Selective\nOxidation of Ethanol on a Nickel Foam Electrode\nFollowed by Aldol Condensation with Furfural: An Electrochemical Approach\nfor the Utilization of Biomass-Derived Molecules

An electrochemical method was developed to achieve the\noxidative\naldol condensation of ethanol with biomass-derived furfural under\nambient conditions. The product distribution was composed of 3-(2-furyl)acrolein\n(F2A) as the major product and 5-(2-furanyl)-2,4-pentadienal (F24P)\nas the minor product, resulting from the cross aldol condensation\nof F2A with a second acetaldehyde molecule. The latter reaction step\nwas successfully eliminated to achieve a single product, 3-(2-furanyl)-2-methyl-2-propenal\n(F22P), by simply substituting ethanol with 1-propanol. Over 90% Faradaic\nefficiency for the electrochemical step was achieved in 0.5 M KOH\nand 50% aqueous ethanol at a nickel foam anode. In addition, the same\nanode and cathode electrodes can be used up to four times without\ncompromising the efficiency of the overall process, thus highlighting\nnickel foam as an inexpensive and robust anode material for ethanol\nto acetaldehyde oxidation.