Insertion of Elemental Sulfur into the Se-Se Bond of Diorganyl Diselenides. Synthesis of Bis-alkyl(seleno) Polysulfides

Abstract

Reaction of dialkyl diselenides R2Se2 (R = Me, n-Bu) with sulfur at room temperature in the presence of the catalytic system DMSO-Na2S·9H2O-triethylbenzylammonium chloride, as well as at 55-60°C in the presence or in the absence of catalysts leads to the insertion of from one to six atoms of sulfur into the Se-Se bond. Bis(methylseleno) polysulfides MeSeSnSeMe with n = 5-6 gradually liberate sulfur on keeping. Dibutyl diselenide is less active than dimethyl diselenide, and diphenyl diselenide does not react with sulfur in boiling carbon disulfide. At 55-60°C a small portion of selenium in dialkyl diselenides passes into unreacted sulfur which is indicative of cleavage of the C-Se bonds in bis(methylseleno) polysulfides.