Transfer Hydrogenation of Levulinic Acid to γ-Valerolactone and Pyrrolidones Using a Homogeneous Nickel Catalyst

We report a well-defined homogeneous nickel-based catalyst using the complex [dippeNi(COD)] (dippe=1,2-bis(diisopropyl phosphino)ethane) as a catalytic precursor with high activity in the hydrogenation of levulinic acid (LVA) to yield gamma-valerolactone (GVL) under relatively mild conditions (4 h, 120 degrees C); formic acid (FA) is the transfer hydrogenation agent in a dehydrogenation-hydrogenation process. Under optimized conditions, GVL was obtained with excellent yield (>99 %) and selectivity (>99 %). The Ni-catalyst was assessed in the LVA hydrogenation with a variety of primary amines using an excess of FA (4 eq) as hydrogen donor at 15 h and 170 degrees C to produce 2-pyrrolydones with excellent yield (>99 %) and fair to good selectivity (from 68 to 92 %).

Automated summary

A well-defined homogeneous nickel-based catalyst was reported for the hydrogenation of levulinic acid to yield gamma-valerolactone under relatively mild conditions, with formic acid as the transfer hydrogenation agent. Excellent yield and selectivity were achieved under optimized conditions. The catalyst was also assessed for the generation of 2-pyrrolydones with high yield and fair to good selectivity under different reaction conditions.