Oxidation of ketones by ceric perchlorate catalysed by iridium(III)

Abstract

In search of economical and effective catalysts it was found that IrCl 3, a sluggish catalyst in alkaline media, surpasses catalytic efficiency of osmium and ruthenium in aqueous perchloric acid medium in the oxidation of aliphatic ketones by ceric perchlorate. Rate decreases in the beginning at low acid concentrations, reaches to a minimum and then becomes proportional to [HClO4], probably due to conversion of hydrolysed to unhydrolysed species of ceric perchlorate, which then accelerates the rate. Reduction of oxidant by water depends on the concentrations of acid and [cerium(IV)] initially used. Orders are one with catalyst, one initially with respect to oxidant and ketones tending to become zeroth order at higher concentrations. No effect of change of μ on the rate was observed. Thermodynamic data suggest that diethyl ketone (DET) forms the activated complex more easily compared to dimethyl ketone (DMT). © 2005 Elsevier B.V. All rights reserved.