Selective oxidation of 5-hydroxymethylfurfural with H2O2 catalyzed by a molybdenum complex

Article abstract of DOI:10.1039/c5gc01991e

Organic solvent free 5-hydroxymethylfurfural (HMF) oxidation into 2,5-furandicarboxylic acid (FDCA) with hydrogen peroxide using quaternary ammonium octamolybdate and quaternary ammonium dectungstate was studied. Tetra-1-ethyl-3-methylimidazolium octamolybdate ([EMIM]₄Mo₈O₂₆), tetra-hexadecyltrimethyl ammonium octamolybdate ([CTAB]₄Mo₈O₂₆) and tetra-ethylpyridinium octamolybdate ([EPy]₄Mo₈O₂₆) displayed high activity for the selective oxidation of HMF to FDCA, and the selectivity of FDCA could reach 100% with a 99.5% conversion of HMF in the presence of [EMIM]₄Mo₈O₂₆. The byproduct formed in competition with FDCA was identified as the intermediate 5-hydroxymethyl-2-furan carboxylic acid (HMFCA) and 5-formyl-2-furan carboxylic acid (FFCA), and neither 2,5-diformyl furan (DFF) nor any other byproducts from the oxidative cleavage of the HMF furan ring were detected during the oxidation process, which indicated that the aldehyde group of HMF oxidizes first, followed by the oxidation of the hydroxymethyl group in this reaction system. Although the quaternary ammonium salts, such as [EMIM]Br, EPyBr and CTAB, prevented FDCA formation from the HMFCA advanced oxidation, they could eliminate the oxidative cleavage of the furan ring and improve the affinity of HMF and catalysts, to make the catalytic active centers readily accessible to HMF molecules. However, tetra-1-ethyl-3-methylimidazolium dectungstate ([EMIM]₄W₁₀O₃₂), tetra-hexadecyltrimethyl ammonium dectungstate ([CTAB]₄W₁₀O₃₂) and tetra-ethylpyridinium dectungstate ([EPy]₄W₁₀O₃₂) were unfavorable for FDCA formation. The great difference in performance of quaternary ammonium octamolybdate and quaternary ammonium dectungstate in HMF oxidation with H₂O₂ was attributed to their different structure.

Full text of DOI:10.1039/c5gc01991e

Green Chemistry
View Article Online
View Journal
PAPER
Selective oxidation of 5-hydroxymethylfurfural
with H O catalyzed by a molybdenum complex†
2
2
Cite this: DOI: 10.1039/c5gc01991e
a
a
a,b
a
Shuang Li, Kunmei Su,* Zhenhuan Li* and Bowen Cheng
Organic solvent free 5-hydroxymethylfurfural (HMF) oxidation into 2,5-furandicarboxylic acid (FDCA) with
hydrogen peroxide using quaternary ammonium octamolybdate and quaternary ammonium dectungstate
was studied. Tetra-1-ethyl-3-methylimidazolium octamolybdate ([EMIM]
trimethyl ammonium octamolybdate ([CTAB] Mo and tetra-ethylpyridinium octamolybdate
[EPy] Mo 26) displayed high activity for the selective oxidation of HMF to FDCA, and the selectivity of
FDCA could reach 100% with a 99.5% conversion of HMF in the presence of [EMIM] Mo 26. The by-
4 8
Mo O26), tetra-hexadecyl-
4
8 26
O )
(
4
8
O
4
8
O
product formed in competition with FDCA was identified as the intermediate 5-hydroxymethyl-2-furan
carboxylic acid (HMFCA) and 5-formyl-2-furan carboxylic acid (FFCA), and neither 2,5-diformyl furan (DFF)
nor any other byproducts from the oxidative cleavage of the HMF furan ring were detected during the oxi-
dation process, which indicated that the aldehyde group of HMF oxidizes first, followed by the oxidation
of the hydroxymethyl group in this reaction system. Although the quaternary ammonium salts, such as
[EMIM]Br, EPyBr and CTAB, prevented FDCA formation from the HMFCA advanced oxidation, they could
eliminate the oxidative cleavage of the furan ring and improve the affinity of HMF and catalysts, to make
the catalytic active centers readily accessible to HMF molecules. However, tetra-1-ethyl-3-methyl-
Received 24th August 2015,
Accepted 19th November 2015
imidazolium dectungstate ([EMIM] W10O32), tetra-hexadecyltrimethyl ammonium dectungstate
4
(
[CTAB]
mation. The great difference in performance of quaternary ammonium octamolybdate and quaternary
ammonium dectungstate in HMF oxidation with H was attributed to their different structure.
