Oxidation by cobalt(III) acetate. Part 9. Effect of substituents on the oxidative cleavage of glycols in acetic acid

Abstract

The kinetics of oxidative cleavage of glycols by cobalt(III) acetate in acetic acid have been studied. The substrates examined include cis- and trans-cyclopentane- and cyclohexane-1,2-diols and their mono- and di-methyl derivatives. The rates were first-order in both cobalt(III) acetate and substrate in all cases. In the oxidation of five-membered ring diols, cis-diols were generally oxidized faster than the trans-isomers. Complex results were obtained in the case of six-membered ring diols. Thermodynamic parameters were calculated for all the substrates. A mechanism involving a bidentate complex of cobalt(III) acetate dimer and the glycol is suggested, except for the case of trans-cyclopentane-1,2- diols, for which a monodentate intermediate is proposed.