Oxidation Kinetics of Amino Acids by 1-Chlorobenzimidazole in Acid Medium – A Kinetic and Mechanistic Approach
J. Environ. Nanotechnol., Volume 10, No 1 (2021) pp. 08-13
Abstract
In this study, the reaction kinetics of oxidation of amino acids such as glycine, alanine, phenylalanine, tryptophan, leucine and cysteine with 1-Chlorobenzimidazole (CBI) has been studied in an aqueous acetic acid medium. The oxidation kinetic mechanism proposed is consistent with observed kinetic data. The reactions were monitored potentiometrically up to 70 % completion using a platinum-saturated calomel electrode assembly to track the potentials of the reaction mixture containing varying concentrations of the [CBI] / [BI] couple (BI = benzimidazole) at recurring intervals. The reactions were found to be first-order, each with respect to [amino acids] and [oxidant]. The rate of the reaction decreases with the increase in HClO4 and the order in [HClO4] was inverse fractional. The rate of reaction decreases as the dielectric constant of the solvent medium decreases, indicating a dipole-dipole reaction. Electrolytes, such as sodium perchlorate, have no significant effect on reaction rates. The addition of benzimidazole, one of the reaction ingredients, slowed down the reaction rates. When acrylonitrile was applied to the reaction mixture, no polymerization occurred. The thermodynamic parameters were measured after the kinetic runs were carried out at four different temperatures. The results of the reactions have carboxylic acid, ammonia and carbon dioxide. The most-likely reactive species have been identified as HOCl. The kinetic effects that have been derived are compatible with a fitting mechanism.
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