Heterogeneous catalysts for the cyclization of dicarboxylic acids to cyclic anhydrides as monomers for bioplastic production

Article abstract of DOI:10.1039/c7gc00538e

Cyclic anhydrides, key intermediates of carbon-neutral and biodegradable polyesters, are currently produced from biomass-derived dicarboxylic acids by a high-cost multistep process. We present a new high-yielding process for the direct intramolecular dehydration of dicarboxylic acids using a reusable heterogeneous Lewis acid catalyst, Nb₂O₅·nH₂O. Various dicarboxylic acids, which can be produced by a biorefinery process, are transformed into the corresponding cyclic anhydrides as monomers for polyester production. This method is suitable for the production of renewable polyesters in a biorefinery process.

Full text of DOI:10.1039/c7gc00538e

View Article Online
View Journal
Green
Chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: K. Shimizu, Md. A.
Ali, S. K. Moromi, S. S. M. A. Hakim, T. Toyao, A. S. Touchy, K. Kon and Md. N. Rashed, Green Chem., 2017,
DOI: 10.1039/C7GC00538E.
This is an Accepted Manuscript, which has been through the
Volume 18 Number
7 7 April 2016 Pages 1821–2242
Royal Society of Chemistry peer review process and has been
accepted for publication.
Green
Chemistry
Accepted Manuscripts are published online shortly after
Cutting-edge research for a greener sustainable future
www.rsc.org/greenchem
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1463-9262
CRITICAL REVIEW
G. Chatel et al.
Heterogeneous catalytic oxidation for lignin valorization into valuable
chemicals: what results? What limitations? What trends?
rsc.li/green-chem

Please do not adjust margins
Green Chemistry
Page 1 of 7
View Article Online
DOI: 10.1039/C7GC00538E
Journal Name
ARTICLE
Heterogeneous catalysts for cyclization of dicarboxylic
acids to cyclic anhydrides as monomers for bioplastics
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Md. N. Rashed,a S. M. A. H. Siddiki,a Md. A. Ali,a Sondomoyee K. Moromi,a Abeda S. Touchy,a
Kenichi Kon,a Takashi Toyao,a,b Ken-ichi Shimizu*a,b
www.rsc.org/
Cyclic anhydrides, as key intermediates of carbon-neutral and biodegradable polyesters, are
produced from biomass-derived dicarboxylic acids by a high-cost multistep process. We present a
new high-yielding process for direct intramolecular dehydration of dicarboxylic acids using a
reusable heterogeneous Lewis acid catalyst, Nb2O5∙nH2O. Various dicarboxylic acids, which can be
produced from biorefinery process, are transformed to the corresponding cyclic anhydrides as
monomers for polyesters. This method can be suitable to the production of renewable polyesters
in
a
biorefinery
process.
because they can be produced from renewable feedstocks
and disposed of with minimal environmental impact.
Introduction
There is a growing demand to develop a new methodology
for substitution of petroleum refinery to biorefinery, that is,
production of chemicals with carbon-neutral and
biorenewable resources.1-8 To establish the biorefinery
process, it is important to develop a new catalytic process for
the selective transformation of biomass–derived feedstocks
to platform chemicals. Dicarboxylic acids are regarded as one
of the key platform chemicals, because they are available in
a minimum number of steps from biorefinery carbohydrate
streams.2-9 For example, succinic acid is one of the top
bioplatform chemicals as it is available from the
bioconversion of glucose.2,8,9 Recently, considerable progress
has been achieved towards commercialization of
fermentative production of succinic acid.9 Among the
derivatives of dicarboxylic acids, recent attentions have
focused on cyclic anhydrides as monomers for the
production of biorenewable aliphatic polyesters.10 Aliphatic
polyesters, which can be produced by ring-opening
copolymerization of epoxides with cyclic anhydrides,10-13 are
important alternatives to petroleum-based polyesters,
The aromatic carboxylic dianhydrides are synthesized
also by thermal dehydration of tetracarboxylic acids at
extremely high reaction temperatures (220-270 °C),14 which
limits industrial application. Generally, cyclic anhydrides are
prepared by dehydration of dicarboxylic acids with excess
amount of dehydrating agents such as an acid chloride,
benzenesulfonyl chloride, ketene, acetic anhydride and
phosphorous pentoxide.15,16 The method suffers from the
use of toxic reagents, limited scope, low atom-efficiency and
difficulty in the complete removal of the dehydrating agent
from the products. Recently, Thomas and co-workers16 have
reported direct high-yielding synthesis of cyclic anhydrides
from dicarboxylic acids by small amount of MgCl2 as Lewis
acid catalyst at 40 °C without azeotropic reflux conditions.
