Synthesis and performance of piperidinium-based ionic liquids as catalyst for biomass conversion into 3-acetamido-5-acetylfuran

Ionic liquids have shown good catalytic performance and been widely used in the biomass conversion process due to their unique properties, including environmental friendship, low toxicity, and simple preparation. In this work, a series of novel piperidinium-based ionic liquids were synthesized under mild conditions via a simple protonation reaction or nucleophilic substitution reaction. Among them, 4,4′-(propane-1,3-diyl)bis(1-(carboxymethyl)piperidin-1-ium) chloride ([PDCMPi]Cl) displayed the best catalytic performance. The highest yield (42.81 %) of 3A5AF from NAG was obtained after reacting in N-methyl-pyrrolidone (NMP) in the presence of piperidinium-based ionic liquids at 180 °C for 20 min under normal atmospheric conditions. Additionally, ionic liquid [PDCMPi]Cl showed good catalytic activity in six repeated catalytic runs. Meanwhile, a possible reaction pathway was also proposed on the basis of the results of NMR spectra.