Direct hydroxylation of aromatics over copper-calcium-phosphates in the gas phase

A new alternative process for the direct gas phase hydroxylation of aromatics is studied using molecular oxygen (air) or nitrous oxide in the presence of copper containing calcium-phosphate. The activity of Cu-Ca-phosphate catalyst in the reaction of benzene with oxygen, N2O or the mixture of oxygen-ammonia as oxidants is compared. Beside benzene also alkyl aromatics were used in the same reaction. The preferred reaction is attack on a side chain. We suggest that the oxidation of benzene starts via formation of phenyl radical.