Tin-catalyzed efficient conversion of carbohydrates for the production of 5-hydroxymethylfurfural in the presence of quaternary ammonium salts

Article abstract of DOI:10.1016/j.carres.2013.01.012

An efficient and tin-catalyzed production of 5-hydroxymethyl furfural (5-HMF) from carbohydrates is reported. The efficient conversion of glucose has been investigated using the combination of SnCl₄ and different quaternary ammonium salts. It was found that tetrabutyl ammonium bromide (TBAB) was able to efficiently promote conversion of glucose to 5-HMF in the presence of SnCl₄. For instance, a 69.1% yield of 5-HMF was obtained with SnCl₄-tetrabutyl ammonium bromide (SnCl₄-TBAB) system in DMSO for 2 h at 100 °C in air. The effects of catalyst amount, reaction time, and reaction temperature were investigated in detail. Furthermore, the SnCl₄-TBAB was also employed to the conversion of fructose, sucrose, inulin, starch, and cellulose. The competitive results were obtained under mild conditions.

Full text of DOI:10.1016/j.carres.2013.01.012

Carbohydrate Research 370 (2013) 33–37
Contents lists available at SciVerse ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Note
Tin-catalyzed efficient conversion of carbohydrates for the
production of 5-hydroxymethylfurfural in the presence of
quaternary ammonium salts
⇑
⇑
Guo Tian, Xinli Tong , Yi Cheng, Song Xue
School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient and tin-catalyzed production of 5-hydroxymethyl furfural (5-HMF) from carbohydrates is
Received 15 December 2012
Received in revised form 17 January 2013
Accepted 21 January 2013
Available online 30 January 2013
reported. The efficient conversion of glucose has been investigated using the combination of SnCl
different quaternary ammonium salts. It was found that tetrabutyl ammonium bromide (TBAB) was able
to efficiently promote conversion of glucose to 5-HMF in the presence of SnCl . For instance, a 69.1% yield
of 5-HMF was obtained with SnCl –tetrabutyl ammonium bromide (SnCl –TBAB) system in DMSO for 2 h
at 100 °C in air. The effects of catalyst amount, reaction time, and reaction temperature were investigated
in detail. Furthermore, the SnCl –TBAB was also employed to the conversion of fructose, sucrose, inulin,
starch, and cellulose. The competitive results were obtained under mild conditions.
Ó 2013 Elsevier Ltd. All rights reserved.
4
and
4
4
4
Keywords:
Dehydration
Carbohydrates
4
5
-Hydromethylfurfural
Quaternary ammonium salts
Tin
Renewable biomass resource provides as a promising substitute
for synthesizing value-added chemical intermediates and liquid
fuels that rely on the limited fossil fuels at present.1 So, with
the decrease of petroleum and the global warning, scientists have
paid great attentions on the efficient conversion of biomass feed-
stock in nature, especially on the downstream chemical process
2 4 3 4
dehydration of fructose with HCl, H SO , and H PO using a bipha-
sic reactor system composed of reactive aqueous phase modified
by DMSO and an organic extracting phase consisting of a 7:3 (w/
w) MIBK-2-butanol mixture or dichloromethane (DCM). This mod-
ifiable biphasic system maximized the 5-HMF selectivity at high
sugar conversions, which reached 89%, 91%, and 53% for fructose,
xylose, and glucose using HCl as catalyst, respectively. Moreover,
–3
4
–6
from sugars.
