THE RELATION BETWEEN PHYSICAL PROPERTIES AND PHYSIOLOGICAL ACTION OF CERTAIN LOCAL ANESTHETICS WALDO BRIGGS BURNETT A. B. Southern Methodist University, 1919 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN CHEMISTRY IN THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 1921 \^ 2 -\ UNIVERSITY OF ILLINOIS THE GRADUATE SCHOOL % Ju ng 3 , 1 92I— I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY ENTITLED THE RELATION 'BETWEEN PHYSICAL PROPERTIES AIID PHYSIOLOGICAL ACTI ON Off CERTAIN LOCAL ANESTHE TICS BE ACCEPTED AS FIJLEILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF _ Head of Department Recommendation concurred in* Committee on Final Examination* *Required for doctor’s degree but not for master’s , TABLE OF CONTENTS I INTRODUCTION 1 II THEORETICAL PART 3 Theories of Anesthesia . 3 Asphyxiation theory 3 Catalase theory . . . . . 3 Valence theory 3 Permeability theory 4 Lipoid hypothesis 4 Jkethods for the Synthesis of Novocaine 6 ^ Di-n-Buty 1 Amino- Ethyl p-Amino Benzoate Monohydrochloride9 Preparation of Secondary Amines * 9 Hofmann method 9 Anilin method 10 Sulfonamide method 10 Cyanamide method 11 Preparation from ketones 11 Preparation from ketoximes and aldoximes. ...... 11 Preparation from nitriles 11 Preparation from alcohol and ammonia. ........ 12 Degradation of tertiary amines. ........... 12 p-Nitroso di-n-Buty 1 Aniline Hydrochloride 13 Di-n-Buty 1 Amine . 13 P Di—n— Butyl Amino Ethyl Alcohol 16 Ethylene Oxide . ........ 17 Digitized by the Internet Archive in 2015 https://archive.org/details/relationbetweenpOObu p-Nitrobenz oyl Chloride . • . * * 17 /3 -Di-n-Butyl Amino Ethyl p-Uitr o Benzoate Hydro chloridel8 ft -Di-n-Butyl Amino Ethyl p-Amino Benzoate Monohydro- chloride IS ft -Biisobutyl Amino Ethyl p-Amino Benzoate Monohydro- chloride ..... 19 Diallyl Amine 21 Y' Bromopropyl p-Nitrobenz oate 21 III EXPERIiiffiNTAL PART 23 p-Nitr os o-di-n-Butylaniline Hydrochloride 23 Di-n-Butyl Amine 24 Ethylene Oxide 23 ^Bi -n-Butyl Amino Ethyl Alcohol 26 /9 Di-n-Butyl Amino Ethyl p-Mitrobenzoate. hydrochloride. 27 ft Di-n-Butyl Amino Ethyl p-Amino benzoate Monohydrochlor- ide 28 Diisobutyl Amine 29 /^Diisobutyl Amino Ethyl Alcohol . 29 ft Di iso’outyl Amino Ethyl p-Nitrobenzoate Hydrochloride JO ft Diisobutyl Amino Ethyl p-Amino benzoate Monohydrochlor- ide 30 )T Bromopropyl p-Nitrobenzoate 30 Unsuccessful Attempts to Prepare Secondary Amines ... 31 Di isobutyl aniline 31 p-Nitroso diisobutyl aniline hydrochloride 32 Diisoburyl amine . 32 Diallyl amine. 32 Di-n-butyl ainine by the sulfonamide method .... 32 IV SUMMARY 34 V BIBLIOGRAPHY 33 THE RELATION BETWEEN PHYSICAL PROPERTIES AND PHYSIO- LOGICAL ACTION OF CERTAIN LOCAL ANESTHETICS. I INTRODUCTION. The literature contains numerous articles which point out the relationship existing between the structure and the physio- logical action of various local anestnetics. Other articles point out the relationship between the structure and the physi- cal properties but there are few which attempt to correlate these three properties and draw definite conclusions from the same . This research was undertaken in an effort to arrive at some such conclusions. In order that the results may be as in- clusive and the conclusions as general as possible it is planned to prepare a series of the monohydrochlorides of the dialkylamino ethyl» propyl, butyl, and anyl esters of p-amino benzoic acid. The alkyl groups will be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, allyl, heptyl and lauryl. It is probable that the entire series of the higher esters such as the dialkylamino butyl and amyl esters will not be pre- pared; only a few representative ones; in order that their re- lation to the members of the lower series may be determined. Various physical constants such as meltiiig point, refractive index, specific gravity, soluoility, lipoid-water partition coef- ficient and the effect upon surface tension will be determined. The pharmacological tests will be made elsewhere and re- ported later - 2 - j?rom the data obtained it is hoped that certain conclusions may be drawn as to the effect of certaiii types of side chains upon the anesthetic properties and the toxicity of the compounds studied. Because of the different types that will be prepared it will be possible to study the effect of a straight or forked side chain, and a saturated or unsaturated side chain in addition to the effect of the mere weight of tne chain alone. 1 2 Jenkins and Peet , who are working upon different phases of this same general problem have prepared and studied certain members of tnese series, namely the monohydrocnlorides of ft di- methyl, ft di-n-propyl,^ di isopropyl and ft di-n-amyl amino ethyl and Y diethylamino propyl esters of p-amino benzoic acid. This paper will treat only of the monohydr ochlorides of the/^ 7 di- n-butyl and ft diisobutyl amino ethyl esters of p-amino benzoic acid. Other members of these series will be prepared and studied at a later date. .. . • ' - “ •* » . v‘ 4 ■ .. i . - 3 - II THEORETICAL PART A great number of theories have been advanced from time to time in an effort to explain the phenomena of local anes- thesia. No set of experiments has ever proven definitely that any particular theory is correct and the real cause of local anesthesia is still a matter of some conjecture. The mere nature! of the problem limits the research largely to a process of trial and error and a theory that appears to hold for one set of con- ditions does not hold for a different set of conditions. A brief explanation of some of the more important theories will tend to show the exact state of affairs as they stand today. 