Reductive amination of levulinic acid or its derivatives to pyrrolidones over heterogeneous catalysts in the batch and continuous flow reactors: A review

Levulinic acid known as promising molecule derived from biomass feedstock can be transformed into different valuable chemicals. One of the important classes of such chemicals is N-containing functional compounds, e.g. N-alkyl-5-methyl-2-pyrrolidones which can be applied as the starting material or solvent for the synthesis of pharmaceuticals and agrochemicals. Reductive amination of levulinic acid and its derivatives with various amines is the main synthesis route of pyrrolidones. Many studies to find the most active and selective heterogeneous catalyst for this reaction were performed in recent years. This review article is focused on the screening of catalytic behavior of various heterogeneous catalysts in reductive amination of levulinic acid and its derivative. The comparison of the pyrrolidone yields at similar reaction conditions was done. Performing the investigated reaction both in batch and continuous flow reactors was also considered in this review.