KINETICS AND MECHANISM OF THE OXIDATION OF BUTANE-2,3-DIOL BY ALKALINE HEXACYANOFERRATE(III), CATALYZED BY RUTHENIUM TRICHLORIDE

The kinetics of oxidation of butane-2,3-diol by alkaline hexacyanoferr ate (III), catalyzed by ruthenium trichloride has been studied spectro photometrically. The reaction rate shows a zero-order dependence on ox idant, a first-order dependence on [Ru(III)](T), a Michaelis-Menten de pendence on [diol], and a variation complicated on [OH-]. A reaction m echanism involving the existence of two active especies of catalyst, R u(OH)(2)(+) and Ru(OH)(3), is proposed. Each one of the active species of catalyst forms an intermediate complex with the substrate, which d isproportionates in the rate determining step. The complex disproporti onation involves a hydrogen atom transfer from the alpha-C-H of alcoho l to the oxygen of hydroxo ligand of ruthenium, to give Ru(II) and an intermediate radical which is then further oxidized. (C) 1997 John Wil ey & Sons, Inc.