Direct oxygenation of benzene to phenol using quinolinium ions as homogeneous photocatalysts

Photocatalytic oxygenation of benzene with oxygen and water to phenol has been achieved under ambient conditions by using the 3-cyano-1-methylquinolinium ion as a photocatalyst (see picture). The mechanism was clarified by detecting the π-dimer benzene radical cation produced by photoinduced electron transfer from benzene to the photocatalyst, and by monitoring the reaction of the radical cations with water molecules.