Alkaline hexacyanoferrate(III) oxidation of substituted 4-oxo acids: A mechanistic study

Maria Pushparaj, F. J. and Kannan, S. and Vikram, L. and Lalitha Kumar, S. and Rangappa, K. S. (2005) Alkaline hexacyanoferrate(III) oxidation of substituted 4-oxo acids: A mechanistic study. Journal of Physical Organic Chemistry, 18 (10). pp. 1042-1049. ISSN 1099-1395

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Abstract The kinetics of the oxidation of substituted 4-oxo-4-arylbutanoic acids by hexacyanoferrate(III) in aqueous alkaline medium were studied. The reactions are found to be first order in each of the reagents, the oxo acid, hydroxide ion and the hexacyanoferrate(III) ion. A mechanism involving the formation of enolate anion from the oxo compound and subsequent rate-determining electron transfer is proposed. Application of the Olson–Simonson rule substantiated the participation of negatively charged ions in the rate-determining step. The experimental rate constant is found to be composite, being the product of the equilibrium constant for the enolate anion formation and the rate constant of the oxidation step (Kk2). The effect of addition of solvents such as methanol and DMSO is discussed and a quantitative relationship is derived between the ionic strength and the composite rate constant. The low activation energies and even the negative activation energy in the oxidation of 4-(3-nitrophey1)-4-oxobutanoic acid are explained. The ρ values are positive and decrease with temperature. Contrary to the expected electronic effect, the methyl group in the ortho position accelerates the reaction owing to steric factors. From the intersection of the lines in the Hammett and Arrhenius plots, the isokinetic relationship is discussed. Copyright © 2005 John Wiley & Sons, Ltd.

Item Type: Article
Uncontrolled Keywords: 4-oxo acids, oxidation, hexacyanoferrate(III), mechanism, kinetics
Subjects: C Chemical Science > Chemistry
Divisions: Department of > Chemistry
Depositing User: manjula User
Date Deposited: 04 Sep 2019 11:36
Last Modified: 04 Sep 2019 11:36

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