3 (1) The asphyxiation theory. Verworn advances tne theory that anesthesia is produced because the cell is prevented from carrying out its normal oxidation processes. The cell remains dormant as long as these oxidation processes are prevented. There is no doubt that oxidation is prevented to some extent, but as some have pointed out, there is a question as to whether this decrease is the cause or result of anesthesia. 4 (2) Tne catalase theory. This theory, held by Burge of the University of Illinois, is similar to that of Verworn except that the decrease in oxidation is supposed to be due to the ac- tion upon the enzyme catalase. Burge thinks that the anesthetic either destroys or inhibits the action of the enzyme. Naturally the same objections that hold for the preceding theory will hold for this one also. 6 ( 3 ) The valenc e theory . Mathews believes that both the - 4 - anesthetic and the protoplasm of the cell possess residual val- ency and a union of the two produces anesthesia* He considers the irritable substance in protoplasm to be an oxygen protoplasm compound. Normal stimulation produces oxidation with the con- sequent rearrangement of this more or less unstaole compound and the liberation of carbon aioxide. The presence of an anes- thetic prevents this action oecause it forms a noil-irritable, dissociable compound with the protoplasm. e Ehrlich upholds this theory and adds to it the idea of certain haptophoric groups which make the union of anesthetic and protoplasm easier. He considers NHa as the nighest of these groups. ( 4 ) The permeability theory. Lillie contends that anes- thesia effects the permeability of the cell. This is quite likely, because the effect of an anesthetic is essentially physi- cal in nature, effecting the inter surface activities especially. a 9 Osterhout agrees with this theory while Harvey opposes it. 10 11 Traube and Clowes , in turn, disagree with the work of Harvey and uphold Lillie's theory. i; (5) The lipoid hypothesis. Although this theory of Overton and Meyer does not attempt to explain definitely the cause of local anesthesia it does in a way attempt to explain the mechan- ics of anesthesia. The nerve cexls which are effected by the anesthetic contain the lipoid, lecithin and the wax, cholesterol in considerable amounts. The anesthetic strength of a compound, has been proven, in a qualitative way at least to be a function of its distribution - 5 - between blood and oil. In experimental work water takes the place of blood. Prom a study of these theories it will be seen that this worm is still in its earliest experimental stages. However, it does seem logical that a lipoid-water partition coefficient w'ould give some indicati on, probaoly quantitative, as to the an- esthetic strength of these substances. Since the free bases of these anesthetics are water insol- uble the y must be administered as salts. The rate at which they take effect should depend upon their rate of hydrolysis if we are to assume that they hydrolyze and then the free base is ab- sorbed by the lipoidal substance of the cell. It would also depend in part upon the rate at which the free base is absorbed. As has been seated before all of the anesthetics that are to be considered in this work are benzoic acid esters. The amine group in trie ring serves only to neutralize the acid prop- erties of the acid salt of the amine group in the side chain. This reduces tne irritating effect of the anesthetic to a mini- mum. It is rather interesting to none their structural relation to the natural anesthetic cocaine. H .0 C - OCR - CHa Coca ine :ch - OCHaCKatf< a CH - k T - CHs UHa - 6 - 13 Einhorn early suggested that allbenzoic acid esters possessed anesthetic properties of a greater or less degree. Working upon this theory he soon succeeded in preparinga con- siderable number of esters which possessed anesthetic proper- ties but tneir insolubility made their use very unsatisfactory, so he next undertook the preparation and study of the alkamino esters . Ke found that the alkamino esters showed anesthetic proper- ties but these were not so marked as those of cocaine. However, /} di et tylamino ethyl p-anino benzoate hydrochloride, known to the trade as "procaine” or "novocaine"has come into general use because its low toxicit3 r makes it superior to cocaine although its anesthetic power is not as great as that of cocaine. 14 Adams and Kairnn have worked on the various methods for preparing "novocaine" and have succeeded in synthesizing a relat- ed compound that has proven much superior to "novocaine" in actual practice. It is the nydrosulfate of T di -n-outyl amino propyl ester of p-amino benzoic acid and is known to the trade as "butyn" . All of the methods for the synthesis of these various anes- thethics are methods that have been used for the synthesis of novocaine. Einhorn used them with varying success. The various methods are represented by the following equations: (1) (a) >C - Cl + HOCHaCHaNN^ HO 2 ,o h cir C - 0 - CHaCHafrC R Fe HO a in . si ^ ■. ■ 1 • - * ■ . i. . . » > ** ... V b . , . .. x ■ . . . . . . , :» • * : . . 