Ru(III) AND Ir(III) CATALYSIS IN OXIDATION OF BUTANOL BY QUINOLINIUM FLUOROCHROMATE. A COMPARATIVE STUDY

摘要

Kinetic investigation in Ru(III) and Ir(HI)-catalysed oxidation of butanol in an acidified solution of quinolinium fiuorochromate (QFC) has been carried out in the temperature range of 30-45°C. First order kinetics was observed in case of catalyst Ru(III) as well as oxidant substrate (butanol). The order of reaction with respect to QFC 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 butanol for both Ru(III) and Ir(III)-catalysed reactions was identified as butanaldehyde. The reaction has been studied in 10 different solvents. The first order rate constant had not been affected by the decrease in the dielectric constant of the medium. The values of rate constants observed at 4 different temperatures (30,35,40 and 45°C) were utilised 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 the obtained data. A transient complex, formed between catalyst and substrate in a slow and rate-determining step, further reacts with QFC to give the products in a series of fast steps.