OXIDATIONS BY THE REAGENT O-2-H2O2 VANADIUM COMPLEX PYRAZINE-2-CARBOXYLIC ACID .8. EFFICIENT OXYGENATION OF METHANE AND OTHER LOWER ALKANESIN ACETONITRILE

Methane, ethane, propane, n-butane and isobutane can be readily oxidiz ed in acetonitrile solution by air and H2O2 at 20-75 degrees C using t he catalytic system [n-Bu(4)N]VO3/pyrazine-2-carboxylic acid. Apart fr om alkyl hydroperoxides which are the primary oxidation products, more stable derivatives (alcohols, aldehydes or ketones and carboxylic aci ds) are obtained with high total turnover numbers (e.g., at 75 degrees C after 4 h: 420 for methane and 2130 for ethane). It was shown in th e case of ethane and cyclohexane that alkanes do not yield oxygenated products in the absence of air. The cyclohexane oxidation under an O-1 8(2) atmosphere showed a high degree of O-18 incorporation into the ox ygenated products. Thus in the oxidation reaction described here H2O2 is only the promoter while O-2 is the ''true'' oxidant. (C) 1997 Elsev ier Science Ltd.