisine, Azo Acid Fuchsine, Fast Red C, Brilliant Crimson. 148 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES For this coupling the filtered diazo is returned to tub No. 6 and mixed to a paste with 2,500 pounds of water. The tempera- ture of the component in tub No. 8 is brought below 15° C., by addition of 1,500 pounds of ice and the diazo suspension in tub No. 6 is then delivered into tub No. 8, taking thirty minutes for the addition. The coupling is agitated until the following day and precipitation is then completed by addition of 1,500 pounds of salt. The charge is delivered to a blow-case for pressure fil- tration. The final volume of the charge should not be greater than that of 7,000 pounds of water. A small volume is favorable to an easy and complete precipitation of the dye with less than 1,500 pounds of salt, whereby an almost quantitative yield is obtained. Filtration of the dye is a slow operation, proceeding at a rate slightly better than that of the average R salt combination; with a well restricted volume, filtration may be completed with one filter press in about fifty hours. The employment of a filtered diazo is not imperative for this coupling but with an unfiltered diazo the final volume of a two-molecule charge cannot be held under 10,000 pounds, whereby the difficulty of completely pre- cipitating the dye is increased and the time required by filtration extends up to one hundred hours, so that advantages from use of a filtered diazo compensate the extra work. The molecular weight of Azo Rubin is 502. As selling strengths ordinarily contain about 40 per cent pure dye and 60 per cent of salt, 2,510 pounds of market ware constitutes the yield theoretic- ally possible from a two-molecule charge. Production of the dye in the United States during 1920 totaled 470,949 pounds, valued at $1.43 per pound. CHAPTER XI MONO AZO DYES PREPARED FROM AMINO NAPHTHOL SUL- FONIC ACIDS. SALICINE BLACK U AND SULFON ACID BLUE R Diazotization of Amino Naphthol Sulfonic Acid, 1: 2: 4.38— 1:2:4 Acid, C,,H,O,NS, Molecular Weight = 2309. NH, N.-7 )" => \ SO,H SO,Na P20 4 Acid Diazo oxide of naphthalene sodium sulfonate Materials.— 1,195 lbs. 1:2:4 acid, 100 per cent, = five mols. 200 lbs. salt 15 lbs. blue vitriol 3,000 lbs. water 1,500 lbs. ice tub No. 5 365 lbs. nitrite of soda, technical 750 lbs. water tub No. I 3 Ibs. bisulfite of soda Method.—A tub 8 feet in diameter and 6 feet deep, fitted with an agitator to turn at a speed of thirty revolutions per minute, such as tub No. 5, Plate F, is used for the diazotization. To pre- pare the nitrite of soda solution, 750 pounds of water is entered in the small tub No. 1, Plate F, filling to a depth of 20 inches; the water is heated to 85° C., and 365 pounds of technical nitrite of soda, or five mols, plus 5 pounds excess, is added and dissolved by stirring with a paddle; the solution will have cooled to room temperature at the time of diazotization. 88 Diazo-21, preparation of the diazo in five-pound molecule quantity. 150 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Commercial amino naphthol sulfonic acid, 1:2:4, is obtain- able in a high degree of purity, and is handled as a powder con- taining over 92 per cent of the pure material, or as a 40 per cent paste. For the diazotization, a quantity of the intermediate equal to I,195 pounds of the 100 per cent material, either in paste or powder form, is entered in tub No. 5; water is then run in to a depth of 16 inches, to make a total of 3,000 pounds of water. The mixture is agitated until well mixed, and further prepared by addition of 200 pounds of salt and a solution of 15 pounds of blue vitriol dissolved in hot water. ‘The suspension is to be exactly neutralized to Congo Red test paper by addition of diluted caustic soda solution. ‘The temperature is then brought below 15° C. by addition of 500 pounds of cracked ice, and the nitrite of soda solution is started flowing slowly onto the surface of the sus- pension in tub No. 5. ‘The flow of the nitrite solution is adjusted so as to occupy two hours; diazotization goes on slowly and entry of the nitrite solution must be controlled in accordance with the consumption of the nitrous acid liberated. Additional ice, up to 1,000 pounds, is required during diazotization to maintain a temperature below 15° C. Agitation is continued for an hour after the nitrite has been added, when a sample of the diazo should dissolve completely upon dilution with water, and a por- tion acidulated with pure dilute hydrochloric acid should show presence of a slight excess of nitrous acid when tested with starch potassium iodide paper. Diazotization may then be considered complete and the excess nitrous acid destroyed by addition of a dilute, acidified solution of bisulfite of soda. The diazo results as a suspension of bronze crystals, and when once formed, is stable toward most treatments. | Under the conditions outlined above the diazotization may be expected to proceed smoothly and without irregularities. By a hurried introduction of the nitrite, or with inadequate agitation, nitrous acid may accumulate faster than it is consumed in diazo- ° tization; under such conditions the 1:2:4 acid may undergo oxidation, indicated by evolution of red fumes and a partial MONO AZO DYES FROM AMINO NAPHTHOL SULFONIC ACIDS I5I blackening of the charge; inefficient agitation is frequently ac- companied by such irregularity. SALICINE BLACK U*® Prepared by coupling diazotized amino naphthol sulfonic acid I:2:4 with beta naphthol in alkaline solution and precipitating the dye in neutral solution. Be oo OF ca pia Beta naphthol ae Bice U Preparation of the Dye.— Materials.— 735 lbs. beta naphthol, technical 600 lbs. caustic soda solution, 40° Bé. 4,000 Ibs. water tub No. 3 5 lb. mols. Diazo-21 1,000 Ibs. ice tub No. 5 500 lbs. muriatic acid, 20° Bé 500 lbs. water tub No. 2 _ Method.—The location and dimensions of tubs No. 2, 3 and 5, used in this preparation, are according to Plate F.. Coupling and precipitation of the dye is conducted in tub No. 5. Filtration is made by vacuum using a filter tub located on the first floor. In preparation of the component, 4,000 pounds of water is entered in tub No. 3, filling to a depth of 4o inches; 735 pounds of beta naphthol is added and followed by 600 pounds of caustic soda solution of 40° Bé. density. The solution obtained by agitating at 70° C. for thirty minutes is allowed to stand over night to cool to ordinary temperature. 