Remarkably, the catalytic conversion of inexpen-
1
4
sive carbohydrates to value-added chemicals has exhibited a
promising economical value in the industrial application, in which
a lot of efforts have been made to achieve the dehydration of hex-
ose into 5-hydroxymethylfurfural (5-HMF), a useful intermediate,
which is able to further produce fine chemicals, pharmaceuticals,
and numerous polymers.7
Qi et al. found that a yield of 5-HMF as high as 73.4% in 94% sugar
conversion was obtained using a cation exchange as the catalyst in
17
the acetone–water mixtures at 150 °C. Moreau et al. reported
that a dealuminated H-form mordenite was able to promote the
fructose dehydration, where a 76% conversion and 92% selectivity
for 5-HMF were achieved in water–MIBK system at 165 °C. Later,
–10
1
1–13
18
Up to now, traditional acid catalysts, such as mineral acids,
the same group reported that fructose was efficiently dehydrated
14–16
17,18
strong acid cation exchange resins,
H-form zeolites,
and
4 6
with Amberlyst-15 as the catalyst in [bmim]BF or [bmim]PF ionic
19
supported heteropolyacids have been tested for the dehydration
liquid, and a 50% yield of 5-HMF was obtained within around 3 h.
of fructose and glucose. For example, Antal and Mok11 reported the
Also, Zhao et al. found a 74% yield of 5-HMF in 94.7% selectivity
19
dehydration of
critical water at 250 °C, and gained a yield of 5-HMF as high as
3%. Furthermore, Dumesic’ group12 reported a two-phase reactor
system with HCl as the catalyst, in which the -fructose could be
D
-fructose with H
2
SO
4
as a catalyst in the sub-
was obtained using a solid heteropolyacid Cs2.5H0.5PW12O40 in a
biphasic system. However, those catalyst systems can favor the
subsequent dehydration of 5-HMF to levulinic acids and formic
5
6
,20
D
acids,
reaction.
and those will lower the yield of 5-HMF after whole
efficiently dehydrated with the assistance of HCl in the aqueous
phase. In the following, Chheda et al.13 investigated the catalytic
Recently, because of the high 5-HMF selectivity and the negligi-
ble acid by-products being achieved, the dehydration of sugars cat-
21
alyzed by metal salts including lanthanide chlorides, chromium
⇑
Corresponding authors. Tel./fax: +86 22 60214259.
E-mail addresses: tongxinli@tju.edu.cn, tongxli@sohu.com (X. Tong), xueson-
2
2–24
25
26
chlorides,
germanium chlorides, stannum chlorides, alu-
2
7
28
g@ustc.edu.cn (S. Xue).
minum chlorides, and iron chlorides has received considerable
0
008-6215/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.carres.2013.01.012

3
4
G. Tian et al. / Carbohydrate Research 370 (2013) 33–37
CHO
high 5-HMF yield was obtained under suitable conditions. It is
well-known that glucose is more economic and promising as raw
HO
H
3
2–35
OH
O
materials in the reaction.
However, the conversion of glucose
Quatermary Ammonium Salt
SnCl4 or SnCl2
O
H
HO
H
OH
H
to 5-HMF still keeps a challenge since some avoidable problems
and drawbacks exist such as the severe conditions and the low
selectivity. In this paper, focusing on the conversion of glucose to
OH
5
-HMF, we developed a combined catalyst system using tin chlo-
ride and quaternary ammonium salts, and it is found that the tet-
rabutyl ammonium bromide-SnCl system (SnCl –TBAB) shows a
OH
4
4
Scheme 1. Catalytic dehydration of glucose in the presence of quaternary ammo-
nium salts.
remarkable catalytic effect in the production of 5-HMF from selec-
tive conversion of glucose under mild conditions.
In the first preliminary experiments, the conversion of glucose
was performed with different quaternary ammonium salts in the
presence of SnCl or SnCl catalyst (Scheme 1), and the correspond-
attentions. Seri et al.21 revealed that Lanthanide (III) could effi-
ciently catalyze the dehydration of hexose to 5-5-HMF in water
at 140 °C. Zhao et al. reported a combination of metal chloride
4
2
2
2
ing dehydration results are summarized in Table 1. It can be seen
that a 20.1% or 5.3% yield of 5-HMF was respectively obtained with
a single SnCl4 or SnCl2 as the catalyst in DMSO (entries 1 and 2).
When the normal quaternary ammonium salts, for example, tetra-
methyl ammonium chloride (TMAC), tetramethyl ammonium bro-
mide (TMAB), tetraethyl ammonium chloride (TEAC), tetraethyl
ammonium bromide (TEAB), tetrabutyl ammonium chloride
(TBAC), or tetrabutyl ammonium bromide (TBAB) were added as
the promoter, the yield of 5-HMF showed an obvious change.
