Kinetics and mechanism of the oxidation of some neutralized α-Hydroxy acids by hexachloroiridate(IV)

The kinetics of oxidation of some neutralized α-hydroxy acids such as lactic (LA), mandelic (MA), α-hydroxyisobutyric (IB) and benzilic (BA) acid by hexachloroiridate(IV) have been studied. The oxidation products are acetaldehyde, benzaldehyde, acetone and benzophenone for the respective reactions, which are first order with respect to each substrate and to iridium(IV). The reaction rate increases with increase in pH and salt concentrations. The temperature influence is quite marked in all these reactions. A mechanism involving the formation of an unstable complex, which decomposesvia a free radical pathway to give the respective reaction products, is proposed.