4 » • i i ' . i *■ - 8 - (4) (5) 0 c"- 0 JR - CHaCHaN^ C - OCHaCHaMV HC1 NHa 0 H Cl_ 6 - OCKaCHa^<^ 9 C - OCaHe + H0CH3 CHaN P <— C - OCHaCHaH NO 3 (f - 0 - CHaCHaN^ EC1 9 T H > c; a C — OCEa CHa — VT , NHa Each of the above methods may be varied by reducing to the amino acid in the first place and then carrying out the other reactions. These are all general methods and will apply for the preparation of the dialkyl, propyl, butyl and arayl esters The processes may be varied still further by using differ- ent methods for the preparation of the secondary amines and alcohols. There are a variety of ways for reducing the nitro group to an amino group. These various methods will be discuss- ed later. method (1) has been used in the synthesis of both of the esters to oe discussed in this tnesis and will, be discussed more in detail later. The reason for its adoption was tnat most of the reactions involved went smoothly and gave good yields. Method (2) was not used because it does not go so smoothly and the reactions are more difficult to control. However it -9- does go fairly well with members of the \ dialkamino propyl ester series and probably will be adopted as the standard method for their syntnesis. Method (3) is similar in several respects t o method (2), but does not give such good yields. The chief objection is that it includes an autoclave reaction and as a rule these reac- tions give poor yields . Method (4) is of theoretical interest out of 210 practical importance. Very poor yields are obtained and it is very doubt- ful that it will ever be developed t 0 any considerable degree. The same may be said for method ( 3 ) in which even poorer yields are ootained. ft Bi-n-Eutvl Amino Ethvl p -Amino Benzoate Monohvdr och^r id e The interned iate which gave the most difficulty in prepara- tion was di-n-butyl amine. Since this is almost universally the case it will be well to tabulate in a brief way some of the methods for the preparation of secondary aliphatic amines. One thing is quite evident from a study of tnese metnods, namely many of them are by no means what might be considered general methods. Another outstanding fact is that the yields are always quite poor and fully fifty per cent of the investigators never report yields, being content to merely mention the fact that they obtained trie product in sufficient quantities to be isolat- ed. Preparation of Secondary Amine s . 16 (1) Hofmann method. Tnis was first used by Hofmann in 1849 and since that time ha s oeeu varied in some of its minor - 10 - details by scores of investigators. In its simplest form it consists of heating an aliphatic halogen compound with ammonia, in e ither an aqueous or alcoholic solution. RX + NH 3 *• RNHa + HX RNHa + RX *■ RaNH + HX RaNH + RX *RaN + HX The chief objection is that a mixture of primary, secondary and tertiary amines is obtained and except in unusual cases the 1 e yield of the secondary amine is very low. Van der Zande's modification in which he uses a 15 per cent solution of ammonia in alcohol was found to be the best method of this type. 1 7 (2) Aniline method. This method as developed by Reilly and Hickinbottom and other investigators works quite satisfactor ily and has the advantage of giving only pure 'secondary amines. The yields fall off very materially with an increase in the number of carbon atoms in the amine. (3) Sulfonamide method. This method, developed by ia Marckwald and Freiherr works well for the lower amines but not so well for the higher ones. The equations are self explanatory RSO 2 NH 2 + 2NaOH + 2R ' Cl *R SOaNR'a + 2NaCl + 2Ha 0 RSOaNR'a + S0a<°?* *RS0 2 C1 + S0 3 <°g 3 , S02< CE + H 2 O ^so 3 < 0ii + HNR*a NRa » OH -Il- ls (4) Cyanamide method . Traube and Engelhardt obtained 60 per cent yields of d imethylamine in this way but the yields of the higher amines were much smaller. It has the advantage, like the preceding one of being a very cheap process. HC1 CaHC H + R3SO4 0*4 ■RaHCH + CaS04 lC lC RaiRCOO; H >RaHH NasHCK + 2 HI RaNlSoS} H la HCH + 2 Had -HRaHH (5) Preparation from ketones. This method as developed by 30 Lftffler is suitable for the preparation of either normal secon- dary amines or mixed amines A3 X1 >c<® + Xl >c Xz' Xi Xa > c — RHR HR Ha y ^ i^CHHHR Ha + alcohol Xa (6) Preparation from ketoximes and aldoxiines . The catalytic 3 1 hydrogenation method, reported by Mailhe gives about one third of the primary and two-thirds of the secondary amine. R - C - R II HOH + Ha Hi 1500 - 200^ V R *■ ( R >CH )a HH + Ha 0 Copper may be used as a catalyst instead of nickel. (7) Preparation from nitriles. This method of Sabatier and Sender ens is quite similar to fhe preceding one. Hi C n Han + 1 + 2H2 1800 22 0^ * + 1 « CHa HHa a 2 2C n H 3n + 1 • CHa .HHa HHs + ( CuHa n + iCHa )sHH (C n H a n+1 .CH 2 )aira + C u H 3u+1 CHa HHa *>HH3+( CjiHa^i+x ‘CHa )sH . . 1 1 . . ' - • ' : *• • . - : . . - 12 - (8) (a) Catalytic preparation from alcohol and ammonia. 3 3 This method as reported by Sabatier and Mailhe gives rather low yields of a mixture of primary and secondary amines. TnOo or W 03. „ Tr ^ RQH + NH3 o_ _) 70 ° + HaO ROH + RNHa *-RaNH + HaO (b) This method has been slightly changed by Merz and Gasiorowski who carry it out in an autoclave in the presence of zinc cnloride Small yields are obtained. (9) Degradation of tertiary amines. 