Therein, 34.5%, 37.6%, 19.9%, 45.2%, 26%, and 69.1% yields of
and 1-ethyl-3-methyl-imidazolium chloride ([EMIM]Cl) that pro-
motes the generation of 5-HMF from
D
-fructose (about 83% with
). Yuan
et al. investigated that the catalytic conversion of glucose to
-HMF with CrCl /CrCl and an inexpensive co-catalyst, tetraethyl
ammonium chloride, in DMSO and a 49.3% 5-HMF yield was ob-
Pt or Rh chloride) and glucose (nearly 70% with CrCl
2
2
3
5
2
3
24
tained at 130 °C within 3 h. Furthermore, Yong et al. found that
6% and 81% yields of 5-HMF were respectively achieved for the
dehydration of fructose and glucose in a new NHC-Cr/ionic liquid
9
25
system at 100 °C for 6 h in air. Next, Zhang et al. studied the
dehydration of fructose catalyzed by GeCl in [BMIM]Cl ionic li-
quid, and the yield of 5-HMF arrived to 92% at 100 °C for 5 min.
5-HMF were obtained when the combination of SnCl –TMAC,
4
4
SnCl –TMAB, SnCl –TEAC, SnCl –TEAB, SnCl –TBAC, and SnCl –
4
4
4
4
4
TBAB was employed in the glucose dehydration, respectively, (en-
tries 3–8). Similarly, the yields of 12.4%, 17.4%, 14.8%, 35.9%, 11.9%,
2
6
Hu et al. found that SnCl
4
could efficiently convert sucrose to
ionic liquid and the yield was as high as
5%. Yang et al. reported a 61% yield of 5-HMF from glucose cat-
in 10 min under microwave heating in a biphasic
medium of water–tetrahydrofuran system. We have reported sev-
5
6
-HMF in [BMIM]BF
4
and 34% for 5-HMF were obtained when SnCl was combined with
2
2
7
TMAC, TMAB, TEAC, TEAB, TBAC, and TBAB (entries 9–14). These
alyzed by AlCl
3
results indicated that SnCl4 is more efficient than SnCl2 which
can be attributed to the preferable existence of the intermediate
a, the chelate complex of glucose with SnCl4 (Fig. 1). Moreover,
TBAB is very efficient for the conversion of glucose in the presence
of SnCl4 and SnCl2 in DMSO, and the bromides are more efficient
than the chlorides as the promoters in the reaction. It is probably
because that the transition from the intermediate a to the
2
8–31
eral catalytic systems for the conversion of carbohydrates,
which that 86% 5-HMF yield was achieved at full conversion of
fructose with a combination of FeCl and tetraethyl ammonium
in
3
30
bromide as catalyst for 2 h at 90 °C in air. The above catalytic pro-
cesses are mainly concentrated on the fructose conversion and a
Table 1
Influence of quaternary ammonium salts in the dehydration of glucosea
Entry
Catalystb
Time (h)
Yieldc (%)
1
2
3
4
5
6
7
8
9
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
SnCl
4
2
4
4
4
4
4
4
2
2
2
2
2
2
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
20.1
5.3
+ Me
+ Me
4
NCl (TMAC)
NBr (TMAB)
34.5
37.6
19.9
45.2
26.0
69.1
12.4
17.4
14.8
35.9
11.9
34.0
54.0
1.0
4
+ Et
+ Et
4
NCl (TEAC)
NBr (TEAB)
4
+ n-Bu
+ n-Bu
4
NCl (TBAC)
NBr (TBAB)
4
+ Me
+ Me
4
NCl (TMAC)
NBr (TMAB)
10
11
12
13
14
15
16
17
4
+ Et
+ Et
4
NCl (TEAC)
NBr (TEAB)
4
+ n-Bu
+ n-Bu
+ NH
4
NCl (TBAC)
NBr (TBAB)
4
4
Br
n-Bu
No
4
NBr (TBAB)
0.2
a
Reaction conditions: 1.0 g glucose, 10 mol % catalyst (1:1), in 10 mL of DMSO, reaction time 2 h, temperature 100 °C.
