Imidazolium ionic liquids/organic bases: Efficient intermolecular synergistic catalysts for the cycloaddition of CO2 and epoxides under atmospheric pressure

Article abstract of DOI:10.1016/j.mcat.2017.12.026

An intermolecular synergistic catalytic system consisting of ionic liquids and organic bases is developed for the cycloaddition of CO₂ and epoxides. This strategy realizes the cycloaddition takes place under atmospheric pressure of CO₂ with high activity. NMR, FT-IR spectroscopy and DFT calculations are applied to investigate the synergistic effect and reaction mechanism on molecules. Plausible ionic liquids/secondary amines and ionic liquids/tertiary amines catalyzed mechanisms are proposed and further confirmed by more detailed DFT calculations including reaction pathways and energy profiles, respectively. The procedure reported here represents a facile, cost-effective and energy-efficient route for chemical fixation of CO₂ into 5-membered cyclic carbonates.

Full text of DOI:10.1016/j.mcat.2017.12.026

Molecular Catalysis 446 (2018) 124–130
Contents lists available at ScienceDirect
Molecular Catalysis
journal homepage: www.elsevier.com/locate/mcat
Imidazolium ionic liquids/organic bases: Efficient intermolecular
synergistic catalysts for the cycloaddition of CO2 and epoxides under
atmospheric pressure
Liangzheng Jia,1, Zhoujie Luoa,1, Yongya Zhanga, Rong Wanga, Yayan Jia, Fei Xiaa,b,∗
,
Guohua Gaoa,∗
a Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663
North Zhongshan Road, Shanghai 200062, China
b NYU-ECNU Center for Computational Chemistry at New York University, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062,
China
a r t i c l e i n f o
a b s t r a c t
Article history:
An intermolecular synergistic catalytic system consisting of ionic liquids and organic bases is developed
for the cycloaddition of CO2 and epoxides. This strategy realizes the cycloaddition takes place under atmo-
spheric pressure of CO2 with high activity. NMR, FT-IR spectroscopy and DFT calculations are applied to
investigate the synergistic effect and reaction mechanism on molecules. Plausible ionic liquids/secondary
amines and ionic liquids/tertiary amines catalyzed mechanisms are proposed and further confirmed by
more detailed DFT calculations including reaction pathways and energy profiles, respectively. The pro-
cedure reported here represents a facile, cost-effective and energy-efficient route for chemical fixation
of CO2 into 5-membered cyclic carbonates.
Received 21 October 2017
Received in revised form
15 December 2017
Accepted 18 December 2017
Keywords:
Carbon dioxide
Synergistic catalysis
Cycloaddition
© 2017 Elsevier B.V. All rights reserved.
Mechanism study
1. Introduction
als, electrolyte solvents for lithium ion battery and fuel additives
[5]. Therefore, a variety of catalysts have been investigated for
With ceaseless increasing CO2 emission since last century, it has
become the primary reason of global climatic warming. As an abun-
dant, non-toxic, non-flammable and easily available source of C1
building block, CO2 is also an attractive environmentally friendly
chemical reagent [1]. However, due to the low energy level of
CO2, a large energy input is inevitable to transform it [2]. Enor-
mous researchers have dedicated themselves to apply CO2 as raw
material for chemical reactions [3].
CO2 can be applied to synthesize high value-added compounds
or fuel products [4,5]. Particularly, the cycloaddition of CO2 and
epoxides to synthesize cyclic carbonates is one of the most suc-
cessful and efficient routes for chemical fixation of CO2 in academia
and industry [1,2]. The cyclic carbonates are widely used as green
reagents, aprotic solvents, precursors for polycarbonate materi-
the coupling reaction, such as, alkali metal salts, transition metal
complexes, functional polymers, quaternary ammonium salts, qua-
ternary phosphonium salts and Schiff bases [6]. However, these
catalytic systems were still suffered from low reactivity, harsh reac-
tion condition, toxic metals, and/or multistep catalyst preparation.
