Mechanism of Ir(III)-Catalysis in Oxidation of Mandelic Acid by N-Bromobenzamide in Acidic Media

Abstract

The kinetic data obtained in Ir(IIl) catalysed N-bromobenzamide(NBB) oxidation of mandelic acid in perchloric acid have beenreported. Mercuric acetate has been used as bromide ions scavenger.Zero-order kinetics with respect to mandelic acid and fIrst orderdependence in Ir(IIl) have been observed. First-order dependenceof the reaction on NBB at its low concentration tends to zero-orderin the higher concentration range. Positive effect of [H⁺] and[Cl^- ] has been observed.  A negative effect of acetamide and ionicstrength of the medium is observed while  mercuric acetate showszero effect on the reaction velocity. (H₂OBr⁺] has been postulatedas the oxidising species. The mechanistic steps are suggested forIr(IIl) catalysed oxidation of mandelic acid by NBB.