b
The chemical structures of quaternary ammonium salts and NH
4
Br are as follows:
Cl-
-
Cl-
Cl
N
+
N+
N
+
TBAC:
TBAB:
TMAC:
TMAB:
TEAC:
TEAB:
-
Br
N
Br-
N+
-
H
N
H
-
Br
N
Br
+
+
+
H
H
NH Br:
4
c
The results were obtained by HPLC analysis.

G. Tian et al. / Carbohydrate Research 370 (2013) 33–37
35
OH
O
OH
OH
HO
HO
HO
Glucose
O
H
5-HMF
O
O
Cl
Sn
OH
O
Cl
H
H
Cl
Cl
H
Sn
Cl
Cl
Cl
Cl
-
+
Br N R
4
(
b)
(
a)
Figure 1. The reaction intermediates for the dehydration of glucose to 5-HMF.
Figure 2. Effect of reaction time on the dehydration of glucose (reaction conditions:
Figure 3. Effect of temperature on the dehydration of glucose (reaction conditions:
1
.0 g glucose, 10 mol % SnCl
4
–TBAB system, in 10 mL of DMSO, the temperature
1.0 g glucose, 10 mol % SnCl
4
–TBAB (1:1), in 10 mL of DMSO, reaction time 2 h).
1
00 °C).
Table 2
intermediate b is favorable in the presence of TBAB (shown in
Fig. 1). Furthermore, when the combination of SnCl and NH Br
was used as catalyst, a 54% yield of 5-HMF was obtained (entry
5), which indicated that the function of tert butyl and SnCl is
helpful to the conversion of glucose to 5-HMF. As comparison, a
.0% yield of 5-HMF was obtained when single TBAB was employed
in the dehydration (entry 16). On the other hand, the dehydration
of glucose only slightly occurs without catalyst in DMSO, in which
only 0.2% yield of 5-HMF was obtained (entry 17).
a
The effect of solvents in the dehydration processes
4
4
Entry
Substrate
Solvent
Yieldb (%)
1
4
1
2
3
4
5
6
7
8
9
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
Sucrose
Sucrose
N-Methyl-2-pyrrolidone(NMP)
Dimethylformamide (DMF)
Dimethyl acetamide (DMAc)
Dimethyl sulfoxide (DMSO)
Isobutanol (IBA)
23.8
42.1
50.2
69.1
9.8
8.9
7.6
1.8
50.3
60.0
1
EtOH
CH
CCl
3
CN
4
The effect of reaction time in the dehydration of glucose with
SnCl –TBAB is exhibited in Figure 2. During the whole dehydration
4
DMF
DMAc
10
of glucose, the yield of 5-HMF increases gradually before 120 min,
and the yield of 5-HMF arrived at 69.1% for 120 min at 100 °C. But,
the 5-HMF yield began to decline after 120 min, probably due to
a
Reaction conditions: 1.0 g glucose, 10 mol % SnCl
4
–TBAB (1:1), in 10 mL of
solvent, reaction time 2 h, temperature 100 °C.
b
The results were obtained by HPLC analysis.
5
-HMF being further converted to by-products such as the dimer
and insoluble humins. The generation of by-products is more rapid
than that of 5-HMF at that time.
Moreover, the effect of reaction temperature in dehydration of
4
glucose with SnCl –TBAB is presented in Figure 3. It is seen that
the yield of 5-HMF increases from 50 to 100 °C, and the yield
dropped down after 100 °C, which is probably ascribed to the
occurrence of side reactions. So, the highest yield of 5-HMF is
isobutanol, ethanol, or acetonitrile as the solvent. Otherwise, the
dehydration reaction is hardly performed when carbon tetrachlo-
ride is used as a solvent, which is probably due to the poor solubil-
ity of glucose. It is concluded that using polar and aprotic solvent is
more effective in this reaction system. It can be attributed to its
better solubility and differentiating effect. In addition, DMSO is a
favorable solvent which is added to suppress the undesired side
reaction and decrease the appearance of by-products. Besides, it
was found that a 50.3% or 60% yield of 5-HMF is obtained from
6
9.1% at 100 °C for 2 h with the SnCl
4
–TBAB system as the catalyst
in the dehydration of glucose.