Newly emerged ionic liquids (ILs) were supposed to solve such
problems to some extent when they were applied to catalyze the
cycloaddition reaction of CO2 and epoxides [7]. We also found that
phenolic hydroxyl-functionalized imidazolium ILs present excel-
lent performance for the cycloaddition reaction [8]. In these studies,
the typical ILs-catalyzed mechanism was established as shown in
Scheme 1a [9]. The cations of ILs activate epoxides through the
interaction with oxygen and the anions of ILs undergo a nucle-
ophilic attack at the least hindered carbon atom of epoxides, which
facilitate the opening of the C O bond. In this strategy, the activa-
tion of CO2 was ignored. On the other hand, it has been reported that
organic bases may provide new opportunities for CO2 activation
through the formation of base-CO2 adducts [10]. As co-catalysts,
organic bases were widely used to activate CO2 in the cycloaddition
of CO2 and epoxides (Scheme 1b) [11].
∗
Corresponding authors at: Shanghai Key Laboratory of Green Chemistry and
Chemical Processes, School of Chemistry and Molecular Engineering, East China
Normal University, 3663 North Zhongshan Road, Shanghai, 200062, China.
E-mail addresses: fxia@chem.ecnu.edu.cn (F. Xia), ghgao@chem.ecnu.edu.cn
(G. Gao).
1
These authors contributed equally to this work.
https://doi.org/10.1016/j.mcat.2017.12.026
2468-8231/© 2017 Elsevier B.V. All rights reserved.

L. Ji et al. / Molecular Catalysis 446 (2018) 124–130
125
Table 1
The synergistic effect of organic bases and ionic liquids for the cycloaddition of CO2
and epichlorohydrin.[a]
Entry
Ionic liquids
Organic bases
Yield[b]
[%]
1
2
3
4
5
6
7
8
BnBimBr
–
–
50
20
96
82
95
53
93
91
72
80
81
85
78
DEA
DEA
DEA
DEA
DEA
DEBA
MIm
DBU
TEA
BnBimBr
BmimBr
DBnimBr
BnMBimBr
BnBimBr
BnBimBr
BnBimBr
BnBimBr
BnBimBr
BnBimBr
BnBimBr
9
10
11
12
13
n-BA
DABCO
Im
[a] Reaction conditions: Epichlorohydrin (10 mmol), CO2 (0.1 MPa), organic base
(0.1 mmol), ionic liquids (0.1 mmol), 80 ◦C, 3 h. [b] GC yield.
Scheme 1. Mechanism of cycloaddition of CO2 and epoxides by different catalytic
system a) ionic liquids; b) organic bases; c) our proposed dual catalysts.
gas chromatography to determine yield using dodecane as internal
standard. The product was purified by chromatography on silica
gel and characterized structurally by NMR spectroscopy.
Herein, we present a study on the combination of imidazolium
ionic liquids and organic bases as synergistic catalytic system for
the cycloaddition of CO2 and epoxides for the first time (Scheme 1c).
In this catalytic system, ionic liquids and organic bases are able to
activate epoxides and CO2, respectively. The dual activation facili-
tates the reaction to proceed under mild conditions. Experimental
and theoretical methods on molecules were applied to investigate
the synergistic mechanisms of ionic liquids/secondary amines or
ionic liquids/tertiary amines.
2.3. Computational methods
The structural optimization by DFT calculations was carried out
at the M06-2x/6–31 + G* level using G09 program package [12,13].
The frequency analyses were then performed at the M06-2X/6-
311G* level based on the optimized gaseous structures to identify
the minima and transition states on potential surfaces. The intrin-
sic reaction coordinate calculations were conducted to verify that
the transition structures connect the correct reactants and prod-
ucts in the forward and reverse directions. The solvent effect on
the solute was evaluated using the SMD [14,15] model in G09. All
the calculated Gibbs free energies ꢀGsol were evaluated under the
experimental conditions with the temperature 353 K and pressure
0.1 MPa. More details about the optimized structures are provided
in Supporting Information.
