1090 RAY : TRIETHYLENE TRI- AND TETRA-SULPHIDES

CXXIII. - Triet h y Zene 2%- and Tetra-sulphid es. By Sir PRAFULLA CHANDRA RAY.

IN the preparation of ethylene mercaptan by the interactioa of ethylene dibrolmide and alcohollic potassium hydrogen sulphide, after removal of aloohol and ethylene meroaptan by s k a m dis- tillation, continued passage of s h a m furnishea a milky distillate solidifying to a crystalline mass, which, when relorystalliseid frolm ho t alcohol, melts a t 1 1 3 O , and consists of triethylene trisulphide, (C2H4)3S3. The non-v~lat~ile oil remaining in the distilling flask a,lso solidified o1n cololing t o a crystalline mass, consisting of a mixture of three polymeric ti-iethylene tetrasulphides. By extrac- tion with alcohol, the a-modificatioa (m. p. 7 6 O ) was obtained; the remainder, on extlraction with benzene, gave the &modification (m. p. 102-104°), and thel insoiluble residue furnished t?he y-moldificatioln (m. p. 1 1 6 O ) . The alkaline liquid which remaineid behind in the flask yielded, on acidificatioln, an oil, which has beein proved to be1 triethylene disulphide dimercaptam, (C,R,),S,(SH),. On tzeiatment with mercuric chlolridel, it gave the oorrelsponding ch lo~om ercapt &Ye, ( C2X14)3S2( S H g Cl), . This d imeir captan, w heln treated in ethereal solution with an alcohollio solution of ioldine, gives the /3-tehrasulphide (m. p. 104O), and it8 methyl-alcoholic solution sloiwly olxidises in the air t o 8-tm'ethyleme tetrasulphide (m. p. 59-60O). The molecular weight olf this variety was fojund to be 816, which colrresponds with four times the formula, (C2HJ3S4. The P-modification is sparingly soluble in boiling benzene or chloroform, and its molecular -welight could not be

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RAY: TKCETHYLENE TRI- AND TETRA-SULPHIDES. 1091

delt.ermined witlh exaatness, but' elvideince pointed to it's having a much highelr mo~le~cula,r weight,, indicating t'hat in this case there was a aoa81esce8nce of more tha8n four simple moleculels. I n boiiling chlolrofolrm, the substanm undelrgoles partial s,lo,w spont,a.nelolus polymelrisa,tion, 8,s Wafs prolveld by the f a.dl t$at successive1 clrops diffelreld in meilting point and welre o'nly sparingly soluble! in be'nzeine. The1 insolublel portion melted at, about 1 1 4 O .

It seems probable tha,t the y-moldifica,tion, which is insolluble in ordimry s,olvelnts., has a much highe'r molletculas weight.

The f ormat,ioln o'f t,he compo,unds may be expladned according t'o, the. following scheme'. The alcoholic sollution of poltassium hydr- oxidel, on beling sa,turat,eld with hydrogeln sulphidel, colntains potlassium sulphidel in a,dditioIn t,o pota.ssium hydrogen sulphide, a.nd this mixture acta OD ethylelne dibromide, thus:

3C2H,Br, + K2S + 2KSH --+ SH*C2H4*S*C,H,*S*C,H4*SH. Evident,ly, t,hei tlelttrasulphides are the prolducts of spo,nt.a;nejows

ae,rial olxidation of t'hel dimelraptan, thus :

S~C2H4*S~C,H4*S.C,H,*S Lpp---.----i

Thel foirrna,t,ioa oC the trisulphidel may be! explaineld thus :

s*c H 3C2H4Br, i- 3K,S = C2H,<S.C2H4>S + 6KBr. 2 4

E x P E R I M E N T A L.

The1 method of preparation (from 100 grams of elthylene dibroimidei) was eiIiactly as described by Fasbender (Be?., 1857, 28, 461). After removal of alcohol and ethyle\ne mercaptan by means o i steam, there separated from the distillate a solid, which was preisseld on porous plate (1.29 grams) and crystallised from alcohol, when it, melted atl 113O, and consisted of triethylene trisulphide (Found": C=37.84; R=6.80; S=53.06, 53.54. C6H12S3 requires C=40-00; H = 6 - 6 7 ; S-53.33 per cent.).

The noln-volatile1 oil, which soilidifield on cooling (6.5 grams), was * As these compounds are very rich in sulphur, the length of the lead

chromate in the combustion tube was much increased so as to preclude the possibility of sulphur dioxide escaping absorption. Moreover, in some cases the alkali hydroxide in the potash bulb, after analysis, was oxidised with bromine, wiwmed and acidified with hydrochloric acid and treated with barium chloride, but no barium sulphate could be detected.

In the estimation of sulphur, Carius' method was adopted by which the compound was converted into the sulphonic acid. The acids were neutralised with sodium carbonate, evaporated to dryness, and then fused with potassium nitrate so as to transform the sulphonate into sulphate.

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1092 RAY TRIETHYLENE TRI- AND TETRA-SUI3HIDES.

elxtracteld completely wit'h hot alcohol, the solution furnishing crystals of a-triethylene tetrasdphide melting at, 750 (Found : C = 33.88 ; H = 7.42. C,H,,S, relquires C = 33.96 ; H = 5.66 per cent.).

The relsiduei was then similarly trelate8d with boiling benzene!, which extracted P-trie thy1 ene t e trmulphide melting at 102-1 0 4 O (Found : C = 33-92 ; H = 6-94. C,H,,S, requires C = 33-96 ; H = 5.66 psr cent.).

The final insoluble portion consisted of y-triethylene tetra- sulphade mellting at' 116O (Found : C =34.30, 33.59 ; H = 6.41, 7.90 ; S = 59.07. C,H,,S, requires C = 33.96 ; H = 5.66 ; S=60*38 per oent.).

The alkaline liquid, on acidification, gave an oil, which was extracteld with etThelr (8.5 grams), and c'onsiste'd of triethyzene d~suJphide dimercaptan boiliiig at, 260-263O (Found : S = 60.86. C,H,,S, requires S = 59.80 per cent .).

Its methyl-alcoholio solution, on exposure to air, gave 6-tri- ethylene tetrasulphide melting at. 59-60° (Found : C = 33.05 ; H = 6.29 ; S = 60.55. M.W. by euullioscopic melthod in ohloro- form = 815.5, 815.8. C24H48S16 require3 C = 33.96 ; H = 5.66 ; S= 60.38 per centl.

On treafment with me'rcuric chloride, it gave the, dichloro- mercaptide (Found: C=10*34; H = 2.22; C! = 9.40, 10.81; S = 18.54; Hg = 58.44. C,,H12C1,S,Hg, re,quiree C = 10.54; H=1*75; C1=10.40; S=18.74; Hg=58*57 per wlnt.).

Various derivatives of the above polysulphides are in course o'f preparation.

CHEMICAL LABORATORY,

M.W. =848).

COLLEGE OF SCLENUE, UNXVERSKTY OF CALCUTTA. [Received, June 3rd, 1930.1

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