The solvents containing polar (ethanol, N,N-dimethyl formam-
ide, acetonitrile, DMSO, NMP, DMAC, and isobutanol) and non-po-
4
sucrose in the presence of SnCl –TBAB when DMF or DMAc is
4
lar one (CCl ) are employed in the dehydration of glucose (Table 2).
employed as the solvent, respectively.
It is seen that 23.8%, 42.1%, 50.2%, and 69.1% yields of 5-HMF are,
respectively, obtained with NMP, DMF, DMAC, and DMSO as the
solvents, which is superior to the yield of 9.8%, 8.9%, or 7.6% with
Figure 4 shows the effect of catalyst amount with regard to
5-HMF yield from glucose. With the amount of SnCl
4
–TBAB being
increased from 2.5%, 5%, and 7.5% to 10%, the yields of 5-HMF

3
6
G. Tian et al. / Carbohydrate Research 370 (2013) 33–37
5
-HMF yield can be elevated to 4.3% for 8 h. These results indicated
4
that the combination SnCl –TBAB can promote dehydration of
numerous carbohydrates, and the conversion of cellulose still need
to be further improved.
1
1
. Experimental section
.1. Reagents and equipment
Glucose, fructose, sucrose, starch, cellulose, inulin, SnCl
4
Á5H
2
O,
SnCl
are of analytic grade and acquired from commercial sources. Isobu-
tanol, DMSO, DMF, CCl , ethanol, acetonitrile, and NMP are recti-
fied before being used. Pure H
2
2 4
Á2H O, NH Br, TMAC, TMAB, TEAC, TEAB, TBAC, and TBAB
4
2
O is obtained with a Ultrapure
À12
Water System (electrical resistivity = 10
mX cm). The 5-HMF
as standard sample is purchased from Alfa Aesar.
The NMR spectra are recorded on an INOVA 500 MHZ spectrom-
eter. The quantitative analyses of the products are performed on a
Cometro 6000 equipped with LDI pump and PVW UV detector.
Figure 4. Effect of catalyst amount on the dehydration of glucose (reaction
conditions: 1.0 g glucose, a certain amount of SnCl
4
–TBAB, in 10 mL DMSO, time 2 h,
Chromatographic column type is Kromasil, C18,
5
l,
250 Â
temperature 100 °C).
4.6 mm. Qualitative analysis is carried out on the Agilent 6890/
5
973 GC–MS.
Table 3
1
.2. General procedure for the conversion of carbohydrates
The dehydration of different sugars with the SnCl
4
–TBAB systema
Time (h)
Entry
Substrate
Solvent
Yieldd (%)
All the dehydration reaction experiments are carried in a 50 mL
flask equipped with a magnetic stirrer and a ball condenser. A typ-
ical procedure for this reaction is given in the following: a solution
of glucose (1.0 g, 5.6 mmol), SnCl (0.56 mmol), TBAB (0.56 mmol),
4
and DMAO (10 mL) solvent are loaded into the flask. Under stirring,
the flask is heated in an oil bath which maintained at 100 °C for 2 h
in air. After the reaction, the mixture solution is taken out into a
volumetric flask with ethanol as diluter and analyzed by Cometro
1
2
3
Fructose
Sucrose
Glucose + fructose
Fructose
Sucrose
Glucose + fructose
Starch
Inulin
Cellulose
Cellulose
DMSO
DMSO
DMSO
DMF
DMF
DMF
DMSO
DMSO
DMSO
DMSO
2
2
2
2
2
2
2
2
2
8
73.8
66.4
70.5
54.6
50.3
51.8
21.5
62.1
2
b
4
5
b
6
c
7
c
8
c
9
6
000 HPLC equipped with UV detector. The 5-HMF yield is calcu-
1
1c
4.3
lated by the external standard method.
a
Reaction conditions: 1.0 g substrate, 10 mol % catalyst of SnCl
4
–TBAB (1:1), in
1
0 ml solvent, reaction time 2 h, temperature 100 °C.