2. Experimental
2.1. General
1-Benzyl-3-butylimidazolium
bromide
(BnBimBr),
1,3-dibenzylimidazolium bromide (DBnimBr), 1-benzyl-2-methy-
3-butylimidazolium bromide (BnMBimBr) were synthesized
according to the literature with minor modification (see Sup-
porting Information). 1-Butyl-3-methylimidazolium bromide
(BmimBr) was supplied by the Centre for Green Chemistry and
Catalysis, LICP, CAS. CO2 was supplied by Doumaoai Factory
with a purity of 99.9%. Epichlorohydrin, epibromohydrin, 2-
(phenoxymethyl)oxirane ethylene oxide, propylene oxide, styrene
oxide and 1,2-hexene oxide were purchased from TCI. The other
reagents were supplied by Sinopharm. All chemicals were used
without further purification.
NMR spectra were recorded on Bruker Ascend400 instruments
with tetramethylsilane as the internal standard. GC analysis was
performed by using a Shimadzu GC–14 B equipped with a capillary
column DM-1701 (60 m-0.32 mm-0.25 mm) equipped with a flame
ionization detector. FTIR spectra were recorded on a Nicolet nexus
670 instrument.
3. Results and discussion
3.1. Synergistic catalysis of organic bases and ionic liquids
To investigate the effect of intermolecular synergistic catalytic
system, diethylamine (DEA) and BnBimBr were selected as catalysts
for the cycloaddition of CO2 and epichlorohydrin. When BnBimBr
was used alone, a moderate yield of 50% of 3-chloro-1,2-propylene
carbonate was obtained after 3 h under atmospheric CO2 pressure
(entry 1, Table 1). If DEA was used alone, a poor yield of 20% was
obtained (entry 2, Table 1). However, the combination of BnBimBr
and DEA gave excellent yield of 96% (entry 3, Table 1), indicating the
intermolecular synergistic effect of organic base and ionic liquid for
accelerating the cycloaddition reaction. The synergistic effect was
also observed in the combination of other ionic liquids and DEA
as well. DBnimBr and BmimBr gave yields of 95% and 82%, respec-
tively (entry 4–5, Table 1). However, BnMBimBr, in which the C2-H
of the imidazolium ring was replaced by methyl group, provided a
lower yield of product (53%) (entry 6, Table 1). These results indi-
cated that C2-H of imidazolium was also crucial for the reaction.
NMR spectroscopy and DFT calculations demonstrated the interac-
tion between epoxide and C2-H through hydrogen bonding which
led to the activation of epoxide (Fig. S1, S2). The similar observa-
tion has been reported by us and others [16]. Various organic bases
2.2. Typical procedure for the cycloaddition of CO2 and epoxide
Typically, epichlorohydrin (0.925 g, 10 mmol), BnBimBr
(0.029 g, 0.1 mmol) and DEA (0.007 g, 0.1 mmol) were mixed
together and put into a 30 mL stainless steel autoclave equipped
with a magnetic stirrer. The reaction was carried out under
atmospheric pressure of CO2 at 80 ◦C. After the completion of
reaction, the autoclave was cooled to room temperature. In order
to remove the ionic liquid, Et2O (40 mL) was added to the reaction
mixture and filtered. The filtrate was subsequently analyzed by

126
L. Ji et al. / Molecular Catalysis 446 (2018) 124–130
Table 2
Optimization of reaction parameters on the cycloaddition in BnBimBr/DEA catalytic
system.[a].
Entry
Ionic liquids
[mol%]
Organic bases
[mol%]
T[◦C]
t [h]
Yield[b][%]
1
2
3
4
5
6
7
8
9
0.5
1
2
1
1
1
1
1
1
1
1
1
2
0.5
1
1
1
1
80
80
80
80
80
70
60
80
80
3
3
3
3
3
3
3
2
1
80
96
96
95
91
75
45
75
59
[a] Reaction conditions: Epichlorohydrin (10 mmol), CO2 (0.1 MPa). [b] GC yield.
3 h, 0.1 MPa were obtained. The BnBimBr/DEBA catalytic system
showed a similar variation trend (Table S1).