However, the method16 has low atom-efficiency requiring
significant excess amount (50 equiv.) of di-tert-butyl
dicarbonate as a dehydrating agent, which suffers from co-
production of large amount of wastes. Catalytic
intramolecular condensation of dicarboxylic acids is the most
atom-efficient route to cyclic anhydrides since it generates
water as the only byproduct. However, to our knowledge,
only one method by Ishihara et al.17,18 succeeded in the
catalytic self-condensation of dicarboxylic acids under mild
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 2 of 7
View Article Online
DOI: 10.1039/C7GC00538E
ARTICLE
Journal Name
conditions. They have used a homogeneous catalyst, an coefficient combined with the area intensities of the bands
arylboronic acid bearing two bulky (N,N-dialkylamino)methyl at 1445 cm-1, the numbers of Lewis acid sites on Nb2O5∙nH2O,
groups at the 2,6-positions, which has drawbacks of limited Nb2O5 and Na+-Nb2O5∙nH2O were calculated to be 98 μmol g-
substrate scope and difficulties in the catalyst synthesis.
1, 58 μmol g-1 and 53 μmol g-1, respectively. A band at 1540
cm-1 due to pyridinium ion (PyH+) is also observed for
Nb2O5∙nH2O, while the band is nearly absent in the spectrum
of Na+-Nb2O5∙nH2O. Thus, Nb2O5∙nH2O has both Lewis and
Brønsted acid sites, whereas Na+-Nb2O5∙nH2O is mostly Lewis
acidic.26
Current process
R2
O
O
O
O
H
O
HO
R2
R1
R1
O
O
O
O
O
RO
OH
RO
H
O
1445cm-1
RO
O
OR
(Py on Nb5+
)
0.1
Proposed process
1540 cm-1
(PyH+)
R2
O
O
O
O
OH reusable solid cat.
H O
2
+
HO
Nb2O5 nH2O
azeotropic reflux
R2
R1
R1
O
Scheme 1 Current and Proposed Process for Production of
Nb2O5
Cyclic Anhydride from Dicarboxylic Acids.
Na+-Nb2O5 nH2O
1600
1500
1400
Wavenumber / cm-1
Potentially, the reaction is catalyzed by Lewis acid, but co-
presence of water as byproduct can suppress Lewis acidity by
hindering coordination. Inspired by recent reports that some
homogeneous19 and heterogeneous20-22 Lewis acid catalysts
act as water-tolerant Lewis acid catalysts, we have recently
reported that Nb2O5 acts as a water- and base-tolerant Lewis
acid catalyst for various dehydrative condensation reactions
such as direct imidation of dicarboxylic acids with amines
Fig. 1 IR spectra of pyridine on niobium oxides at 200 oC.
We carried out catalyst screening adopting the
intramolecular condensation of succinic acid (1a) to succinic
anhydride (2a) as a model reaction. Table 1 lists the yields of
and direct amidation of carboxylic acids with amines.23,24 We 2a for the condensation of 1a (1 mmol) in 2 mL o-xylene
report herein that hydrates of amorphous Nb2O5, generally
named niobic acid or Nb2O5∙nH2O, is an effective and
reusable catalyst for the intramolecular dehydrative
condensation of di- and tetracarboxylic acids. Catalytic
results show wide applicability of the synthetic method, and
control experiments show that Lewis acid site of the catalyst
is catalytically important for the reaction. It is important to
note that a commercial Nb2O5∙nH2O (HY-3400), as received
from a supplier (CBMM), can be utilized for the reactions
without any pretreatments.
under azeotropic reflux conditions for 5 h in the presence of
50 mg of the catalysts. Note that the thermal reaction in the
absence of catalyst showed no conversion of 1a (entry 1).
