Oxygen Exchange Reaction of Sulfoxides in Dinitrogen Tetroxide

Abstract

Abstract Sulfoxides are known to undergo concurrent oxygen exchange and racemization reactions with various reagents (Bull. Chem. Soc. Japan, 41, 1025 (1968)). Especially well studied are the oxygen exchange reactions in acid media. We have found a similar concurrent oxygen exchange and racemization reaction of sulfoxides with liquid dinitrogen tetroxide. The pseudo first order reaction rates of both oxygen exchange and racemization reactions have been determined using both optically active and 18O-labeled sulfoxides. The kex⁄krac value was found to be unity, and the polar effect of substituents on the rates of oxygen exchange of substituted diphenyl sulfoxides was found to be considerably large, and correlated with σ+ values with ρ=−1.30. From these results a plausible mechanism for this reaction has been discussed.