of the Arsines. - 
 
 i 
 
 M 
 
 I 
 
 t 
 
 
 
 
 - ( 
 
 By William M, Dehn. . 
 
I 
 
 \ 
 
 -i 
 
 4 
 
 ,^’;4 
 
19345 
 

 Reprinted from the American Chemical Journal. Vol. XI,. No. i. 
 July, 1908 .] 
 
 [Contributions from the Chemical Laboratory of the University of Illinois.] 
 
 REACTIONS OF THE ARSINES. 
 
 By William M. Dehn. 
 
 In an earlier contribution^ it was held that the reactions 
 of the arsines and their derivatives can be divided into two 
 general classes, viz., those that involve 
 
 (1) Addition. 
 
 (2) Addition and subsequent dissociation; in other words, 
 these reactions result from alternate changes of 
 
 (1) Trivalent arsenic to pentavalent arsenic, and 
 
 (2) Pentavalent arsenic to trivalent arsenic. 
 
 The oscillations of the arsenic valencies are best illustrated 
 b}'” the following reactions: 
 
 I. 
 
 11. 
 
 III. 
 
 IV. 
 
 (a) 
 
 AsXg 
 
 AsXg 
 
 RASX2 
 
 RAsX^ 
 
 R2ASX 
 
 R2ASX 
 
 RgAS 
 
 RgAS 
 
 Halogen- Alkyl Series (A). 
 
 (b) 
 
 RX 
 
 RX 
 
 RX 
 
 RX 
 
 RX 
 
 RX 
 
 RX 
 
 RX 
 
 <— 
 
 (c) 
 
 
 
 RASX2 
 
 + 
 
 X/ 
 
 RAsXg 
 
 + 
 
 X^" 
 
 RgAsX 
 
 + 
 
 X,' 
 
 RgAsX 
 
 + 
 
 X/ 
 
 RgAS 
 
 + 
 
 
 RgAS 
 
 + 
 
 X,'’ 
 
 1 This Journal, 36, 5. 
 
 2 See page 121. 
 
 ^ Evident in the presence of sodium. 
 ^ Ann. Chem. (Liebig), 107, 274. 
 
 5 Ibid., 107, 274. 
 
 ® See page 107. 
 
 ^ Evident in the presence of sodium. 
 8 Ann. Chem. (Liebig), 107, 266. 
 
 RAsX,2 - 
 
 RAsX^s ■ 
 
 RgAsXg® - 
 
 R2AsX3» - 
 R3ASX2'® - 
 R3ASX2'' - 
 R4 AsX'^ 
 
 R^AsX'-^ 
 
 ^ Ibid., 107, 269. 
 
 Probable. 
 
 Evident in the presence of sodium. 
 
 12 Ann. Chem. (Liebig), 89, 330; 112, 231. 
 
 13 Ibid., 89, 330. 
 
 I'l Ibid., 112, 230. Compt. rend., 39, 541 ; 
 
 49, 87. This Journal., 33, 115. 
 
 13 Ann. Chem. (Liebig), 89, 311. 
 
Reactions of the Arsines. 
 
 89 
 
 It will be observed that columns (a) and (c) involve tri- 
 valent arsenic, and column (6) pentavalent arsenic. Now, 
 since it can be demonstrated that the compounds given are 
 really formed in the order indicated, it is concluded that 
 continuous progress through reactions I. to IV. involves a 
 regular alternation of tri~ and pentavalent arsenic. 
 
 This operation of a variable valency is further illustrated 
 by the following 
 
 Hydrogen-Halogen-Alkyl Series (B).^ 
 
 (a) (b) (c) 
 
 I. AsHj + RX RASH3X2 RASH2 + HX^ 
 
 II. AsHg + RX -> RAsHgX -> RAsHX + 
 
 III. RAsH^ + RX — ^ R^AsH^X® <- R^AsH + HX« 
 
 IV. RAsH^ + RX — > R^AsH^X R^AsX + 
 
 V. RAsHX + RX -> R^AsHXa* R2ASH + X2« 
 
 VI. RAsHX + RX -> R2ASHX2 — R2ASX + HX'o 
 
 VII. R2ASH + RX -> RgAsHX^ -> R3AS + HX'2 
 
 ' RgAsHX ^ RgAs + HX '3 
 
 VIII. R2ASX + RX -> R3ASX2'' -> R3AS + X2'« 
 
 R2ASX + RX R3ASX2'' R3AS + X2'’ 
 
 IX. R3AS + RX -> R^AsX'® 
 
 RgAs + RX ^ R4 AsX'» 
 
 From the fact that most of the indicated reactions have been 
 studied, and that their courses proceed as indicated by the 
 arrows, general reversibility of reaction is very improbable. 
 Reactions 1 (a) and 1 (c) both yield the same product. 
 
 H 
 
 } 
 
 X 
 
 RH2As\ , which decomposes as indicated in 11 ( 6 ). Reac- 
 
 tions III (a) and III(c) yield the compound R2HAs< 
 
 .H 
 
 x’ 
 
 ^ It may be observed here that arsenic, unlike nitrogen, has a greater affinity 
 for halogen than for hydrogen, and also for alkyl than for halogen or halogen acid. 
 2 Not studied, but very probable, from analogy to the formation of primary 
 
 arsine. 
 
 3 Vide This Journal, 33 , 126 ; see pages 107 and 115. 
 
 * Ibid. 
 
 ^ Vide ibid., 33 , 128; see page 107. 
 6 Vide ibid., 36 , 22-24. 
 
 T Ibid. 
 
 ® Not studied. 
 
 ® This Journal, 36 , 14-18. 
 
 10 Ibid. 
 
 12 Ibid. 
 
 13 Not studied, but very probable. 
 
 1^ This Journal, 36 , 1. 
 
 15 Ann. Chem. (Liebig), 112 , 228. 
 
 10 Evident in the presence of sodium. 
 11^ Ann. Chem. (Liebig), 112 , 228. 
 
 18 Ibid. 
 
 11 /6id.,36, 18-19;seepages 121, 122and 123. i* 89, 321. Also cf. page 112. 
 
90 
 
 Dehn. 
 
 and this decomposes as shown in IV(6). Reaction V(c) and 
 
 probably V(a) yield the product R2HAs<f , which decom- 
 
 poses as indicated in VI (6). Reactions VII (a) and VII (c) 
 
 /H 
 
 yield the compound RgAs^^ , which decomposes as repre- 
 sented in VII (6). Reactions VIII (a) and VIII (c) yield the 
 product RgAs^ , which probably reversibly decomposes as 
 indicated in Vlll(a). Reaction IX(a) yields the compound 
 
 A 
 
 RgAs^ , which decomposes as indicated in IX (6). 
 
 ^X 
 
 Now, since reactions 1 (a), Ill(a), Vll(a), and Vlll(a), 
 as well as IX (a), all yield the compound R4ASX in the pres- 
 ence of an excess of alkyl halide, it is concluded that the arson- 
 ium compound is formed by a series of intermediate reactions 
 involving molecular compounds which immediately or slowly 
 dissociate, and that the process is repeated until the stable end 
 products are formed} 
 
 As the result of a number of years of observation and study 
 of the reactions of arsenic, the conviction has grown that the 
 activity of this element cannot always be explained on the 
 basis either of ionic or of kinetic-molecular mechanics. Briefly 
 considered, this conviction has resulted from observation of 
 the facts (i) that most of the arsenic reactions are nonelectro- 
 lytic or, in other words, they take place in the absence of water 
 and (2) that, between the starting compounds and the most 
 easily separated end product, there are observed other and 
 
 1 Analogous alternations of valency and formation of intermediate compounds 
 are recognized in the reactions of the amine, phosphine, and stibine derivatives, as, 
 for instance: (1) in the Hoffmann series of reactions, when alkyl iodides and am- 
 monia are heated together and form a mixture of the four classes of amines; (2) when 
 alkyl iodides are heated with phosphonium iodide in the presence of zinc oxide and 
 form a mixture of primary and secondary phosphines; and (3) when alkyl iodides 
 are treated with sodium antimonides and form tertiary and quaternary stibines. 
 Ease of dissociation of the various molecular compounds determines the yields of the 
 respective derivatives ; in general, with the element nitrogen primary amines are formed 
 in greater quantity; with phosphorus, primary and secondary phosphines; and with 
 arsenic and antimony, the respective quaternary compounds are obtained in greater 
 quantity. 
 
Reactions of the Arsines. 
 
 91 
 
 usually crystalline products, which often can be separated and 
 analyzed. Mention of these intermediate products has been 
 made in previous contributions;^ a systematic study is made 
 herein to establish their frequent formation and to secure 
 evidence leading to the general conclusion that compounds 
 of the element arsenic react largely by initial coalescence with 
 the reagent. 
 
 Whereas the nitrogen-organic and the oxygen-organic 
 compounds yield intermediate products, their unstable proper- 
 ties and usually liquid condition prevent their easy and sys- 
 tematic study. The arsenic-organic compounds, on the other 
 hand, containing the heavy element arsenic, usually form 
 crystalline intermediate products which can often be separa- 
 ted and analyzed and therefore the arsenic derivatives offer a 
 productive field for the study of chemical statics and dynamics. 
 
 Let us consider first, by way of illustration, the spontaneous 
 oxidation of methylarsine by means of atmospheric oxygen : 
 
 CH3ASH2 + 02 = CH3ASO + H2O, 
 
 2CH3ASH2 + 3O2 = 2CH3AsO(OH)2. 
 
 The first reaction is instantaneous, but the second is in- 
 complete even after two weeks. 
 
 If applied here, Engler’s theory of autoxidation^ should 
 
 /O 
 
 involve an initial addition of a molecule of oxygen: RH2As<*^ |. 
 
 This “moloxide,” by elimination of water, gives the end 
 products, water and methylarsine oxide, RAs = 0. It is 
 not impossible, however, that the above peroxide form suffers 
 
 .OH 
 
 a molecular rearrangement into the compound RAs<^ 
 
 ^OH 
 
 before splitting off water; confirmation of the probable forma- 
 tion of an addition product of the arsine and oxygen was de- 
 duced (i) from the observed absence of condensed vapors of 
 water, proportional to the theoretical quantity, and (2) from 
 the slow formation of methylarsonic acid, which, in accord- 
 
 ^ See This Journal, 33, 101; 35, 1. J. Am. Chem. Soc., 28, 347. 
 
 ^ C. Engler und J. Weissberg: Kritische Studien tiber die Vorgange der Autoxy- 
 dation (1904), 63. 
 
92 
 
 Dehn. 
 
 ance with Engler’s theory, could be formed in the manner 
 indicated below: 
 
 (HO^RAs 
 
 'v 
 
 'O- 
 
 AsR(OH)2. 
 
 -q/ 
 
 The analogous autoxidations of secondary arsines^ are 
 easily accounted for in the same manner: 
 
 R,As — H 
 
 R,HAs/ 
 
 * S. 
 
