One-pot synthesis of furans from various saccharides such as arabinose, rhamnose, and lactose were performed over solid acid and base catalysts. The combination of Amberlyst-15 and hydrotalcite catalysts showed successful activity for corresponding furans formation such as 2-furaldehyde (furfural), 5-hydroxymethyl-2-furaldehyde (HMF), and 5-methyl-2-furaldehyde (MF) via one-pot synthesis including isomerization and dehydration reactions. Moreover, the acidbase pair catalysts were also found to display excellent activity for the transformation from mixed-sources of sugars to furans. It was indicated that the isomerization of saccharides and successive dehydration in the one-pot synthesis of furans will be a great approach in a biorefinery.Biorefineries have gained much attention due to the potential to serve as a source of carbon-based fuels and chemicals in a carbon-neutral fashion, 13 the CO 2 released during energy conversion is consumed during subsequent biomass regrowth. Lignocellulosic biomass encompassing municipal and animal wastes, forestry residues, and others is a special interest resource on account of being the most abundant, inedible, and inexpensive biomass. The challenge for effective utilization is to develop cost-effective processes for transformation of huge built carbohydrates into value-added chemical compounds. Furan derivatives such as 2-furaldehyde (furfural), 5-hydroxymethyl-2-furaldehyde (HMF), and 5-methyl-2-furaldehyde (MF) have the potential to be substitutes of building blocks derived from petrochemicals in the production of fine chemicals, pharmaceuticals, and polymers. 48 For instance, HMF can be converted to 2,5-diformylfuran, 2,5-furandicarboxylic acid, 2,5-dimethylfuran, and levulinic acid. 4,913 MF is a useful intermediate for the production of agricultural chemicals (pesticides) and fragrances, and is a common flavoring component in the food industry and is considered a potential antitumor agent.1417 Industrial solvents like 1,5-pentanediol, 1,4-butanediol, and building blocks such as succinic acid, maleic acid are the main products derived from furfural.
1821Recently, Lam et al. 22 and Binder et al. 23 have reported the synthesis of furfural from xylose in good yield using Nafion 117 and chromium halide with ionic liquid, respectively. Dehydration of xylose to furfural is investigated using various solid acid catalysts like sulfonic acid appended porous silicas, 24 metal oxide nanosheets, 25 ion-exchange resins, 26 and zeolites.
27Besides, the inorganic acids with subcritical water at 403 K, 28 organic acids such as oxalic, levulinic, and p-toluenesulfonic acids 2932 were also examined for dehydration of D-fructose. From the view point of reaction system activation, dehydration in watermethyl isobutyl ketone or watertoluene biphasic systems were also investigated with H-mordenite and Hfaujasite by Moreau et al. 33 Although the yield obtained is significant in the above-mentioned processes most of them involve use of high temperature, severe reaction conditions, and difficu...