A one-pot approach for conversion of fructose to 2,5-diformylfuran by combination of Fe3O4-SBA-SO3H and K-OMS-2

Article abstract of DOI:10.1039/c2gc35947b

We have demonstrated an efficient, selective and environmentally benign heterogeneous catalyst (K-OMS-2) for aerobic oxidation of 5-HMF to 2,5-DFF. In addition, a combination of Fe₃O₄-SBA-SO₃H and K-OMS-2 successfully catalyzed direct synthesis of 2,5-DFF from fructose via acid-catalyzed dehydration and successive aerobic oxidation in one-pot reaction.

Full text of DOI:10.1039/c2gc35947b

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links
Green Chemistry
Cite this: Green Chem., 2012, 14, 2986
www.rsc.org/greenchem
COMMUNICATION
A one-pot approach for conversion of fructose to 2,5-diformylfuran by
combination of Fe3O4-SBA-SO3H and K-OMS-2†
Zhen-Zhen Yang, Jin Deng, Tao Pan, Qing-Xiang Guo and Yao Fu*
Received 21st June 2012, Accepted 28th August 2012
DOI: 10.1039/c2gc35947b
cost for isolation and purification of 5-HMF still limits scale-up
production of 2,5-DFF.
We have demonstrated an efficient, selective and environ-
mentally benign heterogeneous catalyst (K-OMS-2) for
aerobic oxidation of 5-HMF to 2,5-DFF. In addition, a combi-
nation of Fe3O4-SBA-SO3H and K-OMS-2 successfully cata-
lyzed direct synthesis of 2,5-DFF from fructose via acid-
catalyzed dehydration and successive aerobic oxidation in
one-pot reaction.
Biomass-derived carbohydrates are a sustainable chemical
feedstock and can be used to synthesize 5-HMF via acid-cata-
lyzed dehydration. Thus, a one-pot process for synthesis of
2,5-DFF from cheap carbohydrates may be more efficient.
Several efficient catalyst systems have been reported for this
transformation, such as H-form cation exchange resin/V-based
catalysts,10 CrCl3·6H2O/NaBr/NaVO3·2H2O17 and Amberlyst-
15/polymer-supported IBX amide.15 Very recently, Takagaki
et al. combined hydrotalcite, Amberlyst-15, and Ru/HT for
direct synthesis of 2,5-DFF from carbohydrates. The yields of
2,5-DFF were up to 49% from fructose and 25% from glucose,
respectively.16
Recently, Son et al. reported that K-OMS-2 (a porous manga-
nese oxide with a composition of KMn8O16·nH2O) or H-K-
OMS-2 (H0.2K0.8Mn8O16·nH2O) could be used as a cheap and
nontoxic heterogeneous catalyst for selective oxidization of
benzylic alcohols to aldehydes or ketones (Fig. 1).20 Inspired by
Son’s work, we found that a combined catalyst of Fe3O4-
SBA-SO3H (a magnetic solid acid) and K-OMS-2 can efficiently
convert fructose to 2,5-DFF in a one-pot fashion (Scheme 1).
Fe3O4-SBA-SO3H catalyzes fructose dehydration into 5-HMF
by removal of water, and K-OMS-2 catalyzes an efficient and
selective oxidation of 5-HMF to 2,5-DFF.
With increasing depletion of fossil resources and growing
concern about environmental issues, biomass has attracted the
attention of chemists as an important feedstock for the renewable
production of fuels and bulk chemicals.1 5-Hydroxymethyl-
furfural (5-HMF), which is an important bridge molecule linking
biomass to fuels and chemicals, can be obtained from biomass-
based carbohydrates2 and transformed to many other compounds.
For example, aerobic oxidation of 5-HMF to 2,5-diformylfuran
(2,5-DFF) has attracted much attention due to the various
applications of 2,5-DFF. It can not only be used to synthesize
pharmaceutical intermediates,3 fungicides,4 and heterocyclic
ligands,5 but also can be used as a monomer for making
multifunctional materials.6 Therefore, synthesis of 2,5-DFF from
biomass-based carbohydrates is important.
