Mechanistic investigation of oxidation of atenolol by N-chloro-p-toluenesulfonamide in alkaline medium a kinetic approach

Abstract

Kinetic studies of the oxidation of atenolol (ATN) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in presence of NaOH at 26.0 ′ 0.1°C follows the rate law -d[CAT]/dt = k[CAT][ATN] x [OH] - y , where x and y are less than unity. The variation of ionic strength and addition of the reaction product, p-toluenesulfonamide and Cl - ion had no pronounced effect on the reaction rate. Decrease of dielectric constant of the medium by increasing the MeOH content decreased the rate. Composite activation parameters for the reaction have been computed from Arrhenius plot. Michaelis-Menten type of kinetics is observed and activation parameters for rate limiting step have been computed. Formation and decomposition constants of CAT-ATN complexes in the reaction scheme have been determined. The conjugate acid, CH 3 C 6 H 4 SO 2 NHCl is assumed to be the reactive species. 4-Acetamido-benzene-oxy-acetic acid and isopropyl amine were found to be the main oxidation products of atenolol. The proposed mechanism and derived rate law are consistent with the observed kinetic data.