A superoxochromium(III) ion, CraqOO2+, acts as a catalyst for the co-oxidation of alcohols and nitrous acid with molecular oxygen according to the stoichiometry: CH3OH + HNO2+ O2+ CH2O + NO3-+ H2O + H+. The kinetics are second order in [HNO2] and independent of the concentrations of the superoxochromium catalyst, substrate, and O2. The proposed mechanism features the disproportionation of HNO2to NO and NO2, both of which react rapidly with CraqOO2+. The CraqOO2+/NO reaction generates another equivalent of NO2and a mole of CraqO2+, the active oxidant. The two-electron oxidation of the alcohol by CraqO2+produces Craq2+, which reacts rapidly with O2to regenerate the catalyst, CraqOO2+. The NO2/CraqOO2+reaction yields the peroxynitrato complex, CraqOONO22+, in a dead-end equilibrium process that has no effect on the catalytic reaction. The disproportionation of NO2yields the final nitrogen-containing product, NO3-, and regenerates an equivalent of HNO2. Under a fixed set of conditions, the relative catalytic efficiency (CE) of CraqOO2+decreases as its concentration increases owing to the competition between O2and CraqOO2+for the intermediate Craq2+. © 2003 Elsevier Science B.V. All rights reserved.
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