 /O 
 
 R,As; 
 
 ''O 
 
 O— H 
 O 
 
 or 
 
 0 
 
 1 - 
 
 O 
 
 R, As — H 
 
 RjAsv 
 
 >0 4- H^O, 
 R,As/ 
 
 the addition of one molecule of oxygen to one molecule or to 
 two molecules of the arsine determining whether cacodylic 
 acid or cacodylic oxide is formed. ^ 
 
 The molecular rearrangement of the above-mentioned 
 /O yO 
 
 compounds, RHjAs/ \ and R2HAs< j , to form the compoimds 
 .OH .OH 
 
 R — As<Q and R2As:^ , necessitates a shifting of the hy- 
 ^OH ^O 
 
 drogen atoms^ and a rearrangement of the oxygen valencies, un- 
 less it is assumed that kinetic or ionic dissociations first take 
 place as indicated below: 
 
 H 
 
 H 
 
 R — As/ 
 
 O 
 
 ^O 
 
 H 
 
 and R — As 
 
 R 
 
 / 
 
 O 
 
 o 
 
 and that these dissociated parts readjust themselves. 
 
 1 This Journal, 35, 9. 
 
 * Usually the two compounds are formed in nearly equal quantities. This Jour- 
 nal, 35, 14. 
 
 3 Atomic shifting, an assumption not new in chemical statics and dynamics, can- 
 not, of course, be dispensed with as an explanation of many reactions, particularly 
 those included under tautomeric forms. 
 
Reactions of the Arsines. 
 
 93 
 
 The latter hypothesis is unnecessary and, in fact, is untena- 
 ble because it assumes an effect without providing a probable 
 cause. We have only to conceive that the atoms of hydrogen, 
 by virtue of kinetic motion and while being continuously 
 held within the spheres of attraction,^ pass to the intersection 
 of the spheres of oxygen and arsenic attractions (Fig. I.), 
 and then beyond the appreciable attraction of arsenic (Fig. 
 II.). In this manner we come to an easy understanding of 
 atomic shifting without employing any new theories or re- 
 sorting to other than the fundamental assumptions of the 
 science. 
 
 Fig. I. Fig. II. 
 
 That molecular coalescence is the inevitable preliminary con- 
 dition of arsine reactions is confirmed by the behavior of di- 
 methylarsine with nitric acid.^ Normal nitric acid (i mol.) 
 does not react with the arsine although the mixture is heated 
 for one hour at 125°; concentrated nitric acid (i mol.) reacts 
 with explosive violence. In the former case, the nitric acid 
 is ionized) in the latter, its condition is molecular. In other 
 words, the compound H — O — NO2 has, but the group — O — NOj 
 has not, the property of adding to the arsine and of yielding 
 the end product, cacodylic acid. If the doubly bound oxygen 
 atoms of the nitrate group were the active portion, then both 
 ionic and molecular nitric acid should react; however, since 
 only molecular nitric acid reacts, only the H — O — N part of 
 the acid offers hope of a satisfactory explanation. If initial 
 molecular coalescence is the indispensable criterion, then the 
 following preliminary mechanics are conceivable: 
 
 1 Mechanical arrangements and invariability of quantity and position are, of 
 course, improbable conceptions of valency. 
 
 2 This Journal, 36, 27. 
 
94 
 
 Dehn. 
 
 R,As — H 
 
 II R^As— H 
 
 II ^ hq/^no, ’ 
 
 H— O — NO, 
 
 dimethylarsine nitrate^ being first formed. 
 
 Since the formation of the analogous arsine salt, 
 
 [(CH3),AsH]2.H,SO„ 
 
 was proven in the case of sulphuric acid,* the probable forma- 
 
 1 Objections may be raised as to the structure of this salt, on the grounds that 
 it is not strictly analogous to the structme of ammonium nitrate, H 4 N — O — NO 2 : how- 
 ever, there is no evidence that these salts are strictly analogous. The fact that hy- 
 droxyl attached to arsenic constitutes a more stable combination than hydrogen 
 attached to arsenic, the reverse being true in the case of nitrogen, argues a difference 
 in these salts. 
 
 Since, in the case of ammonia and hydrochloric acid, at least a trace of water 
 is necessary (Hughes; Phil. Mag., 36, 53; Baker; J. Chem. Soc., 65 , 611) to form am- 
 monium chloride, it is usually held that ionized hydrochloric acid adds to ammonia; 
 of course, kinetic dissociation is precluded for the reason that hydrochloric acid does 
 not begin to dissociate below 1000® (Ber. d. chem. Ges., 6 , 423). However, initial 
 ionic or kinetic dissociations are not the only possible explanations of these phenomena ; 
 the water that is necessary may add in the following manner; 
 
 H 
 
 I 
 
 H3N=- =0 — NH4OH ; 
 
 H 
 
 and then the acid and base may react, either through their ions, or as indicated be- 
 low; 
 
 Cl 
 
 I 
 
 H4N — 0= =C 1 — >- H4N— O— H — H4N — Cl -h HOH. 
 
 H H H 
 
 That the ions of water first add to ammonia is rendered improbable from the fact 
 that NHi itself is not an ion. 
 
 When water acts on calcium oxide and other oxides of both metals and nonmetals, 
 it is difficult to conceive of the mechanics of the action on the basis of ionization since 
 the oxides themselves are not ions and water is ionized to the extent of only 2 mg. 
 of hydrogen to a ton of water. Furthermore, kinetic action is precluded because 
 water does not decompose below 1000°. In accordance with the above principles, 
 however, the action is readily explained as follows; 
 
 /OH 
 
 Ca=0= = 0 — H — >- Ca( 
 
 I ^OH 
 
 H 
 
 Whereas molecular affinity is recognized in hydrated salts and other compounds, 
 its rational apphcation here necessitates an assumption of the tetravalency of oxygen. 
 The position of oxygen in the periodic system, the variability of valency of its closest 
 analogue, sulphur, and the necessary postulate of a higher valency of oxygen to ex- 
 plain water of crystalUzation and the addition products of alcohols, ethers, etc., 
 clearly entitles oxygen to an occasional higher valency than two. 
 
 2 This Journal, 35, 24. 
 
Reactions of the Arsines. 
 
 95 
 
 tion of the nitrate is easily deduced. The sulphate gave, as 
 the main end products, cacodyl sulphide (and cacodylic acid), 
 
 (CH,),As— H 
 
 i\ 
 
 therefore, the structure ^ q ^SO., is probable, sul- 
 
 1/ 
 
 (CH3),As-H 
 
 phur being hound to arsenic. Analogously, nitrogen is prob- 
 ably hound directly to arsenic, as is shown in the formula 
 (CH,),As-H 
 
 /\ . Under the influence of heat' (internal kinetic 
 
 H— O NO 2 
 
 dissociation), this compound could split off nitrous acid. 
 
 (CH3)2As H 
 
 I 
 
 O 
 
 (CH3)2As 4- H 
 
 I 
 
 O , 
 
 HO 
 
 NNO 
 
 H— O 
 
 NO 
 
 forming dimethylhydroxylarsine,^ which would react with 
 more nitric acid, as follows: 
 
 (CH3)3As— O— H 
 
 II 
 
 >0 
 
 ^O 
 
 H— O— N 
 
 (CH3)3As— OH 
 
 /\ 
 
 / \ 
 
 HO Nf 
 
 (CH3),As = 0- — H -> (RH,)3As = 0 H 
 
 /\/ ^ I ? 
 
 H— O N = 0 H— O N = 0; 
 
 and thus satisfactorily explain the formation of cacodylic 
 acid, the main end product. 
 
 The above described action of nitric acid illustrates that 
 
 1 It must be remembered that dissociations may be induced not only by heat, 
 light, and other forces, but also by various reagents. Since the latter really involve 
 other chemical changes the term dissociation is used herein to indicate decompositions 
 induced by heat only. 
 
 ^ This compound probably has no separate existence since, under conditions 
 favoring its formation, its anhydrous form, cacodylic oxide, R 2 ASOASR 2 , is always 
 obtained (Baeyer: Ann. Chem. (Liebig), 107 , 282). However, since cacodylic oxide 
 is proved (This Journal, 35 , 9-14) to be an oxidation product of dimethylarsine 
 the above conclusions are justified. 
 
96 
 
 Dehn, 
 
 the process of oxidation is conditioned, not by the mere presence 
 of oxygen but by a facility of coalescence of the reagent with the 
 substance] in other words, the reducing power of the arsines 
 and their derivatives is conditioned by a capacity for pre- 
 liminary molecular linking; at any rate, most reduction pro- 
 cesses of the arsines thus far studied^ have yielded initial molec- 
 ular aggregates, or have given evidence of their formation. 
 
 A striking example of this action of the arsenic atom is 
 observed in the formation of arsonic acids, when sodium 
 arsenite is treated with alkyl iodides. The reaction 
 
 NagAsOg -f RI RAsOgNa^ + Nal 
 
 was discovered by Meyer^ and was described by him as “an 
 anomalous reaction,” because by “double decomposition” it 
 was expected that an alkyloxy compound would be formed. 
 However, it was found that the alkyl group combines di- 
 rectly with the arsenic. This is easily explained on the basis- 
 of initial molecular attraction; the arsenite and the halide 
 uniting, rearranging, and decomposing as follows: 
 
 NaO. /O— Na „ 
 
 NaO— As= =1— R — > >As— I — >Asf .. 
 
 Nao/ NaO/ ■ NaO/ \r 
 
 Thus it is seen that instead of being an “anomalous reaction’^ 
 it may be considered a beautiful example of the normal reaction. 
 
 From the foregoing it is concluded that many reactions of 
 the arsine compounds can best be explained by making the 
 following assumptions: 
 
 1. Unsaturated valencies (partial or latent valencies) in, 
 both substances; 
 
 2. Molecular coalescence of the two substances; 
 
 3. A condition of instability established in the molar ag- 
 gregate, owing to this distribution of the total valencies of the 
 nuclear elements, and thus inducing either 
 
 4. A tendency toward reversible reaction or 
 
 5. A tendency toward rearrangement; and finally, 
 
 J See page 97. 
 
 2 Ber. d. chem. Ges., 16, 1441. 
 
Reactions of the Arsines. 97 
 
 6. A dissociation of the molar aggregate into its more 
 stable components. 
 
 • EXPERIMENTAL. 
 
 7 . Electrolytic Reduction of Arsine Derivatives. 
 
 These experiments were undertaken for the purpose of 
 demonstrating the formation of intermediate products when 
 alkyl arsenic derivatives are reduced to free arsines. It was 
 found hitherto that the final reduction product of both cacodyl 
 chloride^ and cacodyP is dimethylarsine ; it is now proposed 
 to show that cacodyl is an intermediate product of the reduc- 
 tion of cacodyl chloride, and that the successive reactions are 
 as follows : 
 
 2 (CH3)2 AsC1 + 2H = (CH3)2As— As(CH 3)2 -f 2HCI, 
 
 (CH3)2 As— As(CH3)2 -f- 2H = 2(CH3)2 AsH. 
 
