Kinetics of the oxidation of 2-hydroxy-2-methylpropanoic acid by aquavanadium(V) ions in aqueous perchlorate media

Abstract

Measurements on the rate of oxidation of 2-hydroxy-2-methylpropanoic acid (hmpa) by V^V_aq in aqueous perchloric acid at high initial ratios [hmpa] : [V^V_aq] show that the order in [V^V_aq] is unity but that in [hmpa] lies between zero and unity. The variation of rate with acidity shows that two pathways operate, each involving a 1:1 complex of V^V and hmpa; one complex differs from the other by the addition of two protons. Overall values of the enthalpies and entropies of activation are determined; these are compared with values obtained for the oxidation of other substrates by V^V_aq and those for the oxidation of hmpa by other aqua-cations.