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8.
Ruthenium(III) Catalyzed Oxidation of D(+)Galactose and Lactose by
Alkaline Potassium Bromate
* Ashish Kumar, Vidhi Yasir Arafat
Chemical Laboratories, Lovely Professional University, Phagwara,punjab.,
India.
E-mail:
ashishkr_dbdc@yahoo.co.in
Abstract:
Kinetic investigation in Ru (III) catalyzed oxidation of D (+)-galactose
and lactose in an alkaline solution of potassium bromate in the
presence of mercuric acetate as a scavenger for Br– ion has
been carried out in the temperature range 30-45 0C.
The rate shows first order dependence with respect to the
bromate and zeroth order with respect to the substrate (sugars).
The reaction exhibits first order dependence on the catalyst
ruthenium (III) and there is inverse order on the rate of
reaction. Potassium chloride and acetic acid have a positive
effect on the rate. Negligible effect of change in Hg(OAc)2,
ionic strength of the medium and D2O.[RuCl3(H2O)OH]-1
and BrO3- are the most reactive species Ru
(III) chloride and bromated, respectively. Galactonic acid and
lactobionic acid have been identified as the main oxidation
products of the reaction. Various activation parameters have
been calculated and recorded. On the basis of experimental
findings, a suitable mechanism consistent with the observed
kinetics was proposed and the rate law has been derived on the
basis of obtained data.
Key Words:
Alkaline medium, kinetics, oxidation, potassium
bromate, Ru (III) catalyzed, sugars.
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