 After a number of unsuccessful experiments with porous cells 
 used to keep the anode and cathode solutions separate, a cell was 
 devised which was found most convenient, not only for ob- 
 serving the progress of the reductions but also for experiment- 
 ing with small quantities of material. The apparatus used 
 is shown in Fig. III. 
 
 The other details are as follows: (a) platinum cathode 
 spiral, (b) porous clay partition, (c) a packed asbestos ring, 
 (d) platinum anode plate, (e) glass support for the anode plate, 
 (/) exit for anode gas and intake for anode solution, (g) drain 
 for anode solution, (h) exit for cathode gas, (i) intake for 
 cathode solution. 
 
 Method of Using. — The cathode solution first used was pre- 
 pared by mixing 5 grams of cacodyl chloride, 90 grams of 
 formic acid, and 8 grams of alcohol; its specific gravity was 
 1.08. An anode solution of the same specific gravity was 
 prepared from sulphuric acid. After sufficient anode solu- 
 tion and II cc. of cathode solution were run into the reduc- 
 tion cell and all the parts of the apparatus were adjusted, a 
 current of 5 to 6 volts and o . 5 to o . 6 ampere was turned on. The 
 cathode solution clouded almost immediately and after 500 
 
 1 Ber. d. chem. Ges., 27, 1378. 
 
 ^ This Journal, 36, 3. 
 
98 
 
 Dehn. 
 
 cc. of electrolytic hydrogen had been evolved in the voltameter, 
 a heavy oil was found to have separated in the cell and a 
 spontaneously inflammable gas began to be evolved with the 
 cathode hydrogen — this gas increased in concentration during 
 the remainder of the reduction. The oil, insoluble in formic 
 acid, was identified as cacodyl; the gas was found to be di- 
 methylarsine ; hence the above equations are established. 
 
 A. A Hofmann U-tube placed in series with the cell and used as a hydrogen volta- 
 meter. 
 
 B. The reduction cell, made of glass. 
 
 C. Apparatus used to measure the gas evolved at the cathode and subsequently 
 
 to deliver into Hempel burettes (at point fe). 
 
 The following experiment was undertaken for the purpose 
 of determining the relative rates of reduction of cacodyl chlor- 
 ide to cacodyl, and of the latter to dimethylarsine : 
 
 The cathode solution was prepared by dissolving 9 . i grams 
 of cacodyl chloride in a mixture of 90 cc. of alcohol and 25 cc. 
 of hydrochloric acid (sp. gr. 1.2); one fifth of this solution 
 and a current of 5 to 6 volts and 1.05 to 1.20 amperes were 
 used for the reduction. When exactly 50 cc. of hydrogen had 
 
Reactions of the Arsines. 
 
 99 
 
 been evolved in the voltameter (II.) , the current was turned 
 off and the volume of mixed gases (III.) evolved from the 
 cathode solution was measured in the apparatus C; the gas 
 was next drawn over into a Hempel burette containing silver 
 nitrate solution and, after shaking, the volume of the residual 
 gas (unfixed hydrogen) was measured (V.) The loss in vol- 
 ume at this point represented an equivalent volume of di- 
 me thylarsine gas and one half of this volume was equivalent 
 to the volume of hydrogen fixed by dime thylarsine. Fifty 
 cc. of hydrogen, minus the volume of unfixed residual hydro- 
 gen and the hydrogen fixed by dimethylarsine, represented the 
 volume of hydrogen fixed by cacodyl, according to the equation 
 
 2(CH3)2AsC1 + H2 = [(CH3)2As] 2 -h 2HCI. 
 Reduction of Cacodyl Chloride. 
 
 I. 
 
 II. 
 
 III. 
 
 IV. 
 
 50 cc. minus 
 
 V. 
 
 Residual 
 
 VI. 
 
 Di- 
 
 VII. 
 
 Hydrogen 
 
 VIII. 
 
 Hydrogen 
 
 No* of ex- 
 
 Total hy- 
 
 Burette 
 
 burette 
 
 gas 
 
 methyl- 
 
 fixed by 
 
 fixed by 
 
 periment. 
 
 drogen. 
 
 gas. 
 
 gas. 
 
 (AgNOs). 
 
 arsine. 
 
 (CH3)2AsH. 
 
 cacodyl. 
 
 I 
 
 50 
 
 2.5 
 
 47.5 
 
 2.5 
 
 0.0 
 
 0.0 
 
 47.5 
 
 2 
 
 100 
 
 5.1 
 
 44-9 
 
 50 
 
 0. I 
 
 0.0 
 
 450 
 
 3 
 
 150 
 
 7-9 
 
 42.1 
 
 7-9 
 
 0.0 
 
 0.0 
 
 42.1 
 
 4 
 
 200 
 
 II. 9 
 
 38.1 
 
 II. 8 
 
 0. I 
 
 0. 1 
 
 38.1 
 
 5 
 
 250 
 
 15.9 
 
 34-1 
 
 15-7 
 
 0.2 
 
 0. 1 
 
 34-2 
 
 6 
 
 300 
 
 20.4 
 
 29.6 
 
 19.7 
 
 0.7 
 
 0-3 
 
 30.0 
 
 7 
 
 350 
 
 25.0 
 
 25.0 
 
 24.2 
 
 0.8 
 
 0.4 
 
 25-4 
 
 8 
 
 400 
 
 304 
 
 19.6 
 
 293 
 
 I . I 
 
 0.6 
 
 20. 1 
 
 9 
 
 450 
 
 36.3 
 
 137 
 
 34-3 
 
 2.0 
 
 1 .0 
 
 14-7 
 
 10 
 
 500 
 
 413 
 
 8.7 
 
 38.9 
 
 2.4 
 
 I .2 
 
 9 9 
 
 II 
 
 550 
 
 44-5 
 
 5-5 
 
 40.5 
 
 4.0 
 
 2.0 
 
 7-5 
 
 12 
 
 600 
 
 45-3 
 
 4.7 
 
 39-6 
 
 5.7 
 
 2.9 
 
 7-5 
 
 13 
 
 650 
 
 47-5 
 
 2.5 
 
 40.4 
 
 7.1 
 
 3-6 
 
 6.0 
 
 14 
 
 700 
 
 48.6 
 
 1.4 
 
 41.2 
 
 7-4 
 
 3-7 
 
 51 
 
 15 
 
 750 
 
 50.1 
 
 — 0. 1 
 
 40.9 
 
 9.2 
 
 4.6 
 
 4-5 
 
 16 
 
 800 
 
 50.8 
 
 —0.8 
 
 40.7 
 
 10. 1 
 
 51 
 
 4.2 
 
 17 
 
 850 
 
 52.2 
 
 — 2 . 2 
 
 41.9 
 
 10.3 
 
 5-2 
 
 2.9 
 
 18 
 
 900 
 
 52.2 
 
 — 2 . 2 
 
 42 . 2 
 
 10. 0 
 
 50 
 
 2.8 
 
 19 
 
 950 
 
 52.4 
 
 —2.4 
 
 42 . 2 
 
 10 . 2 
 
 51 
 
 2.7 
 
 20 
 
 1000 
 
 52.2 
 
 — 2 . 2 
 
 42.1 
 
 10. 1 
 
 50 
 
 2.9 
 
 22 
 
 1 100 
 
 52.0 
 
 — 2 .0 
 
 42.8 
 
 9.2 
 
 4.6 
 
 2 . 6 
 
 24 
 
 1200 
 
 51.0 
 
 — 1 .0 
 
 43-9 
 
 7.1 
 
 3-5 
 
 2 . 6 
 
 26 
 
 1300 
 
 50.9 
 
 —0.9 
 
 45-1 
 
 5.8 
 
 2.8 
 
 2 . 1 
 
 28 
 
 1400 
 
 510 
 
 — 1 .0 
 
 45-9 
 
 51 
 
 2 . 6 
 
 1-5 
 
 30 
 
 1500 
 
 515 
 
 — 1-5 
 
 47.0 
 
 3-5 
 
 1-7 
 
 13 
 
 32 
 
 1600 
 
 50.7 
 
 — 0.7 
 
 48 . 2 
 
 2-5 
 
 1 . 2 
 
 0.6 
 
 34 
 
 1700 
 
 50.1 
 
 — 0. 1 
 
 49.0 
 
 I . I 
 
 0.6 
 
 0.4 
 
lOO 
 
 Dehn. 
 
 It may be observed in the table: that the volume of gases 
 evolved from the cathode solution, at first, is much less than 
 the volume of the voltameter hydrogen collected during the 
 same interval of reduction; then, at about the middle of the 
 series of reductions, it becomes equal to the voltameter hy- 
 drogen ; during most of the remainder of the reductions, the 
 cathode gas volume is greater than the voltameter hydrogen; 
 but finally, it becomes just equal to it. When cacodyl alone 
 is formed, the residual hydrogen must be less than the volt- 
 ameter hydrogen, owing to the fixing of hydrogen (the product 
 being hydrochloric acid), as shown in the above equation. 
 When dimethylarsine alone is formed by the reaction, 
 
 (CH3)3As-As(CH3)3 + H3 = 2(CH3)3AsH, 
 
 the total volume of gas evolved must be greater than the volt- 
 ameter hydrogen — two volumes of arsine resulting from one 
 volume of hydrogen. Therefore, when both cacodyl and di- 
 methylarsine are being formed, the burette gas represents 
 the algebraic sum of these two reductions; and, depending 
 upon the proportion of the two products, may be less or greater 
 than the voltameter hydrogen. With the cubic centimeters 
 of “fixed” hydrogen as ordinates and the quantity of elec- 
 tricity, measured in 50 cc. of hydrogen, as abscissas, (i) 
 the composite curve of reduction, (2) the dimethylarsine 
 curve, and (3) the cacodyl curve may be plotted, as shown 
 in Fig. IV. 
 
 It will be seen that when the composite curve of reduction 
 crosses the base line, the quantity of arsine is just twice that 
 of the cacodyl. 
 
 As plotted, the area included within the cacodyl and di- 
 methylarsine curves represents the total quantity of hydrogen 
 fixed", the area included between the base line and a parallel 
 line at 50 cc. represents the total electrolytic hydrogen. 
 
 From a consideration of the above experiments it may be 
 anticipated that when cacodyl itself is reduced, the composite 
 curve of reduction becomes coincident with the dimethylarsine 
 curve. This is confirmed by the following experiment. A cathode 
 solution was prepared by dissolving 5 cc. of crude cacodyl 
 
Reactions of the Arsines. 
 
 lOI 
 
 in a mixture of 50 cc. of alcohol and 25 cc. of hydrochloric 
 acid (sp. gr. 1.20). With a current of 5 to 6 volts and i.o 
 to o . 6 ampere, 20 cc. of this solution were reduced in the man- 
 ner described above. 
 
 Reduction of Cacodyl. 
 
 I. 
 
 II. 
 
 III. 
 
 IV. 
 
 50 cc. minus 
 
 V. 
 
 Residual 
 
 VI. 
 
 Number of 
 
 Total 
 
 Burette 
 
 burette 
 
 gas 
 
 Dimethyl- 
 
 experiment. 
 
 hydrogen. 
 
 gas. 
 
 gas. 
 