3 5 (a) Yon Braun's method is intended primarily for the syn- thesis of rather complex amines but should work likewise for simple aliphatic amines. (b) Another degradation method that nas been developed oy 2 6 Bayer and Company for the preparation of dimethyl amine should be general in its application RsN.HCl + 2NaOCl *- RaN.Cl + CHaO + 2NaCl + HaO \2im + hci Other methods for the preparation of secondary amines have 2 4 16 hours ROH + RNHa *-RaNH + HaO been reported but tney are suited only for specific amines and are not general in their application, c onsequerrcly they will not - 13 ” be discussed. Notable among these is the formaldenyde ammonium 2 7 chloride method of Werner for the preparation of dime thy lamine. p-Nitros odi-n-3utyl Aniline Hvdr oc hlor ide The reaction for this preparation is a general reaction for the nitrosation of substituted anilines, molecular quantities of sodium nitrite are added to a solution of di-n-butyl aniline in two and a half moles of hydrochloric acid. The reaction mixture must be well stirred and tne yields are cut down if the tempera- o ture rises above 3 • Under these conditions 90 per cent yields were easily obtained. If this compound is to oe stored for any length of time it should be stored as the free base and not as the hydro chloride because the latter partially decomposes into a tarry-like mass Di-n-Butvl Amine 1 7 Since Reilly and Hickinbottom claimed 100 per cent yields of di-n-butyl amine by the aniline method it w as decided to use R Cl Below upon continued stand ing. that method. H Cl I' } - . !•» - V V V • \ ■ - • . . • . - . . : - 14 - The nitroso group in the ring para to ohe amino group acti- vates it so that it may be easily nydrolyzed off. This is in accordance with the general behavior of the nitrosP and nitro groups • The exact method as reported by Reilly and Hickinbottom was to reflux, for three hours the p-nitroso-di-n-butyl aniline hydrochloride with an excess of 10 pe r cent sodium hydroxide solution. The reaction mixture was then steam distilled and the amine collected in hydrochloric acid. The free nitroso base may be hydrolyzed in a similar way but it was not used because it was an oil and was not as easy to handle as hhe hydrochloride. The exact directi cns as given were carried out, using a thirty gram sample but instead of a 100 per cent yield a 5*5 per cent yield was obtained. A tar-like material was formed in the reaction mixture, resulting most likely from the action of the concentrated alkali. The nitroso compound had been freshly prepared so decomposition could not have taken place previously. A thirty gram sample was used in all of these pre- liminary runs while the above investigators only made one run with a nine gram sample. Evidently they are in error. In an effort to prevent this tar formation more dilute solu- tions of the alkali were used and the time of refluxing was lengthened. Wien a half mole excess of 5 pe r cent sodium hydroxide was used and the mixture refluxed for six hours a 33 per cent yield was obtained. Refluxing with exact molecular proportions of the alkali in -15- 5 per cent solution gave only traces of amine. Another varia- tion tried was starting distillation immediately instead of re- fluxing. The concentration was kept constant by adding water through a dropping funnel as rapidly as it distilled out. Very little if a ty amine was formed in this reaction. A . 1 per cent solution of sodium hydroxide was tried but without much success. Apparently trie splitting process went on smoothly but slowly. The large volume of water made it diffi- cult to isolate all of* the amine. A 2 l/2 solution of sodium hydroxide was next use d and after refluxing for twelve hours a 41 per cent yield was obtain ed. On subsequent runs this yield was increased. to 47*5 per cent. These figures are for pure amine and not for the crude product. The method of absorption in hydrochloric acid was abandon- ed in favor of distillation through a Clarke separator. The objection to absorption in hydrochloric acid was that the pro- duct was very difficult to dry and a second operation was neces- sary to obtain the pure amine. The sulfonamide method for the preparation of di-n-butyl amine was also attempted out was not satisfactorily completed. The chief advantage of this method is that all of the interme- diates are relatively cheap. Tne equations are:- 28 -16- The reason that this method was abandoned was tnat the sub- stituted tolyl sulfonamide is difficult to purify by distilla- tion even under diminished pressure because of the great ease with which it chars and decomposes. A further and greater dif- ficulty is the hydrolysis of the substituted tolyl sulfonamide to obtain the secondary amine. f3 Di-n-Butvl Amino Ethvl Alcohol There are two good methods for the preparation of this com- p.ound, both of which are in actual practice commercially for the 29 preparation of related alcohols. They are the chlorohydrin method and a modification of the ethylene oxide method as report- 3 o ed by Matches . The ethylene chlorohydrin method gives only about a 50 per cent yield but the amine that does not react may be recovered. The chief objection is that continued refractionation is neces- sary in order to get a pure product. A large excess of ethylene chlorohydrin must be used. C4H9 >NH + G1CHaC ^ 0H — C4H 9 > NCHaCHa0H + HC1 The ethylene oxide method is the oetter method of the two because it runs smoothly and gives practically quantitative yields. Mathes ’method is varied by heating the etnylene oxide and dibutyl amine in a sealed tube in the water bath for twelve to fifteen hours. The reaction will not go if both of the react- ing substances are entirely dry. It was found that ethylene oxide prepared in the usual way, if not previously dried, con- tained enough moisture for this purpose. The reaction will also „ . t. * • . ' . ' ..... • ■ v •' *• ’ . - V • t v . ' . . . ... i. ' ' V \ ' - t ' r W ■ . - 3 .