Oxidative kinetics and structure reactivity correlation in bromate oxidation of acetophenones in acid medium

Abstract

Kinetics of acid bromate oxidation of acetophenone and eight <em>para- </em> and <em>meta</em>-substituted acetophenones have been studied in acetic acid (40-90%). The reaction is first order each in [oxidant] and [substrate] and the rate increases with aciditity of the medium. A decrease in the proportion of acetic acid in the reaction mixture decreases the rate. The effect of substituent on the rate has been evaluated and the rate constants correlated well with σ⁺, the Okamato-Br-own's constant, suggesting a cross-conjugation and/or a resonance interaction between the substituent and the reaction centre. The reaction is susceptible to polar influences and the reaction constant (ρ) evaluated at various temperatures and solvent compositions is ~0.8 ± 0.02 indicating an electron-deficient transition state. The Yukawa's enhanced resonance parameter (γ) is calculated to ~0.82 and discussed.