We tested the reaction using 22 types of catalysts including
heterogeneous catalysts (entries 2-15) and homogeneous
acid catalysts (entries 16-21). Among simple metal oxides
tested (entries 4-13), Nb2O5 showed the highest yield (82%)
of 2a, and a Lewis acidic solid, TiO2,25,27 was secondary most
effective (52% yield). As received Nb2O5∙nH2O (uncalcined
precursor of Nb2O5) showed higher yield (99%) than Nb2O5.
Na+-Nb2O5∙nH2O showed
a relatively high yield (89%).
Results and discussion
Combined with the IR results that Na+-Nb2O5∙nH2O is mostly
Lewis acidic and the number of Lewis acid sites of
Nb2O5∙nH2O is larger than those of Na+-Nb2O5∙nH2O and
Nb2O5, the catalytic results suggest that Lewis acid sites are
catalytically relevant sites for the reaction by the niobium
oxides. Commercially available Brønsted acidic resins,
Nafion-SiO2 composite (entry 16) and Amberlyst-15 (entry
17) showed moderate yields of 44 and 68%, respectively.
Conventional homogeneous Brønsted acids (entries 18, 19),
IR spectra (ring-stretching region) of pyridine adsorbed on
niobium oxides are shown in Figure 1. As reported in the
previous IR studies on the similar system,20,23-26 strong bands
at 1445 cm-1 due to the coordinatively bound pyridine on a
Lewis acid site are observed for Nb2O5∙nH2O, Nb2O5 and Na+-
exchanged Nb2O5∙nH2O (Na+-Nb2O5∙nH2O).26 Previously, we
determined the averaged integrated molar extinction
coefficient (1.73 cm μmol-1) of the adsorbed pyridine on
Lewis acid sites on various metal oxides.25 Using this
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 3 of 7
View Article Online
DOI: 10.1039/C7GC00538E
Journal Name
ARTICLE
H2SO4 and p-toluenesulfonic acid (PTSA), and homogeneous presence of molecular sieves 4Å (MS4Å) at the upper part of
Lewis acids (entries 20-23), including Sc(OTf)3, In(OTf)3, the reactor increased the yields of 2a, indicating the
Hf(OTf)4 and MgCl2, gave 0% yields of the anhydride. importance of azeotropic removal of water as reported by
Heterogeneous Brønsted acids, Nafion-SiO2 and Amberlyst- Ishihara et al.17,18 Summarizing the optimization study, use of
15 (entries 14, 15), showed moderate yields (44, 68%), but Nb2O5∙nH2O under azeotropic reflux in o-xylene is the best
the yields were lower than that of Nb2O5∙nH2O (99%). conditions.
Summarizing the results in Table 1, it is concluded that
Nb2O5∙nH2O is the most effective catalyst for the cyclization
of succinic acid to succinic anhydride.
Table 2 Cyclization of 1a to 2a by Nb2O5∙nH2O (50 mg) for 5 h.
Table 1 Catalyst screening for cyclization of succinic acid (1a).
Entry Solvent
MS4Å a
0.2 g
0 g
2a yield (%)b
1
2
3
4
5
6
o-xylene
o-xylene
n-octane
n-octane
toluene
toluene
99
90
58
40
39
29
0.2 g
0 g
0.2 g
0 g
a
SBET
2a yield
Entry
Catalyst
(m2g-1)
(%)b
a Weight of MS4Å inside the reflux condenser. b Determined
by 1H NMR.
