Rhodium(III) catalyzed oxidation of cyclic ketones by alkaline hexacyanoferrate(III)

Abstract

The kinetics of the oxidation of 2-methyl cyclohexanone and cycloheptanone with Fe(CN)63− catalyzed by RhCl3 in alkaline medium was investigated at four temperatures. The rate follows direct proportionality with respect to lower concentrations of hexacyanoferrate(III) ion, but tends to become zero order at higher concentrations of the oxidant, while the reaction shows first-order kinetics with respect to hydroxide ion and cyclic ketone concentrations. The rate shows a peculiar nature with respect to RhCl3 concentrations in that it increases with increase in catalyst at low catalyst concentrations but after reaching a maximum, further increase in concentration retards the rate. An increase in the ionic strength of the medium increases the rate, while increase in the Fe(CN)64− concentration decreases the rate.