Iodide monosulphide

G. Taddei7 prepared potassium iodide by adding a dil. soln. of potassium monosulphide to an alcoholic soln. of iodine. In place pf potassium sulphide, J. von Liebig and C. Wittstock used barium sulphide, prepared by calcining sulphate with coke. According to R. Schindler, the products obtained by the sulphide process are contaminated with sulphur compounds. G. S. Serullas treated potassium antimoniate (prepared by calcining tartar emetic) with an alcoholic soln. of iodine as long as the soln. was decolorized. The filtered soln. was evaporated to the point of crystallization. 

Cyanogen monosulphide crystallises in rhomboidal crystals which partly sublime at 30° to 40° C. and melt at 60° C. It is soluble in water, alcohol, ether, carbon disulphide, chloroform, benzene and sulphuric acid. It is decomposed by hydrochloric acid. It precipitates iodine from potassium iodide. Alcoholic potash decomposes it into potassium cyanate and potassium thiocyanate ... 

In aqueous solution sodium monosulphide reacts with iodine to form. sodium iodide, the liberated sulphur dissolving in excess of the sulphide solution.10 A double sulphide of the formula Na2S,Cu2S has been prepared.11 It melts at 700° C. 

Based on early studies with model systems it was originally concluded that such a product was only obtained from dialkenyl monosulphides (A). Later work by Naylor (1947, 1949) and Trego (1%5) has shown however that trimethyl sulphonium iodide is also obtained from other monosulphides such as t-alkyl sec-alkenyl monosulphides (B) and t-alkyl t-alkenyl monosulphides (C). 

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