The selective catalytic oxidation of toluene

It was found for the first time that the selectivity of toluene transformations into benzaldehyde and benzoic acid decreased and into maleic anhydride and deep oxidation products increased as the ability of vanadium-containing catalysts of toluene oxidation to generate the singlet form of molecular oxygen grew. A scheme of the formation of the products of toluene oxidation with oxygen was suggested. Quinones were shown to be final rather than intermediate oxidation products. The selectivity of the reaction with respect to mild oxidation products in the presence of V₂O₅, MoO₃, and V₂O₅ · MoO₃ could be increased by changing the temperature of catalyst preparation from 400 to 500°C.