Kinetics of Permanganate Oxidation of Acetophenones in Aqueous Acetic Acid: A Mechanistic Study

Abstract

The kinetics of oxidation of acetophenone by potassium permanganate have been studied in 50% aqueous acetic acid medium. The reaction is first order with respect to both, substrate and oxidant. The oxidation is catalyzed by H₂SO₄. Acetic acid in the reaction mixture retards the rate. Ionic strength effect is negligible. The stoichiometry of 1 mol of acetophenone : 1 mol of permanganate was observed. The order of reactivity of the acetophenones decreases as p-NO₂ > m-NO₂ > p-Br > p-Cl > -H > p-CH₃ > p-OCH₃. Hammet’s plot gave linear relation with ρ-value of +7210, indicating that electron withdrawing groups accelerate the process. Activation parameters have been evaluated. Exner’s plot gave linear relation and the isokinetic relationship has been found operating. A suitable mechanism has been proposed.