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.