3.3. Synthesis of cyclic carbonates from CO2 and other epoxides
Fig. 1. The correlation of activities and hydrogen bond between C2-H of imida-
zolium and epichlorohydrin in the presence of various bases. Reaction conditions:
Epichlorohydrin (10 mmol), CO2 (0.1 MPa), BnBimBr (0.1 mmol), organic base
(0.1 mmol), 80 ◦C, 3 h. GC yield.
To investigate the generalities of the dual catalyst system, var-
ious epoxides were applied for cycloaddition under the optimized
reaction conditions (Table 3). Diverse epoxides were transformed
into corresponding cyclic carbonates with good to excellent yields.
In BnBimBr/DEA synergistic catalytic system, epibromohydrin and
2-(phenoxymethyl)oxirane (entry 1–2, Table 3) afforded high
yields of 95% and 93%, respectively, presumably ascribe to the
electron-withdrawing properties of the bromide atom and phe-
noxyl [11c,17]. Due to their low boiling points, ethylene oxide and
propylene oxide reacted with CO2 under higher pressure and gave
yield of 97% (entry 3–4, Table 3). Styrene oxide (entry 5, Table 3)
with large steric hindrance also converted into corresponding cyclic
carbonate in the yield of 94% under a slight higher temperature
(90 ◦C). 1,2-Hexene oxide afforded a good yield (81%) at 110 ◦C
(entry 6, Table 3). The relative lower reactivity of 1,2-hexene oxide
was probably ascribed to the large steric hindrance and electron
donating group of butyl, which would hinder nucleophilic attack on
the least hindered carbon atom of epoxide ring. The BnBimBr/DEBA
system also showed good generalities for various epoxides (Table
S2).
also showed the synergistic effects to different extent in combi-
nation with BnBimBr. Distinctly, N, N-diethylbenzylamine (DEBA)
and 1-methylimidazole (MIm) gave the high yields of 93% and 91%,
respectively (entry 7–8, Table 1). Other organic bases including
1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU), triethylamine (TEA),
n-butylamine (n-BA), 1,4-diazabicyclo[2.2.2]octane (DABCO) and
imidazole (Im) afforded the product in the yields of 72–85% (entry
9–13, Table 1).
In order to verify the effect of organic base on the cycloaddition
reaction in detail, DFT calculations were applied to simulate the
hydrogen bond (H1 O1) between C2 H of imidazolium and oxy-
gen atom of epichlorohydrin in the mixture of BnBimBr, epoxide
and organic bases. The length of H1 O1 bond was ranging from
2.07 Å to 2.25 Å in the presence of different organic bases such as
DEA, DEBA, MIm, DBU, TEA, n-BA, DABCO and Im (Fig. S3), which
might be influenced by the basicity and steric hindrance of organic
base. Interestingly, an approximately linear negative correlation
was obtained between the catalytic activities of organic bases and
the lengths of H1 O1 bonds (Fig. 1). When the length of H1 O1 bond
was shorter, the activation of epoxide was more sufficient, which
led to the higher reaction activity. These results demonstrated that
these organic bases affected the interaction between BnBimBr and
epoxide, and further influenced the reaction activity.
Table 3
Reaction of various terminal epoxides with CO2 under optimized conditions.[a].
Entry
Substate
Product
Yield[e][%]
1
95
3.2. Optimization of reaction parameters
2
93
Subsequently, we investigated the effect of other reaction
parameters including catalysts amount, reaction temperature and
reaction time. In BnBimBr/DEA synergistic catalytic system, when
increasing the amount of BnBimBr from 0.5 mol% to 1 mol%, the
yield of cyclic carbonate increased from 80% to 96%, and remained
the same yield with further increasing the amount of ionic liquid
to 2 mol% (entry 1–3, Table 2). With increasing of the amount of
organic base from 1 mol% to 2 mol%, the yield did not change obvi-
ously, decreasing the amount of organic base to 0.5 mol% resulted
in slightly decrease in the yield from 96% to 91% (entry 4–5, Table 2).