39 Palatine Chrome Black 6B, Eriochrome Blue Black R, Acid Alizarine Black A, Diamond Blue Black EB, Anthracene Blue Black BE. Preparation of the dye in charges of five-molecule size. II 152 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Coupling: Diazo-21 is prepared in tub No. 5 according to directions given; the finished diazo is cooled to 5° C. by addition of 1,000 pounds of cracked ice. The solution of the component in tub No. 3 is then delivered into tub No. 5, under the surface of the diazo suspension. ‘The time taken for the addition should be extended through two hours; a too rapid entry of the naphthol frequently causes uncontrollable foaming. The coupling is agi- tated over night and on the following day is found as a dark blue solution. To precipitate the dye, 500 pounds of muriatic acid, or less than five mols., is diluted with an equal volume of water in tub No. 2, and the acid delivered very slowly into the coupling in tub No. 5, to exactly neutralize the alkalinity of the charge; during this treatment the dye precipitates completely. Excess acid over the amount required for neutralization is un- desirable and addition of the final portion should be made care- fully; it is preferable to leave reaction neutral than faintly acid to Congo Red test paper. The charge is delivered to a suction filter tub for filtration in portions, the filtration usually proceed- ing rapidly. Drying is best conducted at a temperature of 75° C. or below. The molecular weight of Salicine Black U is 416. A common standard for selling strength is that containing one part pure dye and one part salt; on the basis of such reduction the yield of marketable dye theoretically possible from a five-molecule charge amounts to about 4,160 pounds; yields of over 3,500 pounds are ordinarily had in practice. The dye is a highly important chrome color, for wool, production in the United States during 1920 amounting to 1,074,248 pounds, valued at $1.10 per pound. The preparation of Erio Chrome Blue Black B is similar to that of Salicine Black U, alpha naphthol replacing beta naphthol as component ; the coupling for Erio Chrome Blue Black B offers greater difficulty and is advisably conducted in charges of not over two-molecule size. Diazotization of “H” Acid.4°— “H” Acid Disodium Salt, C,,H,O,NS,Na, Molecular Weight = 363. 4 Diazo-22. MONO AZO DYES FROM AMINO NAPHTHOL SULFONIC ACIDS 153 NH, OH N,—O a. te AG 5 SONNE STONOIN 50,0 ““H”’ acid disodium salt Diazo oxide of naphthalene . disulfonic acid Materials.— 341 Ibs. ““H” acid disodium salt, 100 per cent, = one mol. 115 lbs. caustic soda solution, 40° Bé. 75 lbs. nitrite of soda, technical Soo lbs. water tub No. 2 250 lbs. muriatic acid, 20° Bé. 1,000 lbs. water 1,500 Ibs, ice tub No. 6 Method.—A tub 6 feet in diameter and 6 feet deep, fitted with an agitator to turn at a speed of forty revolutions per minute, such as tub No. 6, Plate F, is used for the diazotization. The amine is prepared in a tub such as No. 2, Plate F, by enter- ing 800 pounds of water and a quantity of the intermediate cor- responding to 341 pounds of the 100 per cent material, based on the molecular weight of the monosodium salt. As the commercial product is usually acid in composition, it must be neutralized with sufficient caustic soda solution to faintly redden a Brilliant Yellow test paper. Solution is obtained by agitating for thirty - minutes, and 75 pounds of technical nitrite of soda, or one mol. plus 5 per cent excess, is then added and dissolved with the Ci acic. For diazotization, 1,000 pounds of water is entered in tub No. 6; 250 pounds of muriatic acid, or two mols. plus 20 pounds ex- cess, is added and followed by 500 pounds of cracked ice. The solution of “H” acid in tub No. 2 is then delivered slowly onto the surface of the agitating mixture in tub No. 6; two hours’ time should be allowed for the addition; the desirable tempera- ture is between 10° and 15° C., and the temperature is main- tained by addition of up to 1,000 pounds of ice. Diazotization 154 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES goes on rapidly; the diazo forms as a bright yellow crystalline suspension; the difficulty of diazotization arises chiefly from the heaviness of the paste which is formed. Contact between the reacting materials may be improved by diluting the mixture with ice and water but in general strong agitation gives satisfactory results without increasing the volume. With agitation such as that obtained in tub No. 6 at forty revolutions per minute, and addition of the “H” acid solution in a fine stream, the operation may be completed within three hours’ time; a test portion of the diazo should then be completely soluble upon dilution with water ; the diazo is usually slightly acid to Congo Red paper and contains excess free nitrous acid. Diazotized “H” acid shows little tendency to decompose under the conditions obtained in the above method. A very low tem- perature is undesirable; under 2° C., diazotization proceeds slowly and fuming of nitrous acid occurs, while the undiazotized particles form granules which offer resistance to diazotization when the temperature finally rises. A certain amount of such granulation, or clotting, is to be met with by too hurried addition of the “H” acid solution. SULFON ACID BLUE R Prepared by coupling diazotized “H” acid with peri phenyl naphthylamine sulfonic acid in neutral solution. Preparation of the Dye.— C.H,NH SO,Na N,—O hike, naso\ A A, Pheny] peri salt Diazo-22 SO,Na Sulfon Acid BlueR ~%0sNa MONO AZO DYES FROM AMINO NAPHTHOL SULFONIC ACIDS 155 Materials.— 321 Ibs. phenyl peri salt, 100 per cent in the form of a solution 100 lbs. bicarbonate of soda tub No. 8 1 lb. mol. Diazo-22 tub No. 6 Method.—Coupling is made in a tub such as No. 8, Plate F. The dye is filtered by pressure. As in the preparation of Peri Wool Black, Chapter IX, the phenyl peri acid must be used in the form of a solution. A quantity of stock solution of the intermediate, containing 321 pounds of the 100 per cent material based on the molecular weight of the sodium salt, is entered in tub No. 8 and diluted with sufficient ice and water to bring the concentration to approx- imately 6 per cent of phenyl peri salt and the temperature to 12° C. Before coupling 100 pounds of bicarbonate of soda is added and dissolved in the solution of the component. Diazo-22 is prepared according to the directions given and de- livered ino the component in tub No. 8, taking two hours for the addition. The phenyl peri acid is easily thrown out of solution and addition of the diazo must be made slowly to allow neutrali- zation upon contact with the component. The coupling reaction proceeds quickly when no irregularity develops but a charge is customarily agitated over night for completion and on the day following is made slightly alkaline by addition of soda ash and then delivered to a blow-case for pressure filtration. The final volume of the charge should not be much greater than that of 10,000 pounds of water. The volume has important influence as the yield begins to drop off rapidly when the final volume of a molecule charge becomes greater than the figure above. A small amount of salt will precipitate the dye com- pletely from an abnormally large volume but in such case the shade and bloom of the product is injured. Filtration should proceed rapidly; poor filtration quality in a charge may be at- tributed to presence of phenyl peri acid precipitated during 156 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES coupling, as the precipitated material is not easily redissolved and has a gummy character. In general, the phenyl peri salt requires coupling in a fairly well diluted condition and at a temperature of 10° C. or above; to maintain neutrality during coupling, bi- carbonate of soda is preferable to the acetate; when the acetate is employed for coupling with an acid diazo the acetic acid formed must be neutralized by running in a solution of bicarbonate dur- ing addition of the diazo, or precipitation of the phenyl peri acid occurs; under good agitation, the frothing which results from neutralization with bicarbonate does not offer immoderate dif- ficulty in control. The molecular weight of Sulfon Acid Blue R is 695. The dye is reduced, by milling with sodium sulfate, to a selling strength which ordinarily corresponds to a mixture of one part pure dye and one part sodium sulfate, so that the yield theoretically pos- sible from a one-molecule charge amounts to about 1,690 pounds of market ware. Reduction is made with sodium sulfate to facilitate application of the dye in a bath weakly acidified with acetic acid; a fine blue shade is produced on wool. Ordinarily the yield may be held to a high average, the chief disadvantage to manufacture of the dye lying in the high cost of the phenyl peri salt. Production of the dye in the United States during 1920 amounted to 454,185 pounds, valued at $1.95 per pound. CHAPTER XII TETRAZOTIZATION OF BENZIDINE AND PREPARATION OF DIAMOND FLAVINE G, CHRYSAMINE G AND DIAMINE FAST RED C Tetrazotization of Benzidine.