A practical and concise homogeneous nickel catalyst for efficient solvent-free synthesis of γ-valerolactone

Here, we report an inexpensive nickel-phosphine complex that can catalyse neat levulinic acid (LA) to gamma-valerolactone (GVL) without additive at 1 atm H-2, and the catalyst can be reduced to 0.01 mol% at 30 atm. 5.8 kg LA was successfully converted to GVL in a yield of 94% with 0.1 mol% catalyst. DFT calculations and in situ APXPS indicate that L-Ni+-H species are the key active intermediates.