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Indian Journal of Chemistry -Section B (IJC-B) >
IJC-B Vol.50B [2011] >
IJC-B Vol.50B(07) [July 2011] >
| 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
[1,1,2,2-2H4]ethanediol exhibited primary kinetic isotope
effect (kH/kD = 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   * values
with negative reaction constant,  *. 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. |
| Page(s): | 918-925 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0983(Online); 0376-4699(Print) |
| Source: | IJC-B Vol.50B(07) [July 2011]
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