— Benzidine, C,,H,,.N,, Molecular Weight = 184, NH, N,Cl 9 ) as aS ts WV Sy NH, N,Cl Benzidine Tetrazo diphenyl dichloride Materials.— 184 lbs. benzidine base, 100 per cent, = one mol. 250 lbs. muriatic acid, 20° Bé. 2,000 lbs. water tub No. 2 230 lbs. muriatic acid, 20° Bé. - 1,500 lbs. ice tub No. 6 144 lbs. nitrite of soda, technical 400 lbs. water tub No. 4 3 lbs. bisulfite of soda Method.—The tetrazotization is to be conducted in a tub 6 feet in diameter and 6 feet deep, equipped with an agitator to turn at a speed of forty revolutions per minute, such as tub No. 6, Plate F. The diamine is first dissolved, on an upper floor, in a smaller tub, such as No. 2, Plate F. For holding the nitrite of soda solution, a small tub such as No. 4 is to be used; this tub must be equipped with the large 158 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES outlet and delivery pipe, of 14-inch size, described in the diazo- tization of the nitranilines and alpha naphthylamine, for very rapid discharge of the nitrite solution during the tetrazotization. To prepare the nitrite solution, 400 pounds of water is entered in tub No. 4 and heated to 70° C.; 144 pounds of technical nitrite of soda, or two mols., is added and dissolved by stirring with a paddle; the solution is held in readiness. To prepare the diamine, 2,000 pounds of water is entered in tub No. 2, filling to a depth of 20 inches, and followed by 250 pounds of muriatic acid. A quantity of benzidine base, either the paste or the dry form, containing 184 pounds of the 100 per cent material, is added; steam is passed in and the mixture is agitated at 75° C., for thirty minutes, at the end of which time a clear solution of benzidine hydrochloride should be obtained. This solution is delivered without delay to tub No. 6, and tub No. 2 should be rinsed down; after agitation for two hours in tub No. 6 the temperature will have dropped to about 40° C., at which point crystallization of the hydrochloride begins. The mixture is now cooled to 5° C., by addition of up to 1,500 pounds of ice, whereupon further precipitation of the hydrochloride takes place; 230 pounds of muriatic acid is now added, making a total of over four mols. present for the tetrazotization. Tetrazotization is made by opening the valve in the nitrite de- livery pipe leading from tub No. 4, so as to discharge the nitrite solution onto the surface of the agitating mixture in tub No. 6 in a stream which occupies about one and one-half minutes for completion. The nitrite should be rapidly taken up and no fuming should occur; the tetrazotization is considered complete within fifteen minutes after addition of the nitrite and the solu- tion of the tetrazo should be acid to Congo Red test paper and show presence of nitrous acid in excess. The excess nitrous acid should be destroyed by gradually adding small amounts of a 10 per cent solution of sodium bisulfite until a starch potassium iodide paper is left white when treated with a drop of the tetrazo. The final volume of the solution should be that of about 5,000 pounds of water, filling the tub to a depth of 33 inches; the tem- perature rises to about 12° C. When a pure quality of benzidine \ TETRAZOTIZATION OF BENZIDINE 159 is available tetrazotization can proceed smoothly in the presence of slightly over four molecules of muriatic acid, as with the pure material there is little tendency to form secondary compounds; when an impure benzidine is used, the impurities very often give rise to secondary compounds and a good tetrazotization is then made only in the presence of from five to six molecules of muri- atic acid. In the case when very low grades of benzidine are used, it is best to dissolve the one-molecule quantity of benzidine in a greater amount of water than 2,000 pounds and then filter the solution of the hydrochloride previous to tetrazotizing. DIAMOND FLAVINE G Prepared by coupling tetrazotized benzidine with one molecule of salicylic acid in alkaline solution with filtration of the coupling in acid condition and subsequently converting the unattacked diazonium group into hydroxyl. N,Cl OH NeaNeg > 30H Ne=N <2 0H - ae \ COONa \ COONa | | Vis Gear ry a: ne ras Sodium /\ /\ | | salicylate | | cet V/ \V/ Ws N,Cl N,Cl OH Tetrazotized Intermediate Diamond benzidine compound Flavine G Preparation of the Dye.— Materials.— 138 lbs. salicylic acid, technically pure 115 lbs. caustic soda solution, 40° Bé. 700 lbs. water 150 lbs. soda ash tub No. 3 1 lb. mol. tetrazotized benzidine 1,000 Ibs. ice tub No. 6 160 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES 300 Ibs. muriatic acid 1,500 lbs. ice 250 lbs. oil of vitriol, 66° Bé. tub No. 2 1,350 lbs. water 150 lbs. vitriol tub No. 5 6,000 lbs. water 120 lbs. caustic soda solution, 40° Bé. 25 lbs. soda ash 1,000 lbs. salt tub No. 6 Method.—The work of coupling is to be conducted in tub No. 6, Plate F, subsequent to the tetrazotization of benzidine in this tub. The solution of sodium salicylate used as component is prepared in a tub such as No. 3, Plate F, on the upper floor; a large tub, 8 feet in diameter and 6 feet deep, located on the second floor, is employed for conversion of the diazonium group, and should be provided with a wooden steam pipe for heating an acid mixture. Three filtration operations are required two of which are in the acid condition; for the first acid filtration, a wool-covered suction filter tub is employed, and for the second, using pressure, a lead-lined blow-case and wooden plate filter press. To prepare the component, 700 pounds of water is entered in tub No. 3, filling to a depth of 7 inches; 138 pounds of tech- nically pure salicylic acid is entered and dissolved by addition of 115 pounds of caustic soda solution of 40° Bé. density. No ex- cess Salicylic acid is desired and the amount directed is intended to furnish one pound molecule as closely as possible, without ex- cess. Solution is made by agitating for thirty minutes in the cold, and 150 pounds of soda ash is then added and allowed to dissolve completely by agitation. For the coupling, 184 pounds of benzidine is to be tetrazotized in tub No. 6 according to the directions given. Preparation of the tetrazo and component should be undertaken simultaneously. TETRAZOTIZATION OF BENZIDINE 161 The excess muriatic acid of the tetrazo is first neutralized by ad- dition of 10 pounds of soda ash, and the temperature is then brought to 5° C. by addition of 500 pounds of cracked ice. ‘The alkaline solution of salicylic acid in tub No. 3 is now delivered into the tetrazo in tub No. 6, taking thirty minutes for the addi- ion. The coupling reaction should be complete within 3 hours’ time; the temperature is maintained at 5° C. throughout, by ad- dition of further ice.