Kinetics of oxidative degradation and deamination of atenolol by aqueous alkaline permanganate

Abstract

The kinetics of the oxidative degradation of atenolol (ATN) by permanganate in aqueous alkaline medium at constant ionic strength of 0.30 mol dm^-3 has been studied spectrophotometrically using a rapid kinetic accessory. The reaction is first order in [permanganate ion] and has less than unit order each in [ATN] and [alkali]. Initial addition of products and change in ionic strength have no significant effect on the reaction rate. However, decrease in dielectric constant of the medium increases the rate. The oxidation in alkaline medium has been shown to proceed <i>via</i> permanganate-atenolol complex, which

decomposes slowly in a rate determining step followed by a fast reaction between a free rad ical of atenolol and another molecule of permanganate species to give the products. The main products have been identified by IR, NMR, fluorimetric and mass spectral studies. The reaction constants involved in the mechanism are evaluated and a good agreement between observed rate constants and the calculated rate constants is obtained. The activation parameters are computed with respect to slow step of the proposed mechanism.