Reaction of Organic Sulfur Compounds with Hyperoxide Anion (O2-anion radical). IV. Evidence for Formation of Peroxysulfur Intermediates: Oxidation of Sulfoxides, Phosphines, and Olefins with Intermediary Peroxysulfur Species

Article abstract of DOI:10.1246/bcsj.54.2712

Formations of peroxy-sulfenate(I), -sulfinate(II), and -sulfonate(III) as intermediates have been confirmed by stripping the peroxy oxygen with three kinds of trapping agents such as sulfoxides, phosphines, and olefins, added in the reaction systems of various organic sulfur compounds with hyperoxide anion (O2-anion radical).These sulfoxides, phosphines, and olefins were inert to O2-anion radical alone while electrophilic olefins, such as α,β-unsaturated ketones reacted readily with O2-anion radical to afford the carboxylic acid.Sulfoxides, added into the reaction system of disulfide, thiosulfinic S-ester, thiosulfonic S-ester, or sulfonyl chloride with O2-anion radical, were found to be oxidized to the sulfones with peroxysulfur intermediates formed in situ in the system.Phosphines, added into the reaction system of disulfide or sodium thiolate with O2-anion radical were also oxidized to the phosphine oxides.Not only stilbene and acenaphthylene but also chalcone and its derivatives, placed in the reactions of sulfonyl chloride, sulfinyl chloride and thiosulfonic S-ester with O2-anion radical were found to be oxidized to the corresponding epoxides.These observations suggest clearly that the intermediary peroxysulfur compounds can act as oxidizing agents which oxidize these trapping agents by the nucleophilic oxygenative oxidation.Similar intermediates were postulated and confirmed in the alkaline autoxidations of thiol and disulfide in which added phosphines and sulfoxides were also found to be oxidized to their oxides.The mechanisms of the reactions of these trapping agents with peroxysulfur intermediates are discussed.