** First Filtration: The finished coupling is acidified to test with Congo Red paper, by entering slowly sufficient muriatic acid ;*? the acid form of the coupling precipitates completely, and the charge is delivered to a suction filter tub and, after filtration, is thoroughly pressed out. The cake is removed from the filter bed, using a wooden shovel, and entered in barrels for transfer to tub No. 2 on the third floor; here it is entered in an acid mix- ture made from 1,500 pounds of ice and 250 pounds of oil of vitriol, and mixed to an even paste after adding sufficient water to bring the total volume to 3,000 pounds, or a depth of 30 inches in tub No. 2. Conversion: A solution of sulfuric acid is made in tub No. 5 by slowly entering 150 pounds of vitriol in 1,350 pounds of water; the heat of solution is utilized, and steam is also passed in to bring the temperature to 85° C. The acid suspension in tub No. 2 is then started flowing into the hot acid mixture in tub No. 5 and a temperature of 85° C. is maintained in tub No. 5 through- out the addition, which should be completed in two hours; heat- ing is continued until no further evolution of nitrogen is given, and no test for the diazonium group is shown by spotting a drop of the charge and testing with an alkaline beta naphthol solution. The charge is then allowed to cool under agitation, and finally delivered to a blow-case and filtered. Filtration is slow and takes a number of hours. Most of the acid is then washed out of the cake by running water through the press. For completion of the charge, 6,000 pounds of water is entered in tub No. 6, filling to a depth of 40 inches. The filtered charge 41 At this point, the charge may be carried on for preparation of Chrysamine G, as taken up later. 42 See preparation of Diamine Fast Red C. 162 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES is entered and stirred to an even paste. A solution of 120 pounds of caustic soda, 40° Bé., diluted in tub No. 3 with 250 pounds of water, is delivered slowly into tub No. 6, to neutralize the charge partially, and sufficient soda ash is then added in tub No. 6 to complete the neutralization and create a slightly alkaline condi- tion. Steam is then passed in to bring the temperature to 85° C. and the temperature maintained until the dye goes completely into solution; the hot solution is then salted out by addition of about 1,000 pounds of salt, and the hot charge is delivered to a cotton-covered suction filter tub and pressed out as much as pos- sible after filtration. Drying and milling are conducted as for other dyes. CHRYSAMINE G Prepared by coupling tetrazotized benzidine with two molecules of salicylic acid in alkaline solution. NGl OH N=N< >OH: Ne=Neee /\ 2 COONa é COONa ‘ COONa led | V Li San Sarees sig OH V Fay Sodium /\ ACOONaS fe | | Salicylate ha | | = | | V V V V Hiss N,Cl N,Cl N=N<_ >OH Tetrazotized Intermediate COONa benzidine compound Chrysamine G Preparation of the Dye.— Materials.— For the first coupling, see preparation of Diamond Flavine G. 150 lbs. salicylic acid, technical 120 lbs. caustic soda solution 40° Bé. 700 lbs. water 7 tub No. 3 120 lbs. caustic soda solution 40° Bé. 250 lbs. water tub No. 4 TETRAZOTIZATION OF BENZIDINE 163 Method.—The dye is to be prepared in a tub such as No. 6, Plate F, and filtration is to be made by pressure. The first coupling, of tetrazotized benzidine and one molecule of salicylic acid, is to be conducted according to the directions given for preparation of Diamond Flavine G, up to the point indicated for Chrysamine G. For the second coupling, a solution of 150 pounds of tech- nically pure salicylic acid in 700 pounds of water and 120 pounds of caustic soda solution, 40° Bé. density, is prepared in tub No. 3, and a solution of 120 pounds of caustic soda, 40° Bé. in 250 pounds of water is made up in tub No. 4. When the first coupling has been completed in tub No. 6, the second molecule of sodium salicylate is delivered from tub No. 3 into tub No. 6. Steam is passed in to warm the charge to 30° C., and the solution of caustic soda in tub No. 4 is delivered slowly into the charge, taking two hours for its addition. The charge is then delivered into tub No. 8 and allowed to agitate over night. On the following day the dye should be found completely out of solution, and the charge then delivered to a blow-case for pressure filtration. DIAMINE FAST RED C Prepared by coupling tetrazotized benzidine with one molecule of salicylic acid in alkaline solution, followed by coupling with the 2:8:6 amino naphthol sulfonic acid, or “Gamma Acid,” in a weakly acid solution. NN. OF 1s ANNE ES | SO,Na Diamine Fast Red C 164 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Preparation of the Dye.— Gamma Acid, C,,H,O,NS, Molecular Weight = 2309. Materials.— For the first coupling, see preparation of Diamond Flavine G. 250 lbs. gamma acid, 100 per cent 120 lbs. caustic soda solution 40° Bé. 2,500 Ibs. water tub No. 3 130 lbs. muriatic acid, 20° Bé. 250 lbs. acetate of soda crystals 300 lbs. soda ash 1,000 Ibs. water tub No. 8 1,000 Ibs. salt Method.—The dye is to be prepared in a tub such as No. 6, Plate F, and filtration is to be made by pressure. The first coupling, of tetrazotized benzidine and one molecule of salicylic acid, is to be conducted according to the directions given for the preparation of Diamond Flavine G, up to the point indicated for the Diamine Fast Red C. In preparation of the component for the second coupling, 2,500 pounds of water is entered in tub No. 3, filling to a depth of 25 inches, and followed by a quantity of gamma acid con- taining 250 pounds of the 100 per cent material, or one mol. plus 4 per cent excess; solution is obtained by agitating for thirty minutes with sufficient caustic soda solution to give an alkaline reaction; the gamma acid is then reprecipitated in a fine state of division by adding sufficient muriatic acid, about 130 pounds of 20° Bé. acid sufficing. The excess muriatic acid is then neu- tralized by addition of acetate of soda, the final condition of the component being that of a weakly acetic acid suspension. The first coupling for this dye, as prepared under the heading of Diamond Flavine G, consists of an acid condition of the diazo- benzidine-azo-salicylic compound in tub No. 6; 250 pounds of acetate of soda crystals are added to the first coupling and the TETRAZOTIZATION OF BENZIDINE 165 suspension of the component held in tub No. 3 is then delivered into tub No. 6 and the charge is agitated over night. To complete the charge in the alkaline condition, a solution of 300 pounds of soda ash in 1,000 pounds of water is prepared in tub No. 3 and delivered into tub No. 8 and the charge in tub No. 6 is delivered into tub No. 8; the addition must be made slowly to avoid frothing over. The charge should be definitely alkaline in reaction. Salt is added, up to 1,000 pounds, to com- pletely precipitate the dye and the charge is delivered to a blow- case for pressure filtration. CHAPTER XIII RELATION OF THE CHEMIST TO THE INDUSTRY. EXPERI- MENTAL WORK AND SMALL SCALE PRODUCTION In the manufacture of dyes and intermediates the number of professionally trained employees required to carry on the work forms a high percentage of the total help, as a result of the techni- cal and varied character of the work. The circumstance has been dwelt upon, in the educational advertising campaigns of dye manufacturers, that as a matter of experience rather than point of view a minimum ratio of one professionally trained chemist to ten