Catalytic Conversion of Carbohydrates into 5‐Hydroxymethylfurfural by Germanium(IV) Chloride in Ionic Liquids

Abstract

Direct conversion of carbohydrates into 5‐hydroxymethylfurfural (HMF) catalyzed by germanium(IV) chloride in ionic liquids has been investigated in search of an efficient and environmentally friendly process. Monosaccharides D‐fructose and D‐glucose, disaccharides sucrose and maltose, and even the polysaccharide cellulose were successfully converted into HMF with good yields under mild conditions (yield up to 92 % in 5 min in the case of fructose). The structure of ionic liquids, catalyst loading, reaction temperature and water content had noticeable effects on this catalytic system. Addition of 5 Å molecular sieves during the dehydration of glucose resulted in an increase in HMF yield from 38.4 % to 48.4 %. A mechanism for glucose conversion to HMF catalyzed by germanium(IV) chloride was proposed according to 13C NMR spectra obtained in situ under different conditions using D‐glucose‐2‐13C as the substrate.

Kinetic Study of the Decomposition of Cellulose to 5-Hydroxymethylfurfural in Ionic Liquid

“…Taking advantage of cellulose to prepare 5-HMF is one approach for the effective conversion of biomass resources . There are many kinds of raw materials for the production of 5-HMF (Ståhlberg et al 2011;Zhang et al 2011;. With multiple functional groups within the molecule, 5-HMF can be used to prepare diverse chemicals of high value ) through hydrogenation, halogenation, esterification, and other chemical reactions.…”

The Catalytic Conversion of d-Glucose to 5-Hydroxymethylfurfural in DMSO Using Metal Salts

“…Stahlberg et al [9] reported only moderate yield of HMF (up to 32 mol%) when a lanthanide salt (YbCl 3 ) was used. Zhao and co-workers [10] reported the used of germanium (IV) chloride as catalyst in an ionic liquid ([BMIM]Cl) and an HMF yield of 38.4 % was obtained. Though promising, the use of metal salts in ionic liquids has limitations due to the relatively high price of ionic liquids, requiring very efficient recycling strategies.…”

“…Yuan et al [14] reported HMF yields up to 49 mol% for a catalyst system consisting of CrCl 2 and tetraethylammonium chloride (TEAC) as the co-catalyst. Apart from chromium salts, SnCl 4 [8] and GeCl 4 [10] are also active catalysts for the conversion of D-glucose to HMF in DMSO, and HMF yields up to 40 mol% were obtained for both catalysts.…”

Conversion of fructose into 5-HMF catalyzed by GeCl4 in DMSO and [Bmim]Cl system at room temperature

“…In our previous work (Zhang, Wang, Xie, Liu, & Zhao, 2011), it was found that GeCl 4 showed excellent catalytic activity for the dehydration of fructose in [Bmim]Cl, with HMF yield up to 92.1% for 5 min at 100 • C. To the best of our knowledge, it is the best result for the production of HMF from fructose in Lewis acids-ILs system. Although a good result was obtained, it is also desirable to carry out the dehydration of fructose at ambient temperature as one of the key goals among the twelve Principles of Green Chemistry.…”