Lowering reaction temperature to 70 ◦C and 60 ◦C led to lower
yields of 75% and 45%, respectively (entry 6 and 7, Table 2). In addi-
tion, a shorter reaction time of 2 h and 1 h gave the lower yields
of 75% and 59%, respectively (entry 8 and 9, Table 2). The opti-
mized reaction conditions of 1 mol% BnBimBr, 1 mol% DEA, 80 ◦C,
3[b]
97
97
4[b]
[c]
94
82
6[d]
[a] Reaction conditions: Epoxide (10 mmol), CO2 (0.1 MPa), BnBimBr (0.1 mmol),
organic bases (0.1 mmol), 80 ◦C, 3 h, GC yield. [b] 0.5 MPa; [c] 90 ◦C; [d] 110 ◦C; [e]
GC yield.

L. Ji et al. / Molecular Catalysis 446 (2018) 124–130
127
Scheme 2. The reaction of DEA and CO2.
[18c] CO2 could be activated by diethyl amine to form diethyl car-
bamic acid, which was considered as active intermediate in the
cycloaddition of CO2 and epoxides (Scheme 2).
On the basis of the dual effect of such a binary catalyst
on epoxide/CO2-activation, a reaction mechanism catalyzed by
BnBimBr/secondary amines is proposed as illustrated in Fig. 4(a).
Correspondingly, a detailed DFT calculation on the reaction path-
ways was carried out and the calculated free energy profiles are
shown in Fig. 4(b). In the first step, the epoxide and BnBimBr
can form the stable complex Int-1 through the hydrogen-bonding
interaction between the oxygen atom of epoxide ring and the C2-
H of BnBimBr. Then, the bromide anion attacks the carbon atom
of epoxide nucleo philically via the transition state TS-1, with a
remarkable energy barrier of 23.0 kcal mol−1. The ring opening of
epoxide leads to an oxy anion species Int-2. On the other hand,
CO2 is activated by DEA via the transition state TS-2 to afford
the species Int-4 diethyl carbamic acid, where the new nitrogen-
carbon bond forms. Our calculated results also indicate that, the
energy of another transition state without the water for proton
transfer is higher than that of TS-2 (Fig. S4), since the transition state
with a four-member ring is quite unstable in energetics. Subse-
quently, nucleophilic attack of Int-2 on Int-4 via the transition state
TS-3, yielding a salt Int-5 which contains alkylcarbonate anion. The
DEA is released from TS-3 by abstracting the proton in diethyl car-
bamic acid back through a water molecule as a proton shuttle. The
activation energy barrier for this step is 21.2 kcal mol−1 and the
salt Int-5 is quite stable in energetics. Finally, Int-5 converts to
the corresponding cyclic carbonate Pro through the intramolecular
ring-closure via TS-4, with regenerating the catalyst BnBimBr.
Fig. 2. IR spectrum of DEA before and after reaction with CO2.
3.4. Mechanism study
During the studies of synergistic effect of organic bases and
ionic liquids, we found that secondary amines and tertiary amines
activated CO2 through different approaches. In order to make a
deep insight into the catalytic mechanism, the activation models
of CO2 by secondary amines and tertiary amines and the promo-
tion of ionic liquids were investigated by using experimental and
theoretical methods.
3.4.1. Ionic liquids/secondary amines catalyzed mechanism
It has reported that the reaction of secondary amines and
CO2 form carbamic acids or carbamates depending on the reac-
tion conditions. [4a,18] In order to clarify the intermediates in
BnBimBr/DEA catalyzed system, FT-IR and NMR investigations
were applied to identify the reaction mixture of DEA and CO2. The
FT-IR spectrum of the DEA before and after CO2-bubbling for 1 h was
shown in Fig. 2. Two characteristic peaks centered at 1634 cm−1 and
1661 cm−1 can be assigned to the new formed −COOH moiety. [19]
Besides, the characteristic peak corresponding to dialkylammo-
nium carbamate anion around 1545–1575 cm−1 was not observed.
