Abstract
A systematic study on the oxidative decarboxylation of a series of phenylsulfinylacetic acids (PSAA) by hydrogen peroxide with four oxovanadium(IV)-salophen catalysts in 100% acetonitrile medium is presented. The hydroperoxovanadium(V)-salophen generated from the reaction mixture is identified as the bonafide active oxidizing species. Introduction of electron donating groups (EDG) in the oxovanadium(IV)-salophen catalyst and electron withdrawing groups (EWG) in PSAA enhances the reactivity, whereas EWG in the catalyst and EDG in PSAA have a retarding effect on the reaction. A Hammett correlation displays a non-linear downward curvature, which consists of two intersecting straight lines and the ρ value shifts from small positive to moderately high as the substituents change from EWG to EDG. The importance of the ground state stabilization of PSAA is inferred from a linear Yukawa–Tsuno plot. Based on the observed substituent effects and the spectral changes, a mechanism involving electrophilic attack of PSAA on the nucleophilic peroxo oxygen atom of the vanadium complex in the rate determining step followed by oxygen atom transfer is proposed.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have