Preparation of valeric acid and valerate esters from biomass-derived levulinic acid using metal triflates plus Pd/C

Recently, great attention has been paid to the study of the conversion of biomass-derived compounds to value-added chemicals. Levulinic acid (LA) is a versatile and valuable chemical and its various applications have been described. The selective conversion of biomass-derived LA to produce valeric acid and valerate esters was successfully performed in the presence of H-2, in which metal triflates and Pd/C were used as the catalysts. Under optimal conditions, a 99% conversion of LA and a 92% selectivity of valeric acid was obtained with Hf(OTf)(4) and Pd/C as the catalysts at a relatively low temperature of 150 degrees C. Moreover, the metal center of the catalyst, the solvent, the reaction temperature and other reaction conditions were studied. In addition, the results of the recycling experiment exhibited that the catalysts continued to have a satisfactory activity after being reused 5 times.