 (AgNOs). 
 
 arsine. 
 
 I 
 
 50 
 
 36.0 
 
 14.0 
 
 36.0 
 
 0.0 
 
 2 
 
 100 
 
 37-4 
 
 12.6 
 
 37-3 
 
 0. I 
 
 3 
 
 150 
 
 38.9 
 
 II . I 
 
 38.5 
 
 0.4 
 
 4 
 
 200 
 
 40.3 
 
 9-7 
 
 39-6 
 
 0.7 
 
 5 
 
 250 
 
 41 . 8 
 
 8.2 . 
 
 41. 1 
 
 0.7 
 
 6 
 
 300 
 
 43-6 
 
 6.4 
 
 42 . 6 
 
 I .0 
 
 7 
 
 350 
 
 46.2 
 
 3.8 
 
 44.8 
 
 1.4 
 
 8 
 
 400 
 
 47.6 
 
 2.4 
 
 45-7 
 
 1-9 
 
 9 
 
 450 
 
 49 I 
 
 0.9 
 
 46.6 
 
 2.5 
 
 10 
 
 500 
 
 50.4 
 
 — 0.4 
 
 47.0 
 
 3-4 
 
 II 
 
 550 
 
 52.0 
 
 2 .0 
 
 48 .0 
 
 4.0 
 
 12 
 
 600 
 
 52.8 
 
 —2.8 
 
 49 0 
 
 3-8 
 
 13 
 
 650 
 
 540 
 
 —4.0 
 
 49.0 
 
 50 
 
 14 
 
 700 
 
 550 
 
 —5.0 
 
 49.8 
 
 5-2 
 
 15 
 
 750 
 
 55-6 
 
 —5.6 
 
 50.1 
 
 5-5 
 
102 
 
 Dehn. 
 
 Reduction of Cacodyl — {Continued), 
 
 Number of 
 experiment. 
 
 16 
 
 17 
 
 18 
 20 
 22 
 24 
 
 26 
 
 28 
 
 30 
 
 II. 
 
 Total 
 
 hydrogen. 
 
 800 
 850 
 900 
 1000 
 1 100 
 1200 
 1300 
 1400 
 1500 
 
 III. 
 
 Burette 
 
 gas. 
 
 55-9 
 
 55.8 
 
 55-7 
 55 I 
 53-9 
 
 52.8 
 
 51.8 
 
 50.8 
 50.2 
 
 IV. 
 
 V. 
 
 50 cc. minus Residual 
 
 burette 
 
 gas. 
 
 —5-9 
 
 —5.8 
 
 —5-7 
 
 —51 
 
 —3-9 
 — 2 . 8 
 —1.8 
 —0.8 
 +0.2 
 
 gas 
 
 (AgNOs). 
 
 50 
 
 50 
 
 50 
 
 50 
 
 49 
 
 49 
 
 49 
 
 49 
 
 50 
 
 VI. 
 
 Dimethyl- 
 
 arsine. 
 
 5-6 
 5-5 
 5-4 
 4.6 
 4.0 
 30 
 2 .0 
 0.9 
 o. I 
 
 That the burette readings were not immediately greater 
 than the voltameter readings or, in other words, that the com- 
 posite curve of reduction was not more nearly coincident 
 with the dimethylarsine curve, is explained by the facts (i) 
 that it is almost impossible to prepare and to handle pure 
 cacodyl without its becoming oxidized, (2) crude cacodyl 
 contains large quantities of cacodylic oxide, and (3) dimethyl- 
 arsine is somewhat soluble in the above mentioned cathode 
 
Reactions of the Arsines. 
 
 103 
 
 solution. However, the curves show sufficiently well that 
 cacodyl is electrolytically reduced to dimethylarsine. 
 
 In view of the above experiments and since dimethylarsine 
 is easily prepared from cacodylic acid by reduction with zinc 
 and hydrochloric acid, it might be supposed that the elec- 
 tric current would induce the same reaction: 
 
 (CH3)2 AsOOH + 4H = (CH3)2 AsH + 2H2O. 
 
 However, experiments showed that no arsine was evolved; 
 an explanation of this is seen in the following equations: 
 
 (CH3)2As02H = (CH3)2As03 + H, 
 
 2(CH3)2As02 + H 2 O = 2(CH3)2As 02H -f O. 
 
 11. Primary Arsines. 
 
 With Elrick Williams. 
 
 Studies with Gaseous Primary Meihylarsine. 
 
 The sodium salt of methylarsonic acid^ was reduced by zinc 
 and hydrochloric acid- and the mixture of hydrogen and gas- 
 eous methylarsine was passed into a large bottle filled with water 
 and so arranged that the gaseous mixture could both be pre- 
 served free from oxidation and also so that portions of it, 
 as desired, could be drawn off into Hempel burettes. Usually 
 the gaseous mixture was drawn out by depressing the com- 
 panion tube of the Hempel burette; then boiled water was 
 permitted to run into the gas reservoir, so as to equalize the 
 interior and exterior pressures. Samples of the gas in the 
 Hempel tube were treated with solutions as indicated in the 
 following table of preliminary experiments; from time to time 
 the concentration of the arsine in the reservoir was determined 
 by treatment with silver nitrate solution.^ 
 
 1 Ann. Chem. (Liebig), 249, 147. 
 
 2 This Journal, 33, 120. 
 
 » Ibid., 33, 125. 
 
104 
 
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Reactions oj the Arsines. - 105 
 
 Interpretations of the above data render probable the fol- 
 lowing equations: 
 
 1. 6KMn04 + 5 RASH 2 = 
 
 6MnO + 3RASO3K2 + 2RASO3H2 + 3H2O. 
 
 2. 6KMn04 + 5RASH2 = 
 
 qMnO + 3RASO3K2 + 2RAs03Mn H- 5H2O. 
 
 3. 4K3Fe(CN)« + RASH2 + H2O = 
 
 3K4Fe(CN)6 + H4Fe(CN)e + RAsO.^ 
 
 4. 4FeCl3 + RASH2 + H2O = 4FeCl2 + 4HCI RAsO.^ 
 
 5. 4Pb(AC)2 RASH2 + 3H2O = 
 
 3Pb + 8HC2H3O2 + RAsOgPb.^ 
 
 6. K2Cr207 + RASH2 = (See This Journal, 35, 28). 
 
 7. 6H2Cr04 + 2RASH2 = 
 
 3(2Cr02.H20) + 2RASO3H2 + 3H20.^ 
 
 8. 2H2O2 + RASH2 = RAsO + 3H2O. 
 
 9. 3Br2 + RASH2 + 3H2O = RASO3H2 + 6HBr.'‘ 
 
 10. HgCl2 + RASH2 = RAsHHgCl.HCl (etc.).' 
 
 11. CUSO 4 + RASH 2 = RAsH2.CuS04(?), 
 
 12. 6HNO2 + RASH2 = RASO3H2 4 - 6NO + 3H20.« 
 
 13. H2SO4 + RASH2 = RASH2.H2SO4.’ 
 
 14. HNO3 + RASH2 = (See This Journal, 33, 125; 35, 27). 
 
 15. SbCl3 + RASH2 = (Seepage 112). 
 
 16. ASCI3 + RASH2 = Seepage iii). 
 
 17. (CH3)2AsC 1 + RASH2 = (See page 122). 
 
 18. (CH3)2AsiVs (0113)2 + RASH2 = No reaction. 
 
 19. SnCl4 + RASH2 = (Seepage no). 
 
 20. PCI3 -f RASH2 =*= (Seepage in). 
 
 21. S2CI2 + RASH2 = RASCI2 + S + H2vS.« 
 
 22. SO2 + RASH2 = (See This Journal, 35, 38). 
 
 23. Pb02 + RASH2 = (See This Journal, 35, 30). 
 
 1 Cf. This Journal 35 , 35. 
 
 2 Ibid., 35 , 30. 
 
 3 Ibid., 35 , 28 . 
 
 “ 33 , 126 ; 35 , 14 . 
 
 ^Ibid., 33 , 127 ; 35 , 35 . 
 
 Ibid., 35 , 26 . 
 
 7 Ibid., 35 , 24 . 
 
 ^ Ibid., 35, 39. 
 
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Reactions of the Arsines. 
 
 107 
 
 Hydriodic Acid and Methylarsine. — A mixture of 50.4 cc. 
 of gaseous methylarsine (8.1 cc.) and hydrogen (42.3 cc.), 
 treated over mercury with i cc. of concentrated aqueous hy- 
 driodic acid, increased 2 cc. in volume in 20 minutes; after 
 heating for 20 minutes more at 100°, an increase of 10.9 cc. 
 in volume resulted. The gaseous mixture, after cooling to 
 the original temperature, was treated with a solution of silver 
 nitrate — a decrease in volume of 6.7 cc. resulted. From these 
 experiments it is concluded that the following reactions are 
 slow^ or are easily reversible: 
 
 CH3ASH2 + HI CH3ASH3I — ^ CH3ASHI + H2, 
 
 CH3ASHI + HI CH3ASH2I2 CH3ASI2 + H2. 
 
 Propyl Iodide and Methylarsine. — When a gaseous mixture of 
 75.5 cc. of methylarsine (lo.i cc.) and hydrogen (63.4 cc.), with 
 I cc. of liquid n-propyl iodide, was heated for one hour at ioo° 
 in a mercury eudiometer, a decrease in volume of 4 cc. was ob- 
 served on cooling to the original temperature. When treated 
 with silver nitrate solution, the residual gas suffered a loss of 
 5.8 cc. (unchanged methylarsine). During the experiment, 
 light yellow crystals (melting below 100°) were observed on the 
 walls of the eudiometer; therefore the following equation is 
 justified 
 
 CH3ASH2 + C3H7I (CH3)(C3H7)AsH2l. 
 
 Silver Nitrate and Methylarsine.^ — The black precipitate in a 
 gas burette, after treatment of a silver nitrate solution with 
 quantities of methylarsine, was washed with water and dried at 
 100°. 
 
 0.5439 gram of substance gave 0.4430 gram of AgCl. 
 
 , Calculated for 
 
 CH 8 As 03 Ag 2 . Found. 
 
 Ag 60 .69 79 . 90 
 
 Since methylarsonic acid was found in the precipitate, the 
 latter is evidently a mixture of metallic silver and silver methyl- 
 arsonate. 
 
 1 Cf. This Journal, 36 , 27. 
 
 2 Addition products are almost invariably observed when primary, secondary, 
 and tertiary arsines are treated with alkyl iodides. Cf. This Joxjrnal, 33 , 128, and 
 see pages 121, 122, and 123. 
 
 3 Cf. This Journal, 33 , 126; 36 , 35. 
 
io8 
 
 Dehn. 
 
