Silver-Catalyzed Oxidation of Atropine Drug by Cerium(IV) in Aqueous Perchlorate Solutions: A Kinetics and Mechanistic Approach

摘要

The kinetics of oxidation of atropine drug (ATR) by cerium(IV) in aqueous perchlorate solutions in the presence of silver(I) catalyst has been studied spectrophotometrically at a constant ionic strength and temperature. The reaction showed first order dependence with respect to each [Ce(IV)] and [Ag(I)], and less than unit order kinetics with respect to [ATR]. The reaction exhibited negative fractional-first order kinetics with respect to [H~+]. Increasing ionic strength and dielectric constant of the medium increased the reaction rate. In the present work, the kinetically active species of cerium(IV) was found to be Ce(OH)~(3+). Addition of Ce(III) product had no significant effect on the oxidation rate. The oxidation products of atropine were identified by spectral and chemical analyses as tropine, benzaldehyde, methanol and carbon dioxide. A plausible mechanistic scheme for the catalyzed oxidation was proposed. The activation parameters of the second order rate constant were calculated and the rate law associated with the reaction mechanism was derived.