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Mechanism of oxidation of alanine by chloroaurate(III) complexes in acid medium: Kinetics of the rate processes
Author(s) -
Sen Pratik K.,
Gani Nasimul,
Midya Jayanta K.,
Pal Biswajit
Publication year - 2009
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20422
Subject(s) - chemistry , oxidizing agent , kinetics , reaction rate constant , alanine , acetaldehyde , rate equation , reaction rate , reaction mechanism , inorganic chemistry , medicinal chemistry , organic chemistry , catalysis , amino acid , ethanol , biochemistry , physics , quantum mechanics
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 − 4and 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