Electron spin resonance studies. Part XLIII. Reaction of dimethyl sulphoxide with the hydroxyl radical

Abstract

A kinetic analysis is given of the reaction between the hydroxyl radical (generated from the Ti^III–H₂O₂ couple in a continuous flow system) and dimethyl sulphoxide in aqueous acid at ambient temperature; steady-state concentrations of both Me˙ and MeSO₂˙ have been monitored. Evidence is presented that the former radical arises from addition of ˙OH to the sulphoxide followed by rapid decomposition of the intermediate species Me₂SO₂˙. There was no evidence for the formation of ˙CH₂S(O)Me. Rate constants for the reaction between hydroxyl and Me₂SO, for that between Me˙ and MeSO₂H, and for the dimerisation of methyl are estimated as 5 × 10⁹, ca. 10⁶, and 5·6 × 10⁹ l mol^–1 s^–1, respectively.