MERCURY MXRCAPTIDE N IT1lIT&3, ETC. PART. v. 54 1

X L.-Mercuiy Mercaptide N i t d e s and t h e h lieact ~ O Y L

with the Alkyl Iodides. Part V. Chain Com- pounds of SuZphur (continued).

By SIR PRAFULLA CHANDRA RAY and PRAFULLA CHANDRA GUHA.

THE present series of investigations has hitherto been confined to derivatives of monomercaptans; it has now been extended to those ob the dimercaptans, of which 2 : 5-dithioll-1 : 3 : 4-thiodiazole may be taken as a typical representative.

When this dimercaptan is treated with mercurlc nitrite, a dimercaptide dinitsite,

O,KHgS*C:N*N: C- SHgNO, 1- s-- I 9

is not obtained, but the nitrous acid siinultaneou sly disengaged oxidises the hydrogen atoms of two, three, four, and even six molecules of the dimercaptan, and the sulphur atoms become linked togeither and give rise tol a n interesting series of closed chain com- pounds. The maximum number of sulphur atoms forming the connecting link between two adjacent, nuclei in the condensed complex molecule tmhus formed has so far been found t o be twelve. Thus, in the case of a trinuclear condensation, we have

* S*R”*S H 0 H S*R’’*s H 0 H s*R”oS

I = ON OHg

I tJg NO,

hC.R”.M.S*R”.S.s.K”*S 1 t N,O, + 3H,O.

H g I Hg---O--

*C:N”: C’ R’ denotes the bi\ alelit, group I ” ’ s

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542 RAY AND GUHA: MERCURY MERCAPTIDIJ NlTRXTES AN11

The heavy molecule of the dimercaptide dinitrite cannot retail) the load of two NO, groups, and hence rupture takes place, as indicated by the dotted line, and a closed chain sulphoxy-deriv- ative is finally formed with the liberation of nitrous fumes. The compounds thus generated are not, as a rule, nitrites. Some pre- parations, however, responded slightly to the nitrite tests, but the percentage of nitrogen due to the presence of nitrite was very low, proving that the proportion of the latter was insignificant. The occasional presence of some nitrite goes to establish the fact that the oxy-compound is in reality a decomposition product of the former.

If, instead of the dimercaptan itself, its potassium salt is used, the tendency towards oxidation by nitrous acid is excluded and a mercaptide nitrite of the formula

KS*C:N*N:C*SHgNO, I s - I

is obtained. The sulphoxy-compounds may be represented by the general

formula (C,N,S,),,Hg,O, whelre x=2, 3, 4, or 6. A condensation product of five molecules has not yet been obtained. It is not easy to explain why in one operation the value of x should be two and in others it should rise to six; possibly the concentration of the parent substances is the main determining factor. It has .often been found that two preparations under similar conditions had identical compositions. I n the majority of cases, the value of LL:

was found to be three, occasionally two and four, and only rarely six.

The preparatioiis could iiot have beeii admixtures, because each of them strictly conformed to a definite formula. The most con- vincing proof of these compounds being of definite composit~oi~, holwever, is afforded by their reaction with the alkyl iodides. These sulphoxy-compouiids behave exactly like mercaptide nitrites, and yield, as a rule, hhe corresponding sulphonium derivatives and, in a Sew cases, those with a less number af nuclei. The reducing action of the alkyl iodide reinoves the oxygen atom of the sulphoxy- ring, and, the bonds being thus snapped, an open-chain compound is formed, thus:

I I 1 I I I

0- -Hg I I 1 I ' I I -Erg--

8. R". S 0s. It". s. 8. R" . S 12 i --+ IHgS It"* S S R" 8 H*R"*S HgI .

The six sulphur atoms of the chain now become) quadrivalent by taking up the components of the alkyl iodide.

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THEIR REACTION WITH THE AZKYL IQDIDES. PART V. 543

I n this manner, a series of tetra-, hexa-, oct?a-, and dodeca- sulphonium compounds have been prepared. Each 09 these, with the exception of the propyl and butyl derivatives, is characterised by its crystalline character, and, moreover, its successive crops have the same melting point; the possibility of their being mixtures is thus precluded.

Another interesting point is the shifting of the double bonds, thus :

N-N N=N

where R=meLhyl, ethyl, propyl, or butyl. As a rule, this is con- fined. only to one nucleus. There is here evidently an extleiision of Thiele’s theory to nitrogen compounds.