4 10 4 10
W O32) and tetra-ethylpyridinium dectungstate ([EPy] W O32) were unfavorable for FDCA for-
DOI: 10.1039/c5gc01991e
www.rsc.org/greenchem
2 2
O
9
,10
of HMF.
HMF can be oxidized with aldehyde and methyl
Introduction
1
1
alcohol to give 2,5-diformyl furan (DFF), 5-hydroxymethyl-2-
Due to the rapid development of the world economy and the furan carboxylic acid (HMFCA), 5-formyl-2-furan carboxylic
1
2–15,16
limitation of fossil resources, biomass has been regarded as acid (FFCA) and FDCA.
At the same time, the oxidative
an ideal resource to provide carbon sources for the chemical cleavage of the furan ring of HMF could take place. In this
1
–3
and petroleum industry.
2,5-furandicarboxylic acid (FDCA), case, succinic acid (SA) and 2-oxoglutaric acid (OGA) were
obtained from the oxidation of 5-hydroxymethylfurfural obtained as a major product, and maleic acid (MA) and
4
,5
17
(
HMF), has been identified as one of twelve potential build- fumaric acid (FA) existed with low yields. In addition,
6
ing blocks to produce important chemicals. For example, levulinic acid (LA) and formic acid were also produced through
FDCA can be used as the alternative monomer of terephthalic hydration of HMF in the presence of an acid catalyst
acid to produce polyamides, polyesters and polyurethanes.
The preferred route of FDCA production involves the
efficient catalytic transformation of biomass or biomass- (CrO4 ), dichromate (Cr O ) and permanganate (MnO ),
1
8
7
,8
(see Scheme 1).
Strong stoichiometric oxidation reagents, such as chromate
2
−
2−
−
2
7
4
1
9
derived carbohydrates to HMF, followed by catalytic oxidation were often employed to oxidize HMF.
However, these
oxidants are highly toxic, and some of them leave a lot of
undesirable metal waste after usage. The aerobic oxidation of
HMF to FDCA had been examined with a homogeneous Co/
Mn/Br catalyst, where DFF was the major oxidation
a
State Key Laboratory of Separation Membranes and Membrane Processes, School of
environment Science and Chemistry Engineering, Tianjin Polytechnic University,
Tianjin, China. E-mail: Sukunmei@tjpu.edu.cn
2
0,21
product.
could be carried out over Pt, Ru and Au-based catalysts.
For example a γ-Fe @HAP-Pd(0) magnetic catalyst showed
high activity in HMF oxidation with a 97.0% HMF conversion
The aerobic effective oxidation of HMF to FDCA
b
22–24
School of Materials Science and Engineering, Tianjin Polytechnic University,
3
00160 Tianjin, China. E-mail: Zhenhuanli1975@aliyun.com;
Fax: +86 022 83955055; Tel: +86 022 83955358
Electronic supplementary information (ESI) available. See DOI: 10.1039/
2 3
O
†
2
5
c5gc01991e
and 92.9% FDCA yield under optimal reaction conditions.
This journal is © The Royal Society of Chemistry 2015
Green Chem.

View Article Online
Paper
Green Chemistry
Scheme 1 Reaction pathway for aqueous HMF oxidation.
Using supported gold–copper nanoparticles as a catalyst a 99% Catalyst preparation and characterization
2
6
yield of FDCA was obtained. However, these catalytic systems
are absent of stability and high cost, and molecular oxygen or
According to the method introduced by Ming-lin Guo and his
34,35
coworkers,
4 10 32
the catalysts were prepared. [EMIM] W O ,
2
7,28
air is difficult to control.
