Carbonate-Promoted Hydrogenation of Carbon Dioxide to Multicarbon Carboxylates.

CO hydrogenation is a potential alternative to conventional petrochemical methods for making commodity chemicals and fuels. Research in this area has focused mostly on transition-metal-based catalysts. Here we show that hydrated alkali carbonates promote CO hydrogenation to formate, oxalate, and other C carboxylates at elevated temperature and pressure in the absence of transition-metal catalysts or solvent. The reactions proceed rapidly, reaching up to 56% yield (with respect to CO) within minutes. Isotope labeling experiments indicate facile H and C-H deprotonations in the alkali cation-rich reaction media and identify probable intermediates for the C-C bond formations leading to the various C products. The carboxylate salts are in equilibrium with volatile carboxylic acids under CO hydrogenation conditions, which may enable catalytic carboxylic acid syntheses. Our results provide a foundation for base-promoted and base-catalyzed CO hydrogenation processes that could complement existing approaches.