Isopropanol/Water Bi-Solvent Enhanced the Catalytic Transfer Hydrogenation of Levulinic Acid to γ-Valerolactone over Ru-PC Catalyst

Catalytic transfer hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) was attractive in biomass conversions since GVL is highly useful in different applications, such as polymer synthesis, fuel, and food. Various catalytic systems were reported for the reaction, yet harsh reaction conditions were generally required, which could restrict the scaling up of the reaction. Herein, we developed an effective and green bi-solvent system of isopropanol/water for the catalytic transfer hydrogenation of LA to GVL over a ruthenium-phosphorous carbon (Ru-PC) catalyst. It was found that the presence of water in the solvent system promoted the production of GVL from LA. The effect of isopropanol/water ratios and other reaction conditions were investigated, exhibiting that 93.8% yield of GVL was achieved using isopropanol/water ratio of 2.5:2.5 at 140 degrees C for 4 h and over Ru-PC catalyst. Combining water and organic solvent not only reduced the usage of organic solvent but also created an effective bi-solvent system for catalytic reactions. The topic regarding transformations of biomass-related molecules attracts substantial attention. Herein, a method for the catalytic transfer hydrogenation of levulinic acid to gamma-valerolactone is developed. The success relies on the use of the ruthenium-phosphorous carbon catalyst. The effect of isopropanol/water bi-solvent system to facilitate the hydrogenation is revealed. The method opens up new tactics for transfer hydrogenation of other biomass resources. image