I n one isolated instance, and that in the case of the reaction with methyl iodide, instead of there being a shifting of the double bonds, both the pairs of nitrogem and carbon atorris throughout, t,ho molecule were sai,iirated by talriiig 1 1 1) adtlit ional methyl groups, thus :

N--N MeN-NMe

s S

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

R t cl ph a x y - c ompo 1 I nds . C e n e ~ u 7 Method of I’reparation .-2 : 5-Dithiol-1 : 3 : 4-thiodiazole,

prepared according to Busch’s method (Ber . , 1894, 27, 2518>, in dilute alcoholic solution, was added drop by drop with vigorous stirring to a solution of mercuric nitrite, care being taken that the latter was always in excess. I n this manner, a semi-gelatinous, pale yellow precipitate was obtained, which was washed with water and dried in a vacuum desiccator. The powdered, granular mms was then heated under reflux successively with alcohol1 and benzene to remove any adhering accidmtal orgaiiic iiiipurities, namely, the parent> dimercaptan or its oxidation procluct, the disulphide. This precaution was, however, found to be unnecessary. The corn- poudds obtained in this way are always associated with some mole- cules of water.

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544 RAY AND GUHA: MERCURY MERCAPTIDE NITRITES AND

I’ottrssizrm Salt of 3 : 5-Dithiol-1 : 3 : 4-tlziodiasole a d M e m m i c Nitri te .

With an aqueous solution of the potassium salt, a compound of KS*C:N*N:C*XHgNO,

the formula j -8 1

with 12H,O is obtained. Analysis of the substance gave: Found: Hg=31.50; S=13*89; C-3.53; I1=5-34.*

C,0,N3S,HgK,12H,0 requires Hg = 30.81 ; S = 14-79 ; C= 3.70 ; H = 3.70 per cent.

S-C,N,S Y,*C,N,S*S,- C!,N,S* S Yri?) I I d e n t * S 1 I /id, o I t

~ r o?n 1’ o I I rt d , 1 I ’ I-Tg---- 0---Hg

In this case, each distinct preparation gave the compoiii~(1

C!on~pounGF with 8H,O. Found: I Ig=40.21; S=27-56 ; C=8*50; N=8.18 .

associated with 8, 5, and i! iiiolecules of water respectively.

C,jON,S,Hgl,8H,0 requires Hg = 39.85; S = 28.69 ; C =: 7-17 ; N=8.37 per cent.

Gomporriid with 5R,O. Found : Hg = 42.07 ; S = 30.21 ; N = 9.36.

C,0N,S,Hg2,513,0 requires Hg=42.11; S ~ 3 0 . 3 1 ; hT=8*84 per cent.

Cornliound with 2H,O. Foulld: Hg=45.33; S-31.40; N=9.52.

C,0N,S,Hg2,2H20 requires Hg =44.65 ; S = 32.14 ; N = 9.38 per cent.

On repeating the preparation, the same trinuclear condensation

* The percentage of hydrogen is often too high as traces of mercury vapour are apt t o be carried over t o the calcium chloritle tube; in many cases, therefore, the value of hydrogen has not been given

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THEIR REACTION WITH THE ALKYL IODIDES. PART V. 545

product was obtained, although sometimes in an impure form, Thus in one preparation there was found Hg= 42.52, S = 34-54, and in another, Hg=43-72, S=31.53. However, on treating each of these with the alkyl iodides, the same sulphonium compound was obtained (see p. 546).

Tetralvuclear Sulphoxy- corn pout1 GF, (C,N,S,),, Hg,O.

Compozind with 3H,O. Pound : €Ig = 37.94; S = 37.54 ; N = 11.48.

C,0N,S,,Hg,,31-T20 requires €Ig=37.67; S=36*16; N=10*55 per cent.

Compound with 5H,O. F O U ~ : Hg = 37.21 ; S = 35.13 ; N = 9.55.

C&ON8S,,Hg,,5H,0 requires IIg = 36-43 ; S = 34.97 ; N =- 10.2 per cent.

Benetion m"h th c A lihyl 1odiAr.s.

Cen~rtcl M e t h o d 01 Pt.epuiation,.- - The izhove sill pliosy-tleriv- atives were heated with the alkyl iodides on a water-bath under reflux for several hours, the product being allowed t o remain over- night. Sometimes a crystalline mass, and occasionally ;I heavy, dark brown oil, settled a t the bot tom; the excess of alkyl iodide was decanted or distilled off, and the product dissolved in the minimum quantity of acetone and the solution filtered from t h e insoluble matter whenever necessary. On adding ether to the filtrate, a pale yellow, mealy, crystalline precipitate was obtained, and this process was repeated in order further t o purify the substance.

D i 1% zc c 1 e a r C n n d e n su t i o n .

The Compownd, C40N,S,Hg,, and iWethyr! Iodide : E'oi'mntion of the Compound,

Me N--N Me Me N==K Me I I I l l I I

The product melted a t 101-102°.

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54.6 RAY AND C-UHA: MERCTJRY MERCAPTTDE NITRITES AND

Found : Hg = 25-94 ; I = 49.23 ; C = 7.75. C",,H1,N,S6Hg,16 requires Mg = 25.84 ; I'=49.33 ; C = 7.75 per cent.