Hydrogen peroxide (H O ) is another environmentally
[
CTAB] W O and [EPy] W O were prepared by mixing
4 10 32 4 10 32
2
2
2 4 2
boiling solutions of 16 g of Na WO ·2H O in 100 ml of
friendly and green oxidation reagent. Choudhary applied H O
2
2
distilled water and 33.5 ml of 3 M HCl. After boiling for a few
minutes, the clear yellow solution was precipitated by addition
of an aqueous solution of [EMIM]Br, CTAB and [EPy]Br. The
white precipitate was filtered, and washed with boiling water,
and dried at 60 °C to give a colorless powder. [EMIM] Mo O ,
to the oxidative cleavage of the furan ring of HMF with a 99%
29
conversion. Recently, increasing concerns have arisen from
3
0
the use of heteropoly acids, which are widely used for their
well-defined structure, strong Brönsted acidity, fast multi-
electron transfer, high proton motility, and resistance to hydro-
4
8 26
[
CTAB]
follows:
Na MoO ·2H O (12.0 g, 0.05 mol) and 12% dilute hydrogen
4
Mo
8
O
26 and [EPy]
mixture of 40 ml aqueous solution of
4 8
Mo O26 preparation is listed as
31
lytic and oxidative degradations in solutions. When heteropoly
acid is used as a catalyst, H is regarded as an ideal oxidant
with high tunability. For example, when coupling H O with a
a
2 2
O
2
4
2
2
2
chloride (19.0 ml, 0.076 mol) was added dropwise into a
solution of [EMIM]Br, CTAB and [EPy]Br (0.093 mol) in 100 ml
of distilled water under stirring at 70 °C. A white precipitate
was immediately formed. After continuously stirring for
W-based phase-transfer catalyst as the catalytic system, alcohols,
32
olefins and sulfide can be well oxidized. Most heteropoly acid
catalysts are insoluble in water, but they can dissolve in a mixed
33–35
system of H O .
The insoluble catalyst forms a soluble
active species due to the action of H , and when H is used
up the catalyst precipitates for easy recycling.
2
2
20 min, the resulting product was filtered, washed with water
O
2 2
2 2
O
and dried at 60 °C. The prepared catalysts were characterized
by single X-ray diffraction (SXRD) and Ultraviolet spectra (UV).
The octamolybdate anion is located near an inversion centre
and is structurally a β-isomer.
In this work, we used quaternary ammonium octamolyb-
date and quaternary ammonium dectungstate to directly
convert HMF to FDCA by H O . These W- and Mo-based cata-
2
2
lysts, when coupled with H O , are regarded as phase-transfer
2
2
Oxidation reactions
4 8
catalysts. It was demonstrated that [EMIM] Mo O26 exhibited a
A 50 ml three-necked flask was used as a reactor, which was
equipped with a reflux condenser. The reactor was loaded with
highly efficient performance for the selectivity of FDCA and
the conversion of HMF. Under the optimized conditions, the
selectivity of FDCA reached almost 100%, and a HMF
conversion of 99.5% was achieved. At the same time, the great
difference in performance of quaternary ammonium
octamolybdate and quaternary ammonium dectungstate in
HMF oxidation by H O was well studied.
9
mmol HMF, 18 mmol NaOH and 20 ml distilled water. The
mass ratio of HMF to catalyst was 10 : 1, and the reactor was
heated by an oil bath. When the mixture was heated to the
required temperature, 25 ml 6% H O was added into the
2
2
reactor dropwise during 2 h. After 2 h, the reaction was
finished and the mixture was characterized.
2
2
Analytical methods
Experimental
Materials
The mixture of samples was analyzed by high-performance
chromatography (HPLC, Waters1525) using
a
column
All of the reagents used were of analytical reagent grade and (Scienhome Kromasil C18, 250 mm × 4.6 mm) with UV detec-
were purchased from the Leon Reagent Company and Alfa tion (278 nm) and a 996 photodiode array detector. Aceto-
Aesar Reagent Company, for example HMF, FDCA, HMFA, nitrile and a 0.1 wt% acetic acid aqueous solution, volume
FFCA, DFF, Na
2 4 2 2 4 2
MoO ·2H O, Na WO ·2H O, ethyl bromide, ratio 10 : 90, were used as the mobile phase, and the flow rate
ml min−
. The products were characterized by
1
hexadecyl trimethyl ammonium bromide (CTAB) and glacial was
1
acetic acid et al.
the standard addition method, which is the special internal
Green Chem.