 Methylarsine Oxide and Methylarsine. — When the white 
 methylarsine oxide, formed on the walls of a Hempel burette 
 by the reaction of atmospheric oxygen with methylarsine, was 
 treated with gaseous methylarsine, all of the methylarsine was 
 fixed and a brick red solid replaced the white oxide. Evi- 
 dently the following reaction : 
 
 2CH3ASO -f 2CH3ASH2 -> (CH3 As)4 - 1 - 2H2O; 
 
 explains the formation of the red polymers always formed 
 by the spontaneous oxidation of the arsines. The details of the 
 reaction are shown as follows : 
 
 CH,— As =0 CH3— As— OH CH,— As 
 
 !! -> I -^1 +H,0; 
 
 CH3— As^H^ CH,— As— H CH3— As 
 
 two groups, CH3 — As — As — CH3, condensing and evidently 
 forming CH3 — As — ^As — CH3 
 
 CH,— As— As— CH3’ 
 
 The following substances failed to react with gaseous methyl- 
 arsine: hydrogen sulphide, yellow ammonium sulphide, potas- 
 sium nitrite, potassium hydroxide, nickelous chloride, formal- 
 dehyde, acetic acid, aniline, nitrobenzene, and benzotrichloride. 
 
 Reactions of Ethylarsine. 
 
 Iodine, — When equimolecular quantities of the two substances 
 were brought together in a sealed tube containing ether, the 
 color of the iodine was quickly discharged and a golden yellow 
 solution resulted. Hydrogen and an oil boiling at 205® to 210® 
 and containing 63.8 per cent of iodine (calculated for CjHjAsI,' 
 is 70.9 per cent) were obtained. The following equation is 
 justified : 
 
 C3H3ASH3 + I3 =- C3H3ASI3 + H^. 
 
 Bromine. — When equimolecular quantities of ethylarsine 
 and bromine were brought together in ether, a red brown, amor- 
 phous solid was formed immediately and remained permanently 
 (one year) undissolved. Considerable pressure (hydrogen) 
 
 Ann. Chem. (Liebig), Hi, 367. 
 
Reactions of the Arsines. 
 
 109 
 
 was observed on opening the tube; the ether solution yielded, by 
 distillation, an oil, ethylarsine dibromide, boiling at 192°. 
 
 0.4120 gram substance gave 0.5812 gram AgBr. 
 
 Calculated for 
 
 C2H5AsBr2. Found. 
 
 Br 60.60 60.03 
 
 When treated with platinic chloride the dibromide liberated 
 heat and slowly formed yellow white crystals, which were dried 
 on the water bath and ignited. 
 
 0.8622 gram substance gave 0.2700 gram Pt. 
 
 Calculated for 
 
 C2HBAsBr2.PtCl4.i Found. 
 
 Pt 32.68 31.31 
 
 The brown residue from the sealed tube experiment was 
 analyzed : 
 
 o. 1865 gram substance gave 0.0260 gram AgBr. 
 
 0.2106 
 
 i < < 
 
 “ 0 . 2247 gram Mg2As207. 
 
 
 Calculated for 
 
 
 
 (C2H5As)4. 
 
 C2H5AsHBr. 
 
 Found. 
 
 Br 
 
 0.00 
 
 > 43-24 
 
 10.25 
 
 As 
 
 72.11 
 
 40.54 
 
 51.62 
 
 Evidently this shbstance is a mixture. The end reaction of the 
 arsine with bromine is as follows : 
 
 C2H5ASH2 + Br2 = C 2 H 5 AsBr 2 + H2; 
 while positive evidence of intermediate products is deduced. 
 
 Sulphur . — When 2 grams of ethylarsine (i mol.) and 1.2 
 grams of sulphur (2 atoms) were brought together in a sealed 
 tube filled with carbon dioxide, the sulphur was seen to dissolve 
 rapidly, and to yield a viscid, colorless liquid. On opening the 
 tube, great pressure (hydrogen sulphide, but no hydrogen) was 
 observed. The percentage of sulphur in the gluelike mass was 
 determined : 
 
 0.1962 gram substance gave 0.3475 gram BaS04. 
 
 Calculated for 
 
 CJH5ASS2. C2H6ASS. Found. 
 
 s 38.09 23.52 24.28 
 
 1 Cf. This Journal, 36, 32. 
 
no 
 
 Dehn. 
 
 Evidently the substance is ethylarsine sulphide with an admix- 
 ture of free sulphur or the disulphide, and the original reaction 
 is as follows: 
 
 C2H5ASH2 + 82 = C2H5ASS + HgS. 
 
 Mercuric Chloride. — When equimolecular quantities of the 
 two substances were brought together in a sealed tube filled 
 with carbon dioxide, a dark yellow black precipitate formed im- 
 mediately. and changed after a time to a compact, finely divided, 
 black precipitate. On opening the tube no hydrogen or mer- 
 curous chloride, but gaseous hydrochloric acid and metallic 
 mercury were found. An ether solution of the oil became 
 yellow red in the air and ethylarsine dichloride was detected in 
 the ether solution, therefore the final reaction is expressed by 
 the following equation 
 
 C2H5ASH2 + 2HgCl2 = C2H5ASCI2 + 2Hg + 2HCI. 
 
 Mercuric Iodide. — When 2.5 grams of ethylarsine (i mol.) 
 and 10.7 grams of mercuric iodide (i mol.) were brought to- 
 gether in ether contained in a sealed tube, a bright yellow product 
 was formed immediately. On opening the tube hydrogen, mer- 
 curous iodide (4 grams — calculated, 7.7 grams), and an oil (5.7 
 grams) were obtained ; the oil showed the presence of ethylarsine 
 diiodide, therefore the reaction here is as follows : 
 
 C2H,AsH 2 + 2Hgl2 = C2H5ASI2 + 2HgI + H3. 
 
 Stannic Chloride. — When 2.14 grams of ethylarsine (i mol.) 
 and 5.9 grams of stannic chloride (i mol.) were sealed with 
 ether in a tube, no solid formed even after standing for 14 
 months. No pressure was observed on opening the tube; the 
 greenish yellow solution was concentrated and then treated 
 with water; the aqueous solution contained the Sn" ion and 
 the oil separating was found to distil at 156° (ethylarsine di- 
 chloride boils at 156°).^ The formation of the end products is 
 explained by the equation 
 
 C2H5ASH2 + 2SnCl4 = C2H5ASCI2 + 2SnCl2 + 2HCI, 
 
 1 See page 104, and cf. This Journal, 33, 127; 35, 35. 
 
 2 La Coste: Ann. Chem. (Liebig), 208, 33. 
 
Reactions of the Arsines, iii 
 
 though evidence of intermediate products* was manifest in 
 the oil separated. 
 
 Phosphorus Trichloride. — When equimolecular quantities of 
 the two substances were brought together in an ether solution 
 contained in a sealed tube, a fine yellow powder separated slowly. 
 After 14 months the tube was opened; gaseous hydrochloric 
 acid, ethylarsine dichloride, and a yellow orange solid were ob- 
 tained. The residue persisted in giving off the odor of ethyl- 
 arsine dichloride even though washed repeatedly with ether; 
 the main ether solution, on being shaken with solid calcium 
 chloride, gave a voluminous precipitate of a red brown sub- 
 stance. Evidently there was in solution some substance other 
 than the free original compounds or the end product, ethyl- 
 arsine dichloride. 
 
 Arsenic Trichloride. — When equimolecular quantities of the 
 two substances were brought together in a sealed tube contain- 
 ing ether, a yellow solid appeared and changed rapidly to a 
 curdy, brick red solid. Ethylarsine dichloride was found in the 
 ether solution ; the residue was analyzed for arsenic : 
 
 0.1387 gram substance gave 0.2214 gram Mg2As207. 
 
 Calculated for 
 
 (C2H5As)a:. Found. 
 
 As 72.11 77-24 
 
 Evidently this residue is a mixture of the polymer (C2H5As)^ 
 with metallic arsenic and the equation representing the reaction 
 is 
 
 8C2H5ASH2 + 8ASCI3 = 4C2H5ASCI2 + 16HCI+ 8AS.2 
 
 Antimony Trichloride. — When equimolecular quantities of 
 the two substances were brought together in a sealed tube con- 
 taining ether, a red brown, amorphous solid was formed imme- 
 diately, but in the course of 14 months it changed to a jet 
 black solid. Considerable pressure of gaseous hydrochloric acid 
 was observed on opening the tube. The ether solution yielded 
 ethylarsine dichloride and a little unchanged antimony tri- 
 chloride ; the black residue was washed repeatedly with ether but, 
 
 1 Cf. This Journal, 35, 39. 
 
 2 Cf page 126. 
 
II2 
 
 Dehn, 
 
 on drying, inflamed spontaneously. Unquestionably interme- 
 diate products were formed in this experiment. 
 
 Water . — When 2 grams of ethylarsine and 5 grams of water 
 were heated in a sealed tube for six hours at 180°, no evidence 
 of a reaction could be observed. 
 
 Hydrochloric Acid Solution . — When ethylarsine was treated 
 with an excess of one molecule of hydrochloric acid (sp. gr. 1.20) 
 and the mixture was heated for two hours at 70°, no evidence 
 of a reaction could be observed. 
 
 Isopropyl Iodide and Ethylarsine . — When 3.7 grams of ethyl- 
 arsine and 18 grams of isopropyl iodide were heated to 70° for 
 one hour in a sealed tube filled with carbon dioxide, no conden- 
 sation was observed; after heating for three hours at 110°, a 
 dark, red brown oil was obtained. The arsonium iodide (90 
 per cent) was separated in the usual manner; 0.2450 gram re- 
 quired 0.1155 gram of AgNOg = 35.22 per cent iodine; calcu- 
 lated, 35.18 per cent. 
 
 When a sample of 0.0546 gram of the triisopropylethylar- 
 sonium iodide was heated in the tensimeter molecular weight 
 
 apparatus^ 
 
 the following data were 
 
 obtained : 
 
 
 
 Vapor 
 
 Vapor 
 
 Apparent 
 
 Theoretical 
 
 t. 
 
 pressure. 
 
 volume. 
 
 mol. wt. 
 
 mol. wt. 
 
 130 
 
 0.0 
 
 0.0 
 
 
 360 
 
 179 
 
 I . 2 
 
 0.007 
 
 
 
 198 
 
 8.3 
 
 0.044 
 
 
 
 234 
 
 388.3 
 
 2.066 
 
 411.6 
 
 
 240 
 
 1092.0 
 
 2.578 
 
 279.0 
 
 
 262 
 
 2138.0 
 
 3.428 
 
 14^' 5 
 
 
 The volume of nonreversible vapor at 28° was 2.7 cc. ; it burned 
 with a luminous flame, was free from arsenic and iodine, and 
 was not affected by bromine water. On cooling, the residue,, 
 possessing an odor of tertiary arsine, consisted of a red yellow 
 oil and light yellow crystals; the product reacted strongly with 
 bromine water. Evidently triisopropylethylarsonium iodide 
 decomposes at its melting point, according to the following re- 
 actions : 
 
 (03117)3(02155) Asl = (03117)3 As -f 02HgI, 
 
 2 ( 03 H 7 ) 302 H 5 AsI = (03H7)3ASI2 + O^H^o + (03H7)3As. 
 
