A THEORETICAL AND EXPERIMENTAL INVESTIGATION OF THE ELECTROPHILIC OXIDATION OF THIOETHERS AND SULFOXIDES BY PEROXIDES

In the electrophilic oxidation by peroxides the reactivity of sulfoxid es is considerably less affected by structural effects than that of th ioethers. This feature has not been, so far, rationalized. We have cal culated by semiempirical methods the charge on the sulfur atom, Q(S), and the energy of the HOMO for a series of thioethers and sulfoxides. Then we have correlated the rate constants for the oxidation of thioet hers by H3O2+ and of sulfoxides by perbenzoic acid with Q(S) and with F (F = (E(LUMO)(Ox) - E(HOMO)(Sub))(-1) respectively. We find that the reactivity of thioethers is mainly dependent on Q(S), while that of s ulfoxides is dominated by F.