Catalytic Transfer Hydrogenation of Furfural for the Production of Ethyl Levulinate: Interplay of Lewis and Bronsted Acidities

Ethyl levulinate is sought after due to its applications as a fuel additive in biodiesel fuels. Currently it's industrially produced using harmful, highly reactive acids like H2SO4 and HCl, which are used to produce levulinic acid, the common precursor used for EL production. Herein, ethyl levulinate is produced from the synergistic effect of BrOnsted and Lewis acids, which catalyze the hydrogenation of furfural leading to the alternative precursor for EL production, furfuryl alcohol. The subsequent ethanolysis reaction of furfuryl alcohol to produce EL, is also enhanced by using an optimal ratio of BrOnsted to Lewis acids. Ethanol is chosen as the sacrificial hydrogen donor for proton transfer hydrogenation since it is environmentally friendly, more abundant and affordable than other alcohols that are commonly used for large-scale production processes. The tandem catalytic reaction can be effectively used to sustainably and responsibly produce ethyl levulinate in relatively short reaction times.