operators is compatible with successful produc- tion. The chemistry of a factory process allows the possibility of varied results, similar to a laboratory experiment. While for the azo dyes the mechanical features of a process, such as the filtration, drying and milling, may be regulated and conducted in the factory by non-professional operators, the chemical nature of the “making” operation resists standardization to the extent that every factory charge is in degree an experiment whose course must be followed by a chemist as for a laboratory ex- periment. If any one dye were to be produced continually in amount it would seem practical to train operators for the routine process adopted and dispense with most of the personal control by the chemist. Standardization of processes in this manner is more prevalent in the manufacture of synthetic drugs, perfumes and toilet goods, where the output consists of a limited number of standard products put up in small package for retail consumption. In such industries the chemical production involves a relatively smaller percentage of the total employed, as one kettle or still or mixer furnishes sufficient stock daily to give employment to many persons in the work of finishing, that is, bottling, pack- ing and distributing. The chemical operations conducted are fully as technical as those of the dye industry, but the identity of the articles produced is seldom varied and constant repetition gives the process a mechanical rather than chemical character. RELATION OF THE CHEMIST TO THE INDUSTRY 167 The dye industry, especially in the case of azo dyes, is re- quired to manufacture a large number of products. ‘The dyes are numerous and the demand for each type fluctuates. To stock a full line of the different types is possible for only the largest firms. Packing and distribution is of smaller importance as the dye is usually put up in bulk, for industrial consumption. The work devolves practically on preparing the dye from valu- able raw materials whose properties can be estimated with diffi- culty by even the chemist. The chemical personnel finds occupation both in the laboratory and the factory. The factory chemist works as or with a fore- man to carry out processes similar to those described in the previous chapters. In the laboratory chemists are required for analysis and experimental work. The necessity for maintaining an analytical laboratory with at least one professionally trained chemist devoting full time to analysis is seldom questioned, but the extent to which a research or experimental department is de- veloped varies with the status of each concern. Some manufac- turers maintain a research department as a training school for factory chemists while others require the factory chemist to de- vote part time to the experimental work. Nevertheless the value of such industrial research is steadily becoming better known; it is a question chiefly of an investment to show returns by finding the way to more economical production and the develop- ment of new and better types of dye. An organized system for small scale experimentation on pro- cesses is very desirable when the adoption of new and untried methods is considered or when alterations are to be made for improvement of methods in use. Without such a system it is difficult to obtain exact information for properly working a method under the conditions of any one factory, and to proceed to manufacturing from written directions too often results in great waste to be permissible as a general procedure. The practicability of a new method, or idea, cannot be fully demon- strated by means of test experiments conducted in the ordinary chemical laboratory. The technique of such laboratory work involves experimentation with very small quantities of material, 12 168 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES usually on the 1/1oth-gram molecule scale, in glass or porcelain vessels cooled by an ice bath or heated with an open flame; ex- cellent filtration facilities are had with the Buchner suction funnel and the small amount of dye can be dried within twenty-four hours. The laboratory work is done by the chemist and derives all advantage possible from his observation and care and it is then possible to obtain excellent results with complex methods and difficult conditions. In the factory the work must be done with unskilled operators and, with the matter of profit imperative, the method which appears successful in the laboratory may often as not fall short of satisfaction, notwithstanding the super- vision by a chemist. Laboratory investigation is necessary and valuable as the first step in estimating the value of a process but the information afforded cannot be applied directly to factory routine charges for experimentation on a large scale. Experimentation must be considered from a more purely scientific standpoint than that held for production. It is some- times necessary to investigate conditions which are influencing a method adversely and in such cases while the information de- rived is valuable, it is obvious that the product of a charge con- ducted for such a purpose is of little value for selling purposes. In order to obtain data satisfactorily, after a method has been investigated on the 1/10th-gram molecule scale in the laboratory it must be possible to conduct experimentation on the smallest scale that simulates actual factory conditions. For this purpose a set of small-sized equipment should be available; installation of such equipment can be justified by the advantages obtained from its use in stabilizing factory procedure and by its use in production of small quantities of dyes less commonly required, for sale or use in shading of standard products. For the azo dyes, a suitable scale for experimental factory work is that which allows conducting of charges as small as the 1/1oth-pound mole- cule size, in small wooden tubs patterned after those used in ordinary factory work; cooling must be made by addition of ice and heating by steam passed directly into the charge as in the factory; filtration is most suitably made by vacuum in a small filter tub. Plate H illustrates the construction and arrangement RELATION OF THE CHEMIST TO THE INDUSTRY 169 searee as re Plot foria t= i —— "bdr TL Ope tele Wa : vata : 40 ELEVATION” 1929222 PLATE a 170 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES of three tubs and a suction filter, for use in an experimental out- fit to conform with the requirements of charges as small as 1/1oth-pound molecule. The tubs are advisably constructed from 2-inch stock, tub A to be 2 feet in diameter and 2 feet deep, tub B 3 feet by 3 feet and tub C 4 feet by 4 feet, with agitators in B and C to turn at a speed of forty revolutions per minute, and in A at thirty revolutions per minute. For heating materials in the largest tub, C, where most of the couplings of the experi- mentation are made, a permanent wooden steam pipe should be in- stalled similar to the use in the factory; for tubs A and B a removy- able brass or lead pipe with steam connection will serve; fixed water connections to the tubs are unnecessary as water can be entered by means of a small hose. Ice is to be carried up to the tubs in buckets. For diazotization of small charges, nitrite of soda may be dissolved in a bucket and delivered under the sur- face of the charge through a large wooden funnel held by hand; for some charges the diazotization may be conducted