KINETICS OF OSMIUM(VIII) CATALYSIS OF PERIODATE-OXIDATION OF DMF IN AQUEOUS ALKALINE-MEDIUM

The osmium(VIII) catalysed IO4- oxidation of DMF in aqueous alkaline medium follows the rate law: -d[IO4-]/dt = kK2K3[DMF][OH-][Os(VIII)]T/1 + K2K3[DMF][OH-] + K2[OH-] where K2 is the equilibrium constant of the reaction [OSO4(OH)2]2- + OH- half arrow right over half arrow left [OsO5(OH)]3- + H2O K3 is the formation constant for the complex between DMF and [OsO5(OH)]3- and k is the decomposition rate constant. The data suggest that the oxidation of DMF proceeds via the formation of a complex between DMF and osmium(VIII) which decomposes slowly, followed by a fast reaction between the reduced osmium(VI) species and IO4-. The reaction constants involved in the mechanism are derived.