1
2
blank
Nb2O5∙nH2O
Na+-Nb2O5∙nH2O
Nb2O5
-
118
42
54
47
25
12
73
124
22
81
12
3
0
99
89
82
52
9
Nb2O5 nH2O
100
3
4
5
TiO2
80
6
SnO2
TiO2
60
40
20
7
ZnO
7
8
ZrO2
5
9
Al2O3
4
10
11
12
13
14
15
16
17
18
19
20
21
CaO
4
CeO2
4
Al2O3
Sc(OTf)3
Ta2O5
2
0
1
2
t (h)
3
4
5
MoO3
1
Nafion-SiO2
Amberlyst-15
H2SO4
-
44
68
0
-
-
Fig. 2 Time-yield profiles for cyclization of 1a by various
catalysts under azeotropic reflux in o-xylene.
PTSA
-
0
Sc(OTf)3
In(OTf)3
Hf(OTf)4
MgCl2
-
0
-
0
with MS4Å
100
without MS4Å
80
-
0
-
0
aSpecific surface area of the catalyst determined by N2
adsorption at -196 oC. bYields were determined by the
integration of 1H NMR.
60
with MS4Å
40
20
Table 2 shows the effect of reaction conditions on the
yield of 2a for the standard reaction of 1a under reflux
conditions in different solvent. Among the three solvents
tested, the yield increased with increase in the boiling point
of the solvent as follows: o-xylene > n-octane > toluene. The
without MS4Å
0
Nb2O5nH2O
TiO2
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 4 of 7
View Article Online
DOI: 10.1039/C7GC00538E
ARTICLE
Journal Name
Fig. 3 Yields of 2a for cyclization of 1a (5 h) in the absence b In 10 mL mesitylene.
and presence of 0.2 g of MS4Å inside the reflux condenser.
Figure 2 compares time-yield profiles for the standard
reaction of 1a by three heterogeneous Lewis acid catalysts
and a homogeneous Lewis acid catalyst. The reaction rate
estimated from the initial slope of the curve changed in the
following order: Nb2O5∙nH2O > TiO2 > Al2O3 > Sc(OTf)3. In our
previous studies,23,24 we have shown that Lewis acid
activation of carbonyl group of carboxylic acids by metal
oxides increases in the order of Nb2O5 > TiO2 > Al2O3. Hence,
the high catalytic activity of Nb2O5∙nH2O can be due to the
activation of carbonyl group by the surface Nb5+ Lewis acid
sites of Nb2O5∙nH2O. A possible mechanism for the present
catalytic system involves the initial activation of carbonyl
groups of dicarboxylic acid by the Nb5+ Lewis acid site. The
electrophilic carbonyl group undergoes intermolecular
nucleophilic attack by the OH group of 1a.
100
80
60
40
20
0
1
2
3
4
Cycle number
Fig. 4 Reuse of Nb2O5∙nH2O (50 mg) for cyclization of 1a (1
mmol) to 2a under azeotropic reflux in 2 mL o-xylene (30 h).
Table 3 Gram scale cyclization of various dicarboxylic acids.a
Another advantage of Nb2O5∙nH2O is water-tolerance.20
Figure 3 compares the yields of 2a for cyclization of 1a by
Nb2O5∙nH2O and TiO2 in the absence and presence of 0.2 g of
MS4Å inside reflux condenser used for azeotropic water
removal. For both catalysts, the presence of MS4Å increased
the yields, but the increase in the yield was larger for TiO2.
This suggests that Nb2O5∙nH2O is more water-tolerant than
TiO2, which can be an additional reason of the high catalytic
activity of Nb2O5∙nH2O.
Nb2O5nH2O (50 mg)
dicarboxylic acid
10 mmol
cyclic anhydride
10 mL o-xylene
azeotropic reflux
Entry
Substrates
Products
t/ h T/ °C Yield/ %
O
1
24
60
36
160
200
200
96
91
92
O
O
O
OH
HO
2a
1a
O
2b
O
O
O
O
O
HO
OH
We studied catalyst reusability for the standard reaction of
1a to 2a by Nb2O5∙nH2O under the conditions shown in Table
3 (entry 1). After the first cycle, the catalyst was separated
from the mixture by centrifugation, followed by washing
with acetone, and by drying at 90 °C for 3 h. The catalyst was
reused three times (Fig. 4). ICP-AES analysis of the solution
after the first cycle showed that the contents of Nb in the
solution was only 0.8 ppm, corresponding to 0.004% of Nb in
the 50 mg catalyst. We also checked the hot filtration test.
