Selective hydrogenation of levoglucosenone over Pd/C using formic acid as a hydrogen source

Abstract

Selective hydrogenation of lignocellulosic biomass-derived chemicals is of great importance for future energy and chemical supply. So far formic acid is considered as one of the most promising materials for hydrogen storage. Herein, we report a novel pathway for the hydrogenation of Levogluosenone (LGO), a biorenewable platform chemical, to dihydrolevoglucosenone (Cyrene) and levoglucosanol (Lgol) using formic acid as a hydrogen source. Testing with typical hydrogenation catalysts indicated the crucial influence of the type on reaction selectivity and identified Pd/C as the most suitable catalyst. Among solvents screened, THF in combination with Pd/C showed the best performance for LGO hydrogenation, producing Cyrene in >99% yield at a low temperature (60 °C). Nevertheless, hydrogenation of Cyrene to Lgol required a harsher condition as a result of the difficult reduction property of its C=O bond. Elevating the reaction temperature to 180 °C and increasing double Pd dosage enabled a high yield of Lgol, attaining to 94.8%.