OXIDATIVE KINETICS OF AMINOACIDS BY N-BROMOACETAMIDE. A STUDY OF SOLVENT EFFECT AND GENERAL BASE CATALYSIS

Article abstract of DOI:10.1016/S0040-4020(01)96659-1

The kinetic results of the oxidation of aminoacids by N-bromoacetamide in acid and alkaline media are presented.It is noticed that the order with respect to substrate is dependent on the nature of the medium, 0.30-0.80 in perchloric acid (except phenylalanine in which case the order is 1.0) and alkaline media and zero order in aqueous acetic acid.Irrespective of the medium, the reaction is first order in .The rate of oxidation increases with and decreases with .The changes observed in the direction of the pH-rate profile correspond to the ionization constans of the aminoacids.The reaction is inhibited by the addition of acetamide in pechloric acid medium but, is independent of it in alkaline medium.The rate of oxidation is susceptible to changes in the composition of acetic acid and is maximum at 25percent aqueous acetic acid.The oxidation of aminoacids by N-bromoacetamide is also catalysed by carboxylate anions.The catalytic constants of propionate, butyrate, acetate, chloropropionate and chloroacetate are measured and Broensted coefficients (β) so evaluated are in the range 0.38-0.46.The proposed mechanism and the derived rate laws are consistent with the observed kinetics.