Please use this identifier to cite or link to this item: http://nopr.niscair.res.in/handle/123456789/12093
Title: Kinetics and mechanism of the oxidation of diols by butyltriphenylphosphonium dichromate
Authors: Panday, Dinesh
Kothari, Seema
Keywords: Diol
Butyltriphenylphosphonium dichromate
Kinetics
Mechanism
Oxidation
Kinetic isotope effect
Hydroxyaldehyde
Issue Date: Jul-2011
Publisher: NISCAIR-CSIR, India
Abstract: The oxidation of four vicinal, four non-vicinal diols and one of their monoethers by butyltriphenylphosphonium dichromate (BTPPD), in dimethylsulfoxide (DMSO), resulted in the formation of corresponding hydroxyaldehyde as a main product of the oxidation. The reactions are of first order with respect to BTPPD, however, second order dependence is obtained with respect to each the diol and hydrogen ion. The oxidation of [1,1,2,2-<sup>2</sup>H<sub>4</sub>]ethanediol exhibited primary kinetic isotope effect (<i style="">k</i><sub>H</sub>/<i style="">k</i><sub>D</sub> = 6.61 at 298 K). The temperature dependence of the kinetic isotope effect suggested the symmetrical transition state in the rate-determining step. The rate constants of oxidation of four vicinal diols show excellent correlation with Taft’s <img src='/image/spc_char/sum.gif' border=0> <img src='http://www.niscair.res.in/jinfo/sigma.gif' border=0><sup>*</sup> values with negative reaction constant, <img src='http://www.niscair.res.in/jinfo/rho.gif' border=0><sup>*</sup>. The rate of oxidation of ethanediol has been determined in nineteen different solvents. An analysis of the solvent effect indicates the importance of the cation-solvating power of the solvents. A suitable mechanism has been postulated involving the formation of chromate ester in a pre-equilibrium.
Description: 918-925
URI: http://hdl.handle.net/123456789/12093
ISSN: 0975-0983(Online); 0376-4699(Print)
Appears in Collections:IJC-B Vol.50B(07) [July 2011]

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