^1 > •<* - - * ‘ i - 17 - go to completion if x-he reacting substances are allowed to stand in contact with each other for several days. Bthvlene Oxide Ethylene oxide may oe prepared by treating ethylene chloro- 3 1 hydrin with sodium hydroxide CHa - CHa Cl OH HaOH + HC1 50 per cent yields are obtained by this method. A consid- erable quantity is lost during condensation because of its low boiling point. It may be kept quite satisfactorily in sealed tubes . p-Hitrobenzovl Cnloride 32 P-nitrobenzoyl chloride is prepared in the usual way for the preparation of acid chlorides, that is, by treating nitro- benzoic acid with phosphorus pentachloride C - OK C - Cl pels + POCls + HC1 NO3 ^KOa The reaction goes very smoothly, merely warming on the steam-bath. It is purified by vacuum distillation removing the phosphorus oxychloride first, by the same means. If a rather high vacuum is used excellent yields of the product are obtained. Certain precautions are necessary in the distillation. It cannot be distilled with a free flame because it decomposes with explosive violence. An oil bath in which the temperature of the oil does not exceed 25 O 0 will serve excellently for the purpose. A very short delivery tube should be used to prevent the product -18- from solidifying in it. Care should be taken tnat some of it does not go on through and clog the pump. /?Di-n-Butvl Amino Ethyl p-iiitro Benzoate Hvdrocnloride / 3 Di-n-butyl amino ethyl alcohol was condensed with p— nitro benzoyl cnloride in a benzene solution bjr merely mixing and allow- ing to stand. C ' C1 .XUHo + HOCHaCHatf< C4H JO2 Cf-OCHaCHa •C 4 H 9 14 iJ02 Adams and Kamm found it best to reflux the reaction mix- ture. This process will probably speed up the rate of reaction. It is rather difficult to purify oecause its solution in alcohol and ethyl acetate is much given to supersaturation. The free base is an oil that cannot be crystallized. /3 Di-n-Butvl Ami in 0 Ethyl p-Amino Benzoate MoiB-nvdrochloride This compound may be secured by the reduction of the nitro base by any one of several methods. The method used by Einhorn was reduction with tin and hydrochloric acid. The tin was then removed with hydrogen sul- tide. This method is open to the objection that it is very diffi- cult to remove all of the t in and then the reaction as a whole . - . » ' -19- does not go as cleanly as the iron reduction that was used. Another possibility is reduction with hydrogen sulfide. This is open in a large part to the same objections as the pre- ceding method. The method that was actually used is one that has come into general use only recently. The hydrochloride of the nitroester is made up to a thick paste with powdered iron and water. The temperature must be controlled rather carefully. If it heats up too rapidly hydrolysis is apt to take place. The presence of too much water will cause hydrolysis to take place. The reaction is probably started by the action of the hydro- chloric acid of the salt. After that the action for the most part is between the iron arid water. Under ordinary conditions the yield should run from 60 per cent to 70 per cent. The loss is most likely due to hydrolysis. The free base may be extract- ed with ether after treating with sodium hydroxide ana tartaric acid which holds the ferrous hydroxide in solution, due to the formation of a complex. If the free case is titrated with alcoholic hydrochloric acid, using litmus. as an indicator, the mono hydrochloride is formed. The hydrochloric acid makes the base soluble and the amino group on the ring neutralizes its acid properties. The resulting compound has marked anesthetic properties. / 3 Diisobutyl Amino Ethyl . o-Amino Benz oat, e mono-hydro chloride All of the theoretical considerations in the preparation of p-amino /^di-n-butyl amino ethyl /b enzoate mono-hydroc'nloride are appli- - 20 - I cable to this synthesis also. However, there are several radical l e differences. \ 'ihe secondary amine was prepared by Vein aer Zande's modification of the Hofmann method. The yields were fair but a considerable quantity of the alkyl halide was not converted, pos- sibly because the action was not. continued long enough. Better yields may be obtained by uniting the primary amine obtained in this manner with an additional quantity of alkyl halide. A peculiar thing was noticed in the preparation of isobutyl bromide which is used as an intermediate. It was prepared by the usual method for the preparation of alkyl halides as developed 33 by Hamm and marvel ( CHg JsCHCHaOH + RBr ( CHs )2CxiCH 3 3r + HaO The yield was poor and a large low-boiling fraction was obtained. This was probably a constant boiling mixture of the aiisobutyl ana tertiary butyl bromides . Another interesting feature that has not as yet been explained is the fact that at least half of the good boiling fraction dropped 5° in boiling point upon stand- ing for several days. • 17 Preparation of diisobutyl amine by the aniline method . The aniline method in its present development can not be used for the preparation of diisobutyl amine. In the first place only very small yields of the diisobutyl aniline caxi be obtained by the 34 usual method for the preparation of the substituted anilines. This might be due to the questionable purity of the isobutyl bromide, but this is doubtful. In the second place, diisobutyl aniline cannot be nitrosated in the usual way. Steric hinderance is probably the cause of this ' . ■ - 21 - rather