in tub C and tub A used for dissolving the nitrite. Transfer of contents between tubs is made through a 3-inch rubber hose. The filter tub is elevated from the floor to allow access with buckets at the bottom outlet when it is desired to recover a filtrate, and the location of the filter tub is made with a view to allowing the contents of any of the tubs to be discharged into it through a large hose. With care in operation, a single set of three tubs and filter such as described above will permit preparation of almost any azo dye in; a maaner; which sreproduces.the essentials of a large scale: factory process; ut due to’ the- ‘difficult 4y Gf washing out the colors completely one set of tubs should be available for the dark colors and: another set for the. light colors. Practical points to be observed in the éxperimental work include approximation of the time required to bring about solution of materials, com- pletion of reactions, the sequence to be followed in transferring mixtures between tubs, the efficacy of the agitation and the ex- tent to which volumes increase. It is not necessary that the plan of the experimental outfit be carried out to an extent which RELATION OF THE CHEMIST TO THE INDUSTRY I7I duplicates each detail of factory equipment; for the more ex- tended work, such as that of the disazo and trisazo dyes, with only three tubs available it may be necessary to use one tub for several stages of the charge, in which case the contents of a lower tub may be transferred to an upper by means of buckets, to leave the lower tub free for the next step. The quantity of material which can be produced in an experi- mental outfit of the size described will vary from 50 to 250 pounds of standard ware. Operation cost on the amount pre- pared is often high enough to overcome profit and for actual production purposes the set is best used in the cases of the higher priced dyes which are less conveniently prepared in the larger tubs of the factory. A dye such as Orange I could be prepared in one-half molecule quantity in the small set more satisfactorily than on the molecule scale recommended for the factory pro- duction. The following outline may be used to illustrate the general course taken in experimental work. The preparation of Helian- thin, or Orange III, is given in Chapter VIII, based on the principle of dissolving the component, or dimethyl aniline, in the excess acid of the diazo, diazo benzene sulfonate, the coupling reaction being completed by neutralization. An alternative method, of Moehlau and Bucherer,** is as follows: Twenty-one grams of sulfanilic acid is mixed with 12 grams of dimethyl aniline and 100 cc. of water; a clear solution should -result; 6.9 grams of sodium nitrite dissolved in 50 cc. of water is added; gradually the mixture becomes yellow and deposits gold yellow crystals of Helianthin. The yield is almost quanti- tative. An explanation of the chemistry of the reaction involved in this method may be based upon the hydrolysis of the salt of dimethyl aniline and sulfanilic acid. The sulfanilic acid re- generated reacts with sodium nitrite to form nitrous acid and diazotization ensues, followed progressively by coupling of the diazo and dimethyl aniline. 438 Farbenchemisches Praktikum, (1908), 135. 172 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES NH, NH, 5-020 SO,H N(CH,), SO, — N(CH,), N= fo + NaNO,=> | | | =| +2H,0 i ee In so far as is apparent from its statement the method offers features of excellence, including the great desiderata of sim- plicity in operation and favorable yield. Cost of material con- sumed is at a minimum as only those chemicals are used which of themselves form a part of the product and no icing or salt is necessary. The employment of such a method should be con- sidered when it is desired to manufacture Helianthin. The directions given form sufficient basis for a laboratory ex- periment on the 1/10-gram molecule scale, using 6.9 grams of pure sodium nitrite. The 21-gram quantity of sulfanilic acid directed may be considered as referring to the pure crystalline material with two molecules of water of crystallization and a molecular weight of 207; in an experiment conducted for com- mercial purposes this quantity would need to be adjusted pro- portionately for employment of the commercial sulfanilic acid with a molecular weight of 173, and in general the commercial grades of materials must be employed if the results of the ex- periment are to have value for manufacturing. Laboratory experiments conducted with a view to demonstrat- ing the adaptability of this method should evolve information on the following points: the feasibility of dissolving 1/10-gram molecule quantities of sulfanilic acid and dimethyl aniline in the 100 cc. quantity of water; the manner suitable for introducing the nitrite of soda, whether the solid material may be added directly to the reaction mixture or whether a solution of the nitrite may be added rapidly or allowed to flow in slowly; the in- RELATION OF THE CHEMIST TO THE INDUSTRY 1735 fluence of the volume and agitation and the range of temperature during the reaction; the completeness of precipitation of the dye without salting. It would also be desirable to note whether the nitrous acid formed for diazotization had effect upon the dimethyl aniline present. Several laboratory tests may be conducted simultaneously and from the results of these first hand evidence as to the practicability of the chemical features of the method may be had quickly and at small cost. From the data obtained by laboratory experimentation proportions for a small trial charge may be calculated, and in this instance the experimental plant described earlier in the chapter affords equipment for con- ducting charges of any fraction of a pound molecule size. The following outlines, Methyl Red and Butter Yellow, are given to illustrate use of the experimental set in small scale pro- duction. METHYL RED Prepared by coupling diazotized anthranilic acid with dimethyl aniline. Materials.—For one-fourth-pound molecule charge. 35 lbs. anthranilic acid, 100 per cent 30 Ibs. caustic soda solution, 40° Bé. 19 Ibs. nitrite of soda, technical 250 Ibs. water tub B 150 lbs. water 250 lbs. ice 100 Ibs. muriatic acid, 20° Bé. | tub C | 70 lbs. acetate of soda crystals 150 lbs. water tub A 2 lbs. bisulfite of soda ' 20 lbs. dimethyl aniline 174 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES Method.