1
.3. Purification of 5-hydroxymethylfurfural
b
The mass ratio of fructose and glucose is 1:1.
Reaction conditions: 10 mol % catalyst of SnCl –TBAB (1:1), in 10 ml solvent,
4
c
The reaction mixture is transferred into a 100 mL flask and then
reaction in autoclave, temperature-programed and keeping in 140 °C.
d
The results were obtained by HPLC analysis.
3
added saturated aqueous NaHCO solution. After being stirred with
a magnetic stirrer overnight, the mixture is extracted with ethyl
acetate (10 mL Â 4) and after a certain amount of water is added.
Only the organic layer is collected and dried with anhydrous
can be increased from 19%, 24.1%, and 43% to 69.1% for 2 h at
1
00 °C. However, when the amount of catalyst was further in-
creased to 12.5%, the yield of 5-HMF is decreased to 57.4%. This
phenomenon can be ascribed to the fact that more catalyst acceler-
ates side reactions (including rehydration or condensation, etc.).
So, the maximum 5-HMF yield was obtained using 10 mol %
2 4
Na SO ; then, the obtained main product is 5-HMF after distillation
under reduced pressure. The purity was more than 97% through
1
analysis of HPLC. HNMR spectrum (DMSO-d
6
): 3.396–3.438 (d,
1H, J = 7.078), 4.483 (s, 2H), 6.580–6.586 (d, 1H, J = 3.417) 7.466–
1
3
4
SnCl –TBAB as the catalyst.
7.473 (d, 1H, J = 3.417), 9.522 (s, 1H); CNMR spectrum (DMSO-
6
d ): d 56.524, 56.650, 110.385, 152.413, 162.805, and 178.667.
In order to further reveal the merit of this catalytic system, the
conversions of fructose, sucrose, inulin, starch, and cellulose were
investigated with the SnCl
are summarized in Table 3. It can be found that fructose and
sucrose are efficiently dehydrated with SnCl –TBAB in DMSO in
which 73.8% and 66.4% yields of 5-HMF were obtained (entries 1
and 2). Moreover, the yield of HMF reaches 70.5% for 2 h when glu-
cose and fructose (1:1) were used as the substrate (entry 3). Even
in DMF solvent, 54.6%, 50.3%, and 51.8% yields of HMF are obtained
from fructose, sucrose, and fructose–glucose (1:1) in the presence
4
–TBAB as the catalyst, and the results
2. Conclusion
4
In summary, the efficient and catalytic production of 5-HMF
from different carbohydrates has been successfully performed with
the SnCl –TABAB system as the catalyst. A 69.1% yield of 5-HMF is
4
obtained from glucose for 2 h at 100 °C. Moreover, it is also effi-
cient to the catalytic selective conversion of other carbohydrates
(such as fructose, sucrose, inulin, starch, etc.) to 5-HMF. This effi-
cient catalyst system will generate a promising application strat-
egy for biomass transformation.
4
of SnCl –TBAB system (entries 4 and 5). It is concluded that dehy-
dration of ketose can be promoted in this reaction system as well
as that of aldose in DMSO and DMF. Moreover, the conversion of
starch and inulin is also studied, and the 5-HMF yields reached
Acknowledgment
2
1.5% and 62.1% under the suitable conditions (entries 7 and 8).
However, only 2.0% yield of 5-HMF was obtained for 2 h when cel-
lulose is used as reactant in the dehydration reaction, and the
We thank the financial support of the Natural Science Founda-
tion of China (project Number 21003093).

G. Tian et al. / Carbohydrate Research 370 (2013) 33–37
37
1
7. Moreau, C.; Durand, R.; Pourcheron, C.; Razigade, S. Ind. Crop. Prod. 1994, 3, 85–
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