unusual action* Jenkins' has shown that diisopropyl ani- line acts in a similar manner. Apparently some of it did react to form the nitroso compound because upon refluxing the nitrosa- tion mixture with sodium hydroxide traces of amine were actually obtained • All of the other reactions in the synthesis of /3 diiso- butyl amino ethyl benzoate monohydrochloride may be run in a manner similar to those for trie preparation of di-n— butyl amino ethyl benzoate monohydrochloride. One surprising thing is that most of the reactions apparently go more smoothly with the iso compound than with the normal compound. .Diallvlamine Theoretically it should be possible to prepare aiallylamine by the aniline method but the literature reports no attempt to prepare it in this manner. The diallyl aniline like diisopropyl aniline cannot be suc- cessfully nitrosated in the usual manner. An oil was formed but its composition was not determined. Apparently a small amount of it was nitrosated because upon splitting with alkali there is no doubt but that small amounts of amine were formed. It should be entirely possible to vary this method in sucn a way as to make it available for the preparation of diallylamine. r Bromopropyl p-Hi t r ob enz oat e This compound which is an intermediate in the pr eparati on of the 'f dialkylamino propyl esters of p -amino benzoic acid may best be prepared by condensing trimethylene bromide with the - 22 - sodium salt of nitrobenzoic acid using diethylamine as a cata- lyst . NO a + BrCHaCHaCHaBr 110 ° - 0CH2CH 3 CH 2 Br + NaBr \ . -25- III EXPERIMENTAL PART j-jJitrosodi-n-Butv!ani.Line Hydrochloride 410 gm. CeH.<5N( C 4 H 9 )a 610 cc. cone. EC1 800 cc. water 1^8 gm. HaN 02 The d i -n-buty lan i line was dissolved in the hydrochloric 17 0 acid solution and tne mixture cooled to below 5 » A concen- trated solution of sodium nitrite was slowly added through a dropping funnel. This addition should take from an hour to an hour and a half. The reaction mixture was stirred mechanically 0 and the temperature was not allowed to rise aoove 5 during the reaction. The reaction mixture became an orange red at first but as the reaction proceeded the color deepened until at the end it was almost black. At the completion of the reaction the mixture was allowed to come to room temperature and the product was fil- tered out and dried. The yield was 462 grams or 85.3 per cent of the theory. On another typical run the yield was increased to 490 grams or 90 per cent of the theory. When moist the nitroso compound was a buff color, but upon drying became yellow green. It was purified by precipitation from an alcohol solution with ether. This procedure often gave a tarry substance that would not crystallize. It was also puri- fied by washing with hot acetone. The pure compound crystallized -24- o out in the form of yellow green needles that melted at 107 * If it is planned to store any of this compound it should be stored as the free base and not as the hydrochloride because the latter decomposes into a tarry-like mass upon standing for any great length of time. For the preparation of di-n-butyl amine it was found that the crude product would work satisfactorily so it was not puri- fied. In many cases it was not even dried and weighed but a 90 per cent yield was assumed and the yield o.f di-n-butyl amine calculated upon that basis. Di-n-buty l Amine 270.9 gm. p-NO -CeH4-U0C4H« )aHCl 120 gin, UaOK 3200 cc . water . Enough sodium h 3 r dr oxide to make an excess of one mole was used. Sufficient water was added to form a 2 l/2 per cent sol- ution of the alkali after the hydrochloric acid had teen neutral- ized. After refluxing for a short time an oily layer with a IV dark blue cast formed on top . This was the free case. The mixture was refluxed for 10 hours and then distilled through a Clarke separator for an additional 10 hours. The yield was 6 0.99 grams or 47.9 per cent of the theory. This was not figured on the basis of the crude amine but upon the pure product. On an- other run during which the mixture was refluxed for 9 hours and distilled through the Clarke separator for 6 hours* a 49 per cent yield was obtained. Toward the end of the run the water returning to the distill' ijv K* . ' ' . * ■ -25- 3 8 ing flask through the Clarke separator still contained traces of amine, but it was found unprofitable to v/ork it for the ad- ditional amine that might be obtained. A certain amount of ta.rry material was formed during the refluxing. It was proba- bly formed by a side reaction of the alkali upon the nitroso compound. The amine was dried with sodium hydroxide and distilled, o o the fraction boiling between 157 and 161 being collected (correct B.P. 159°) * It is a cle ar liquid, lighter than water, gradually turning yellow upon standing. The odor is strongly ammoniacal . Several precautions in procedure might be noted: ( 1 ) Do not attempt to dry the amine with calcium chloride, use sodium hy- droxide; (2) do not use rubber stoppers, but cork stoppers seal- ed in with sodium silicate. Ethvlene Oxide 80.5 gm. CHaOHCHsCl 80 gm. NaOH The sodium hydroxide was s lowly added to the ethylene 3 1 chlorohydrin through a dropping funnel . A saturated solution containing an excess of one mole was fouiid to give the best re- sults. The generating flask was heated until it was warm to the touch. An evolution of the gas started almost immediately and sodium chloride precipitated out. The ethylene oxide was condensed by passing it through a spiral ice