Dual role of water in the oxygenation of phenylmercaptoacetic acids catalyzed by [oxo(salen)chromium(V)]+ PF6-

The sulfoxidation of eleven PMAAs by the oxo(salen)chromium(V) complex in aqueous acetonitrile medium was studied spectrophotometrically. [O=-Cr(V)salen-H2O](+) adduct was found to be the active oxidizing species. The rate of the sulfoxidation increases with increase in the polarity of the medium. The rate of the reaction is accelerated by electron donating substituents on PMAA while it is retarded by the electron withdrawing substituents. Based on the observed spectral and kinetic changes, electrophilic attack of the adduct [O=Cr(V)salen-H2O](+) on the sulfur atom of the PMAA has been proposed.

Automated summary

The sulfoxidation of PMAAs by the oxo(salen)chromium(V) complex in aqueous acetonitrile medium was studied. The rate of the reaction is influenced by the polarity of the medium and the substituents on PMAA, with electron donating substituents accelerating the reaction and electron withdrawing substituents retarding the reaction.