Transition metal-free catalytic oxidation of aromatic alcohols with molecular oxygen in the presence of a catalytic amount of N-bromosuccinimide

• A new transition metal-free catalyst system for aerobic oxidation is developed.
• The efficient oxidation of alcohols with molecular oxygen is achieved.
• The catalytic system is composed of DDQ, NaNO2 and NBS.
• 76–99% yields of aldehydes are obtained from oxidation of aromatic alcohols.

A highly efficient N-bromosuccinimide (NBS)-mediated transition metal-free catalytic system has developed for the efficient aerobic oxidation of aromatic alcohols. Various aromatic alcohols are successfully oxidized to the corresponding aldehydes or ketones under mild condition. For instance, benzyl alcohol is oxidized to benzaldehyde with 99% conversion in 94.5% selectivity with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)–NaNO2–NBS system under 0.3 MPa of O2 at 90 °C for 2 h. The effects of reaction time, catalyst amount and solvents are investigated in detail, and a possible reaction mechanism is proposed.

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