[18c,20] These results indicated that CO2 could be captured by DEA
to generate carbamic acid under the reaction condition. Subse-
quently, NMR investigations based on the bubbling of CO2 into DEA
were performed to further verify the formation of diethylcarbamic
acid (Fig. 3). Upon prolonging the reaction time, the resonance of
active proton was shifted downfield gradually from 0.88 ppm to
7.89 ppm and all the peaks were broadened, which were presum-
ably due to the fast proton exchange between continuous formed
carbamic acid and free amine. In the 13C NMR spectrum, a new
signal at ␦ = 161.89 ppm was observed, which indicates that a CO2
molecule was inserted into the N H bond of DEA to form the car-
bamic acid. Dijkstra also found similar results that carbamic acid
was formed in the organic solvent and in the supercritical CO2.
3.4.2. Ionic liquids/tertiary amines catalyzed mechanism
During the study of the mechanism for BnBimBr/DEBA catalyzed
the cycloaddition of CO2 and epoxide, we found that adventitious
water could affect the catalytic activity significantly. Accordingly,
the effect of additional water on the cycloaddition of CO2 and
epichlorohydrin was investigated. As shown in Fig. 5, without any
additional water, a yield of 50% was obtained after 1 h under atmo-
spheric CO2 pressure. With increasing of additional water from
1 mol% to 4 mol% base on the epoxide, the yields were increased
gradually to around 70%. However, with further increasing of addi-
tional water from 4 mol% to 10 mol%, the yields were decreased
significantly. The effect of water in other BnBimBr/tertiary amine
systems was also evaluated. As shown in Fig. 6, in the presence of
4 mol% water, the yields of target product increased about 10% in
Fig. 3. 1H NMR spectra of a) only DEA, b) the complex of DEA react with CO2 for 1 h, c) 2 h, d) 3 h in CDCl3, and e) 13C NMR spectra of the complex of DEA react with CO2 for
3 h in CDCl3.

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L. Ji et al. / Molecular Catalysis 446 (2018) 124–130
Fig. 4. (a) Proposed Ionic liquids/secondary amines catalyzed mechanism for the cycloaddition of CO2 and epichlorohydrin. (b) Calculated reaction pathways and energy
profiles for the reactions in (a). Path A denotes the ring-opening process of epoxide, Path B denotes the formation of diethyl carbamic acid and Path C denotes the process of
yielding the final products.
the BnBimBr/tertiary amines (e.g. DBU, TEA, DABCO, Mim and Im)
systems. It has reported that DBU could react with CO2 to form
corresponding bicarbonate salt [DBUH+][HCO3−] in the presence
of trace amount of water. [21] Similarly, in the BnBimBr/tertiary
amines system, adventitious water was capable of assisting tertiary
amines to activate CO2 through in-situ generation of bicarbonate
salts. The appropriate amount of water would facilitate the forma-
tion of bicarbonate salts, which were considered to be active species
of CO2 for the cycloaddition, and lead to acceleration of the reaction.
Based on the above results, a reaction mechanism catalyzed by
BnBimBr/tertiary amines is proposed as illustrated in Fig. 7(a). Cor-
respondingly, a detailed DFT calculation on the reaction pathways
was carried out and the calculated free energy profiles are shown
in Fig. 7(b). The ring-opening process of epoxide is the same as
Path A shown in Fig. 4(b). Path D denotes the proposed pathway
for the activation of CO2 existing in solution by the tertiary amine.
Tertiary amine, CO2, and water molecules can form stable com-
plex Int-6 through the hydrogen bonding interactions in solution.
Due to the strong basicity of tertiary amine, the nitrogen atom is
capable of abstracting the proton from H2CO3 through the transi-
Fig. 5. The effects of additional water in the BnBimBr/DEBA catalytic system for
tion state TS-5. The energy barrier for the proton abstraction via
the cycloaddition of CO2 and epichlorohydrin. Reactin conditions: Epichlorohydrin
TS-5 is only 5.9 kcal mol−1, which is quite easy to occur in solu-
(10 mmol), CO2 (0.1 MPa), DEBA (0.1 mmol), BnBimBr (0.1 mmol), 80 ◦C, 1 h. GC yield.
tion. The capture of CO2 by DEBA with water molecules generates
the ion pair [HDEBA+][HCO3−], denoted as Int-7. The ion pair Int-7
reacts with Int-2 to generate the stable complex Int-5, with DEBA
and a water molecule liberated. The energy barrier of this step is
21.2 kcal mol−1. In the last intramolecular cyclization step via the
transition state TS-4, the target product Pro is formed and BnBimBr
is regenerated.
