NaOH alone can be a homogeneous catalyst for selective aerobic oxidation of alcohols in water

Abstract

Sodium hydroxide (NaOH) has been an indispensable additive in the selective aerobic oxidation of alcohols/polyols in water for ketone and carboxylic acid syntheses over supported metal catalysts, including Au, though the exact function of NaOH remains far from clear. We disclose here that NaOH alone can independently serve as a homogeneous catalyst for the oxidation reactions. This conclusion is supported by rigorous investigations of the effects of NaOH alone (without the presence of any metal catalyst) on the reactivity of aqueous glycerol, ethylene glycol, 2-propanol, and ethanol and their product distribution. Computational results based on density functional theory are also provided to explain the experimentally measured reactivity order of the various alcohols and to generate insight into the molecular mechanisms for the oxidation reactions. Besides challenging existing knowledge about the function of NaOH in alcohol oxidation reactions, this study opens a new avenue for catalytic alcohol/polyol upgrading.