Conversion of d-glucose into 5-hydroxymethylfurfural (HMF) using zeolite in [Bmim]Cl or tetrabutylammonium chloride (TBAC)/CrCl2

Article abstract of DOI:10.1016/j.tetlet.2011.12.059

The formation of hydroxymethylfurfural (HMF) from glucose was studied. It was found that the CrCl₂-catalyzed conversion in the ionic liquid, butylmethylimidazolium chloride ([Bmim]Cl) leads to negligible quantities of 3-deoxyglucosone confirming that fructose is the main intermediate. It was found that the environmentally unfriendly chromium salt could be replaced with zeolite (H-ZSM-5) leading to a 45% yield of HMF. It was also found that the solvent [Bmim]Cl could be replaced with non-toxic tetrabutylammonium chloride (TBAC) giving a 56% yield of HMF.

Full text of DOI:10.1016/j.tetlet.2011.12.059

Tetrahedron Letters 53 (2012) 983–985
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Tetrahedron Letters
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Conversion of D-glucose into 5-hydroxymethylfurfural (HMF) using zeolite
in [Bmim]Cl or tetrabutylammonium chloride (TBAC)/CrCl2
Harishandra Jadhav a, Esben Taarning b, Christian Marcus Pedersen a, Mikael Bols a,
⇑
a Department of Chemistry, University of Copenhagen, Denmark
b Haldor Topsøe A/S, Nymøllevej 55, 2800 Kgs. Lyngby, Denmark
a r t i c l e i n f o
a b s t r a c t
Article history:
The formation of hydroxymethylfurfural (HMF) from glucose was studied. It was found that the CrCl2-cat-
alyzed conversion in the ionic liquid, butylmethylimidazolium chloride ([Bmim]Cl) leads to negligible
quantities of 3-deoxyglucosone confirming that fructose is the main intermediate. It was found that
the environmentally unfriendly chromium salt could be replaced with zeolite (H-ZSM-5) leading to a
45% yield of HMF. It was also found that the solvent [Bmim]Cl could be replaced with non-toxic tetrabu-
tylammonium chloride (TBAC) giving a 56% yield of HMF.
Received 6 September 2011
Revised 8 December 2011
Accepted 16 December 2011
Available online 23 December 2011
Keywords:
Biomass conversion
Biofuel
Ó 2011 Elsevier Ltd. All rights reserved.
Hydroxymethylfurfural
Zeolite
Tetrabutylammonium chloride
The present continuous increase in atmospheric CO2 and the
resulting or expected climate changes as a result thereof, has led
to the common agreement that the present heavy dependence on
fossil fuels is untenable. Therefore it has become increasingly
important to look at the biosphere as an alternative carbon source
for carbon based fuels and chemicals.1 As most of the organic
material in the biosphere is carbohydrate, particularly cellulose,2
the most important problem to solve in biomass conversion is to
find good methods for the conversion of these carbohydrates into
fuels or chemicals. One of the most direct methods, which has re-
ceived much attention, is acid-catalyzed dehydration to furfurals.
The furfural of main importance, the product from dehydration
of glucose, hydroxymethylfurfural (HMF), has generated interest3
as an intermediate for new biofuels such as dimethylfuran4 or for
chemicals.5 The key to success is to develop efficient methods to
obtain HMF from biomass.6
readily dehydrates to HMF.8–10 The mechanism differs from the
acid-catalyzed dehydration of glucose into HMF, which primarily
proceeds via 3-deoxy-D-erythro-hex-2-ulose (3-deoxyglucosone,
Scheme 1),11 and gives a lower yield.12,13 In the imidazolium based
ionic liquids [Emim]Cl/DMA an over 81% yield of HMF was ob-
tained using CrCl2 as the catalyst.14 However, neither [Emim]Cl
or CrCl2 are ideal, as the imidazolium based ionic liquids are toxic
and expensive and CrCl2 is hazardous to the environment. Alterna-
tives are therefore needed and here we report our findings in this
regard.
Current methods for the preparation of HMF mainly use acid
catalysis and preferably fructose as the starting material. HMF is
inherently unstable in acid so when HMF is made from glucose
or glucose based polysaccharides, such as cellulose, where the
reaction time required is significantly longer, the HMF yield de-
creases due to its decomposition.
A recent improvement was the finding that chromium salts cat-
alyze the formation of HMF from glucose.7 Cr(III) is able to catalyze
isomerisation of glucose into fructose, a monosaccharide that more
⇑
Corresponding author.
E-mail address: bols@kemi.ku.dk (M. Bols).
Scheme 1. Acid- and Cr(III)-catalyzed conversions of glucose into HMF.
0040-4039/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2011.12.059