4. Conclusion
In summary, a simple and efficient intermolecular synergistic
catalyst system consisting of imidazolium ionic liquids and organic
bases has been developed for CO2 chemical fixation with epox-
ides under metal- and solvent-free conditions. The binary system
exhibits distinctly higher catalytic activity than using organic bases
or imidazolium ionic liquids alone. The combination of imidazolium
ionic liquids and organic bases is found to be applicable for the
transformation of a range of epoxides under very mild conditions.
Fig. 6. The effects of additional water in the BnBimBr/organic base catalytic system
The mechanism studies based on the NMR, FT-IR investigations and
DFT calculations indicate that imidazolium ionic liquids activate
epoxides and organic bases activate CO2, respectively. The appli-
for the cycloaddition of CO2 and epichlorohydrin. Reaction conditions: Epichlorohy-
drin (10 mmol), CO2 (0.1 MPa), BnBimBr (0.1 mmol), Organic base (0.1 mmol), water
(0.4 mmol) 80 ◦C, 1 h. GC yield.

L. Ji et al. / Molecular Catalysis 446 (2018) 124–130
129
Fig. 7. (a) Proposed Ionic liquids/tertiary amines catalyzed mechanism for the cycloaddition of CO2 and epichlorohydrin. (b) Calculated reaction pathways and energy profiles
for the proposed tertiary amine-catalyzed mechanism. Path D denotes the activation of CO2 by DEBA and Path E denotes the synthesis of cyclic carbonate.
cation of imidazolium ionic liquids/organic bases catalytic system
in the cycloaddition reaction provides a cost-effective and energy-
efficient route to obtain 5-membered cyclic carbonates from CO2
at atmospheric pressure.
[6] (a) D.H. Gibson, Chem. Rev. 96 (1996) 2063–2095;
(b) A. Decortes, A.M. Castilla, A.W. Kleij, Angew. Chem. Int. Ed. 122 (2010)
10016–10032;
(c) P.P. Pescarmona, M. Taherimehr, Catal. Sci. Technol. 2 (2012) 2169–2187;
(d) D.-W. Kim, R. Roshan, J. Tharun, A. Cherian, D.-W. Park, Korean J. Chem.
Eng. 30 (2013) 1973–1984;
(e) J.W. Comerford, I.D.V. Ingram, M. North, X. Wu, Green Chem. 17 (2015)
1966–1987;
Acknowledgements
(f) C. Martín, G. Fiorani, A.W. Kleij, ACS. Catal. 5 (2015) 1353–1370;
(g) H. Büttner, J. Steinbauer, T. Werner, ChemSusChem 8 (2015) 2655–2669;
(h) V. D’Elia, J.D.A. Pelletier, J.M. Basset, ChemCatChem 7 (2015) 1906–1917;
(i) L. Qin, B. Wang, Y. Zhang, L. Chen, G. Gao, Chem. Commun. 53 (2017)
3785–3788.
We thank the National Key Research and Development Pro-
gram of China (2017YFA0403102), the National Natural Science
Foundation of China (21573072, 21773068, 21433004) Shang-
hai Natural Science Foundation (14ZR1411800) and Shanghai
Leading Academic Discipline Project (B409) for financial sup-
port. We acknowledge the support of the NYU-ECNU Center for
Computational Chemistry at NYU Shanghai. We also thank the
supercomputer center of ECNU for providing computer time.
[7] (a) Z.-Z. Yang, Y.-N. Zhao, L.-N. He, RSC Adv. 1 (2011) 545–567;
(b) H. Li, P.S. Bhadury, B. Song, S. Yang, RSC Adv. 2 (2012) 12525–12551;
(c) W. Cheng, Q. Su, J. Wang, J. Sun, F.T.T. Ng, Catalysts 3 (2013) 878–901;
(d) Q. He, J.W. O’Brien, K.A. Kitselman, L.E. Tompkins, G.C.T. Curtis, F.M.