condenser and was collected in tubes packed in ice. -26- The tubes were then sealed off. The yield was 21.6 grams or 49*2 per cent of the theory . On another typical run a yield of 52 per cent was obtained. The product was a colorless liquid 0 boiling at 12.0* Precautions: ( 1 ) Do not heat the generating flask too hot; (2) Have several tubes prepared for collecting the product because condensation proceeds very rapidly after it has once started. (3) It is not necessary to dry the product if it is to be con- densed with an amine because the presence of moisture is essen- tial in this reaction. /3 Di-n-butvl Amino Ethyl Ale ohol 5 01 gm. CH 3 CH 2 0 150 gm* (C 4 H 9 )aHH The ethylene oxide, sealed in a small tube, was placed in a large tube with the di-n-butyl amine and the large tube sealed 30 off . The smaller tube was then broken by shaking and the mix- ture allowed to stand for an hour after which it was placed in the steam bath for 5 hours. The tube was then opened and the product distilled. B. P. 142° - 145° at 55 mm.; 225° - 230 ° with slight decom- position at 760 mm. Yield 19>2 grams or 92 l/2 per cent of the theory. The loss probably occurred in handling, because only traces of low and high boiling fractions were obtained. On other typical runs the same high yields were consistently obtained. The unpurified alcohol was a light reddish brown in color - 27 - but the pure product w&s colorless and slightly viscous. It hac a faint ammoniacal odor. The ethylene oxide should not be dried before use, or if it has been dried previously a drop of water should be added, since the condensation does not run smoothly if both of the reacting substances are dry. /3 Di-n-butvl Amino Ethyl o-N i t r ob e nz oa t e Hyd r ochloride 20 gm. ( C4H0 ) a NCHaCHaOH 21.4 gm. p-i;0 3 CeH4C0Cl 500 cc. benzene The p-nitrobenzoyl chloride was dissolved in the benzene 1 + and the alcohol added . The solution turned yellow and warmed up slightly after which it was warmed on the steam bath and allowed to stand. After an hour the ester began to form in flakes throughout the solution. Within 30 minutes more the sol- ution had almost solidified. The precipitate was filtered out and dried. Yield - 2 ) grams or 56 per cent of the theory. The filtrate was allowed to stand for several hours and then the remainder of the ester was obtained as a heavy oil, upon evaporation of the benzene. This oil solidified after standing for several days. This brought the yield up to theore- tical. Probably refluxing, as advised Adams and Kamm, would have speeded up the reaction. The hydrochloride of the ester which is obtained in this reaction resembles soap very much in appearance and melts at 88°-89°.It is very difficult to purify because its solution is - 28 - much given to supersaturation. The best method for its purifi- cation is to re c rystallize from absolute alcohol and ethyl ace- tate. Even after recrystallizing a second time the product re- mained slightly sticky. The free case is a light yellow oil that cannot be crystallized. /3 Di-n-butvl Amino Ethyl p -Amino benz oate ikono-hvdrochloride 27.5 gm. p— NOa CeH* COOCHa CH3xI( C 4 H 9 )HC1 75 gm. powdered iron. The nitro-ester and powdered iron were mixed together with just enough water to make a ve.ty thick paste. After a short time the mixture began to warm up. The temperature was controlled by placing the beaker in an ice bath and during the reduction the mixture was constantly stirred. After an hour, when the reaction had practically ceased, a small additional amount of iron was added and the mixture warmed for a short time on the steam bath. An excess of tartaric acid solution was added and then the solution was made alkaline with sodium hydroxide. The iron was then filtered out and bot b the iron residue and the solution ex- tracted with ether. Upon evaporating the ether the amino ester was obtained as a heavy oil. Yield 14 grams or 62.5 per cent, of the theory. On other runs the yield was raised to 70 per cent. The oil was dissolved in alcohol and titrated to neutrality with alcoholic hydrochloric acid, using ±itmus as an indicator. Upon concentrating tne alcoholic solution the product crystallized out in needle-like crystals. It may be purified by recrystallization from absolute alcohol and ethyl acetate or from water. o , 0 The hydrochloride of the ester melts at 167 - 169 • - 29 - Diisobutvl Amine 51 gm. (CHs ) 2 CHCH 3 Br 70 gm. 15 per cent alcoholic iiHa | The 15 per cent alcoholic ammonia solution was made by sat- l e urating alcohol with ammonia . The mixture of isobutyl bromide and alcoholic ammonia was sealed in a tube and heated in the water bath for 60 hours. A white precipitate slowly formed. This precipitate was later proven to be ammonium bromide. It was filtered out and the amine hydrobromide obtained upon the dis- tillation of the alcohol. A mixture of primary, secondary, and tertiary amines was obtained upon treating the hydrobromide salt with sodium hydrox- ide. The secondary amine was separated from the mixture by frac- tionation. Yield -4.3 gm. or 10 per cent of the theory. Diiso- butylamine is a colorless liquid with an ammoniacal odor, is 0 0 lighter than water and boils at 139 - 140 . 4?