This journal is © The Royal Society of Chemistry 2015

View Article Online
Green Chemistry
Paper
standard method. The characterization process was listed as [CTAB]
4
Mo
8
O
26 and [EPy]
4
Mo
8
O
26 displayed high activity for
follows: the reaction mixture was diluted to 100 ml with pure the selective oxidation of HMF to FDCA (entry 1–3). The selecti-
water, and 0.3 g HMF was dissolved into 100 ml pure water. vity of FDCA reached 92.7% with 96.2% conversion of HMF in
Then 4 ml diluted reaction solution was diluted to 5 ml with the presence of [EMIM]
pure water and diluted HMF in two colorimetric tubes. The competition with FDCA was identified as the intermediate
2 2
mass concentrations of the products were calculated from HMFCA by HPLC. In the absence of both catalyst and H O ,
4 8
Mo O26, and the byproduct formed in
HPLC-peak integrations, and the selectivity of HMFCA and FDCA was not detected and 12.6% HMF was consumed into
FFCA was calculated based on the carbon balance. The related some other byproducts, which came from the oxidative
formula is as follows:
cleavage of the furan ring of HMF (entry 4). When HMF was
oxidized by H without catalyst, the selectivity of FDCA and
HMFCA was 49.7% and 46.3%, and the conversion of HMF
reached 98.0%. Importantly, some other byproducts from the
2 2
O
W
m1 ¼
A′
=
ꢀ 1
A
m
1
: mass of HMF after reaction, A’: HPLC areas of HMF when oxidative cleavage of the furan ring were also detected, while
.03 g HMF is added, A: HPLC areas of HMF after reaction, W: the increase of FDCA selectivity was not obvious by prolonging
the mass of HMF added, 0.03 g.
the reaction time to 12 h (entry 5). Na MoO significantly
0
2
4
ꢀ
ꢁ
promoted the advanced oxidation from HMFCA to FDCA,
which resulted in the FDCA selectivity increasing to 85.2% and
the furan ring cleavage byproduct selectivity declining to 2.0%
m1
HMF conversion ðmass% Þ ¼ 1 ꢀ m2 ꢁ 100%
m
2
: mass of HMF before reaction, S: HPLC area of reaction pro- (entry 6). Although the quaternary ammonium salts such as
ducts.
[EMIM]Br, EPyBr and CTAB prevented FDCA formation from
the HMFCA advanced oxidation, they could effectively
eliminate the oxidative cleavage of the furan ring and act as a
phase transfer catalyst to promote well the conversion of HMF
into HMFCA (entry 7, 8 and 9). The results in Table 1 clearly
demonstrated that the simultaneous presence of both
quaternary ammonium and molybdate is essential for the
selective conversion of HMF to FDCA. Herein, inorganic
anions acted as the active center, but organic cations improved
S1
Selectivity of FDCA ¼
S1 þ S2 þ ꢂ ꢂ ꢂ
Results and discussion
Effects of different catalysts on HMF oxidation by H O
2 2
Previous studies have shown that the presence of some the affinity of HMF and catalysts, making the catalytically
amount of base in the reaction mixture can restrain by-product active centers readily accessible to HMF molecules to promote
1
1
formation from the side reactions of HMF. In order to avoid HMF conversion into HMFCA and prevent the furan ring from
some side reaction occurrence, HMF oxidation by H O was oxidative cleavage.