—The diazotization of anthranilic acid for this prepa- ration follows the method outlined in Chapter VIII in connection with the preparation of Acid Alizarine Red B. Two hundred and fifty pounds of water is entered in tub B, filling to a depth of 7 inches; 35 pounds of pure anthranilic acid is added and followed by 30 pounds of caustic soda solution 40° Bé. density. Solution of the amine is obtained by agitating for fifteen minutes and 19 pounds of technical nitrite of soda is then added and allowed to dissolve with the amine. For the diazotization a cooling, acid, mixture is prepared in tub C by entering water to a depth of 2% inches, followed by 250 pounds of ice and 100 pounds of muriatic acid 20° Bé. density. Agitation is commenced in tub C as soon as the mix- ture melts sufficiently and the sodium anthranilate-nitrite solu- tion in tub B is then delivered into tub C through a 3-inch hose, taking thirty minutes for the addition. Diazotization should be complete as soon as the addition has been made; the diazo re- sults in solution; the excess nitrous acid present should be de- stroyed by carefully adding portions of a Io per cent sodium bisulfite solution until no further test for nitrous acid is shown; this treatment is necessary to prevent formation of nitroso dimethyl aniline in small amounts. When the diazo has been prepared, 30 pounds of dimethyl an- iline, corresponding to slightly less than one-fourth-pound mol- ecule, is entered in tub C and allowed to dissolve with the diazo; the mixture is to be agitated for thirty minutes. A solution of ace- tate of soda, previously prepared by entering water to a depth of 10 inches in tub A and dissolving 70 pounds of the crystalline acetate, is delivered into tub C in a stream adjusted so as to occupy two hours for the addition; the dye gradually precipitates as a bluish red material. The charge is allowed to agitate over night and on the following day excess diazo should be shown present by the spotting test; no odor of dimethyl aniline should be noticeable. The final volume is about that of 1,000 pounds of water, filling the tub to a depth of 17 inches. The charge filters well and the yield obtainable with the method is practically quantitative. To obtain a pure grade product, for use as indi- RELATION OF THE CHEMIST TO THE INDUSTRY 175 cator, the dye is not dried, but after filtering and pressing out thoroughly is purified on a laboratory scale by recrystallizing from six parts of glacial acetic acid and finally drying at ordinary temperature. BUTTER YELLOW Prepared by coupling diazotized aniline with dimethyl] aniline. Materials.—For one-half-pound molecule charge. 47 lbs. aniline oil 180 lbs. muriatic acid, 20° Bé. 1,000 lbs. ice tub C 37 lbs. nitrite of soda, technical 150 lbs. water tub A 150 Ibs. acetate of soda 300 Ibs. water tub B 2 Ibs. bisulfite of soda 60 lbs. dimethyl aniline Method.—The diazotization of aniline for this preparation follows the method outline in Chapter ITI. A nitrite of soda solution is prepared in tub A, by entering 150 pounds of water, filling to a depth of Io inches, and dis- solving 37 pounds of technical nitrite of soda. Five hundred pounds of cracked ice is then entered in tub C and followed by 180 pounds of muriatic acid 20° density and 47 pounds of aniline oil; a small amount of water is added to loosen the mix- ture and the agitator is then carefully started. The nitrite of soda solution is then delivered onto the surface of the agitating mixture in tub C, taking thirty minutes for the addition and holding the temperature below 2° C., by addition of 500 pounds of ice. Diazotization is finished and tested according to the directions given in the method of Chapter III, and the excess nitrous acid is to be destroyed by adding sufficient 10 per cent bisulfite of soda solution. 176 FACTORY PRACTICE IN MANUFACTURE OF AZO DYES When the diazotization has been completed, 60 pounds of dimethyl aniline, or slightly less than one-half-pound molecule, is entered in tub C and allowed to dissolve in the excess acid of the diazo. The solution is agitated for thirty minutes. A solution of acetate of soda, previously prepared in tub B by entering 300 pounds of water, filling to a depth of 8 inches, and dissolv- ing 150 pounds of the crystalline acetate, is now delivered into the coupling in tub C, taking two hours for the addition. The mixture is allowed to agitate over night and the dye precipitates completely. The final volume of the charge is about that of 1,750 pounds of water, filling the tub to a depth of 27 inches. The crude product may be purified by recrystallization from ten parts of alcohol, and dried at a low temperature. — SCIENTIFIC BOOKS PUBLISHED BY The Chemical Publishing Company, Easton, Penna. ARNDT-KATZ—A Popular Treatise on the Colloids in the Indus- trial Arts. Translated from the Second Enlarged Edition. Izmo. Pages VI + 73. ARNOLD—The Motor and the Dynamo. 8vo. Pages VI + 178. 166 Figures. BENEDICT—Elementary Organic Analysis. Small 8vo. Pages VI + 82. 15 Illustrations. BERGEY—Handbook of Practical Hygiene. Small 8vo. Pages 164. BILTZ—Practical Methods for Determining Molecular Weights. (Translated by Jones.) Small 8vo. Pages VIII + 245. 44 Illustrations. BOLTON—History of the Thermometer. 12mo. Pages 96. 6 Illus- trations. BRYDEN AND DICKEY—A Text Book of Filtration. 8vo. Pages XII + 376. 264 Illustrations. BURGESS—Soil Bacteriology Laboratory Manual. 12mo. Pages VIII + 123. 3 Illustrations. CAMERON—The Soil Solution, or the Nutrient Medium for Plant Growth. 8vo. Pages VI + 136. 3 Illustrations. CLINTON—Further Light on the Theory of the Conductivity of Solutions. Pages 15. Paper Cover. CRAIG—Notes on Chemical Analysis. 8vo. Pages IV + 162. 16 Illustrations. DOLT—Chemical French. 2nd Edition. 8vo. Pages VIII-+ 413. EMERY—Elementary Chemistry. 12mo. Pages XIV + 666. 191 Illustrations. ENGELHARDT—The Electrolysis of Water. 8vo. Pages X + 140. 90 Illustrations. FRAPS—Principles of Agricultural Chemistry. 8vo. 2nd Edition. Pages VI + sor. 94 Illustrations. GILMAN—A Laboratory Outline for Determination in Quantita- tive Chemical Analysis. Pages 88. GUILD—The Mineralogy of Arizona. Small 12mo. Pages 104. Illustrated. HALLIGAN—Elementary Treatise on Stock Feeds and Feeding. 8vo. Pages VI +: 302. 24 Figures. HALLIGAN—Fertility and Fertilizer Hints. 8vo. Pages VIII + 156. 12 Figures. HALLIGAN—Soil Fertility and Fertilizers. 8vo. Pages X + 398. - 23 Figures. HARDY—lInfinitesimals and Limits. Small 12mo. Paper. Pages 22. 6 Figures. HART—Text Book of Chemical Engineering. 2nd Edition 8vo. Pages XIV + 236. 229 Illustrations. HART—Chemistry for Beginners. Small 12mo. Vol. I. Inorganic. Pages VIII + 214. 55 Illustrations, 2 Plates. HART, R. N.—Leavening Agents. 8vo. Pages IV + 90. 13 IIlus- trations. HEESS—Practical Methods for the Iron and Steel Works Chemist. 8vo. Pages 60. HILL—A Brief Laboratory Guide for Qualitative Analysis. 3rd Edition. 12mo. Pages VIII + 104. HINDS—dQualitative Chemical Analysis. 8vo. Pages VIII + 266. HOWE—Inorganic Chemistry for Schools and Colleges. 8vo. 3rd Edition. Pages VIII + 443. JONES—The Freezing Point, Boiling Point and Conductivity Meth- ods. Pages VIII + 76. 2nd Edition, completely revised. KRAYER—The Use and Care of a Balance. Small 12mo. Pages IV + 42. 18 Illustrations. LANDOLT—The Optical Rotating Power of Organic Substances and Its Practical Applications. 8vo. Pages XXI + 751. 83 Illus- trations. LEAVENWORTH—Inorganic Qualitative Chemical Analysis. 8vo. Pages VI + 153. LE BLANC—The Production of Chromium and Its Compounds by the Aid of the Electric Current. 8vo. Pages 122. LOCKHART—American Lubricants. 2nd Edition. 8vo. Pages XII + 341. Illustrated. MASON—Notes on Qualitative Analysis. 8th Edition. Small 12mo. Pages 58. MEADE—Chemists’ Pocket Manual. 12mo. 3rd Edition. Pages IV + 530. 42 Figures. MEADE—Portland Cement. 3rd Edition. 8vo. Pages X + 5i2. 169 Illustrations. MOELLER-KRAUSE—Practical Handbook for Beet-Sugar Chemists. 8vo. Pages VIII + 132. 19 Illustrations. MOISSAN—The Electric Furnace. 2nd Edition. 8vo. Pages XVI + 313. 42 Illustrations. NIKAIDO—Beet-Sugar Making and Its Chemical Control. 8vo. Pages XII + 354. 65 Illustrations. NISSENSON—The Arrangement of Electrolytic Laboratories. 8vo. Pages 81. 52 Illustrations. NOYES—Organic Chemistry for the Laboratory. 4th Edition, revised. 8vo. Pages XII + 293. 41 Illustrations. NOYES AND MULLIKEN—Laboratory Experiments on Class Reac- tions and Identification of Organic Substances. 