EPR studies of the copper-catalysed oxidation of thiols with peroxides

Abstract

EPR spectroscopy has been employed to monitor the reactions of Cu^II and the formation of organic radicals in the copper-catalysed oxidation of thiols to disulfides in the presence of oxygen and peroxides. Reaction of Cu^II with RSH gives Cu^I and disulfide (a process whose stoichiometry is 1:1 in certain solvents), which is followed by electron transfer to the peroxide to give Cu^II and, for example, HO˙(from H₂O₂) and Bu^tO˙(from Bu^tO₂H) which convert more thiol into disulfide. EPR and UV–VIS spectroscopy allow the kinetic parameters of these reactions to be determined in N,N-dimethylformamide (DMF).