Single-electronic cleavage of a carbon–sulphur bond in the cathodic reduction of 2,3-bis(phenylsulphonyl)-1,4-dimethylbenzene in dimethyl sulphoxide

Abstract

2,3-Bis(phenylsulphonyl)-1,4-dimethylbenzene, dissolved in dimethyl sulphoxide, undergoes a one-electron single reduction wave at –1.6 V with respect to Ag–Ag+(0.01M). The reduction was studied by differential pulse polarography, cyclic voltammetry, and controlled-potential electrolysis. Fast chemical steps follow the initial reduction and the isolated products are 1,4-dimethyldibenzothiophene 5,5-dioxide and 1,4-dimethyl-2-(phenylsulphonyl)benzene. In some experiments small percentages of 5a,9a-dihydro-1,4-dimethyldibenzothiophene 5,5-dioxide are also obtained. The results argue in support of the electron-transfer mechanism previously proposed for the photoinduced reactions of the same substrate with sodium arenethiolates in dimethyl sulphoxide.