 1 J. Am. Chem. Soc., 29, 1052. 
 
Reactions of the Arsines, 
 
 113 
 
 n-Propyl Iodide and Ethylarsine. — When 2 grams of ethyl- 
 arsine and 10 grams of rt-propyl iodide were sealed in tubes 
 filled with carbon dioxide and heated for one hour at 70°, no 
 effect was observed; heated for three hours at 110°, much pres- 
 sure (hydrogen) and a red oil were observed. Tri-n-propyl- 
 ethylarsonmm iodide was separated and found to soften at 230° 
 and melt at 237°, with decomposition. An alcoholic solu- 
 tion of the iodide treated with an alcoholic solution of mercuric 
 iodide gave a light, yellow white precipitate, which, after re- 
 crystallizing from alcohol, gave, on analysis, 22.09 cent of 
 iodine; calculated for (C2H5)(C3H7)3AsHgI = 22.64 pcr cent.^ 
 
 Propylarsine. 
 
 M-Propylarsonic acid^ (95 grams) and amalgamated zinc dust 
 (500 grams) were placed in a flask and treated with concen- 
 trated hydrochloric acid, in the usual manner;® the propyl- 
 arsine was condensed in a sulphur dioxide condenser surrounded 
 by a freezing mixture. After transferring to bulbs of the proper 
 size, it was analyzed: 
 
 0.1603 gram substance gave 0.1724 gram CO2 and 0.1088 
 
 gram HjO. 
 
 Calculated for 
 
 
 
 CsHtAsH,. 
 
 Found. 
 
 C 
 
 7-50 
 
 7.54 
 
 H 
 
 30.00 
 
 Monobenzylarsine. 
 
 29*33 
 
 A 2 -liter, hard glass, round bottom flask, containing 52 
 grams of benzylarsonic acid,^ 200 cc. of ether, and 500 grams of 
 amalgamated zinc dust® was connected with a reflux condenser, 
 a dropping funnel, and a mercury valve; concentrated hydro- 
 chloric acid was dropped in until the reduction was complete : 
 
 C^HjCHjAsOsH^ H- 6H - -h 3H2O. 
 
 As the reduction proceeded, some red oxidation product was 
 deposited upon the inner walls of the flask and a distinct odor 
 
 1 Cf. Ann. Chem. (LiebigX S41, 182. 
 
 * J. Am. Chem. Soc., 28, 352. 
 
 3 This Journal, SS, 120; 95, 3. 
 
 * J. Am. Chem. Soc., 38, 354. 
 
 ^ This Journal, 99, 118. 
 
Dehn. 
 
 114 
 
 of arsine was observed. After 2 to 3 days, more ether was 
 added and the flask was shaken, then water was admitted 
 through the dropping funnel until all of the ether solution 
 (somewhat green in color) was forced up into a separatory 
 funnel containing sticks of calcium chloride and filled with 
 carbon dioxide. The separatory funnel was closed and shaken 
 until the ether solution was dried. A Briihl distilling apparatus, 
 properly connected with a condenser, a flask, and an inverted 
 TJ-shaped delivery tube, was partially exhausted by means of 
 the water pump ; the delivery tube with proper connections was 
 dipped to the bottom of the ether solution contained in the 
 separatory funnel and the distilling flask was about half filled 
 with the ether solution. By means of the pump, the ether solu- 
 tion was soon concentrated, then more of it was drawn in; this 
 process was repeated until all of the ether solution had been 
 evaporated at room temperature. The residual liquid, light 
 yellow in color, was distilled, and the following fractions were 
 obtained : 
 
 I. 
 
 140° 
 
 262 mm. 
 
 8.5 grams 
 
 2. 
 
 140° 
 
 260 “ 
 
 4.1 “ 
 
 3 - 
 
 141° 
 
 260 “ 
 
 3-2 “ 
 
 The residue in the distilling flask changed finally and rather 
 abruptly to a dark red solid. The apparatus was . then filled 
 with carbon dioxide and small bulbs, containing carbon dioxide, 
 were filled with the different fractions : 
 
 0.1236 gram of fraction (i) gave 0.2260 gram CO2 and 0.0602 
 gram H2O. 
 
 Calculated for 
 
 C7H9ASH2. Found. 
 
 C 50.00 49-87 
 
 H 5-35 5-41 
 
 Benzylarsine is a faintly yellow liquid boiling at 140° under 
 262 mm. pressure. 
 
 Benzylarsine and Platinic Chloride . — When equimolecular 
 weights of benzylarsine and platinic chloride (10 per cent solu- 
 tion) were brought together in a sealed tube, a black, oily sub- 
 stance, followed by a black amorphous mass, was noticed. 
 After being washed with alcohol and ether, the chlorplatinate 
 
Reactions of the Arsines. 115 
 
 "was dried and ignited ; the odors of arsenic trioxide and stibine 
 were given off during the heating. 
 
 0.112 1 gram substance yielded 0.0423 gram Pt. 
 
 Calculated for 
 
 C7H7AsH2.PtCl4. Found. 
 
 Pt 38.49 38.18 
 
 Hydriodic Acid. — Heated with 2 molecules of hydriodic acid 
 at 140° for one hour, the benzylarsine yielded hydrogen, a 
 brown black solid, ^ and an oil (evidently benzylarsine diiodide). 
 
 Bromine. — With a molecule of bromine at ordinary tempera- 
 ture, the arsine yielded hydrogen, transparent crystals, and a 
 heavy, dark oil. 
 
 Oxygen. — Permitted to oxidize in the air, the arsine yielded 
 benzylarsonic acid (melting at 167°) and a red product, which 
 was analyzed: 
 
 0.1180 gram substance gave 0.1837 gram Mg2As207. 
 
 Calculated for 
 
 (C7H7As) 4. Found. 
 
 As 76.72 75.33 
 
 T ripropylarsine. 
 
 When 103 grams of ti-propyl chloride, 120 grams of arsenic 
 trichloride, and 75 grams of sodium were brought together in a 
 flask attached to a long reflux condenser, a reaction took place;^ 
 after standing all night and heating gently for i to 2 hours on the 
 water bath, the reaction was found to be complete. After 
 filtering rapidly and distilling off the ether, 60 grams of oil were 
 obtained ; this was distilled three times at ordinary pressure and 
 the following fractions were obtained : 
 
 1. ioo°-i40° 2 grams 4. 205°-220° 10 grams 
 
 2. I40°-200° 8 “ 5. 220°-270° 4 “ 
 
 3. 200°-205° 18 “ 
 
 The lower fractions showed the presence of 2 to 3 per cent of 
 chlorine; evidently primary and secondary arsine chlorides 
 were present; on standing exposed to the air, a white solid 
 formed and the oil separated into two layers ; the solid gave, on 
 
 1 See page 120 . 
 
 * Cf. This Journal, 35, 42. 
 
Ii6 
 
 Dehn, 
 
 analysis, 4 per cent of chlorine; evidently the compound (CgHy)^ 
 AsO.(C3H7)2AsOC 1 was formed. 
 
 The fractions below 210° were boiled with an excess of bromine 
 water; after concentrating, the heavy, red oil (25 grams) was 
 washed with water, dried, and analyzed for bromine (21.42 per 
 cent Br, calculated for (C3H7)3AsBr2 = 43.90 per cent). To re- 
 move the primary and secondary arsine derivatives which 
 evidently were present, the oil was heated with aqueous am- 
 monia and the residual oil was removed, reduced by means of 
 zinc and hydrochloric acid, extracted with ether, and distilled 
 under reduced pressure. It boiled at 167° (90 mm.) and 158° 
 (73 mm.). 
 
 0.1312 gram substance gave 0.2550 gram CO2 and 0.1183 
 gram H2O. 
 
 Calculated for 
 
 (C 3 H 7 ) 3 As. Found. 
 
 C 52-94 53-02 
 
 H 9.95 10.02 ■ 
 
 A molecular weight determination by the Dehn method^ was 
 made: 0.2242 gram substance gave 12.99 cc. of vapor at 1564 
 mm. and above 251 °. Vapor pressures: 92 ° — 16 1 mm. ; 143° — 
 283 mm.; 195° — 482 mm.; 212° — 844 mm.; 251° — 1564 mm. 
 
 Calculated for 
 
 (C 8 H 7 )sAs. Found. 
 
 Mol. Wt. 202 204 
 
 Oxygen. — When tripropylarsine was brought into contact 
 with air contained in the Dehn hygrometer,^ no change in 
 volume was observed; when a little concentrated sulphuric 
 acid was then admitted, rapid oxidation resulted, as was shown 
 by the rapid decrease of the air volume. 
 
 Decomposition of Arsenic Derivatives by Heat.^ 
 
 Isoamylarsonic Acid.* — When 7.2 grams of the pure acid were 
 heated in a sealed tube filled with carbon dioxide, no reaction 
 was noticeable even after heating for 15 hours at 180° (the acid 
 
 1 J. Am. Chem. Soc., 29, 1063. 
 
 ^ Ibid., 29, 1053. 
 
 2 Cf. J. Am. Chem. Soc., 28, 355-59; This JoxmKAL, 36, 8. 
 
 * J. Am. Chem. Soc., 28, 353. 
 
Reactions of the Arsines. 
 
 117 
 
 melts at 194°). After heating for three hours at 240°, a slight 
 darkening and a partial yield of a liquid were observed; after 
 heating for four hours at 285°, the formation of the liquid and a 
 mass of pearly crystals was complete. On opening the tube, 
 no pressure was observed; on distilling the liquid contents, a 
 large yield of isoamyl alcohol and some isoamyl oxide was ob- 
 tained. Since the flat, pearly crystals did not melt at 300°, 
 did not suffer a loss in weight on subliming, and when dissolved 
 in hydrochloric acid yielded with hydrogen sulphide a yellow 
 precipitate, they were identified as arsenic trioxide. Therefore 
 the above decomposition was as follows : 
 
 2C5H11ASO3H2 = 2C5H11OH + AS2O3 + H2O. 
 
 Phenylarsonic Acid} — This acid did not decompose on heating 
 for three hours at 285° (melting point, 158°); after heating 
 for twenty-four hours at 320° it was changed to two liquid 
 layers and a white solid (arsenic trioxide). The upper, dark 
 colored liquid layer was separated from the lower layer (water) 
 and identified as phenyl oxide (boiling point, 252°), therefore 
 we have the following reaction: 
 
 2CeH5As03H2 = -b AS2O3 + 2H2O. 
 
 Monophenylarsine} — When this compound was sealed in a 
 tube with carbon dioxide and heated for two hours at 180°, no 
 change was observed on cooling; after heating for three hours 
 at 240°, a red brown solid and a light green oil were found; 
 after heating for three hours more at 310°, a black residue 
 coating the inner surfaces of the tube was observed. The excess 
 of gas found in the tube proved to be hydrogen; an ether ex- 
 tract of the residue yielded well-defined crystals of triphenyl- 
 arsine; the black residue contained 95.1 per cent of arsenic. 
 Therefore the reaction is expressed by the following equation: 
 
 3C6H5ASH2 = (C6H5)3As -b 2As -b 3H2. 
 
