Oxidation of cyclohexane, cyclohexanone, and cyclohexanol to adipic acid by a non-HNO3 route over Co/Mn cluster complexes

mu(3)-Oxo-bridged Co/Mn cluster complexes, CoMn2(O), exhibit high catalytic activity and selectivity for the aerial oxidation, in the homogeneous liquid phase, of cyclohexane, cyclohexanol, and cyclohexanone to adipic acid by a non-HNO3 route. The cluster complexes are superior to the individual Co and Mn acetates. The yields of adipic acid are comparable to those in the current processes using HNO3. Electron paramagnetic resonance and electronic spectra indicate that the cluster complex is probably decomposed during the reaction process. Attempts to use these cluster complexes encapsulated in zeolite-Y as solid catalysts for the oxidation reactions were unsuccessful due to significant leaching out of the complexes during the reaction. (C) 2002 Elsevier Science (USA).