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6.
Kinetics and mechanism of the acidic quinolinium fluorochromate
oxidation of some unsaturated acids in acetone catalyzed by
Aquachlororuthenium(III) complex
Sheila Srivastava*
and Parul Srivastava
Chemical Laboratories, Feroze Gandhi College, Raebareli – 229001,
U.P., India.
E-mail: she_ila72@yahoo.com / parul_9880@yahoo.com
Abstract: Kinetic
investigation in Ru(III) catalyzed oxidation of fumaric acid
(FA) and crotonic acid (CA) in an acidified solution of
quinolinium fluorochromate (QFC) has been studied in the
temperature range of 300-450 C. First order kinetics was
observed in case of catalyst Ru(III) as well as oxidant QFC. The
order of reaction w.r.t. substrate (unsaturated acids) was found
to be zero. Increase in [Cl-] showed fractional
positive order. The influence of [H+] and ionic
strength on the rate was found to be insignificant. The main
product of oxidation of fumaric acid (FA) and crotonic acid (CA)
were identified as pyruvic acid and acetone respectively. The
reaction has been studied in ten different solvents. The first
order rate constant had no effect with decrease in the
dielectric constant of the medium. The values of rate constants
observed at four different temperatures (30, 35, 40 and 450C)
were utilized to calculate the activation parameters. A
suitable mechanism in conformity with the kinetic observations
has been proposed and the rate law has been derived on the basis
of obtained data. A transient complex formed between RuIII and
oxidant in a slow and rate determining step, further reacts with
substrate to give the products in a series of fast steps.
Key words:
Kinetics, oxidation, quinolinium fluorochromate, Ru(III)
chloride, unsaturated acids.
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