现代化学与应用

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Kinetics and Mechanistic Approach to the Chromic Acid Oxidative Degradation of Atropine Drug in Perchlorate Solutions and the Effect of Ruthenium(III) Catalyst

Ahmed Fawzy, Ishaq , Ismail and Hatem

The effect of ruthenium(III) catalyst on the kinetics of oxidation of atropine drug (ATR) by chromic acid in perchlorate solutions was studied spectrophotometrically at a fixed ionic strength of 1.0 mol dm-3 and at 25°C. Both uncatalyzed and Ru(III)-catalyzed omedicine xidation reactions showed a first order dependence in [Cr(VI)], and less than unit order dependences with respect to both [ATR] and [H+]. The reaction was first order in [Ru(III)]. The effects of both ionic strength and dielectric constant of the reactions medium were investigated. Addition of Mn(II) was found to decrease the oxidation rate. The rate of Ru(III)-catalyzed oxidation of atropine was found to be about 10-fold higher than that of the uncatalyzed reaction. In both cases, the main oxidation products of atropine were identified as tropine, benzaldehyde, methanol, and carbon dioxide. Plausible mechanisms for both uncatalyzed and Ru(III)- catalyzed oxidations were proposed and the rate-law expressions associated with these mechanisms were derived. The activation parameters related to the second order rate constants were evaluated and discussed.