Aerobic oxidation of secondary alcohols using NHPI and iron salt as catalysts at room temperature

• A new system including NHPI/Fe(NO3)3·9H2O for oxidation of alcohols was developed.
• The system was suitable for secondary benzyl and aliphatic alcohols, up to 92% yield.
• The reaction took place at room temperature under 1 atm oxygen.
• A free-radical mechanism for NHPI/Fe(NO3)3·9H2O/O2 oxidation of alcohols is proposed.

Aerobic oxidation of various alcohols has been accomplished by using a novel catalytic system, N-hydroxyphthalimide (NHPI) combined with Fe(NO3)3·9H2O. Secondary alcohols, especially benzylic and aliphatic alcohols, were smoothly transformed into corresponding ketones with up to 92% yields at room temperature under one atmosphere pressure of oxygen. The influences of reaction conditions such as solvent, different metal catalyst, catalyst loading and the structure of alcohols on the promotion effect were studied. And a possible radical mechanism for the oxidation of secondary alcohols in Fe(NO3)3·9H2O/NHPI/O2 system was proposed.

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