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Palladium(II)-catalyzed oxidation of tranexamic acid by bromamine-B in alkaline medium and uncatalyzed reaction in acid medium: A study of kinetic and mechanistic chemistry

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Title: Palladium(II)-catalyzed oxidation of tranexamic acid by bromamine-B in alkaline medium and uncatalyzed reaction in acid medium: A study of kinetic and mechanistic chemistry
Authors: Puttaswamy pswamy_chem@yahoo.com, Sukhdev, Anu1, Shubha, J.P.1
Source: Journal of Molecular Catalysis A: Chemistry. Nov2010, Vol. 332 Issue 1/2, p113-121. 9p.
Subjects: Palladium catalysts, Chemical kinetics, Antifibrinolytic agents, Oxidation-reduction reaction, Temperature effect, Activation (Chemistry)
Abstract: Abstract: Tranexamic acid (TA) possess antifibrinolytic properties and finds extensive applications in pharmaceuticals. Its oxidation-kinetic study is of much significance in understanding the mechanistic profile of TA in biological systems. In this context, a systematic kinetic study of palladium(II) (Pd(II)) catalyzed oxidation of TA by sodium N-bromobenzenesulfonamide or bromamine-B (BAB) in alkaline medium and uncatalyzed reaction in perchloric acid medium at 303K was investigated. In acid medium, the reaction exhibits a first-order dependence of rate on [BAB]o and less than unity order dependence on [TA]o. The reaction rate shows inverse less than unity order dependence with respect to [H+]. In alkaline medium, the reaction shows first-order dependence on both [BAB]o and [Pd(II)] and zero-order with respect to [TA]o. The order with respect to [OH−] is less than unity. Activation parameters have been evaluated. The oxidation reactions are nearly 10-fold faster in acid medium in comparison with alkaline medium. In alkaline medium, the Pd(II) catalyzed reactions are about 6-fold faster than the uncatalyzed reaction. Further, the catalytic constant (K C ) has been calculated at different temperatures and activation parameters with respect to Pd(II) catalyst have also been evaluated. The conjugate acid C6H5SO2NHBr and the anion C6H5SO2N−Br of BAB have been postulated as the reactive oxidizing species in acid and alkaline media, respectively. The proposed mechanisms and derived rate laws are in agreement with the observed kinetics. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Abstract: Tranexamic acid (TA) possess antifibrinolytic properties and finds extensive applications in pharmaceuticals. Its oxidation-kinetic study is of much significance in understanding the mechanistic profile of TA in biological systems. In this context, a systematic kinetic study of palladium(II) (Pd(II)) catalyzed oxidation of TA by sodium N-bromobenzenesulfonamide or bromamine-B (BAB) in alkaline medium and uncatalyzed reaction in perchloric acid medium at 303K was investigated. In acid medium, the reaction exhibits a first-order dependence of rate on [BAB]o and less than unity order dependence on [TA]o. The reaction rate shows inverse less than unity order dependence with respect to [H+]. In alkaline medium, the reaction shows first-order dependence on both [BAB]o and [Pd(II)] and zero-order with respect to [TA]o. The order with respect to [OH−] is less than unity. Activation parameters have been evaluated. The oxidation reactions are nearly 10-fold faster in acid medium in comparison with alkaline medium. In alkaline medium, the Pd(II) catalyzed reactions are about 6-fold faster than the uncatalyzed reaction. Further, the catalytic constant (K C ) has been calculated at different temperatures and activation parameters with respect to Pd(II) catalyst have also been evaluated. The conjugate acid C6H5SO2NHBr and the anion C6H5SO2N−Br of BAB have been postulated as the reactive oxidizing species in acid and alkaline media, respectively. The proposed mechanisms and derived rate laws are in agreement with the observed kinetics. [ABSTRACT FROM AUTHOR]
ISSN:13811169
DOI:10.1016/j.molcata.2010.09.005