Catalytic dehydration of hexose sugars to 5-hydroxymethylfural

The catalytic conversion of cellulosic biomass to downstream products provides a viable solution to alleviate the energy crisis and global warming. This article provides a relatively comprehensive review of the dehydration of glucose (the monomer of cellulose) and fructose considering various catalyst and solvent systems. Biphasic solvents and heterogeneous systems are recommended from the point of view of industrial applications. A two-step catalytic conversion of glucose via fructose has been envisaged: first, isomerization of glucose to fructose, which has been extensively discussed in this review, and then transformation of fructose to downstream products. Two-step tandem catalytic reactions from glucose to downstream products (i.e., one-pot synthesis via fructose) are also attractive for industrial applications and should be given more attention. (c) 2018 Society of Chemical Industry and John Wiley & Sons, Ltd