The reaction was completely terminated by a removal of the
catalyst from the reaction mixture after 15 min (28% yield);
further heating of the filtrate for 5 h under the reflux
condition did not increase the yield. These results indicate
that the present method is a heterogeneous reusable
catalytic system.
O
O
3 b
O
O
O
O
OH
HO
O
O
4
5
72
72
160
160
90
94
O
OH
OH
O
O
OH
OH
O
O
O
O
6
7
60
60
160
160
95
96
OH
OH
O
O
O
O
OH
OH
O
O
O
O
O
8
9
60
72
72
160
160
160
94
95
86
OH
OH
O
O
O
O
O
The present method was generally applicable to gram-
scale intramolecular condensation of various dicarboxylic
acids to the corresponding cyclic anhydrides (Table 3).
Succinic acid (entry 1), glutaric acid (entry 2), itaconic acid
(entry 3), maleic acid (entry 4), citraconic acid (entry 5),
phenyl-succinic acid (entry 6), cis-4-cyclohexene-1,2-
dicarboxylic acid (entry 7), phthalic acid (entry 8), 4,5-
dichlorophthalic acid (entry 9), and diglycolic acid (entry 10)
underwent cyclization to give the corresponding cyclic
Cl
Cl
Cl
Cl
OH
OH
O
O
O
O
O
O
10
O
HO
OH
O
O
O
a Yields of isolated products were reported.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 5 of 7
View Article Online
DOI: 10.1039/C7GC00538E
Journal Name
ARTICLE
anhydrides with high isolated yields (85-96%). The results H2SnO2 (Kojundo Chemical Laboratory Co., Ltd.), H2MoO4
indicate that the present catalytic method is generally
applicable to condensation of dicarboxylic acids to cyclic
anhydride with wide functional group tolerance. Some of the
(Kanto Chemical), Ca(OH)2 (Kanto Chemical) and Ta2O5∙nH2O
(Mitsuwa Chemicals). Al2O3 was prepared by calcination of γ-
AlOOH (Catapal B Alumina purchased from Sasol) for 3 h at
900 °C. Sulfonic resins (Amberlyst-15 and Nafion-SiO2
composite) were purchased from Sigma-Aldrich. The BET
surface area of the oxide (Table 1) was measured by N2
adsorption at -196 oC using BELCAT (MicrotracBEL).
Scandium(III) trifluoromethanesulfonate [Sc(OTf)3], In(OTf)3,
Hf(OTf)4, MgCl2, sulfuric acid (H2SO4) and p-toluenesulfonic
acid (PTSA) were purchased from Sigma-Aldrich or WAKO.
dicarboxylic acids in Table
3 can be produced from
biorefinery process, and many of the anhydrides in Table 3
are commonly applied to the synthesis of polyesters by ring-
opening copolymerization with epoxides.10-13
Conclusions
In conclusion, we have presented
a versatile and
sustainable method for direct cyclization of dicarboxylic acids
to the corresponding cyclic anhydride using Nb2O5∙nH2O as a
reusable, inexpensive and commercially available
heterogeneous catalyst. This simple method shows high
yields for the cyclization of various dicarboxylic acids which
can be produced from biorefinery process. This method can
simplify current high-cost synthesis routes to renewable
polyesters.
IR (infrared) study of pyridine adsorption on the catalysts
was performed using JASCO FT/IR-4200 spectrometer
equipped with an MCT detector using a flow-type IR cell
connected to a flow reaction system. The IR disc of the
sample (40 mg, 20 mm) was first dehydrated under He flow
at 200 or 300 °C , and then a background spectrum was
taken under He flow at 200 °C. Then, pyridine (0.3 mmol g-1)
was introduced to the sample, followed by purging by He for
600 s, and by IR measurement of adsorbed pyridine at 200 °C.
