Electron spin resonance studies. Part XXXVII. Oxidation of β-hydroxy-sulphides by the hydroxyl radical and structural features of sulphur-conjugated radicals

Abstract

E.s.r. spectroscopy in conjunction with a rapid-flow system has been used to show that both carbon radicals and thiyl radicals mediate in the oxidation of some β-hydroxy-sulphides with the hydroxyl radical in aqueous solution; the carbon radicals are detected directly and the thiyl radicals by way of their adducts with a spin trap. It is suggested that both types of radical are formed following the abstraction of an electron from sulphur; thus, the sulphur radical cation can undergo loss of a proton from an adjacent carbon atom or heterolysis of an adjacent C–C bond, to yield a carbon radical, or heterolysis of a C–S bond, to yield a thiyl radical. The structures of the carbon radicals are discussed in the light of the trends shown in their e.s.r. parameters.