Kinetics and mechanism of Rh(III) catalysed oxidation of maleic acid by Ce(IV) in aqueous sulphuric acid medium

The kinetics of oxidation of maleic acid by Ce(IV) has been carried out in aqueous sulphuric acid medium at different temperatures (35-40 degrees C) under the condition [maleic acid](T) >> [Ce(IV)](T) >> [Rh(III)] (T) in 1.0 mol dm(-3) sulphuric acid media. The reaction shows first order dependence on [maleic acid], [Ce(IV)] and [Rh(III)]. The change of concentration of medium, i.e. H-2 SO4, and variation of ionic strength by adding NaClO4 have no significant effect on the reaction rate indicating interaction in the rate-determining step being an ion-dipole type and not ion-ion type.