Oxidation of organic sulphides. I. Interaction of cyclo hexyl methyl sulphide with hydroperoxides in alcohols

Cyclohexyl methyl sulphide is oxidized quantitatively to the sulphoxide by alcoholic solutions of cyclo hexenyl and t-butyl hydroperoxides at moderate temperatures. Kinetically the oxida­tion appears to be a simple bimolecular reaction, first-order with respect to both the sulphide and hydroperoxide. However, the reaction rates vary in different alcohols in the order of varying solvent acidity, and correspondingly the addition of much stronger acids produces powerful catalysis. The solvent and the acids clearly play a part in the reaction, and it is concluded that the actual oxidant is a cyclic complex between the hydroperoxide and a hydrogen-donating molecule, oxygen atom transfer to the sulphide being promoted by a synchronous hydrogen atom exchange process within the complex. Energies and entropies of activation for the oxidation under various conditions are reported and their significance discussed.