The photolysis of dialkyl sulphides, disulphides, and trisulphides

Abstract

Several dialkyl mono-, di-, and trisulphides have been irradiated in the absence of solvents with ultraviolet light (2537 Ǻ), with direct sunlight, and with y-rays; the irradiation products were identified and estimated by gas chromatography. Trisulphides rapidly gave a mixture of di-, tri-, and tetrasulphides by a disproportionation reaction initiated by S-S fission. Monosulphides and symmetrical disulphides were much more stable, although both gave products via C-S fission. The former yielded the corresponding disulphide and hydrocarbon, while the latter gave mainly the corresponding tri- and tetrasulphides with traces of mono- sulphides and hydrocarbons. Study of these results and those concerned with disulphide interchange and the dismutation of trisulphides leads to the conclusion that, if both types of fission are possible in the irradiation of a simple dialkyl polysulphide, then S-S fission occurs at the expense of C-S fission.