Anodically generated manganese(III) oxidation of L-serine and DL-threonine in aqueous acetic acid medium: Kinetics and mechanism

Chandraju, S. and Mahadevappa, D. S. and Rangappa, K. S. and Made Gowda, N. M. (1997) Anodically generated manganese(III) oxidation of L-serine and DL-threonine in aqueous acetic acid medium: Kinetics and mechanism. Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 27 (9). pp. 1329-1346. ISSN 0094-5714

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Abstract

Manganese(III) acetate solutions were prepared by electrolytic oxidation of Mn(OAc)(2) in aqueous HOAc. The electrogenerated Mn(III) species was characterized by spectroscopic and redox potential studies. The kinetics of oxidation of the alpha-amino acids (AA) L-serine and DL-threonine by Mn(III) ions have been studied in aqueous HOAc medium at 323 K. The reaction follows the following rate law. rate = k' Mn(III)](1/2) AA] H+](X-)OAc-](y) where k'= rate constant and x = y = fractional. Variation of the concentration of the reduction product Mn(ll) had no effect on the reaction rate. Added anions such as F-, Cl- and ClO4- affected the rate by changing the formal redox potential of the Mn(III)-Mn(II) couple. The effect of varying the solvent composition with HOAc was studied. Kinetic studies showed that the reaction rate decreased in D2O (40% v/v) giving solvent isotope effects of k'(H2O)/k'(D2O) 1.46 and 1.69 for serine and threonine, respectively. Activation parameters have been evaluated using the Arrhenius and Eyring plots. A mechanism consistent with the kinetic data has been proposed. The kinetic data for the oxidation of some alpha-amino acids by various Mn(III) species are summarized and compared.

Item Type:	Article
Subjects:	C Chemical Science > Chemistry
Divisions:	Department of > Chemistry
Depositing User:	Users 23 not found.
Date Deposited:	27 May 2021 09:02
Last Modified:	04 Jul 2022 09:25
URI:	http://eprints.uni-mysore.ac.in/id/eprint/16660

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