8vo. Pages 81. NUGEY—Oil Refinery Specifications. 8vo. Pages VIII + 210. 4o Illustrations. O’BRIEN—Factory Practice in Manufacture of Azo Dyes. PARSONS—The Chemistry and Literature of Beryllium. 8vo. Pages VI + 180. PFANHAUSER—Production of Metallic Objects Electrolytically. 8vo. Pages 162. 100 Illustrations. PHILLIPS—Chemical German. 2d Edition. 8 vo. Pages VIII + 252. PHILLIPS—Methods for the Analysis of Ores. Pig Iron and Steel. 2nd Edition. 8vo. Pages VIII + 170. 3 Illustrations. PRANKE—Cyanamid (Manufacture, Chemistry and Uses). 8vo. Pages VI + 112. 8 Figures. PULSIFER—Structural Metallography. $8vo. Pages VIII + 210. 146 Illustrations. PULSIFER —The Determination of Sulphur in Iron and Steel—With a Bibliography 1797-1921. 8vo. Pages VI-+ 160. 7 Illustrations. SEGER—Collected Writings of Herman August Seger. Papers on Manufacture of Pottery. 2 Vols. Large 8vo. STILLMAN—Briquetting. 8vo. Pages XI + 466. 159 Illustrations. STILLMAN—Fngineering Chemistry. 5th Edition. 8vo. Pages Vill + 760. 150 Illustrations. STILLMAN—Examination of Lubricating Oils. 8vo. Pages IV + 125. 35 Illustrations. TOWER—The Conductivity of Liquids. 8vo. Pages 82. 20 Illus- trations. Van KLOOSTER—Lecture Demonstrations in Physical Chemistry. 1z2mo. Pages VI + 196. 83 Figures. VENABLE—The Study of the Atom. 12mo. Pages VI + 290. VULTE—Household Chemistry. 12mo. 3rd Edition. Pages VI + 243. VULTE AND VANDERBILT—Food Industries—An Elementary Text-book on the Production and Manufacture of Staple Foods. 3rd Edition. 8vo. Pages X + 325. 82 Illustrations. WILEY—Principles and Practice of Agricultural Analysis. Vol. I—Soils. Pages XII + 636. o92 Illustrations. WILEY—Principles and Practice of Agricultural Analysis. Vol. Iil—Fertilizers and Insecticides. Pages 684. 40 Illustrations 7 Plates. WILEY—Principles and Practice of Agricultural Analysis. Vol. IlI—Agricultural Products. Pages XVI + 846. 127 Illustrations. WINSTON—Laboratory Leaflets for Qualitative Analysis. 8 x Io. 10 pages Reactions with 21 sets of 4 pages each of Analysis Sheets. WYSOR—Analysis of Metallurgical and Engineering Materials—a Systematic Arrangement of Laboratory Methods. Size 8% x 101%4. Pages 82. Illustrated. Blank Pages for Notes. WYSOR—Metallurgy—a Condensed Treatise for the Use of College Students and Any Desiring a General Knowledge of the Sub- ject. 2d Edition, revised and enlarged. 8vo. Pages XIV + 391. 104 Illustrations. ZIEGEL—Brief Course in Metallurgical Analysis. Pages VI + 72. BARDORF—The Story of Sugar. 12mo. Pages VII + 191. Illus- trated. BOWEN —The Story of the Oak Tree. I2mo. Pages127. Illustrated. CLYDE—A Drop of Water.. I2mo. Pages 172. Illustrated. DAVIS—Roger Bacon’s Letter—Concerning the Marvelous Power of Art and of Nature and Concerning the Nullity of Magic. 12mo. Pages 76. HART —Our Farm in Cedar Valley. 12mo. Pages 250. Illustrated. HART—The Silica Gel Pseudomorph—and Other Stories. Pages VI + 176. RUSSELL—The Romance of the Holes in Bread. Pages 156, Illus- trated. evita, 4 pee 7, Pa 7 Lf. S34 : beiuyrciayts SAP AAS AES yaar see fe ( , < rpm cpare jpeee fo seeiss sade . ‘ ; Salo : ‘ y ee Rona eke ST a eg ys. 2 3 poe 23 iss mgt eA afewatety f , Patel ante 7 S famed wd yo pala econ a chon fale cavinlnctatty edu undeg end plogs 5 zy Setespinstechoespiet pay opees ; it a ted rata rs F Fant : Ld pueidaye #e ales. * fea + Etat 3 ree = Y Soemehye pes Sc ke . Nia ble Reta seorrreigite herd etcetera! a5 hie an ans : Soeetesr fey ab fiery jaa, a oe ya ESIC SST, ? is A ont hte anh glen wad ist optetert pitted Hp: Spa sep pep ure Sire dhpbanaipenek os Aone ipemppeceses, ope ale pore fiat ota vata aha Nii ela lear neds weeps eo nha bata cadet hee oe asepor oles ; iletoka wtetin a ecata eee oda aie yaw oi dotaly hcn ponder nie - not prre ap hsbes renee pawennenimeepaes fm Soe dnote ie Recerca nae F eee . wiped eat ; £5 7 So pias bah data cw y aude Z 7 la vahed aid of ean waka aio ht sal aly onto antag Wein wale is ES SA OT : 7 rashenik datecina escapee eee ? id rn ioe ies ces Sodas pare, : : Serccore nicer See Ware Sen Meelin inners Pe = ve te Pe nee a nee ern erraae ncn etnsdatricerwrhctue ites z 2 fe pda la rar ently Slo og tab eect Wim ol eae ad Alea paki anln caf lcd ese In tT fa aban eicheonteeshrbelt fa pueicnictcne Snlryated cd itetabates Pahdah ahaa os 7 itt Ne del delat nica pada ieee Doel Che wate anlginipatensoetes F ereris aA a a Wren od ents atctiwror had tiatnacotcnt oa Z iy “aes ny ‘4 eas ¢ a fant ectlthitatibe wickets! Br Mensa AAAS ASME EASES ES Ste BRED Mae hrm The os ro ven a ge wat eet en CLAP Rr MEER LRT e Naha ahe ML MReSNRE LALA mene hapoerchraag homer becabpmdamianenilen sat ar eae hd Bl oped traces teeta na aan dN ag a an A a Tao Ee tag hn Se a i RR I NS oA RI ANT TITEL we », pas oF s iets, - ¥ we ” ig 4 4 Aa t _ prs . a - + pee 8 i - ia eee EE A ly ee ce oR SS har ey a Lh ER IR a A a aac I fee STOR C EI pee oe III TREC RR ae SOI NIE A TIS T eR TE EOE etre LALLA aR aol ete E eras bimeir hides feseat apace SSeS ar as eA Nr aap a al re nt aT Bia eteclan gen ios aan eens more eaes tener ren Sea eres Bortimrieae Le Ree fe earth RCo a eae LEE EER a ae it scr Rl Set Dh hae Ln lecnlynerontaes de ed Cl wearers olen goa an 3 awn sy notte wana eees Salle sen dite viel nin olds nlc letwedginiete recy lcs ivitde bla oo pon ae oiaoecome Reape * Py 2 , rz) 1 epi a Se ren ‘ Sash tmwe eos ne ty a wie hs ih digas pe ore n ret ~ 4 3 agers 7 y M i os SecA ann SREB RRL RD SRS Cae Nin aetna et etat eran SS Rae ee ake wa Dal ea Sl ATC a SO NT IIL eo BEANS EA TG EO TEE SESE Eee ence ip ous stage a toeees pies reste iT nied : net, tes ge att I ah Lae LC LI ea Pc leah oI Teed PR SCR TT ce AEB te TIO I POR aed Ree re ne a es Oe ere Pes eens a a ee Sli eRe a wo el fy EU le Sept saree hae : RAR AML as 7 TR el oe Re a eee MATTER a UTS TR TA IE I eee e openac iin tengo ree = oni le ! > - rs - we EERO ALL ARN OL aE T Ssateeuthreware ale ntin cde Stace Wee Pa Tween mee nrhpaee aarp pmol tm napeernoeiyeeeietiaaeary ee i lala ety ek atv loly gala Sven ae peLAc nt hai teeth ets PaLcas ei hnes Brannon Dy ws! SEAR AMADA ARES AROMAS ARE SEERA ERB R AE MSEE ate eaE: : Leet SEE PL ges eres pia swas ans sa aes sands, Say eee i ED shes aad (iss seine tepecteaesreen se ELM DEXA PARR RE re Rik RUE RE sacred eee ee es toupee rome ens stoner SPeclgs cee Shy es SN AP oa TE Mb EE aS tte Tepe Re capteripabon, itcrcrerytarey® enetberslarpistieerdernsnsccsreinearastcerrer ats saspeennaassiapescaves itnenarnemuncenarees St teeeneee nett ; EERE PERC nternnntee on By akEe da eI LE Fs LAE OID UI : as : z Rebeca, es 8s : on s . = ialahidel ‘ems paceanteaeh th be pense Siete meets ea a IS Beata I esis Semen one enone Sesieere Beare ro nem neem name eae BoE as pies Sacer nan Cennard vn saan aevsanmna stamens ve anmnnap nena Dorn es eee Nn aa et ee eK a ah a oe ne meray pe fod ES antes Naan a =o) Paes TREC PI OIE an a Se ahaa haa Datta as LLIB AD EE RES RAR Ns Rees SO EEAOR LEE erie ee zs 7 nes ts eerie - ; crete: “ teat re IoiCot SL EPR LY Tree Pan ered ov bas wa iB hake pr oesenpTne seine? sp nemd eee aye Breer ite se) ibaa rae cf ee me Tepes sh Lifer ledge eee 2 TD me Me Rane al pcegee bel ete tere on! hestranenssreresecsbpar easy sy elitpsdbssintts oe pre eee & Leon, fg aS Mb 8 ae oie : en turns 2 Rrrcglgh ater hs Aicoeralinneiebistnsrperenes Abpearsepaienrstacas hepns een oe ee ? 5 mie MOET Sa Pa : Etat aed adet PAs hima bn oe meade s ae? eece nga sak ae Bernese easter : in peuprar ern : F reheee. WE eee Ag peayeo - nate PIE SET YEN