 Monomethylarsine.^ — This primary arsine was heated for 
 three hours at 240° without effect; after heating for three 
 
 1 Ann. Chem. (Liebig), 208, 34; This Journal, 33, 132. 
 
 * This Journal, 33, 147. 
 
 3 Ber. d. chem. Ges., 34, 3597. This Journal, 33, 120. 
 
Ii8 
 
 Dehn, 
 
 hours at 310° it yielded a black, metallic mirror. The excess of 
 gas formed was washed successively with solutions of sodium 
 hydroxide, silver nitrate, and bromine; the residual gas, which 
 burned with a blue flame, was proved by the explosion method 
 to be a mixture of methane and hydrogen. At least one phase 
 of the decomposition is expressed by the equation 
 
 2CH3ASH2 = 2CH4 + 2As + H2. 
 
 Monoethylarsine .^ — When this arsine was heated for three 
 hours at 210°, only a slight blackening was noticed; after three 
 hours at 235°, the black metallic deposit on the walls of the 
 tube was complete. The excess of gas in the tube was washed 
 as described above. On exploding 0.9 of the residual gas in 
 the presence of an excess of oxygen, it suffered a loss of 1 1.3 cc. ; 
 with potassium hydroxide a further loss of 8.4 cc. resulted. 
 The black deposit (0.1036 gram) yielded 95.17 per cent of 
 arsenic (0.1990 gram Mg2As207). An alcohol-ether extract 
 of the original contents of the tube yielded some triethylarsine. 
 Therefore the following reactions are involved: 
 
 2C2H5ASH2 = 2C2He 4 - 2As + H2, 
 
 3C2H6ASH2 * (C2H5)3As -f 2 As -t- 3H2. 
 
 Dtisoamylarsine .^ — Heating for two hours at 220° yielded a 
 little red solid; heating for three hours at 240° to 260° gave a 
 black, metallic deposit. When 65 cc. of the excess gas were 
 freed from carbon dioxide (22.2 cc.) and then was treated with 
 bromine water, a contraction of 2.0 cc. resulted; the residual 
 gas burned with a luminous flame. The liquid contents of the 
 tube, after extracting with alcohol and ether, yielded at about 
 175° a liquid burning without depositing arsenic (decane) and 
 at about 240° a liquid which, by its odor, by its decomposition 
 on heating, and by its reaction with bromine, was proved to be 
 triisoamylarsine. The black solid (0.1407 gram) gave on one 
 analysis 86.48 per cent of arsenic (0.2466 gram Mg2As207). 
 The consecutive reactions probably are as follows : 
 
 6 (C 5 HJ 2 AsH = 4(C5HJ3As -h 2 As 4 - 3H2, 
 
 2(C5Hii)2AsH = CsHjq -\r C5HJ2 4" Cjo H22 4" 2 As. 
 
 1 This Journal, SS, 143. 
 
 2 Ibid., S6. 53. 
 
Reactions of the Arsines, 
 
 119 
 
 Diphenylarsine} — Heating for two hours at 245° produced 
 only a little blackening; heating for three hours at 295° effected 
 decomposition. The residual excess gas proved to be hydro- 
 gen; the alcohol-ether extract of the residue yielded a white, 
 crystalline product, which (0.0852 gram) yielded on analysis 
 25.15 per cent of arsenic (0.0443 gram Mg2As207) — evidently 
 it was triphenylarsine (calculated. As = 24.51 per cent). Two 
 analyses of the black residue (77.46 per cent As and 77.70 per 
 cent As) showed here, as in other cases of its production, that 
 it is probably mixed with the tertiary arsine. The reactions 
 are expressed by the following equations: 
 
 6(C6H5)2AsH = 4(C6H5)3As + 2As -H 3H2, 
 
 2(CeH5)3As = 3C12H10 + 2 As. 
 
 Tripropylarsine} — No evidence of decomposition was notice- 
 able below 287°; after heating for two hours at 295°, a yellow 
 liquid was observed. On opening the tube considerable pres- 
 sure was noticed; 44 cc. of this gas, after washing successively 
 with caustic soda and bromine water, gave 16 cc. of gas which 
 by shaking with alcohol lost 8.5 cc. The gas which was sol- 
 uble in alcohol burned with a blue flame. The residual liquid 
 in the tube had a cacodyllike odor. The probable partial 
 reaction was 
 
 4(C3H7)3As = (C 3 H 7 AS), -h 4 CeH,,. 
 
 Triethylarsine. — Heated at 190° to 215° for three hours, it 
 darkened; at 245° for two hours, a yellow oil and some solid 
 were formed; at 265° for three hours, considerable excess gas, 
 a greenish yellow to gray black residue and only a little liquid 
 were observed. The solid gave, on analysis, 44.09 per cent 
 arsenic (o. 1264 gram gave o. 1 129 gram Mg2As207) ; calculated for 
 (C2H5)3 As = 46.29. The alcohol-ether extract of the solid 
 yielded an oil which by its odor and reaction with bromine was 
 shown to be unchanged triethylarsine. The probable partial 
 reaction was 
 
 4(C2H5)3As = (C3H3AS), + 4C.H,„. 
 
 * This Journal, 36 , 45. 
 
 * See page 115. 
 
120 
 
 Dehn. 
 
 Benzylarsine } — When 0.5 gram of benzylarsine, in a sealed 
 tube from which the air had been exhausted, was heated for 
 two hours at 250°, a reaction resulted. A little gas, a little oil, ' 
 and a glistening, black solid were formed. The black solid was 
 washed and analyzed; 0.1473 gram gave 0.1370 gram Mg2As207, 
 which is equivalent to 45.00 per cent of arsenic — calculated for 
 (C6H5CH2 As) 4 is 45.18 per cent. Therefore the following re- 
 - action probably takes place : 
 
 4CeH5CH2AsH2 -> (CeH 5 CH 2 As )4 + 4 H 2 . 
 
 Cacodyl ? — When 5.3 grams of crude cacodyl (cacodylic 
 oxide) were heated for two hours at 340° in a sealed tube filled 
 with carbon dioxide, a black, metallic deposit and a mobile, 
 yellow oil were formed; on opening the tube considerable pres- 
 sure was observed. After washing with a solution of potash, 
 the residual gas (about 25 per cent) was found to burn with an 
 arsenic flame and to dissolve in a solution of silver nitrate; its 
 odor and other properties characterized it as trimethylarsine.^ 
 After freeing it from the oil and washing it with alcohol and 
 ether, 0.1446 gram of the black residue yielded 0.2500 gram 
 Mg2As207 or 83.65 per cent As; calculated for (CH3As)4 is 83.33 
 per cent As. The oil distilled mostly below 80° (trimethylarsine 
 boils at 70°).^ The decomposition of cacodyl at high tempera- 
 tures is represented by the following equation: 
 
 4(CH3)2AsAs(CH3)2 4(CH3)3 As + (CH3As)4. 
 
 That the oil was trimethylarsine was confirmed by the fol- 
 lowing experiments. Treated with an excess of an aqueous 
 solution of mercuric chloride, a voluminous white precipitate 
 was formed; by recrystallization from hot water, pearly white 
 leaflets were obtained. 0.7070 gram substance gave 0.3918 
 gram AgCl. 
 
 Calculated for 
 
 [(CH 3 ) 3 As] 2 HgCl 2 . Found, 
 
 Cl 13.86 13.68 
 
 Trimethylar sine-mercuric chloride was formed. 
 
 ^ See page 113. 
 
 2 Ann. Chem. (Liebig), 107 , 261. This Journal, 36 , 2. 
 
 » Ann. Chem. (Liebig), 92 , 361; 112 , 228. 
 
 * Jahres. d. Chem., 1865 , 538. 
 
Reactions of the Arsines, 
 
 I 2 I 
 
 A chloroform solution of trimethylarsine, treated with a 
 chloroform solution of bromine, evolved much heat and pre- 
 cipitated a heavy, red oil that soon solidified to coarse, red 
 orange, prismatic crystals. The substance was rapidly de- 
 composed by atmospheric moisture and melted at 94°. 
 
 0.7088 gram substance gave 0.9481 gram AgBr. 
 
 Calculated for 
 
 (CH3)3AsBr2. Found. 
 
 Br 57.14 56.92 
 
 Trimethylarsine dibromide was formed. 
 
 III. Reactions of Dimethylarsine.^ 
 
 With Burtox B. Wilcox. 
 
 Isoamylene. — When equimolecular quantities of dimethyl- 
 arsine and isoamylene were heated for one hour at 120°, no 
 change was noticeable. Evidently a reaction indicated in the 
 equation 
 
 (CH3)2AsH -h CsH.o = (CH3)2(C5 H,,)As 
 
 does not take place.^The vapor pressures of amylene, methyl- 
 arsine dichloride, and a mixture of the two in equal volumes 
 were determined; these and other data are given below: 
 
 Temperature. Isoamylene. 
 
 CH3ASCI2. 
 
 Mixture. 
 
 Vapor pressure 
 depression.* 
 
 26.5 531.7 
 
 9.0 
 
 262.4 
 
 260.3 
 
 Amyl chloride. 
 
 28.5 64.3 
 
 AsCls. 
 
 II .0 
 
 54-9 
 
 20.6 
 
 Propyl iodide. 
 
 28.5 50.1 
 
 AsClj. 
 
 II .0 
 
 24.1 
 
 37-0 
 
 Benzyl Chloride. — Equimolecular quantities of dimethyl- 
 arsine and benzyl chloride in ether solution in a sealed tube 
 
 1 Secondary Arsines. Dehn and Wilcox: This Jothinal, 35 , 1 - 54 . 
 
 * If the depression of vapor pressures of liquid mixtures is an indication of molec- 
 ular coalescence, then the products 
 
 (CH,)2AsH CI3AS CI3AS 
 
 CH2='CH— CsHy’ ci—CgHn’ i— C3H7* 
 
 are probably formed, though the molecularly rearranged products 
 
 (CH3)2As— CH2— CH?— C3H7, CbAs— CsHu, CblAs— C3H7, 
 
 are not formed. 
 
122 
 
 Dehn, 
 
 showed no evidence of reaction, after standing for two months. 
 
 Phosphoric Acid. — Equimolecular quantities of dimethyl- 
 arsine and metaphosphoric acid in a sealed tube showed no 
 evidence of reaction, even after heating for two hours at 95°. 
 
 Phenylarsine Dichloride. — When 2.06 grams of dimethyl- 
 arsine (2 mols.) and 4.3 grams of phenylarsine dichloride 
 (i mol.) were brought together in a sealed tube filled with car- 
 bon dioxide, a dark, red brown solid and jine, glistening crystals 
 were formed. Little pressure was observed on opening the 
 tube (absence of hydrogen or hydrochloric acid gas) ; an ether 
 extract of the contents of the tube, on being filtered and con- 
 centrated in a vacuum desiccator, yielded beautiful, white, 
 compact crystals, which were immediately decomposed by 
 atmospheric moisture. After washing with a little carbon 
 disulphide, the crystals were dried and quickly analyzed for 
 chlorine. 0.3683 gram of substance gave 0.3058 gram of 
 AgCl. 
 
