Oxidation of atenolol by diperiodatoargentate(III) in aqueous alkaline medium – a multimechanistic reaction

Abstract

The kinetics of oxidation of antihypertensive drug, atenolol by diperiodatoargentate(III) (DPA) in a wide range of alkali has been studied spectrophotometrically. In a lower range of [OH⁻], the periodate had a retarding effect whereas at higher range of [OH⁻] the rate of reaction was accelerated. In the higher range of [OH⁻], the periodate had no effect whereas at lower range of [OH⁻], periodate and product, [Ag(I)] retarded the rate of the reaction. In the entire range of [OH⁻], the reaction was unit order in [DPA] and fractional order in [ATN]. Mechanisms consistent with the observed kinetic data for both lower and higher ranges of [OH⁻] were proposed and discussed. The active species of [Ag(III)] was found to be mono periodatoargentate(III) in lower range of [OH⁻] and dihydroxymonodiperiodatoargentate(III) in the higher range of [OH⁻]. The hydrolyzed species of atenolol was found to be the active form of atenolol. Mechanisms for both higher and lower range of [OH⁻] have been proposed. A composite rate law has been derived and verified for different experimental conditions.