Oxidation of L-tryptophan by Ag(III) complex in alkali media: a kinetic, mechanistic approach

Issue title: Exploring the Relationships Between Main Group and f-Element Chemistry

Article type: Research Article

Authors: Tatagar, Asma M. | Shetti, Nagaraj P. | Nandibewoor, Sharanappa T.

Affiliations: P.G. Department of Studies in Chemistry, Karnatak University, Dharwad 580003, Karnataka, India

Note: [] Corresponding author. Email: stnandibewoor@yahoo.com

Abstract: The oxidation of amino acid, L-tryptophan (L-trp) by diperiodatoargentate (III) (DPA) in alkaline medium at a constant ionic strength of 0.02 mol dm−3 was studied spectrophotometrically. The reaction between L-trp and DPA in alkaline medium exhibits 1:2 stoichiometry (L-trp:DPA). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidences, a mechanism involving the monoperiodatoargentate (III) (MPA) as the reactive oxidant species has been proposed. The products were identified by spot test and characterized by spectral studies. The reaction constants involved in the different steps of mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed. The thermodynamic quantities were also determined for different equilibrium steps. Isokinetic temperature was also calculated and found to be 192.2 K.

Keywords: kinetics, mechanism, oxidation, L-tryptophan, diperiodatoargentate (III), thermodynamic parameters

DOI: 10.1080/10241220903377499

Journal: Main Group Chemistry, vol. 8, no. 4, pp. 307-321, 2009