-£)iisobutvl Amino Ethvl Ale ohol 1.1 gm. CH 3 CH 3 0 3.2 gm. ( ( CHs )aCHCH 2 )a NH The details of the reaction are exactly the same as in the case of the/?di-n-butyl amino ethyl alcohol. The mixture was heat- ed for 10 hours. Yield 3 » 2 grams of 75 per cent of the theory. The low yield was probably due to the fact that small amounts 0 0 were used. The alcohol boils at 212 - 215 which checks with the boiling point reported by Matthes. Einhorn reports a boiling -31- of trimethylene bromide, using dietnylamine as a catalyst* It o was heated from 6 to 8 hours at a temperature of 110 . The tem- perature of the oil bath should be carefully regulated to pre- vent its temperature going above this point. At the end of this refluxing the excess of trimethylene bromide was removed by vacuum distillation. The bromester was then removed from the sodium bromide by extraction with ether. An effort was next made to purify it oy vacuum distillation but due to a mishap to the vacuum system it became badly charred and the distillation had to oe abandoned. The charred mass was extracted with ether and some of the product was recovered. It may be purified by recrystallization from alcohol. In the last vacuum distillation it is aosoiutely essential that the pressure be reduced to at least 5 run. The distilling flask should be fitted with a large side arm and should be set as low as possible in tne oil bath. It would be advisable to have a wire extend through the side arm, to serve as a heat con- ductor and in this way prevent tne clogging of the side arm. Unsuccessful Attempts to Prepare Secondary Amines . Application of the aniline method to the preparation of diisobutyl and d daily 1 • amines . hi is obutyl Aniline: 60 gm. CeHeHHa 226 gm. ( CHs )aCHCHaBr 6 0 gm. NaOH Half of the isobutyl bromide was added to tne aniline and . , ' >■ - * ~ i. V, J . . . . 1 . . ■ w ' ■ t W » - , , J — ... . ■, • ' . J ' i - . . .. . • ' ... . . . • - 1 • • - ' . * , ,V jI V. . . ; - . ' * • . . J - ’ ; , ^ » / «. • 1 ... .. . : ....... .. . v,r .. -32- t he mixture refluxed for 12 hours. The remainder of the isobutyl bromide and the sodium hydroxide were added and the mixture again refluxed for 12 hours. The product was then dried and distilled. weighed 20 grams, 15 per cent of the theory. p-.Nitr oso-diisobuty 1 aniline hydrochloride . An attempt was I made to prepare this compound using tne same procedure and the j same proportions as in the case of p-nitr oso-di-n-butyl aniline hydrochloride . An oil was formed and all attempts to crystallize I it failed. Diisobutyl Amine. The oil obtained above was treated in exactly the same way as the p-nitr oso-di-n-butyl aniline h 3 r aro- chloriae in the preparation of di-n-butyl amine . Only traces of the amine were obtained. Diallyl amine. The same procedure as above was carried out j on diallyl aniline with the same results, only traces of the j amine being formed. i Attempt to Prepare Di-n-butvi Amine bv the Sulfonamide method The toluene sulfonamide was prepared by treating toluensul- fonjrl chloride with ammonium hydroxide. The toluene sulfonamide and butylbromide were dissolved in the alcohol, a 40 per cent solution of half of the alkali added and the mixture refluxed u 0 It boiled between 160 and 250 . Diisobutyl aniline boils at 0 o 00 240 - 245 . The fraction that boiled between 255 and 245 85.5 gm. P-CH3C0H4SO3NH3 157 gm. C 4 K 9 Br 40 gm. i^aOH 500 cc. alcohol I ... « v 1 ' V. » - *-j o> • - . . . ' . 11 1 ( . * <' , ■} . >. I 1 .'.. • v . : ' r v .. . c - 33 - until it became neutral. This required 4 hours. The reminder of the alkali was added and the mixture again refluxed until it became neutral. This required 9 hours. The ale dhol was then distilled off and the sodium bromide removed with water. An attempt was made to purify the toluene sulf ondibutylarnide by vacuum distillation. The vacuum failed and the product charred instantly. The method was then abandon- ed in favor of the aniline method. -34- IV SUMMARY 1. The chief theories for local anesthesia have oeen Uriel - ly discussed. 2. Available methods for preparing secondary amines have been discussed with respect to their relative merits. 3. The best conditions for the preparation of di-n-butyl amine have been determined. 4. A method for the preparation of di—n— butyl and /3 diiso— butyl amino ethyl alcohol oy the condensation of the correspond- ing amine with ethylene oxide has been worked out. This is un- questionably the best method for the production of these alcohols 5* /3 di-n-butyl and /f?diisooutyl amino ethyl p-amino ben- zoate hydrochlorides have been prepared. These compounds show marked anesthetic power. 6. It has been shown that diisobutyl and diallylaniline cannot be nitrosated in the usual way. It follows then that the corresponding secondary amines cannot be prepared by the ani- line method. -35- V BIBLIOGRAPHY 1. Jenkins - University of Illinois Thesis (1921) 2. Feet - University of Illinois Thesis (1921) 3» Verworn - "Irritability" (1913) 4. Burge - Amer. Jour, of Physiol* 45., 38S (1918) 5* Mathews - Intern. Zeit. Physik.. Biologie I, 432-449 (1914) 6. Ehrlich - Revue General de Chemie 14, 93 (1911) 7* Lillie - Science, 1Z> 764-67; 959-72 (1913) 8. Osterhout - Proceedings Arner. Physiol. Soc. (1911) Amer. Jour. Physiol., 25, 11 9* Harvey - Bull. Carnegie Inst., Vol. 11 Pt . 4 ( 1915 ) 10. Traube - Biochem. Zeit. 177 (191) 11. Clowes - Proces. Soc.^xP* Biol, and Med. ll r 8-10. 12. Overtoil and Meyer - "Studien tioer die Markose" (1901) 13. Einhorn - Annalen 371 . 125-179 (1910) 14. Adams and Kamm - Jour. Amer. Chem. Soc., 12, IO3O-53 (1920) U. S. Pat. 1, 358, 750; 1, 358, 751 (1920) Chem. Abs., 15, 412 (1921) 15. Hofmann - Jour. Chem. Soc., 1, 300 (l84. r 9) 16. 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