Oxidant-Free Transformation of Ethylene Glycol toward Glycolic Acid in Water

Full utilization of oxygen in biomass can greatly improve its atomic efficiency because of its nature of containing 40%–45% oxygen. In this work, we achieved a complete conversion of ethylene glycol toward glycolic acid with accompanying evolution of hydrogen via a cascade dehydrogenation and Cannizzaro reaction in water without any external oxidant. The yield of glycolic acid can reach 81%, and the whole homogeneous catalytic system displays a long-term continuous reaction stability. Moreover, this dehydrogenative oxidation process can be applied into the one-pot conversion of biomass carbohydrates toward α-hydroxyl acid. This finding provides a closer insight into the application of catalytic dehydrogenative oxidation techniques in designing value-added products from biomass-derived compounds as well as hydrogen evolution as a byproduct.