Hydrogenation of Carbon Dioxide to Formate Catalyzed by a Copper/1,8-Diazabicyclo[5.4.0]undec-7-ene System

Hydrogenation of carbon dioxide to formate was achieved using copper (Cu) catalysts in the presence of strong organic bases including amidines and guanidines. Specifically, 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU) proved to be effective for the transformation of a 1: 1 mixture of hydrogen and carbon dioxide into its formate salt under increased pressure in the presence of various Cu(I) and Cu(II) salts at 100 degrees C. A novel complex derived from copper iodide and DBU equally promoted the same reaction, indicating that DBU-Cu species are involved as real catalysts in this hydrogenation.