The reported routes for 2,5-DFF synthesis have mostly been
based on aerobic oxidation of pure 5-HMF. Many classic oxi-
dants, such as pyridinium chlorochromate (PCC),7 NaOCl,8 and
2,2,6,6-tetramethylpiperidine-1-oxide (TEMPO)9 show good
performance for 2,5-DFF synthesis. However, from the view-
point of cost and sustainability, air or molecular O2 is more inter-
esting as an oxidant. A number of catalyst systems using air or
O2 as oxidant have been developed for the oxidation of 5-HMF
to 2,5-DFF, including vanadium-based catalysts, such as V2O5,10
VOPO4·2H2O,11 V-containing polymeric catalyst12 and Cu-
(NO3)2/VOSO4.13 Other catalyst systems, such as metal/bromide
(Co/Mn/Br) catalyst,14 polymer-supported IBX amide15 and
Ru/HT16 have also been reported for the same application. These
studies have contributed to the development of catalyst systems
for oxidation of 5-HMF to 2,5-DFF. However, the high energy
Table 1 lists the results for 2,5-DFF formation via aerobic oxi-
dation of 5-HMF under different reaction conditions with the
Fig. 1 The structures of K-OMS-2 and H-K-OMS-2.
Anhui Province Key Laboratory of Biomass Clean Energy, Department
of Chemistry, University of Science and Technology of China, Hefei
230026, P.R. China. E-mail: fuyao@ustc.edu.cn;
Fax: (+86) 551-360-6689
†Electronic supplementary information (ESI) available. See DOI:
10.1039/c2gc35947b
Scheme 1 The one-pot approach for synthesis of 2,5-DFF from fruc-
tose by a combination of Fe3O4-SBA-SO3H and K-OMS-2.
2986 | Green Chem., 2012, 14, 2986–2989
This journal is © The Royal Society of Chemistry 2012

View Article Online
Table 1 Aerobic oxidation of 5-HMF to 2,5-DFFa,b
the reaction process undergoes a simultaneous transfer of two
electrons. The active sites may be derived from the Mn3+ ions in
the tunnel sites of K-OMS-2. A redox mechanism was proposed
for K-OMS-2-catalyzed conversion of 5-HMF to 2,5-DFF.
Entry
Catalyst
Catalyst (g)
Solvent
Yield (%)
1
2
3
H-K-OMS-2
K-OMS-2
H-K-OMS-2
K-OMS-2
H-K-OMS-2
K-OMS-2
K-OMS-2
K-OMS-2
K-OMS-2
MnO2
0.05
0.05
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMF
MIBK
Toluene
DMSO
46
−
5-HMF is oxidized by Mn4+O2−, simultaneously Mn4+O2 is
43
99 (92)e
reduced to a Mn3+ ion which is reoxidized by O2. In the whole
process, the removal of a secondary H atom is the rate-control-
ling step.19 Eqn (1)–(4) summarize this process:
4
99 (92)e
5c
6c
7d
8
57
39
99
38
19
4
ð1Þ
9
10
a 1 mmol 5-HMF, 0.05–0.1 g (∼0.38–0.75) equiv K-OMS-2/H-K-
OMS-2, 3 mL solvent, 10 mL min−1 O2. React at 110 °C for 6 h.
b Selectivity of all oxidation reactions were 100%. c Air as primary
oxidant. d Reaction time was 8 h. e Isolated yield in the parenthesis.
ð2Þ
ð3Þ
K-OMS-2 or H-K-OMS-2 catalyst. Reaction parameters, such as
solvent, temperature, reaction time, and catalyst loading, have
been examined. As reported in previous literature, K-OMS-2 has
the ability to absorb aldehydes, so the yields of 2,5-DFF were
detected after the catalyst was washed with DMSO several times.
It was found that the catalyst loading was an important factor. In
the presence of molecular oxygen (10 mL min−1), 5-HMF
(1 mmol) and catalysts K-OMS-2/H-K-OMS-2 (0.05 g), the
yield of 2,5-DFF was about 45% with 100% selectivity at
110 °C for 6 h (entries 1, 2). Subsequently, when we increased
the catalyst loading to 0.1 g, 5-HMF was transformed completely
to 2,5-DFF with 100% selectivity (entries 3, 4). However, by
using air as the oxidant instead of molecular oxygen, 5-HMF
was not converted completely, even after 12 h (entries 5, 6). This
observation showed that molecular oxygen has a higher activity
than air in this system. In addition, when we used air as the
oxidant, H-K-OMS-2 was more efficient than K-OMS-2 because
the Brønsted acid sites in H-K-OMS-2 promote the oxidation
process, maybe by affecting the Mn–O bond strength.18,19
However, there was no significant difference between the
two catalysts if molecular oxygen was used, it may be that
the higher oxidizing ability of molecular oxygen minimised the
effect of catalyst nature. Thus, in the following experiments
we used K-OMS-2 as the catalyst, and molecular oxygen as the
oxidant.
