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ISRN Physical Chemistry
Volume 2014 (2014), Article ID 924827, 7 pages
http://dx.doi.org/10.1155/2014/924827
Research Article

Perborate Oxidation of Substituted 5-Oxoacids in Aqueous Acetic Acid Medium: A Kinetic and Mechanistic Study

1Research and Development Centre, Bharathiar University, Coimbatore 641 046, India
2Department of Chemistry, Arignar Anna Government Arts College, Cheyyar 604 407, India
3Department of Chemistry, Presidency College, Chennai 600005, India
4Department of Chemistry, Dr. Ambedkar Government Arts College, Chennai 600 039, India

Received 22 November 2013; Accepted 5 January 2014; Published 4 March 2014

Academic Editors: M. Sikorski, D. Strout, and D. A. Wild

Copyright © 2014 S. Shree Devi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Kinetics and mechanism of oxidation of substituted 5-oxoacids by sodium perborate in aqueous acetic acid medium have been studied. The reaction exhibits first order both in [perborate] and [5-oxoacid] and second order in [H+]. Variation in ionic strength has no effect on the reaction rate, while the reaction rates are enhanced on lowering the dielectric constant of the reaction medium. Electron releasing substituents in the aromatic ring accelerate the reaction rate and electron withdrawing substituents retard the reaction. The order of reactivity among the studied 5-oxoacids is p-methoxy ≫ p-methyl > p-phenyl > –H > p-chloro > p-bromo > m-nitro. The oxidation is faster than H2O2 oxidation. The formation of is the reactive species of perborate in the acid medium. Activation parameters have been evaluated using Arrhenius and Eyring’s plots. A mechanism consistent with the observed kinetic data has been proposed and discussed. Based on the mechanism a suitable rate law is derived.