Mn(II) Catalyzed Oxidation of Atenolol by Cerium(IV) in Aqueous Sulfuric Acid Medium: A Spectrophotometer Aided Kinetic, Mechanistic and Thermodynamic Study

摘要

The kinetics and mechanism of manganese(II) catalyzed oxidation of atenolol by cerium(IV) sulfate in aqueous H2SO4 at a constant ionic strength of 0.50 mol dm(-3) was studied spectrophotometrically. The reaction showed first order kinetics in cerium(IV) whereas fractional order in both manganese(II) and atenolol. Addition of products showed no effect on the rate of the reaction. The main product, 2-(4-(2-hydroxy-3-oxopropoxy) phenyl) acetamide, was identified with the aid of IR and mass spectral data. Stoichiometry with respect to the drug substrate and reagent was established as 2:1. Added H2SO4, SO42- and HSO4 showed negligible effect on the rate of the reaction. HCe(SO4)(3)(-) was found to be the predominant reactive species under the specified experimental conditions. The rate constants (k), catalytic constant (k(c)) and equilibrium constant (K-6) for the proposed mechanism were determined. The kinetic and thermodynamic activation parameters were computed for both the slow rate determining step and complex forming equilibrium step.