The experimental results presented in this paper show beyond doubt, that thionyl iodide though highly unstable, can be prepared by the method described. Two important factors should be borne in mind while attempting to prepare such unstable compounds. First and foremost, it is necessary to adjust the experimental conditions, such that the substance gets produced in the form of dilute solution, since the compound decomposes with great rapidity both in the pure state and in concentrated solutions. In fact, treatment of pure thionyl chloride with potassium iodide, yields but little thionyl iodide and results only in the formation of sulphur, sulphur dioxide and iodine. Similarly very little sulphur iodide¹⁷ is produced when sulphur chloride is treated with potassium iodide. Secondly, it is also necessary to bear in mind the decomposing effect that light may have. In fact both sulphur iodide⁵ and thionyl iodide (especially the latter) are easily decomposed by light. It is the negleet of these two factors, that is responsible for the failure of carlider workers in preparing these compounds. The method worked out by the author for the preparation of sulphur iodide⁵ and thionyl iodide appears to be general in seope and applicable tothe preparation of many new compounds.

Authors and Affiliations

1. Department of Chemistry, University of Mysore, Central College, Bangalore

   M. R. Aswathanarayana Rao

[Communicated by Prof. B. Sanjiva Rao, M.A., Ph.D. (Lond.)f.a.sc.]

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