Disulphur Dithiocyanate, S2(SCN)2, is formed by the interaction of sulphur chloride and a metallic/thiocyanate, the best and most uniform results being obtained when mercuric thiocyanate is used. Chloroform or carbon tetrachloride forms a suitable solvent if the product is only required in solution, since these do not dissolve mercury salts; if the compound is to be isolated, carbon disulphide is the required solvent. Disulphur dithiocyanate forms colourless crystals which melt at -3.3° C., forming a viscous, yellow, odourless liquid, which is somewhat unstable. On cautious heating it becomes dark yellow, then red, and finally detonates. It is hydrolysed by water according to the equations:
S2(SCN)2 + 2H2O → HO.S.S.OH + 2HCNS,
HO.S.S.OH + 2HCNS → 2S + 2H2O + (SCN)2,
and
3(SCN)2 + 4H2O → 5HCNS + H2SO4 + HCN. |