Oxidation of Alcohols by Cerium(IV). I. Oxidation of Methanol by Ceric Perchlorate

Abstract

Abstract The oxidation of methyl alcohol by ceric perchlorate in perchloric acid solution was studied at 13, 20 and 26°C. The stoichiometry consisted of two cerie ions for the oxidation of one molecule of methanol. While the rate of disappearance of ceric ions directly depended on the concentration of ceric ions, the dependence on methanol concentration was such as to suggest a ‘broken order’: \frac−dCeivdt=\frack(Ceiv)(MeOH)1+k′(MeOH) This rate also depended on the concentration of perchloric acid in such a way that at high acidity it became independent of it. These data were explained on the basis of Duke’s mechanism for 2,3-butane diol-ceric perchlorate reaction, i. e. the oxidation of methanol by ceric ions proceeded via an intermediate complex between one Ce4+ ion and one methanol molecule. The formation of this complex was also proved independently by a spectrophotometric method. The kinetic data were further used to derive the true heat of formation of the methanol-cerate complex and the heat of hydrolysis of the cerie ions in aqueous perchloric acid.