2
2
carried out in the presence of some NaOH, and the efficiencies
2 4 2 4
Similar to the Na MoO performance, Na WO could also
of various acid catalysts for the oxidation of HMF to FDCA in catalyze the advanced oxidation of HMFCA to FDCA, and FDCA
the presence of H O were listed in Table 1. [EMIM] Mo O , selectivity reached 79.0% with a 98.0% HMF conversion (entry
2
2
4
8 26
10). However, the simultaneous presence of quaternary
ammonium and dectungstate was unfavorable for FDCA for-
mation due to the high steric hindrance, and the molar ratio
Table 1 HMF oxidation by H
2
O
2
using different catalysts
2 2
decrease of metal to HMF and H O was another minor factor
Product selectivity (mol%)
Conversion
FDCA HMFCA Cleavage (HMF %)
resulting in the HMF conversion and FDCA selectivity decline
(entry 11, 12 and 13). By comparison of Na MoO with
Entry Catalysts
2
4
2 4 2 4
Na WO , we see that Na MoO displayed higher activity in
1
2
3
4
[EMIM]
[CTAB]
[EPy] Mo
NO CATALYST and
4
Mo
8
O
26
92.7
90.4
77.0
—
7.3
9.6
23.0
—
—
—
—
100
96.2
94.5
85.1
12.6
HMFCA oxidation to FDCA and lower activity in HMF conver-
sion, while Na WO was beneficial for HMF conversion into
4
Mo
8
O
26
4
O
8 26
2
4
HMFCA and unfavorable for FDCA formation from HMFCA. In
2 2
H O
addition, inorganic anions are rapidly oxidized to a new form
5
NO CATALYST
49.7
60.0
85.2
23.2
34.1
32.7
79.0
50.2
47.0
68.6
46.3
34.2
12.8
76.8
65.9
67.4
19.2
49.8
53.0
31.4
4.0
5.8
2.0
—
—
—
1.8
—
—
98.0
99.0
75.4
90.6
85.1
97.6
97.8
81.1
62.1
84.2
a
36
NO CATALYST
Na MoO
during HMF oxidation by H O
2
2
(Scheme 2).
6
7
8
9
1
1
1
1
2
4
[EMIM]Br
EPyBr
CTAB
Difference in performance of the Mo O anion and W O
8 26 10 32
anion in HMF oxidation with H
Herein UV spectra were used to study the great difference in
performance of the Mo 26 anion and W10 32 anion in HMF
oxidation with H O ; namely, the presence of the quaternary
2 2
O
0
1
2
3
Na
[EMIM]
[CTAB]
[EPy]
2
WO
4
4
W
W
10
10
32
O
32
8
O
O
4
O
32
4
W
10
O
—
2
2
8
ammonium and Mo O26 anion is essential for the selective
Reaction conditions: 9 mmol HMF, 18 mmol NaOH, the mass ratio of
conversion of HMF to FDCA, however, the simultaneous
presence of the quaternary ammonium and W O anion is
HMF to catalyst = 1/10, 20 ml deionized water, 25 ml 6% H
O
2 2
, 70 °C
a
and 2 h. Indicated reaction time was 12 h.
1
0 32
This journal is © The Royal Society of Chemistry 2015
Green Chem.

View Article Online
Paper
Green Chemistry
2 2
Scheme 2 HMF oxidation by H O in the presence of the molybdate anion and tungstate anion.
appeared around λ = 259 nm despite no UV spectrum peak of
WvO being detected in the near ultraviolet region (λ =
200–400 nm), which implied that there existed a strong π–d
interaction between the imidazole or pyridine and W center.
The bonds of Mo (or W) and O in octamolybdate (or dectung-
2 2
state) were single and double bonds, without any H O
3
4,35,37
present.
When H O was added, only one new UV spec-
2 2
trum peak appeared around λ = 291 nm and λ = 283 nm for
quaternary ammonium octamolybdate and quaternary
ammonium dectungstate, respectively, which showed that the
epoxy groups were formed and that the MovO (or WvO)
3
6,38
species disappeared
(see Scheme 3). The epoxy groups in
quaternary ammonium octamolybdate and quaternary
ammonium dectungstate played a crucial role in HMFCA
advanced oxidation to FDCA. The strong π–d interaction
between the imidazole (or pyridine) and W center resulted in a
UV spectrum peak tailing of epoxy groups, which was respon-
sible for the higher activities of [EMIM]
4 10
W O32 and
[
EPy] W O than that of [CTAB] W O in HMF conversion
4
10 32
4
10 32
and HMFCA oxidation to FDCA. The great difference in per-
formance of quaternary ammonium octamolybdate and qua-
ternary ammonium dectungstate in HMF oxidation with H O
2
2
was attributed to their different structure.
