Mechanistic investigation of oxidation of a diketone by aromatic N-bromamines in alkaline buffer medium: A kinetic study

Abstract

Kinetics of oxidation of aceylacetone (AA) by bromamine-T (BAT) and bromamine-B (BAB) has been investigated at 298K in alkaline buffer of<em> p</em>H 9.4. The oxidation behaviour is similar for both the oxidants. The rate is first order in [oxidant], and is fractional order each in (AA]_o and (OH^-). Addition of the reaction products, <em>p</em>-toluenesulphonamide and benezenesulphonamide retards the rate. The influence of the halide ions and ionic strength of the medium on the rate has been studied. Decrease in dielectric constant of the medium by adding methanol increases the rate. Solvent isotope studies have been made in D₂O medium. Kinetic parameters for the reaction have been computed from the Arrhenius plots. A-mechanism in which the substrate interacts with the OBr^- to form an intermediate, which is subsequently oxidised to acetic acid and formic acid, is proposed.