A Mechanistic Studies of Mn(II) Catalyzed Oxidation of a Gabapentin by Peroxomonosulphate in Aqueous Alkaline Medium

Abstract

Abstract A mechanistic approach to the influence of Mn(II) catalyzed oxidative deamination of an anti-convulsant drug [GP] by peroxomonosulphate (PMS) at a constant ionic strength of 1.0 mol dm –3 have been studied, spectrophotometrically. The reaction shows first order dependence on [PMS] and [Mn(II)] and apparent less than unit order dependence each in [GP] and alkali concentrations. Influence of dielectric constant and ionic strength of the medium on the reaction rate have been evaluated. It was observed that the added sulphate ion, the reduction product of the oxidant, had insignificant effect on the reaction rate. The reaction stoichiometry and oxidation products deprotonated GP, SO4 2− and MnO2 have been identified and a suitable mechanism has been proposed. The reaction fails to initiate polymerization in the presence of acrylonitrile under the experimental conditions employed. In a composite equilibrium step, deprotanated GP binds to catalyst and form a complex C that subsequently decomposes with oxidant to yield the products. Investigations of the reaction at different temperatures allowed the determination of the activation parameters and a tentative reaction mechanism in good consistency with the kinetic results is discussed.