Quaternary ammonium dectungstate had an equal number
of single epoxy groups and double epoxy groups in the pres-
2 2
ence of H O , but the double epoxy groups were simul-
taneously attached by quaternary ammonium (see Scheme 3).
Most importantly, the double epoxy groups acted as the main
active sites for HMFCA oxidation to FDCA, but this process
was inhibited by the high steric hindrance of quaternary
ammonium, which prevented the HMFCA from approaching
the active double epoxy group sites. However, quaternary
ammonium octamolybdate contained a quarter of the single
epoxy groups and three quarters of the double epoxy groups in
Fig. 1 UV spectra of quaternary ammonium octamolybdate and the presence of H
O , and no quaternary ammonium was
2 2
2 2
quaternary ammonium dectungstate within and without H O .
bundled to a certain double epoxy group site, which made the
Mo based catalyst display higher activity in HMF oxidation.
Effects of different temperatures on HMF oxidation
unfavorable for FDCA formation. As shown in Fig. 1, the intensive
UV spectrum peak of MovO was located at λ = 208 nm, but a The effects of reaction temperature on HMF oxidation were
weak UV spectrum peak of [EMIM] W O and [EPy] W O
10 32
studied under similar reaction conditions. Fig. 2 showed the
4
10 32
4
Green Chem.
This journal is © The Royal Society of Chemistry 2015

View Article Online
Green Chemistry
Paper
2 2
Scheme 3 HMF oxidation with H O in the presence of ammonium octamolybdate and ammonium dectungstate.
Fig. 2 HMF oxidation under different temperatures (reaction con-
ditions: 9 mmol HMF, 18 mmol NaOH, the mass of [EMIM] Mo 26 is
.113 g, the molar ratio of HMF to [EMIM] Mo 26 is 1/129, 20 ml
Fig. 3 Effects of reaction time on HMF oxidation (reaction conditions:
9 mmol HMF, 18 mmol NaOH, the mass of [EMIM] Mo 26 is 0.113 g,
the molar ratio of HMF to [EMIM] Mo 26 is 1/129, 20 ml deionized
4
8
O
4
8
O
0
4
8
O
4
8
O
deionized water was used as the reaction solvent, 0.16 mol H
oxidant and the reaction time was 2 h).
2
O
2
as
water is used as the reaction solvent, 0.16 mol H
100 °C).
2
O
2
as oxidant, and at
This journal is © The Royal Society of Chemistry 2015
Green Chem.

View Article Online
Paper
Green Chemistry
Scheme 4 The pathway of HMF oxidation to FDCA.
effect of temperature on the FDCA selectivity and HMF an equal number of single epoxy groups and double epoxy
conversion in the presence of [EMIM] Mo O . Experiments groups in the presence of H O , and the double epoxy groups
4
8
26
2 2
were conducted at 6 different temperatures between 60 and were attached by a quaternary ammonium. The double epoxy
10 °C to study the effects of temperature on HMF conversion groups acted as the main active sites for the HMFCA advanced
1
and FDCA formation. An increase in both the HMF conversion oxidation to FDCA, but this process was inhibited by the high
and FDCA selectivity was observed when the reaction tempera- steric hindrance of quaternary ammonium. However, quatern-
ture was raised from 60 to 110 °C. For example, HMF ary ammonium octamolybdate was constituted of a quarter of
conversion and FDCA selectivity were 67.4% and 80.3% after single epoxy groups and three quarters of double epoxy group
2
9
h at 60 °C, respectively, whereas at 100 °C the figures were in the presence of H O , and no quaternary ammonium was
2 2
9.5% and 100%. However, there was practically no difference bundled on a certain double epoxy group site, which made the
in FDCA selectivity and HMF conversion at reaction tempera- Mo based catalyst display high activity for HMF oxidation.
tures between 100 and 110 °C.