The corresponding compourwl with etlhyl iodide (11) was sparingly soluble in acetone, and was therefore purified by crystallisation from the bodling solvent; it melted a t 107'.

Found: Hg=24.19, 24-58; 1=43*20*; C = 11.25, 11.42; N = 3 .53 . C16H30N,S6Hg,16 requires Hg=24*51 ; 1=46*69; c= 11.76; N=3'43

per cent..

The corresponding dinuclear t'etrasulphonium compounds with n-propyl and n-butyl iodides did not crystallise, but consisted of dark brolwn, pasty masses, which were purifield by repeated p r e cipication with ether from acetone solution.

Compound with n-propyl iodide (111). Found : Hg = 23-89 ; I = 44.74 ; C = 14.05.

Compound wi&h n-71 u f y l i o d i d e (IV).

C,',,H,4W,S,Hg,T, reqiiircs H g x= 23-22 ; T

C,,H,,N,S6Hg,16 requires H g = 23.31 ; I == 44.40 ; C = 15.38 per cent.

Found: Mg-21.77; 1-41-75; CT-17.66; N==3*11. 42.33 ; (1-- 18-60 ; W L- 3.1 1

per cent.

The product of the interaction was an oil. It was dissolved in hot acetone, and the solution, on coolling, deposited a crystalline mass, which when recrystallised from hot acet'one yielded needle- shaped crystals melting a t 101-102°, identical with the compound, c 1 ~ ~ 1 ~ ~ & ~ ~ & 1 6 , described above. The original mother liquor, 0011 concentration, gave two1 successive, crops melting atl 85-86O.

Found: Hg=21.55; C=8-66. Cl4IL1N6SgHg2I, requires Hg = 20.20 ; C = 8.48 per cent.

'' As a large quantity of copper powder has to be used and the process is it tedious one, the values for iodine and sulphur are sometimes too low (see T., 1916, 109, 611).

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TI-IEIR REAC'TION WITH THM RLKYL JOl>IDES. PART V. 547

The met8hold of preparatiofn and purification was the same as iii It is a white, crystalline the case1 of the preceding compound.

substance melting a t 9 4 O . Found: Hg=18.24; S=11.36; c"=13*15; H=2.54.

C,,H,,N,S,Hg,I, requires H g = 18.78; S= 13.52 ; (2- 13.52; H = 2.53 per cent.

The formation of this type of compound has been observed only ill this one instance.

Conzpoimd m~1ilh n-7'ropyZ 7odid'c (VII ) .

This conforms t o the ordinary type. Found: Hg=18-54; 1=44*61; (2-16.47.

@3,€I,,jN,,S,Hg21s requires Hg= 18.14; 1=46*1 ; c"= 16-33 per cent. As will he noticed, the trinuclear sulphoxy-compound gives with

niethyl iodide compounds I and V, the latter being the chief pro- duct. This tendency towards the formation of the dinuclear tetra- sulphonium compound from the higher nudear sulphoxy-compounds is particularly iioticeable in the case of the reaction with ethyl iodide, when only the dinuclear sulphcnium compound (11) is obtained, even from tri- and tetra-nuclear sulphoxy-derivatives. In all these cases of formation o f a lower member from the higher sulphoxy-corni)ounds, a dark brown, pasty sulstance with a penetrating odour and lachrymatory properties was always pro- duced, which resisted all attempts a t purification.

H e x a IL ZL c I c a t s C'o n rt e n s cc t i o n.

the Compurzd, rEt N--N Et,

' l h i h melted a t 90-91*.

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548 RAY: MERCURY MERCAYTIDE NITRITES AND THEIR

Found: I=50*03; N=3*90; C=13.14. C,,H70Nl,S,8Hg,Il, requires I = 51.20 ; N = 4-54 ; C= 13-82 per ceiit.

It will thus be seen that the type persists throughout, in that the alteration in the position of the double bond is limited to olnly one nucleus of the chain.

I n the previous communications, the compounds there described were tentatively classed under tahe sulphonium group, although no direct proof could be adduced in support of this view. One of the purest compounds of this series, namely, MeEtS,,HgI,,EtI (T., 1916, 10.9, 606), was selected for molecular weight determination i n acetone solution by the ebullioscopic method ; the value obtained was 712, that required by theory being 718. It is thus evident that the constitution is atomic (compare Hilditch and Smiles, T., 1907, 91, 1396).

A study of the physical properties of the interesting poly- sulphoiiiuui coiiipouiids treated of ill this paper is being under- taken which, i t is hoped, will throw additional light on their constitution.

CHEMICAL LABORATORY,

UNIVERSITY OF (2ALCUTTA. [ftec.c.iwd, Nouerr&r 30th, 1918.1

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