Effects of nonionic micellar aggregates on the electron transfer reaction between l‐glutamic acid and gold(III) complexes

Abstract

AbstractThe effect of nonionic micelles of Triton X‐100 on the oxidative decarboxylation of l‐glutamic acid by chloroaurate(III) complexes has been investigated in acetate buffer medium. The reaction is first order with respect to Au(III), but a complex order with respect to glutamate. H+ ion has both accelerating and retarding effects in the pH range 3.72–4.80, whereas a Cl− ion has an inhibiting effect in the range 0.02–0.56 mol dm−3. Under the experimental conditions, AuCl−4 and AuCl3(OH)− are the predominant and effective oxidizing species, whereas the zwitterion (H2A) and mononegative anion (HA−) are the predominant reducing species of the amino acid. The reaction involves a one‐step two‐electron transfer process and passes through the intermediate formation of iminic cation. In the presence of surfactant, the reaction passes through a maximum and it appears to follow Berezin's model, where both the oxidant and the substrate are partitioned between the aqueous and the micellar phase and then react. The binding constants between the reactants and the surfactant have been evaluated at different temperatures. Compensation between substrate–water interaction and substrate–micelle interaction plays an important role in such redox reactions in the presence of a surfactant. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 482–493, 2012