984
H. Jadhav et al. / Tetrahedron Letters 53 (2012) 983–985
Table 2
H-ZSM-5 zeolite as a catalyst for the conversion of D-glucose into HMF
Entry Glucose
Solvent
H-ZSM-5
(mg/mL)
Temperature
(°C)
Time
(h)
Yield
(%)
Conc.
(M)
Figure 1. Structures of catalyst H-ZSM-5 and the ionic liquid TBAC.
1
2
3
4
5
6
7
8
0.28
0.28
0.28
0.28
0.28
0.28
0.28
0.28
0.56
0.22
0.56
DMA
DMA/LiCl
PhMe
c-C5H9OH
BuOH
DMSO
sulfolane
[Bmim]Cl
[Bmim]Cl
[Bmim]Cl
[Bmim]Cl/
TBAC (1:1)
25
25
25
25
25
25
25
100
40
50
110
110
110
110
110
110
110
110
110
110
110
12
12
12
12
12
12
12
8
0
0
0
0
0
0
0
45
22
24
27
Table 1
Conversion of D-fructose into HMF using zeolite H-ZSM-5 as catalyst
9
10
11
24
4
4
100
Entry
Solvent
Temperature (°C)
Yield (%)
1
2
3
DMA
DMSO
PhMe/H2O
110
110
90
5
65
50
Table 3
The ratio was 50 mg fructose and 25 mg H-ZSM-5 per mL of organic solvent.
TBAC as a solvent for the conversion of D-glucose into HMF. The reaction time was 4 h
and the temperature 110 °C
Zeolites are used as shape selective, reusable and economical
acid catalysts in petrochemistry, and they have also been em-
ployed successfully in biomass conversion reactions,15,16 being
more environmentally friendly than CrCl2. Tin-containing zeolites
have recently been shown to catalyze carbohydrate isomerisations
(somewhat similar to CrCl2) into lactate17 or fructose18 and dehy-
dration into HMF.19 Alternatively, acidic zeolites might catalyze
dehydration via the 3-deoxyglucosone route.13a Our attention
therefore became focused on H-ZSM-5,20 a very acidic zeolite used
in other isomerisations (Fig. 1).21 The H-ZSM-5 zeolite has a pore
size of 5–6 Å, which should make it ideal for accommodating mol-
ecules the size of glucose and HMF. H-ZSM-5 zeolite used in this
study was obtained from Zeochem and has a Si/Al ratio of 50:1.
Though the imidazole based ionic liquids have excellent quali-
ties in terms of dissolving carbohydrates and salts they have the
drawback of toxicity and high cost. This is by no means the case
for all ionic liquids22 and we therefore also looked for alternative
ionic liquids and report here our work with tetrabutylammonium
chloride (TBAC), which melts at 83–86 °C, as a solvent. (Two recent
papers report the use of tetraethylammonium chloride as a
solvent.23).
Entry
Glucose conc. (M)
Solvent
Catalyst
Yield (%)
1
2
3
4
5
6
7
8
9
10
0.74
2.2
0.74
2.2
1.1
1.1
1.1
1.1
1.1
1.1
TBAC/DMA (1:2)
TBAC
TBAC/DMA (1:2)
TBAC
TBAC
TBAC
TBAC
TBAC
TBAC
TBAC
CrCl2
CrCl2
CrCl3Á6H2O
CrCl3Á6H2O
Boric acid
H2SO4
56
54
52
49
29
5
10
<2
<2
—
HCl
SrCl2
SrCl2Á6H2O
ZnCl2
The amount of catalyst was 10 mol % relative to glucose.
to dissolve ions and disrupt H-bonds. Therefore an ionic liquid re-
lated solvent mixture, DMA/LiCl (entry 2), was tried, as well as the
ionic liquid obtained when tetrabutylammonium chloride (TBAC)
melts (entries 12 and 13). Neither solvent gave a positive result
however TBAC gave only a 27% yield of HMF when combined with
[Bmim]Cl (entry 11). Compared to other acid catalysts the yield of
45% was very good; SnCl425 or tantalum hydroxide26 have recently
been reported to give HMF in yields of 58–63% as determined by
HPLC analysis.
An initial study employing H-ZSM-5 as the catalyst for the
dehydration of fructose showed that the catalyst performed well
(Table 1). Yields of hydroxymethylfurfural of 54–65% were ob-
tained depending on the solvent with dimethylsulfoxide (DMSO,
entry 2) being better than dimethylacetamide (DMA, entry 1)
and toluene (PhMe)/water (entry 3).
However transferring these conditions to glucose was very dis-
appointing (Table 2). Treatment of glucose with H-ZSM-5 in DMA,
DMSO or toluene (entries 1, 3 and 6), in alcohols (entries 4 and 5)
or sulfolane (entry 7) gave no isolable yield of HMF. Only when 1-
butyl-3-methylimidazolium chloride [Bmim]Cl24 was used as the
solvent was a yield of up to 45% of HMF obtained (entries 8–10).
Since HMF is unstable at high temperature a comparatively short
reaction time with a relatively large amount of catalyst gave the
best result (entry 8), while a longer time and less catalyst give low-
er yields (entries 9 and 10). The remarkable effect of [Bmim]Cl is
likely related to its polarity, being an ionic liquid and better able
Nevertheless these experiments showed that TBAC was a much
more convenient solvent to work with than [Bmim]Cl and we
therefore investigated its performance as a solvent with other cat-
alysts (Table 3). Protic acids gave low yields (5–10%) of HMF (en-
tries 6 and 7) which corresponds with previous observations of
H-ZSM-5 not working in TBAC. Lewis acids performed even worse
(entries 8–10). Boric acid6 functioned considerably better (entry 5),
but CrCl2 or CrCl3 gave the best yields (49–56%) in either pure TBAC
or TBAC/DMA (entries 1–4). This is a clear improvement since TBAC
is a cheaper and a more environmentally friendly alternative to the
imidazolium based ionic liquid.