 Calculated for 
 
 (C6H5AsCl2)(CH3)2AsH. Found. 
 
 Cl 21.59 20.57 
 
 Dimethylarsinephenylarsine dichloride decomposes rapidly 
 when exposed to the air, precipitating from an ether solution 
 an oil, which was analyzed. 0.2514 gram substance gave 
 0.1641 gram AgCl. 
 
 Calculated for 
 
 CeHsAsCl — A s(CH3)j. Found. 
 
 Cl 12.00 16.62 
 
 The oil was evidently a mixture. The initial reaction of 
 phenylarsine dichloride and dimethylarsine may be expressed 
 (CH3)2AsH 
 thus: 11 
 
 C,H — AsCl, 
 
 Diisoamylarsine Chloride.^ — When equimolecular quantities 
 of dimethylarsine and diisoamylarsine chloride were brought 
 together in a sealed tube filled with carbon dioxide, no change 
 was apparent to the eye, even after heating for five hours at 
 100°. On opening the tube no pressure (absence of dimethyl- 
 arsine) was observed; after treating with water, the oil fumed, 
 
 1 Cf. This Journal, 36, 31 . 
 
Reactions ^of the Arsines, 
 
 123 
 
 possessed the odor of amylarsine, and undoubtedly was df- 
 isoamyldimethylcacodyl. The reaction evidently was as follows : 
 
 (CH,),AsH (CH3)2 As 
 
 II -> I +HC1. 
 
 (C3H„)2AsC1 (C,H,0,As 
 
 Propyl Iodide. — When 1.84 grams of dimethylarsine (i mol.) 
 and 5.83 grams of propyl iodide (2 mols.) were brought together 
 in a sealed tube filled with carbon dioxide and the mixture 
 was allowed to stand for a number of days, a slightly colored 
 oil and some white crystals were formed. On opening the tube, 
 pressure was observed; the crystals, easily decomposed by 
 atmospheric moisture and forming an oil of a tertiary arsine 
 odor, were nearly insoluble in chloroform (all tetralkylarsonium 
 iodides are easily soluble in chloroform). After washing with 
 chloroform they were analyzed with the following results: 
 0.9038 gram substance gave 0.7651 gram Agl. 
 
 Calculated for 
 
 (CH3)2(C3H7)AsHI. Found. 
 
 I 46.01 45.75 
 
 Some of this dimethyl-n-propylarsonium iodide was treated 
 with an excess of isoamyl iodide and heated in a sealed tube for 
 two hours at 120°. The dimethyl-n-propylisoamylarsonium 
 iodide was separated by the usual method : 
 
 0.6805 gram substance gave 0.4663 gram Agl. 
 
 Calculated for 
 
 (CH3)2(C3H7)(C5Hn)AsI. Found. 
 
 I 36.70 37.03 
 
 Diisoamylarsine and n-Propyl Iodide. When 2.5 grams of 
 diisoamylarsine (i mol.) and 2.8 grams of n-propyl iodide (2 
 mols.) were heated for two hours at 160° in a sealed tube filled 
 with carbon dioxide, a dark red liquid was obtained. On 
 opening the tube, considerable gas was given off ; after washing 
 with caustic potash, alcohol, and water, the residual gas gave 
 an excellent test for hydrogen. The product, diisoamyldi-n- 
 propylarsonium iodide, was separated in the usual manner and 
 analyzed with the following results: 0.6909 gram substance 
 gave 0.3761 gram Agl. 
 
 Calculated for 
 
 (C6H„)2(C3H7)2AsI. Found. 
 
 29.53 29.42 
 
 I 
 
124 
 
 Dehn, 
 
 Cacodyl and Propyl Iodide. — When 4.1 grams of crude 
 cacodyl (i mol.) and 12.5 grams of n-propyl iodide (4 mols.) 
 were heated for 2 hours at 140° in a sealed tube filled with 
 carbon dioxide, a red oil was obtained. After heating with a 
 concentrated solution of potash, filtering, dissolving in chloro- 
 form, and reprecipitating with ether, the substance was obtained 
 as yellow crystals. The process of purification was repeated 
 2 or 3 times but a colorless product could not be separated; 
 after dissolving in a little water, filtering, and evaporating to 
 dryness, light yellow crystals were obtained. 0.6882 gram 
 substance gave 0.4980 gram Agl. 
 
 Calculated for 
 
 (CH3)2(C8H7)aAsI. Found. 
 
 I 39-93 39-11 
 
 When dimethyldi-n-propylarsonium iodide was treated with an 
 excess of mercuric chloride, a white precipitate was formed; 
 after crystallizing from hot water, white leaflets were obtained ; 
 0.2960 gram substance gave 0.2556 gram AgI.2AgCl. 
 
 Calculated for 
 
 (CH 3 )j(C 3 H 7 ) 2 AsIHgCl 2 . Found. 
 
 I.2CI 33.59 32.74 
 
 Acetyl Iodide and Dimethylarsine. — When equimolecular 
 quantities of acetyl iodide and dimethylarsine were brought 
 together in ether in a sealed tube, an immediate precipitation 
 of a yellow solid and the liberation of considerable heat were 
 observed. After some time the solid changed to a yellow oil 
 and clusters of needlelike crystals. After two years, the tube 
 was opened; the ether solution was treated with an aqueous 
 solution of mercuric chloride, when a voluminous white precipi- 
 tate was formed. After washing with water, alcohol, and ether 
 the substance was analyzed. 0.3803 gram substance gave 
 0.2756 gram silver halide. 
 
 Calculated for 
 
 (CH3)2AsHiO.HgICl. Found. 
 
 Cl.I 33.51 31.10 
 
 The residue in the tube was washed repeatedly with ether 
 and was then dissolved in water and boiled with a solution of 
 mercuric chloride. The odor of acetaldehyde was observed, 
 
Reactions of the Arsines. 
 
 125 
 
 while the oil, which was first formed, was slowly changed to 
 mercurous iodide and the double compound with mercuric 
 chloride. The reactions evidently can be represented as fol- 
 lows : 
 
 (CH3 ),AsH 
 
 H 
 
 I 
 
 (CH3),As-I 
 
 (CH3)3AsI + CH3CHO. 
 
 CH3CO— I 
 
 CHgC^O 
 
 Chlorcarbonic Ethyl Ester and Dimethylarsine. When equi- 
 molecular quantities of the two substances were brought to- 
 gether in a sealed tube filled with carbon dioxide, no reaction 
 was evident to the eye; however, on opening the tube, great 
 pressure (ethyl formic ester boils at 54.4°) and combustible 
 vapors were observed; the residual oil possessed the odor of 
 cacodyl chloride, therefore a reaction had resulted, as follows: 
 
 (CH3)2 AsH + CICOOC2H5 -> (CH3 )2 AsC1 + HCOOC2H5. 
 
 The oil was further identified as cacodyl chloride by shaking 
 its ether solution with an aqueous solution of mercuric chloride 
 — a voluminous white precipitate resulted. The substance 
 was recrystallized from hot water. 0.5451 gram substance 
 yielded 0.3970 gram AgCl. 
 
 Calculated for 
 
 (CH3)2AsH20.HgCl2i. Found. 
 
 Cl 17-98 * 18.07 
 
 Sulphur Bichloride.^ When 2.13 grams of dimethylarsine 
 (2 mols.) and 2.06 grams of sulphur dichloride (i mol.) were 
 brought together in a sealed tube containing carbon dioxide, 
 a very violent reaction (much heat) resulted. After standing 
 for two years, a slightly yellow oil, a yellow amorphous solid 
 (sulphur), and transparent tablets and needles were observed. 
 On opening the tube a considerable pressure of methyl sulphide 
 (identified by its odor and by the blackening of lead acetate 
 paper) was observed. By heating the tube on the water bath, 
 the liquid distilled out and the crystals increased in quantity 
 (they did not melt at 100°). When treated with ether (evi- 
 
 » Cf. page 127, 
 
 2 Cf. This Journal, 35, 38. 
 
126 
 
 Dehn, 
 
 dently containing a little water) the crystals were decomposed, 
 thereby giving rise to the odor of cacodyl chloride and precipi- 
 tating finely divided sulphur. A chloroform solution of the 
 crystals standing in a desiccator deposited sulphur. These 
 crystals were not analyzed ; that they are an intermediate prod- 
 uct in the following reaction is sufficiently evident: 
 
 2 (CH3)2 AsH -f- SCI2 2 (CH 3 ) 2 AsC 1 -}- S. 
 
 Arsenic Trioxide. — When 1.7 grams of dimethylarsine (3 
 mols.) and 2.1 grams of arsenic trioxide (2 mols.) were brought 
 together in a sealed tube filled with carbon dioxide, a very slow 
 reaction ensued — a dark brown solid gradually replaced the 
 trioxide. The tube was heated for five hours at 100° and then 
 was permitted to stand for two years; on opening the tube 
 some unchanged arsine but no arsenic trioxide was observed. 
 The red brown solid was analyzed. 
 
 0.1246 gram substance gave 0.2137 gram Mg2As207. 
 
 0.1046 gram substance gave 0.1790 gram Mg2As207. 
 
 Calculated for Pound. 
 
 AsjOafCHsAs)!. (CH3As)4. I. II. 
 
 As 75.75 83.33 ■ 82.99 82.80 
 
 Evidently the reaction is largely as follows: 
 
 2(CH3)2AsH + AS2O3 = (CH3As)4 + H2O 02 - 
 
 Arsenic Trichloride.^ — When 3 grams of dimethylarsine 
 (2 mols.) and 2.56 grams of arsenic trichloride (i mol.) were 
 brought together in ether in a sealed tube, a dark brown solid 
 was precipitated at once. After standing for two years the 
 ether solution was poured out; the amorphous brown solid 
 was seen to be mixed with /ong, prismatic, transparent crystals, 
 which were decomposed rapidly by contact with the atmosphere, 
 hence they were not separated and analyzed. Evidently they 
 were an intermediate compound. The red brown substance 
 was washed with dilute hydrochloric acid and analyzed : 
 
 0.2453 gram substance gave 0.4238 gram Mg2As207. 
 
 Calculated for 
 
 (CH 3 As) 4 . Found. 
 
 As 83.33 83.60 
 
 1 Cf. This Journal, 35, 40. 
 
Reactions of the Arsines. 
 
 127 
 
 The ether solution was treated with an aqueous solution 
 of mercuric chloride; the voluminous white precipitate was 
 recrystallized from hot water and analyzed. 
 
 0.6630 gram substance gave 0.4800 gram AgCl. 
 
 Calculated for 
 
 (CH3)2AsH20HgCV. Found. 
 
 Cl 1798 17-87 
 
 Evidently the end reaction is as follows: 
 
 4(CH3)2AsH + 2ASCI3 = (CH3As)4 + 2(CH3)2AsC1 + 4HCI 
 
 Urbana, Illinois, 
 
 August 5, 1907. 
 

 
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