Transfer hydrogenation of carbon dioxide and bicarbonate from glycerol under aqueous conditions

The transfer hydrogenation of CO₂ from glycerol to afford formic and lactic acid is a highly attractive path to valorizing two waste streams and is a significantly more thermodynamically favorable process than direct CO₂ hydrogenation. We report the first homogeneous catalyst for this transformation consisting of a water-soluble Ru N-heterocyclic carbene complex. The catalyst affords lactic and formic acid selectively in the presence of a base at temperatures between 150 and 225 °C. Carbonate salts can also be utilized in place of CO₂, affording the same products at higher rates.