Experimental
The heterogeneous catalysts were used for catalytic
reactions without dehydration treatments. Typically,
dicarboxylic acids (1 mmol) in 2 mL o-xylene with 50 mg of
catalysts and a magnetic stirrer bar were added to a reaction
vessel (Pyrex cylinder) with a reflux condenser, and the
mixture was heated to reflux under N2 with stirring (400
rpm). For azeotropic removal of water, a funnel containing
4Å molecular sieves (MS4Å, 0.2 g) wrapped in a filter paper
(Advantech, No. 4A) was fixed at the upper part of the
cylinder surmounted by a cooling part (reflux condenser).
Yields were determined by 1H NMR using DMSO as an
internal standard as follows. After completion of the reaction,
2-propanol (4 mL) and acetone (3 mL) was added to the
mixture, and the catalyst was separated by centrifugation
and filtration, followed by washing the catalyst with acetone
(6 mL). The solution was evaporated to give crude mixture,
which was analyzed by 1H NMR and 13C NMR. The Nb content
in the reaction mixture was determined by an inductively
Commercially available organic compounds (from Tokyo
Chemical Industry, WAKO or Sigma-Aldrich) were used
without further purification. GC (Shimadzu GC-2014) and
GCMS (Shimadzu GCMS-QP2010) analyses were carried out
with Ultra ALLOY+-1 capillary column (Frontier Laboratories
Ltd.) with N2 and He as the carrier. All reactions were carried
out in oven-dried glassware under an inert atmosphere of
nitrogen. Analytical TLC was performed on a Merck 60 F254
silica gel (0.25 mm thickness). Column chromatography was
performed with silica gel 60 (spherical, 63-210 μm, Kanto
Chemical Co. Ltd.). Molecular sieves 4Å (MS4Å) was
dehydrated at 100 °C.
Niobic acid (Nb2O5∙nH2O, HY-340) was kindly supplied by
CBMM. Nb2O5 was prepared by calcination of the niobic acid
at 500 °C for 3 h. According to the previous method,26 Na +
exchanged Nb2O5∙nH2O (Na+-Nb2O5∙nH2O) was prepared by
-
stirring 1.0 g of Nb2O5∙nH2O in 400 mL of 1 M NaCl solution coupled plasma (ICP-AES) method (ICPE-9000, Shimadzu).
The gram-scale reactions of dicarboxylic acids to cyclic
anhydrides (Table 3) were carried out as follows using 2 g of
MS4Å for azeotropic water removal. After the reaction,
followed by addition of 10 mL 2-propanol and 10 mL acetone
to the mixture, the catalyst was removed by filtration.
Evaporation of the mixture at 60 °C gave a solid, which was
recrystallized using mixture of ethylacetate (5 mL) and
hexane (3 mL) to get pure anhydride. The anhydrides were
identified by 1H NMR and 13C NMR.
at 60 °C for 52 h. The pH was adjusted to 11.0−11.4 by
adding 0.05 M NaOH solution. Then, the sample was washed
repeatedly with distilled water, followed by drying in an oven
at 100 ° C for 12 h. TiO2 (JRC-TIO-4), CeO2 (JRC-CEO-3),
amorphous SiO2-Al2O3 (JRC-SAL-2, Al2O3 content = 13.75 wt%,
surface area = 560 m2 g-1) were supplied from Catalysis
Society of Japan. SiO2 (Q-10, 300 m2 g-1) was supplied from
Fuji Silysia Chemical Ltd. ZrO2, ZnO, SnO2, MoO3, Ta2O5 and
CaO were prepared by calcination (500 °C, 3 h) of the
hydrous oxides: ZrO2∙nH2O, ZnO∙nH2O (Kishida Chemical),
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 6 of 7
View Article Online
DOI: 10.1039/C7GC00538E
ARTICLE
Journal Name
Shimizu, Chem. Eur. J., 2014, 20, 14256–14260.
Acknowledgements
24. M. A. Ali, S. M. A. H. Siddiki, W. Onodera, K. Kon, K.
Shimizu, ChemCatChem., 2015, 7, 3555–3561.
25. M. Tamura, K. Shimizu, A. Satsuma, Appl. Catal. A, 2012,
433−434, 135−145.
