EPR STUDIES OF THE COPPER-CATALYZED OXIDATION OF THIOLS WITH PEROXIDES

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(t)O(.) (from Bu(t)O(2)H) which convert more thiol into disulfide. EPR and W-VIS spectroscopy allow the kinetic parameters of these reactions to be determined in N,N-dimethylformamide (DMF).