Effect of Different Ionic Liquids on 5-Hydroxymethylfurfural Preparation from Glucose in DMA over AlCl3: Experimental and Theoretical Study

In this work, effect of different ionic liquids (ILs) on 5‐hydroxymethylfurfural (HMF) preparation from glucose in N,N‐dimethylacetamide (DMA) over AlCl₃ was revealed by a combined experimental and computational study. ILs used as cocatalysts in this work included N‐methyl‐2‐pyrrolidone hydrogen sulfate (NMP]HSO₄), N‐methyl‐2‐pyrrolidone methyl sulfate (NMP]CH₃SO₃), N‐methyl‐2‐pyrrolidone chlorine (NMP]Cl) and N‐methyl‐2‐pyrrolidone bromide (NMP]Br) which were endowed with the same cation but different anions. According to the conclusion that fructose was intermediate product from glucose to HMF, we found fructose was transformed to more by‐products by NMP]HSO₄, making HMF yield decline significantly when glucose was treated as substrate. Neither glucose nor fructose could be converted by NMP]CH₃SO₃ efficiently, leading to its no influence on glucose conversion to HMF. NMP]Br had a higher selectivity for HMF from fructose than NMP]Cl and AlCl₃. Besides, Al³⁺ preferred to combine with Br^?, slightly decreasing both the overall free energy barrier for glucose isomerization and activation barrier for H‐shift at 393.15 K. So a high HMF yield of 57% was obtained from glucose catalyzed by AlCl₃ together with NMP]Br under mild conditions.