Kinetics and mechanism of redox reactions in aqueous solution. Part 3. Oxidation of diols by aquacerium(IV) species in perchlorate solution

Abstract

Michaelis–Menten kinetics have been observed for the oxidation of diols and 3-methoxybutan-1-ol by aquacerium(IV) ions in acid perchlorate solution of 2 mol dm^–3 ionic strength. The reaction has a first-order dependence on cerium(IV) concentration and the rate is accelerated by increasing acidity. An analysis of the equilibrium constants for complex formation between Ce^IV and the substrates, the rates of disproportionation of the intermediate complexes, and the entropy values associated with the latter suggests the formation of chelate complexes in the oxidation of propane-1,3-, butane-1,3-, and butane-1,4-diols. whereas in the oxidation of pentane-1,5- and hexane-1,6-diols and 3-methoxybutan-1-ol the substrate is believed to act as a unidentate ligand.