The polarographic reduction of organic sulphides in NN-dimethylformamide

Abstract

Sulphides (thioethers) PhSR (R = aryl, alkyl, or aliphatic) are reduced polarographically in anhydrous NN-dimethylformamide. For most of the compounds the electrode process involves a two-electron transfer and fission of the S–R bond. This mechanism is substantiated by the controlled-potential electrolysis of diphenyl sulphide. A few sulphides are also reduced by a one-electron process. The presence of a proton donor (phenol) does not affect the two-electron waves, but induces the transfer of a second electron in the otherwise one-electron reductions. The polar effect of the substituent R is the predominant factor governing E_½ and therefore the polarographic results are satisfactorily correlated by the Taft–Hammett equation.