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A variety of polyethylene glycol-400-functionalized dicationic acidic ionic liquids (ILs) (PEG-DAILs) were synthesized and tested in the dehydration of fructose. Among these catalysts, hydrogen sulfate anion-based ILs showed the higher catalytic performance in the conversion of fructose. The highest HMF yield of 96.5 % with 100 % consumption of fructose were obtained after 60 min at 110 °C. The effects of catalyst concentration, reaction time, reaction temperature, and solvents were systematically investigated. In addition, the generality of the catalysts was examined by processing inulin and sucrose to HMF with yield of 71.9 and 52.1 % under certain conditions, respectively. PEG-DAILs possess modified physicochemical properties such as low viscosity, strong hydrophilicity and hydrogen bonding with sugars so as to improve activity for the dehydration of fructose into HMF. The used IL catalyst could be separated and recycled repeatedly without significant loss of catalytic activity. The research emphasizes preparation of the novel catalysts combining polymers with functionalized ILs for conversion of renewable biomass. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The one-pot dehydration/hydrolysis of mono- and disaccharides to 5-hydroxymethylfurfural (HMF) in the presence of several imidazolium ionic liquids was efficiently performed. The study aims to make a mechanistic insights on the direct transformation of sugars to HMF, including glucose, fructose, galactose, sucrose, maltose and lactose. With the catalyst of [NMP][HSO], a HMF yield of 87 % was achieved from sucrose. In addition, [AMIM]Cl revealed a remarkable catalytic activity for the transformation of fructose to HMF without other catalyst or co-solvent and the yield of HMF was 91.1 %. Theoretical calculation results showed that [AMIM]Cl expressed a more efficient catalytic activity than [BMIM]Cl. Graphical Abstract: Fructose could directly convert into HMF in [AMIM]Cl without catalyst. Behaviors of disaccharides are largely determined by their basic units. The mechanism to explain the activity of [AMIM]Cl has been confirmed by using DFT method. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]