ð4Þ
In the rate-controlling step, the positive charge has been dis-
persed. According to related knowledge of solvent effects, the
electronic pairs of O, N, S in strong polarity solvents can attract
and disperse the positive charge of the cations. Thus, strong
polarity solvents (such as DMSO and DMF) promote the rate-
controlling step of 5-HMF oxidation and affect the conversion of
5-HMF.
MnO2 has been used as a catalyst for comparison with
K-OMS-2 (entry 10). As shown in Table 1, MnO2 was not
efficient for aerobic oxidation of 5-HMF to 2,5-DFF in this re-
action system. This is probably due to the different structure of
the two materials and the different forms of Mn in these two
materials. Fig. S2 and S3† show the N2 adsorption–desorption
isotherms of K-OMS-2 and MnO2. The K-OMS-2 sample exhi-
bits a type I isotherm, which is a characteristic of a mesoporous
material but MnO2 has a much smaller pore size (Fig. S2, S3,
Solvents also have a significant effect on 2,5-DFF formation.
According to Table 1, solvents with strong polarity and high
boiling point (such as DMSO and DMF) were favorable. When
5-HMF (1 mmol) and catalyst K-OMS-2 (0.1 g) were heated at
110 °C for 6 h in DMSO under 10 mL min−1 O2, the yield of
2,5-DFF was up to 99%. For DMF, we needed to prolong the
reaction time to 8 h for complete conversion of 5-HMF (entry
7). However, if other solvents such as MIBK (methyl isobutyl
ketone) and toluene were used, the yields of 2,5-DFF were
reduced to 38% and 19% (entries 8, 9). The effect of reaction
time and temperature has also been studied (Fig. S1, ESI†).
According to Son’s work, the interesting oxidation properties
of K-OMS-2 is due to the coexistence of Mn4+, Mn3+ and Mn2+
ions in the material.20 Mechanistic studies by Son et al. point to
a Mars–van Krevelen mechanism of oxidation for the catalytic
oxidation of alcohols by heterogeneous catalyst K-OMS-2 and
ESI†). In addition, K-OMS-2 has a much larger BET
surface area (77.2106 m2 g−1) than MnO2 (BET surface area:
0.1324 m2 g−1). (Table S1, ESI†). The XPS patterns also
provide evidence for the existence of Mn3+ in K-OMS-2
(Fig. S4, ESI†).
The K-OMS-2 catalyst was recovered by centrifugation,
washed with DMSO and then recycled for further reaction. The
yields of 2,5-DFF were plotted against reuse times, indicating
that the activity of the catalyst is not decreased after being reused
five times (Fig. S5, ESI†). The possibility for loss of the
K-OMS-2 catalyst during the oxidation reaction was also tested.
The reaction was stopped after 1 h, and K-OMS-2 was filtered.
The filtrate was reacted again for another 6 h under the same
reaction conditions. The results show that the 5-HMF conversion
and 2,5-DFF yield do not change after K-OMS-2 was removed
(Fig. S6, ESI†). Simultaneously, the IR spectra and XRD spectra
This journal is © The Royal Society of Chemistry 2012
Green Chem., 2012, 14, 2986–2989 | 2987

View Article Online
Table 2 One-pot synthesis of 2,5-DFF from fructose using SBA-SO3H and K-OMS-2a
Entry
Substrate
Acid catalyst
Oxidation catalyst
Conversion (%)
5-HMF yield (%)
2,5-DFF yield (%)
1
Fructose
Fructose
Fructose
Fructose
Glucose
Inulin
Fe3O4-SBA-SO3H
—
Fe3O4-SBA-SO3H
Fe3O4-SBA-SO3H
Fe3O4-SBA-SO3H
Fe3O4-SBA-SO3H
—
>99
>99
>99
>99
>99
>99
81
0
<5
0
0
18
0
0
<5
80
<5
29
2b
3c
4d
5d
6d,e
K-OMS-2
K-OMS-2
K-OMS-2
K-OMS-2
K-OMS-2
a 1 mmol substrate, 0.1 g (∼0.1 equiv) Fe3O4-SBA-SO3H, 0.1 g (∼0.75 equiv) K-OMS-2, 3 mL DMSO, 10 mL min−1 O2. Reaction at 110 °C. b O2
flow for 6 h. c One step reaction in O2 flow for 8 h. d Two-step reaction without catalyst separation. After 2 h reaction in air, K-OMS-2 was added in
O2 flow for 6 h. e 0.108 g water was added before beginning the reaction.
of fresh and regenerated catalyst also indicated that there was no
loss of catalyst activity after being reused five times (Fig. S7, S8,
ESI†). In addition, scale-up conditions showed a good result for
the heterogeneous catalyst system. After 2 g 5-HMF and 2 g
K-OMS-2 were heated at 110 °C for 6 h in the presence of mole-
cular oxygen or air, the 2,5-DFF yield was 70% and 20% with
100% selectivity, respectively (Table S2, ESI†).
