Studies on the Kinetics and Mechanism of Oxidation of Nitrones by Pyrazolinium Dichromate in aqueous DMSO medium

Abstract

The kinetics and mechanism of oxidation of N, α- diphenylnitrones by some substituted nitrones by Pyrazolinium dichromateyielding benzaldehyde and nitrosobenzene in aqueous dimethyl sulphoxidemedium have been investigated. First order dependence with respect to both [PyDC] and [NO]. The compound was prepared and purity of the oxidant was estimated by iodometric method. The reaction is fractional order with respect to [H+]. Electron-releasing substituents increase the rate of the reaction and electron withdrawing substituents decrease the rate of the reaction. No polymerisation observed with acrylamide ruling out a free radical mechanism. There was no discernible effect with increasing in ionic strength but the rate of oxidation decreased with decreasing dielectric constant of the medium. Addition of MnSO4 had a significant and acrylonitrile no effect on the reaction rate.