Kinetics of oxidation of antidiabetic drug metformin hydrochloride by vanadium(V) in acidic and micellar medium

Abstract

The kinetics of oxidation of antidiabetic drug metformin by vanadium(V) have been studied spectrophotometrically under pseudo-first order conditions in aqueous acidic and micellar medium. The observed rate of oxidation is first order with respect to both metformin and H +. The pseudo-first order rate constant is independent of ionic strength and varies inversely with dielectric constant of the medium. The effect of micelles (SDS and TX 100) on such reactions has been investigated. Sodiumdodecyl sulphate (SDS) and iso-octylphenoxy polyethoxyether (TX100) accelerate the rate of electron transfer reaction except for cationic CTAB due to the cloudiness of the reaction mixture. It is a one electron transfer process where vanadium(V)is reduced to vanadium(IV) supported by cyclic voltammetric study. The main oxidation product was identified as metformin N-oxide by FTIR and LCMS method. Activation parameters of such reaction have been calculated and reaction mechanism is suggested. Computational study based on Hartree-Fock method supports the reaction mechanism.