Reactions catalyzed by methylrhenium trioxide

Methylrhenium trioxide (CH3ReO3 or MTO) reacts with H2O2 to form two peroxo complexes, CH3ReO2(eta(2)-O-2), A, and CH3ReO(eta(2)-O-2)(2)(H2O), B. Peroxide binding to MTO is an equilibrium process, rapid but not instantaneous, characterized by the equilibrium constants K-1 = 16 L mol(-1) and K-2 = 132 L mol(-1) at pH 0, mu = 2.0, and 25 degrees C. MTO catalyzes the oxidation of many organic and inorganic substrates by H2O2 The evaluation of the catalytic kinetics showed that both A and B react with a given substrate at comparable rates. The various steps of peroxide activation consist of nucleophilic attack of substrate on peroxide ions that have become electrophilically activated by binding to MTO. The versatility of MTO as a catalyst is demonstrated by its ability to catalyze the oxidation even of electron-deficient substrates such as beta-dicarbonyl compounds. Catalyst deactivation occurs in the presence of hydrogen peroxide, much more rapidly than in its absence, and produces methanol and perrhenate ions as final products. The rate of decomposition is dependent on both acid and hydrogen peroxide concentrations.