Mechanism of Oxidation of Alanine by Chloroaurate(III) Complexes in Acid Medium: Kinetics of the Rate Processes

作者：Sen Pratik K^*; Gani Nasimul; Midya Jayanta K; Pal Biswajit

来源：International Journal of Chemical Kinetics, 2009, 41(7): 473-482.

DOI：10.1002/kin.20422

The kinetics of the oxidation of alanine by chloroaurate(III) complexes in acetate buffer medium has been investigated. The major oxidation product of alanine has been identified as acetaldehyde by H-1 NMR spectroscopy. Under the experimental conditions, AuCl4- and AuCl3(OH)(-) are the effective oxidizing species of gold(III). The reaction is first order with respect to Au(III) as well as alanine. The effects of H+ and Cl- on the second-order rate constant V have been analyzed, and accordingly the rate law has been deduced: k(2)' = (k(1)[H+][Cl-] + k(3)K(4)K(5))/(K4K5+[H+][Cl-]). Increasing dielectric constant of the medium has an accelerating effect on the reaction rate. Activation parameters associated with the overall reaction have been calculated. A mechanism involving the two effective oxidizing species of gold(III) and zwitterionic species of alanine, consistent with the rate law, has been proposed.

• 出版日期2009-7