Under the optimized conditions of 100 °C and 2 h, almost
9.5% HMF conversion and 100% selectivity of FDCA can be
achieved. Although the exact pathway of HMF oxidation to
9
Effects of reaction time on HMF oxidation
The effectiveness of [EMIM] Mo O was evaluated by conduct- FDCA is a matter of debate, herein the aldehyde group of HMF
4
8 26
ing the HMF oxidation reactions for a longer time under oxidizes first, followed by oxidation of the hydroxymethyl
atmospheric pressure, and analyzing the products by HPLC. group by H in the presence of quaternary ammonium
O
2 2
We analyzed the specimens sampled from the reaction octamolybdate or quaternary ammonium dectungstate, which
mixture at specified time intervals. The variation of product contrasted with some earlier observations that the hydroxy-
selectivity and HMF conversion with time reveals the evolution methyl group of HMF was oxidized first into DFF as an
of the products during HMF oxidation. As shown in Fig. 3, oxidation product, followed by oxidation of the aldehyde
HMF converted quickly, reaching a conversion of 95.6% at group.
2
1
0 min, and the selectivity of HMFCA and FFCA reached
4.9% and 14.6%, respectively. FDCA was detected as a major
product with HMFCA and FFCA being the main intermediates,
while no DFF was detected. As the reaction progressed, the
selectivity of FDCA increased to 97.8%, but that of HMFCA and
FFCA decreased to 0.98% and 1.4% after 80 min.
When prolonging the reaction time to 100 min, the intermediate
HMFCA disappeared, and FFCA selectivity further declined to
Acknowledgements
The authors are grateful for the financial support of the
Tianjin and National Natural Science Foundation of China
(
No. 12JCZDJC29800 and 21376177).
0.7%. FDCA selectivity achieved 100% and HMF conversion
came up to 99.5% at 120 min. The absence of formation of DFF
was attributed to the fact that the aldehyde group of HMF was References
oxidized first, followed by the oxidation of the hydroxymethyl
1
S. E. Davis, L. R. Houk, E. C. Tamargo, A. K. Datye and
R. J. Davis, Catal. Today, 2011, 160, 55.
2 S. Siankevich, G. Savoglidis and Z. Fei, J. Catal., 2014, 315,
7.
S. E. Davis, A. D. Benavidez and R. W. Gosselink, J. Mol.
Catal. A: Chem., 2014, 388, 123.
B. Liu, Z. Zhang and K. Lv, Appl. Catal., A, 2014, 472, 64.
M. Toshinari, K. Hirokazu, K. Takenobu and M. Hirohide,
Method for producing furan-2,5-dicarboxylic acid, US
Patent, 20070232815, 2007-03-07.
group. Similar to the above observation, when HMF was oxidized
with a basic hydrotalcite-supported gold catalyst in an aqueous
39
medium and Au/TiO and Au/CeO catalysts in methanol in
2
2
6
the presence of a homogeneous base additive, the oxidation of
the aldehyde group took place in the first step, followed by the
3
40,41
hydroxymethyl group (Scheme 4).
4
5
Conclusions
A simple and effective method to synthesize FDCA from HMF
was developed, and the difference in performance of the
6 B. Saha, D. Gupta and M. M. Abu-Omar, J. Catal., 2013,
299, 316.
Mo
8
O
26 anion and W10
O
32 anion in HMF oxidation with H
2
O
2
7 G. Yi, S. P. Teong and X. Li, ChemSusChem, 2014, 7(8),
was studied. Quaternary ammonium dectungstate consisted of
2131.
Green Chem.
This journal is © The Royal Society of Chemistry 2015

View Article Online
Green Chemistry
Paper
8
9
C. Moreaua, M. N. Belgacemb and A. Gandini, Top. Catal., 25 Z. H. Zhang, J. D. Zhen, B. Liu, L. L. Lv and K. J. Deng,
004, 27, 11. Green Chem., 2015, 17, 1308.
A. A. Rosatella, S. P. Simeonov, R. F. M. Frade and 26 T. Pasini, M. Piccinini, M. Blosi, R. Bonelli, S. Albonetti,
2
C. A. M. Afonso, Green Chem., 2011, 13, 754.
0 S. Dutta, S. De, B. Saha and M. M. Abu Omar, J. Catal.,
012, 288, 8.