26. G. S. Foo, D. Wei, D. S. Sholl, C. Sievers, C. ACS Catal.
2014, 4, 3180−3192.
This work was supported by Grant-in-Aids for Scientific Research B
(26289299) from MEXT and a MEXT program “Elements Strategy
Initiative to Form Core Research Center”. The authors thank the
technical division of Institute for Catalysis, Hokkaido University, for
their help in building the experimental equipments.
27. R. Noma, K. Nakajima, K. Kamata, M. Kitano, S. Hayashi,
M. Hara, J. Phys. Chem. C, 2015, 119, 17117−17125.
Notes and references
1. P. Van Wouwe, M. Dusselier, E. Vanleeuw, B. Sels,
ChemSusChem, 2016, 9, 907– 921.
2. I. Delidovich, P. J. C. Hausoul, L. Deng, R. Pfützenreuter,
M. Rose, R. Palkovits, Chem. Rev., 2016, 116, 1540–
1599.
3. R. Kopitzky, A. Springer, Chem. Eng. Technol., 2008, 31,
647−654.
4. C. Delhomme, D. Weuster-Botz, F. E. Kuhn, Green Chem.,
2009, 11, 13–26.
5. P. Gallezot, Chem. Soc. Rev., 2012, 41, 1538–1558
6. J. J. Bozell, G. R. Petersen, Green Chem., 2010, 12, 539–
554.
7. A. Corma, S. Iborra, A. Velty, Chem. Rev., 2007, 107,
2411−2502.
8. H. Danner, R. Braun, Chem. Soc. Rev. 1999, 28, 395−405.
9. M. L. A. Jansen, W. M. van Gulik, Curr. Opin. Biotechnol.,
2014, 30, 190−197.
10. S. Paul, Y. Zhu, C. Romain, R. Brooks, P. K. Saini, C. K.
Williams, Chem. Commun., 2015, 51, 6459−6479.
11. N. J. Van Zee, G. W. Coates, Angew. Chem., Int. Ed.,
2015, 54, 2665–2665.
12. N. J. Van Zee, M. J. Sanford, G. W. Coates, J. Am. Chem.
Soc., 2016, 138, 2755−2761.
13. C. Robert, F. de Montigny, C. M. Thomas, Nat. Commun.,
2011, 2, 586.
14. D. Davidson, P. Newman, J. Am. Chem. Soc., 1952, 74,
1515−1516.
15. R. Sustmann, in Comprehensive Organic Synthesis (Eds B.
M. Trost, I. Fleming, E. Winterfeldt) 1991, Vol. 6, pp.
301–321 (Pergamon: Oxford).
16. C. Robert, F. de Montigny, C. M. Thomas, ACS Catal.,
2014, 4, 3586–3589.
17. A. Sakakura, T. Ohkubo, R. Yamashita, M. Akakura, K.
Ishihara, Org. Lett., 2011, 13, 892−895.
18. A. Sakakura, R. Yamashita, T. Ohkubo, M. Akakura, K.
Ishihara, Aust. J. Chem., 2011, 64, 1458–1465.
19. S. Kobayashi, K. Manabe, Acc. Chem. Res., 2002, 35,
209–217
20. K. Nakajima, Y. Baba, R. Noma, M. Kitano, J. N. Kondo,
S. Hayashi, M. Hara, J. Am. Chem. Soc., 2011, 133,
4224− 4227.
21. Y. Wang, F. Wang, Q. Song, Q. Xin, S. Xu, J. Xu, J. Am.
Chem. Soc., 2013, 135, 1506−1515
22. E. V. Beletskiy, X. Hou, Z. Shen, J. R. Gallagher, J. T.
Miller, Y. Wu, T. Li, M. C. Kung, H. H. Kung, J. Am. Chem.
Soc., 2016, 138, 4294−4297.
23. M. A. Ali, S. M. A. H. Siddiki, K. Kon, J. Hasegawa, K.
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 7 of 7
Green Chemistry
View Article Online
DOI: 10.1039/C7GC00538E