Pyrolysis of S-alkyl-S-phenyl-N-p-tolylsulphonylsulphimides with no β-hydrogen atoms

Abstract

S-Alkyl-S-phenyl-N-p-tosylsulphimides with no β-hydrogen atoms were thermally decomposed in sealed tubes at 180° in various solvents. The products obtained depended markedly on the solvent used. When pyrolysis of S-methyl-S-phenyl-N-p-tosylsulphimide was carried out in methanol, the major products were methyl phenyl sulphide, methyl phenyl sulphoxide, and toluene-p-sulphonamide. When dimethylformamide (DMF) or benzene was used as solvent. N-methyltoluene-p-sulphonamide and diphenyl disulphide were obtained in substantial yields. With dimethyl sulphoxide (DMSO), the main product was methyl phenyl disulphide which is considered to be formed by the reaction of S-methyl-S-phenyl-N-p-tosylsulphimide with DMSO. When alkyl aryl or diaryl sulphoxide was used as solvent, the sulphoxide or sulphimide was reduced to the corresponding sulphide accompanied by ammonium toluene-p-sulphonate in substantial yield. The distribution of products and the implication of this for the mechanism are discussed.