Mechanism of oxidation of alanine by chloroaurate(III) complexes in acid medium: Kinetics of the rate processes

✍ Scribed by Pratik K. Sen; Nasimul Gani; Jayanta K. Midya; Biswajit Pal

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 204 KB
• Volume: 41
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20422

✦ Synopsis

Abstract

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 ^1^H NMR spectroscopy. Under the experimental conditions, AuCl and AuCl~3~(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 k~2~′ have been analyzed, and accordingly the rate law has been deduced: k~2~′ = (k~1~[H^+^][Cl^−^] + k~3~K~4~K~5~)/(K~4~K~5~ + [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. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 473–482, 2009