Catalytic Oxidation Of Aromatic Alcohols With Molecular Oxygen To The Corresponding Aldehydes Or Ketones

The use of molecular oxygen as the oxidant and water as reaction medium is a charmingresearch orientation in the oxidation of alcohols. In the paper, the efficient aerobic oxidationof alcohols to the corresponding carbonyl compounds in aqueous media has been achievedwith TEMPO-containing catalytic systems. In absence of base/acid, a99%conversion and94%selectivity for benzaldehyde was obtained for the oxidation of benzyl alcohol byTEMPO-Ce(IV)-NaNO2in water. Moreover, the effects of quaternary ammonium salts andanionic surfactants were investigated. The aerobic selective oxidation of differentnon-heterocyclic alcohols in aqueous media was further investigated, and the moderate tohigh yields (45.5-98.0%) of products were obtained.And a highly efficient N-bromosuccinimide (NBS)-mediated transition metal-freecatalytic system has developed for the efficient aerobic oxidation of aromatic alcohols.Various benzylic alcohols are successfully oxidized to the corresponding aldehydes or ketonesunder mild condition. For instance, benzyl alcohol is oxidized to benzaldehyde with99%conversion in94.5%selectivity with NBS-DDQ-NaNO2system under0.3MPa of O2at80oCfor2h. The effects of reaction time, catalyst amount and solvents are investigated in detail,and a possible reaction mechanism is proposed.