Furthermore, we have examined the one-pot synthesis of
2,5-DFF from fructose by using Fe3O4-SBA-SO3H and
K-OMS-2. Fe3O4-SBA-SO3H is a magnetic solid acid catalyst,
and has been previously reported for cellulose hydrolysis by our
group.21 The advantage of this catalyst is that it is easy to separ-
ate from other solid catalysts due to its magnetic properties. As
shown in Table 2, using Fe3O4-SBA-SO3H can produce 5-HMF
from fructose with 81% yield at 110 °C in DMSO (entry 1).
Fig. 2 A plot of 5-HMF yield, 2,5-DFF yield for the transformation of
A combination of Fe3O4-SBA-SO3H and K-OMS-2 afforded
fructose as a function of reaction time. K-OMS-2 was added after 2 h
2,5-DFF directly from fructose. However, the coexistence of
under O2 flow (10 mL min−1). Reaction conditions, 1 mmol fructose,
0.1 g Fe3O4-SBA-SO3H, 0.1 g K-OMS-2, 3 mL DMSO, 110 °C.
Fe3O4-SBA-SO3H and K-OMS-2 in the initial stage of reaction
resulted in trace formation of 2,5-DFF (entry 3). The low yield
of 2,5-DFF from fructose in the one-step reaction may be due to
the formation of humins or the undesired oxidation of fructose
by K-OMS-2 in the presence of molecular oxygen. Further tests
showed that K-OMS-2 did indeed lead to oxidation of fructose
to unknown compounds (entry 2). To overcome this problem, we
carried out a two-step but still one-pot reaction. Gratifyingly, the
yield of 2,5-DFF was up to 80% by stepwise addition of cata-
lysts, i.e. Fe3O4-SBA-SO3H and K-OMS-2 without any inter-
mediate separation (entry 4). As shown in Fig. 2, the addition of
Fe3O4-SBA-SO3H resulted in the disappearance of fructose and
simultaneous formation of 5-HMF. Further addition of K-OMS-2
without catalyst separation under molecular oxygen flow
afforded 2,5-DFF from aerobic oxidation of 5-HMF. The two
heterogeneous catalysts could be recovered by centrifugation,
washed with ethanol and water, dried in oven, and then separated
by using a magnet for further reuse (Fig. 3). After being reused
five times, the activities of the two catalysts show no significant
decrease (Fig. S9, ESI†).
Fig. 3 The separation of Fe3O4-SBA-SO3H and K-OMS-2 simply by a
magnet.
Glucose and inulin were also used as substrates for 2,5-DFF
synthesis, the yields of 2,5-DFF from glucose and inulin were
∼5% and 29%, respectively (entries 5, 6). The reaction con-
ditions for glucose was the same as fructose, but for inulin, we
added a little water before beginning the reaction for conversion
of inulin to fructose. The yield of 2,5-DFF from glucose was so
low due to Fe3O4-SBA-SO3H having no ability to transform
glucose to fructose. The yield of 2,5-DFF from inulin was not
high because the existence of water poisoned the oxidation cata-
lyst K-OMS-2 and leaded to incomplete oxidation of 5-HMF in
the second step.
In conclusion, we demonstrated an inexpensive, efficient,
selective, easily regenerable and environmentally benign hetero-
geneous catalyst (K-OMS-2) for aerobic oxidation of 5-HMF to
2988 | Green Chem., 2012, 14, 2986–2989
This journal is © The Royal Society of Chemistry 2012

View Article Online
3 K. T. Hopkins, W. D. Wilson, B. C. Bendan, D. R. McCurdy, J. E. Hall,
R. R. Tidwell, A. Kumar, M. Bajic and D. W. Boykin, J. Med. Chem.,
1998, 41, 3872.
4 M. Del Poeta, W. A. Schell, C. C. Dykstra, S. Jones, R. R. Tidwell,
A. Czarny, M. Bajic, A. Kumar, D. Boykin and J. R. Perfect, Antimicrob.
Agents Chemother., 1998, 42, 2495.
5 D. T. Richter and T. D. Lash, Tetrahedron Lett., 1999, 40, 6735.
6 O. W. Howarth, G. G. Morgan, V. McKee and J. Nelson, J. Chem. Soc.,
Dalton Trans, 1999, 12, 2097.
