NISCAIR Online Periodicals Repository

Research Journals >
Indian Journal of Chemistry -Section A (IJC-A) >
IJC-A Vol.46A [2007] >
IJC-A Vol.46A(08) [August 2007] >

Title: Homogeneous catalysis of aquachlororuthenium(III) complex and evaluation of individual kinetic and thermodynamic parameters of bromate-lactic acid redox reaction at low and high acid strengths
Authors: Reddy, Ch Sanjeeva
Kumar, T Vijaya
Issue Date: Aug-2007
Publisher: CSIR
IPC CodeInt. Cl. ⁸ B01J8/00; C07B33/00
Abstract: Aquachlororuthenium(III) complex catalysed oxidation of lactic acid (LA) by bromate at low and high acid strengths has been studied and different reaction mechanisms have been proposed, depending on the composition of the mixture. At low acid strength, the reaction exhibits 1.0 order in [bromate], 0.13 order in [LA], 0.5 order in [catalyst] and a dualistic effect in [acid]. Primary kinetic isotope effect (kH/kD =1) has been found to be absent. However, an inverse solvent isotope effect (kD₂O/kH₂O = 0.75) is observed. The proposed mechanism involves oxidation of the formed Ru(III)-substrate complex by bromic acid, through complexation, to Ru(V)-substrate intermediate in the rate-determining step, which subsequently decomposes into CH₃CHO and CO₂ through C-C bond cleavage with regeneration of Ru(III) in the fast step. The same reaction at high acid strength exhibits first order each in [bromate] and [LA], 1.5 order in [catalyst], and an inverse fractional (-0.25) order in [acid]. The reaction also exhibits solvent isotope effect, while primary isotope effect is absent. The rate law is interpreted by a mechanism involving oxidation of Ru(III) to Ru(V) by Br(V) followed by the ternary complex formation between the formed Ru(V) and the preformed Ru(III)-substrate binary complex, which decomposes into products in the rate-determining step with regeneration of the catalyst. Spectroscopic data and the effects of dielectric constant and ionic strength are also in accordance with the mechanisms proposed. All the individual rate/formation constants involved in the mechanism proposed have been determined at different temperatures and their thermodynamic parameters have been evaluated and discussed.
Page(s): 1240-1251
ISSN: 0376-4710
Source:IJC-A Vol.46A(08) [August 2007]

Files in This Item:

File Description SizeFormat
IJCA 46A(8) 1240-1251.pdf139.42 kBAdobe PDFView/Open
 Current Page Visits: 997 
Recommend this item


Online Submission of Articles |  NISCAIR Website |  National Knowledge Resources Consortium |  Contact us |  Feedback

Disclaimer: NISCAIR assumes no responsibility for the statements and opinions advanced by contributors. The editorial staff in its work of examining papers received for publication is helped, in an honorary capacity, by many distinguished engineers and scientists.

CC License Except where otherwise noted, the Articles on this site are licensed under Creative Commons License: CC Attribution-Noncommercial-No Derivative Works 2.5 India

Copyright © 2015 The Council of Scientific and Industrial Research, New Delhi. All rights reserved.

Powered by DSpace Copyright © 2002-2007 MIT and Hewlett-Packard | Compliant to OAI-PMH V 2.0

Home Page Total Visits: 172026 since 01-Sep-2015  Last updated on 30-Jun-2016Webmaster: