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Indian Journal of Chemistry -Section A (IJC-A) >
IJC-A Vol.50A [2011] >
IJC-A Vol.50A(05) [May 2011] >
| Title: | Mechanistic studies of aquachlororhodium(III) catalysis in potassium iodate oxidation of 1,2-propanediol in acidic medium: A kinetic approach |
| Authors: | Singh, Bharat
Singh, Aniruddh Kumar
Singh, Anamika |
| Keywords: | Kinetics
Reaction mechanisms
Oxidation
Rhodium
Propanediol |
| Issue Date: | May-2011 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | The kinetics of homogeneously Rh(III) catalysed oxidation of 1, 2-propanediol
by acidic solution of potassium iodate at constant ionic strength of the medium
has been investigated at 308 K. The reaction follows complex kinetics, being
first order in [KIO3], zero order in 1, 2-propanediol and inverse
fractional order in both [H+] and [Cl¯]. The first order
rate constant increases linearly with increase in [Rh(III)] in its lower
concentration range but as the concentration of Rh(III) is increased towards
the higher range, the rate constant becomes almost constant, indicating
positive fractional order in [Rh(III)]. Variation of ionic strength of the
medium and successive addition of mercuric acetate (used as I¯ ions
scavenger) has a positive effect on the rate of the reaction. IO3¯
and [RhCl5(H2O)]-2 have been postulated as the
reactive species of KIO3 and Rh(III), respectively. Activation
parameters for the slow and rate determining step of the proposed mechanism,
which involves the formation of the most activated complex, [Cl5Rh(HO→Hg)]¯,
prior to the slowest step, have been obtained from rate measurements at 30, 35,
40 and 45 °C. The rate law conforming to the observed kinetic results has been
derived
as  650-657-image.gif) . The main oxidation products have been
identified as acetic acid and formic acid |
| Page(s): | 650-657 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0975(Online); 0376-4710(Print) |
| Source: | IJC-A Vol.50A(05) [May 2011]
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