Conversion of mono/di/polysaccharides into furan compounds using 1-alkyl-3-methylimidazolium ionic liquids


The one-pot hydrolysis/dehydration of mono/di/polysaccharides into furfural (FUR) or 5-hydroxymethyl-2-furaldehyde (HMF) in the presence of an acidic ionic liquid. 1-ethyl-3-methylimidazolium hydrogen sulfate ([EMIM][HSO(4)]), at 100 degrees C, was investigated and the results were compared with those using 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), with or without CrCl(3) or H(2)SO(4). The ionic liquid [EMIM][HSO(4)] is effective in converting xylose and fructose or related polysaccharides into FUR (e.g. from xylose: 84% yield at 6 h) or HMF (e.g. from fructose: 88% yield at 30 min), but not glucose and polymers containing these units, which contrasts to that observed for the [BMIM][Cl]/CrCl(3) system. The latter is quite effective in converting glucose and related disaccharides into HMF, but not the polysaccharides cellulose and starch. For the latter feedstocks, the addition of H(2)SO(4) or [EMIM][HSO(4)] to cellulose/[BMIM][Cl]/CrCl(3) enhances HMF yields, presumably by accelerating the hydrolysis step, although the selectivity of the dehydration of glucose monomers seems rather poor (HMF yield < 13 wt.%). In the case of the xylose to FUR conversion in [EMIM][HSO(4)], two systems involving the reaction and simultaneous separation of the target product were investigated, namely reaction/solvent extraction and reaction/evaporation systems, and for both the ionic liquid could be recovered and reused without a significant drop in FUR yield in recycling runs. (C) 2009 Elsevier B.V. All rights reserved.




Chemistry; Environmental Sciences & Ecology


Lima, S; Neves, P; Antunes, MM; Pillinger, M; Ignatyev, N; Valente, AA

nossos autores


We are grateful to the FCT, POCI 2010, OE and FEDER for funding (Projects POCI/QUI/56112/2004 and PTDC/QUI/71198/2006). We acknowledge Dr. F. Domingues (Department of Chemistry) for access to HPLC equipment. S.L. is grateful to the FCT for a post-doctoral grant and P.N. for a grant from CICECO (FCT funding).

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