Kinetic study of oxidation of diols by sodium N-bromobenzenesulphonamide

Abstract

The kinetics of the oxidation of five vicinal diols, four other diols, and one of their monoethers by sodium N-bromobenzenesulphonamide have been studied. The vicinal diols yielded products arising out of glycol bond fission while other diols yielded hydroxycarbonyl compounds. The reaction is first order with respect to the diol and the oxidant. The oxidation of vicinal diols follows two mechanistic pathways, one acid-independent and another acid-dependent. The oxidation of the other diols shows a first-order dependence on hydrogen ion. The oxidation of [1,1,2,2-²H₄]ethanediol showed the absence of a primary kinetic isotope effect. The values of solvent isotope effect, k(H₂O)/k(D₂O), at 303 K for the oxidation of ethanediol, propane-1,3-diol, and 3-methoxybutan-1-ol are 2.24, 0.42, and 0.42, respectively. An acyclic mechanism involving glycol bond fission has been proposed for the vicinal diols. The other diols are oxidized by a hydride-transfer mechanism as are monohydric alcohols.