N. Dimitratos, J. A. Lopez-Sanchez, M. Sankar, Q. He,
C. J. Kiely, G. J. Hutchings and F. Cavani, Green Chem.,
2011, 13(8), 2091.
1
2
1
1
1 F. H. Xu and Z. H. Zhang, ChemCatChem, 2015, 7, 1470.
2 N. Mei, B. Liu, J. D. Zheng, K. L. Lv, D. G. Tang and
Z. H. Zhang, Catal. Sci. Technol., 2015, 5, 3194.
27 R. Noyori, M. Aoki and K. Sato, Chem. Commun., 2003,
1977.
28 J. Q. Lu, M. F. Luo, H. Lei and C. Li, Appl. Catal., A, 2002,
237(1), 11.
1
1
1
1
1
1
1
2
2
2
3 S. G. Wang, Z. H. Zhang and B. Liu, ACS Sustainable Chem.
Eng., 2015, 3, 406.
4 B. Liu, Y. S. Ren and Z. H. Zhang, Green Chem., 2015, 17,
29 H. Choudhary, S. Nishimura and K. Ebitani, Appl. Catal., A,
2013, 458, 55.
30 J. Lan, J. Lin and Z. Chen, ACS Catal., 2015, 5(4), 2035.
1
610.
5 Z. H. Zhang, B. Liu, K. L. Lv, J. Sun and K. J. Deng, Green 31 Y. Liu, L. Zhu, J. Tang, M. Liu, R. Cheng and C. Hu, Chem-
Chem., 2014, 16, 2762. SusChem, 2014, 7(12), 3541.
6 B. Siyo, M. Schneider and J. Radnik, Appl. Catal., A, 2014, 32 R. Noyori, M. Aoki and K. Sato, Chem. Commun., 2003,
78, 107. 1977.
7 H. Choudhary, S. Nishimura and K. Ebitani, Appl. Catal., A, 33 X. Zuwei, Z. Ning and S. Yu, Science, 2001, 292(5519), 1139.
013, 458, 55. 34 M. L. Guo, Green Chem., 2004, 6, 271.
8 P. A. Son, S. Nishimura and K. Ebitani, React. Kinet., Mech. 35 M. L. Guo and H. Z. Li, Green Chem., 2007, 9, 421.
4
2
Catal., 2012, 106, 185.
9 T. S. Hansen, I. Sádaba and E. García-Suárez, J. Appl. Catal.
A, 2013, 456, 44.
36 R. Noyori, M. Aoki and K. Sato, Chem. Commun., 2003,
1977.
37 J. Fuchs, H. Hartl, W. Schiller and U. Gerlach, Acta Crystal-
logr., Sect. B: Struct. Crystallogr. Cryst. Chem., 1976, 32, 740.
38 A. Bayat, M. Shakourian-Fard and M. M. Hashemi, Catal.
Commun., 2014, 52, 16.
39 N. K. Gupta, S. Nishimura, A. Takagaki and K. Ebitani,
Green Chem., 2011, 13, 824.
40 Y. Y. Gorbanev, S. K. Klitgaard, J. M. Woodley,
C. H. Christensen and A. Riisager, ChemSusChem, 2009, 2, 672.
0 B. Saha, S. Dutta and M. M. Abu-Omar, Catal. Sci. Technol.,
2
012, 2, 79.
1 W. Partenheimer and V. V. Grushin, Adv. Synth. Catal.,
001, 343, 102.
2 Y. Y. Gorbanev, S. Kegnæs and A. Riisager, Catal. Lett.,
011, 141(12), 1752.
3 N. KumaráGupta, Green Chem., 2011, 13(4), 824.
2
2
2
2
4 H. A. Rass, N. Essayem and M. Besson, Green Chem., 2013, 41 O. Casanova, S. Iborra and A. Corma, ChemSusChem, 2009,
5(8), 2240. 2, 1138.
1
This journal is © The Royal Society of Chemistry 2015
Green Chem.