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

Abstract

The kinetics and mechanism of manganese(II) catalyzed oxidation of atenolol by cerium(IV) sulfate in aqueous H2SO4at a constant ionic strength of 0.50 mol dm-3was 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 (kc) and equilibrium constant (K6) 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.

Impact of substitution on reactions and stability of one-electron oxidised phenyl sulfonates in aqueous solution

“…§ E1(HO , H + /H 2 O) = 2.7 V, E1(HOO , H + /H 2 O 2 ) = 1.5 V,31 the electrode potential E1'(Ce(IV)/H + , Ce(III)) in water is strongly dependent on the electrolyte, 1.3-1.7 V 32. Given that reactions (9) and (12) are one-sided, hydroperoxyl radicals will not oxidise the aromatic structures used here.…”