7 L. Cottier, G. Descotes, J. Lewkowski and R. Skowronski, Pol. J. Chem.,
1994, 68, 693.
2,5-DFF with 99% yield and 100% selectivity. In addition,
a combination of Fe3O4-SBA-SO3H and K-OMS-2 catalysts
successfully catalyzed direct synthesis of 2,5-DFF from fructose
via acid-catalyzed dehydration and successive aerobic oxidation
in a one-pot reaction. Stepwise addition of catalysts gave
2,5-DFF in 80% yield. These two heterogeneous catalysts could
be easily separated by using a magnet and re-used for further
reaction (Fig. 3).
8 A. S. Amarasekara, D. Green and E. McMillan, Catal. Commun., 2008,
9, 286–288.
Acknowledgements
9 L. Cottier, G. Descotes, J. Lewkowski, R. Skowronski and E. Viollet,
J. Heterocycl Chem., 1995, 32, 927.
10 G. A. Halliday, R. J. Young and V. V. Grushin, Org. Lett., 2003, 5,
2003.
11 C. Carlini, P. Patrono, A. M. R. Galletti, G. Sbrana and V. Zima, Appl.
Catal. B, 2005, 289, 197.
12 O. Casanova, A. Corma and S. Iborra, Top. Catal., 2009, 52, 304.
13 J. P. Ma, Z. T. Du, J. Xu, Q. H. Chu and Y. Pang, ChemSusChem, 2011,
4, 51.
This work was financially supported by the National Basic
Research Program of China (973 program, No. 2012CB215305,
2012CB215306), the National Natural Science Foundation of
China (21172209) and Chinese Academy of Science (KJCX2-
EW-J02).
14 W. Partenheimer and V. V. Grushin, Adv. Synth. Catal., 2001, 343, 102.
15 H. J. Yoon, J. W. Choi, H. S. Jang, J. K. Cho, J. W. Byun, W. J. Chung,
S. M. Lee and Y. S. Lee, Synlett, 2011, 165.
16 A. Takagaki, M. Takahashi, S. Nishimura and K. Ebitani, ACS Catal.,
2011, 1, 1562.
17 X. Xiang, L. H. Yu, Y. Yang, B. Guo, D. M. Tong and C. W. Hu, Catal.
Lett., 2011, 141, 735.
18 V. D. Makwana, Y. C. Son, A. R. Howell and S. L. Suib, J. Catal., 2002,
210, 46.
Notes and references
1 A. Corma, S. Iborra and A. Velty, Chem. Rev., 2007, 107, 2411;
J. N. Chheda, G. W. Huber and J. A. Dumesic, Angew. Chem., 2007, 119,
7298, (Angew. Chem., Int. Ed., 2007, 46, 7164); B. Kamm, Angew.
Chem., 2007, 119, 5146, (Angew. Chem., Int. Ed., 2007, 46, 5146);
T. Stahlberg, W. Fu, J. M. Woodley and A. Riisager, ChemSusChem,
2011, 4, 451; Y. T. Cheng, J. Jae, J. Shi, W. Fan and G. W. Huber, Angew.
Chem., Int. Ed., 2012, 51, 1387.
2 Y. Roman-Leshkow, J. N. Chheda and J. A. Dumesic, Science, 2006,
312, 1933; H. B. Zhao, J. E. Holladay, H. Brown and Z. C. Zhang,
Science, 2007, 316, 1597; J. B. Binder and R. T. Raines, J. Am. Chem.
Soc., 2009, 131, 1979; G. Yong, Y. Zhang and J. Y. Ying, Angew. Chem.,
Int. Ed., 2008, 47, 9345; X. L. Tong and Y. D. Li, ChemSusChem, 2010,
3, 350; S. Q. Hu, Z. F. Zhang, Y. X. Zhou and B. X. Han, Green Chem.,
2009, 11, 1746.
19 G. Qiu, H. Huang, S. Dharmarathna, E. Benbow, L. Stafford and
S. L. Suib, Chem. Mater., 2011, 23, 3892.
20 Y. C. Son, V. D. Makwana, A. R. Howell and S. L. Suib, Angew. Chem.,
Int. Ed., 2001, 40, 4280.
21 D. M. Lai, L. Deng, J. J B. Liao, Q. X. Guo and Y. Fu, ChemSusChem,
2011, 4, 55; D. M. Lai, L. Deng, Q. X. Guo and Y. Fu, Energy Environ.
Sci., 2011, 4, 3552.
This journal is © The Royal Society of Chemistry 2012
Green Chem., 2012, 14, 2986–2989 | 2989