|
9. A KINETIC STUDY OF Ru(III)
CATALYZED OXIDATION OF DEXTROSE BY POTASSIUM BROMATE IN ALKALINE
MEDIUM
Sheila Srivastava*,
Lakshmi Chaudhary
Chemical Laboratories, Feroze Gandhi College, Rae Bareli – 229001,
INDIA
E-mail :
she_ila72@yahoo.com
ABSTRACT
Kinetic investigation in
ruthenium(III) catalyzed oxidation of dextrose by an alkaline
solution of KBrO3 have been carried out in the
temperature range 300 – 450 C. Mercuric acetate is used in the
reaction mixture as a scavenger for Br – ion to prevent parallel
oxidation by bromine. The reaction exhibits first order kinetics
with respect to KBrO3 and catalyst Ru(III) while zero
order kinetics with respect to substrate dextrose. An Increase in
[Cl -] showed negative effect while acetic acid (AcOH)
showed positive effect.
Negligible effect of [OH-], mercuric acetate and ionic
strength of the medium was observed. Ruthenium(III) chloride has
been reported to give a number of possible chloro species depending
on the pH of solution. The reactive species of Ru(III) in alkaline
medium is [RuCl2(H2O)3(OH)] under
the experimental pH range. A suitable mechanism in conformity with
the kinetic observation has been proposed.
The various activation parameters such as energy of activation
(DE*), Arrhenius factor (A), entropy of activation (DS*) were
calculated from the rate measurements at 300, 350, 400, and 450C. A
rate law has been derived on the basis of obtained data.
<<< |