H. Jadhav et al. / Tetrahedron Letters 53 (2012) 983–985
985
3. For some alternatives to HMF, see: (a) Mascal, M.; Nikitin, E. B. Angew. Chem.,
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Chun, J.-A.; Lee, J.-W.; Yi, Y.-B.; Hong, S.-S.; Chung, C.-H. Starch/Stärke 2010, 62,
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Overall this work has led to two improvements in the synthesis
of HMF from glucose: in the acid-promoted dehydration we found
that an acidic zeolite, H-ZSM-5, catalyzed the reaction and led to a
45% isolated yield of HMF, which is among the highest yields ob-
tained when chromium salts are not added. Secondly, we found
that in the Cr-catalyzed reaction, imidazole-based ionic liquids
could be substituted with inexpensive and non-toxic tetrabutyl-
ammonium chloride to give yields of HMF of 50–55%. A combina-
tion of our two findings, which would avoid both the toxic solvent
and catalyst, has not yet been possible, but should be a future
direction of biomass conversion research.
10. For the synthesis of HMF from cellulose using
a chromium- containing
heteropolyacid, see: Zhao, S.; Cheng, M.; Li, J.; Tian, J.; Wang, X. Chem. Commun.
2011, 47, 2176–2178.
11. Jadhav, H.; Pedersen, C. M.; Sølling, T.; Bols, M. ChemSusChem 2011, 4, 1049–
1051.
General procedure
The solvent/ionic liquid was placed in a round-bottomed flask
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2010, 383, 149–155.
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15. Taarning, E.; Osmundsen, C. M.; Yang, X.; Voss, B.; Andersen, S. I.; Christensen,
C. H. Energy Environ. Sci. 2011, 4, 793–804.
16. For a report on the hydration of xylose into furfural using zeolites, see: Lima, S.;
Antunes, M. M.; Fernandes, A.; Pillinger, M.; Ribeiro, M. F.; Valente, A. A. Appl.
Catal., A 2010, 388, 141–148.
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and heated to 80–90 °C to give a clear solution. D-Glucose was
added followed by the activated27 zeolite28 and the mixture was
stirred at 110 °C for the indicated time. The mixture was cooled
to 40 °C, H2O and EtOAc were added (10 mL each per 100 mg car-
bohydrate), and the mixture stirred for 30 min at 40 °C. The mix-
ture was filtered and the aqueous layer extracted with EtOAc
(3 Â 10 mL). The combined organic layers were washed with brine
and dried over anhydrous Na2SO4. After evaporation the residue
was subjected to flash chromatography on a SiO2 column using
petroleum ether as the eluent and eluting HMF with EtOAc. 1H
NMR (500 MHz, CDCl3) d 9.61 (s, 1H), 7.18 (d, J = 3.6 Hz, 1H), 6.56
(d, J = 3.6 Hz, 1H), 4.59 (s, 2H). 13C NMR (126 MHz, CDCl3) d
177.9, 156.3, 153.1, 121.9, 112.1, 36.7.
Acknowledgment
24. Significantly higher yields were obtained in [Bmim]Cl compared to [Emim]Cl
for the lanthanide-catalysed conversion of glucose into HMF, see: Ståhlberg, T.;
Sørensen, M. G.; Riisager, A. Green Chem. 2010, 12, 321–325.
25. Hu, S.; Zhang, Z.; Song, J.; Zhou, Y.; Buxing, H. Green Chem. 2009, 11, 1746–
1749.
26. Yang, F.; Liu, Q.; Yue, M.; Bai, X.; Du, Y. Chem. Commun. 2011, 47, 4469–4471.
27. Before use the zeolite was activated by heating at 120 °C for 1 h.
28. H-ZSM-5, Zeochem Zeolite PZ-2/100H 30 81 200.000.
We thank Forskningsrådet for Teknologi og Produktion for
financial support.
References and notes
1. Rostrup-Nielsen, J. R. Science 2005, 308, 1421–1422.
2. Pérez, S.; Samain, D. Adv. Carb. Chem. Biochem. 2010, 64C, 25–116.