Kerton, Catal. Sci. Technol. 4 (2014) 1513–1528.
[8] (a) S. Wu, B. Wang, Y. Zhang, E.H.M. Elageed, H. Wu, G. Gao, J. Mol. Catal. A
Chem. 418 (2016) 1–8;
(b) S. Wu, Y. Zhang, B. Wang, E.H.M. Elageed, L. Ji, H. Wu, G. Gao, Eur. J. Org.
Chem. 3 (2017) 753–759.
[9] B.-H. Xu, J.-Q. Wang, J. Sun, Y. Huang, J.-P. Zhang, X.-P. Zhang, S.-J. Zhang,
Green Chem. 17 (2015) 108–122.
Appendix A. Supplementary data
[10] (a) C. Villiers, J.-P. Dognon, R. Pollet, P. Thuéry, M. Ephritikhine, Angew. Chem.
Int. Ed. 49 (2010) 3465–3468;
(b) C.D.N. Gomes, O. Jacquet, C. Villiers, P. Thuéry, M. Ephritikhine, T. Cantat,
Angew. Chem. Int. Ed. 51 (2012) 187–190.
[11] (a) J. Sun, W. Cheng, Z. Yang, J. Wang, T. Xu, J. Xin, S. Zhang, Green Chem. 16
(2014) 3071–3078;
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.mcat.2017.12.
026.
(b) X. Liu, S. Zhang, Q.-W. Song, X.-F. Liu, R. Ma, L.-N. He, Green Chem. 18
(2016) 2871–2876;
References
(c) L. Wang, K. Kodama, T. Hirose, Catal. Sci. Technol. 6 (2016) 3872–3877.
[12] (a) R. Huenerbein, B. Schirmer, J. Moellmann, S. Grimme, Phys. Chem. Chem.
Phys. 12 (2010) 6940–6948;
[1] (a) A.J. Hunt, E.H.K. Sin, R. Marriott, J.H. Clark, ChemSusChem 3 (2010)
306–322;
(b) A. Goeppert, M. Czaun, G.K.S. Prakash, G.A. Olah, Energy Environ. Sci. 5
(2012) 7833–7853;
(b) Y. Zhao, D.G. Truhlar, Org. Lett. 8 (2006) 5753–5755;
(c) Y. Zhao, D.G. Truhlar, Theor. Chem. Acc. 120 (2008) 215–241.
[13] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R.
Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji,
M. Caricato, X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L.
Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida,
T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery Jr., J.E.
Peralta, F. Ogliaro, M. Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N.
Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J.C. Burant,
S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J.B.
Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O.
Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, R.L. Martin, K.
Morokuma, V.G. Zakrzewski, G.A. Voth, P. Salvador, J.J. Dannenberg, S.
Dapprich, A.D. Daniels, Ö. Farkas, J.B. Foresman, J.V. Ortiz, J. Cioslowski, D.J.
Fox, Gaussian, Inc Wallingford CT, 2017.
[14] M. Dolg, U. Wedig, H. Stoll, H. Preuss, J. Chem. Phys. 86 (1987) 866–872.
[15] D. Andrae, U. Häußermann, M. Dolg, H. Stoll, H. Preuß, Theor. Chem. Acc. 77
(1990) 123–141.
[16] (a) Y.J. Kim, R.S. Varma, J. Org. Chem. 70 (2005) 7882–7891;
(b) L. Zhang, X. Fu, G. Gao, ChemCatChem 3 (2011) 1359–1364;
(c) B. Wang, X. Feng, L. Zhang, S. Yang, X. Jiang, J. Zhou, G. Gao, J. CO2 Util. 1
(2013) 88–91;
(c) M. Drees, M. Cokoja, F.E. Kühn, ChemCatChem 4 (2012) 1703–1712;
(d) M. He, Y. Sun, B. Han, Angew. Chem. Int. Ed. 5 (2013) 9620–9633;
(e) L. Yang, H. Wang, ChemSusChem 7 (2014) 962–998;
(f) Q. Yi, W. Li, J. Feng, K. Xie, Chem. Soc. Rev. 44 (2015) 5409–5445.
[2] (a) T. Sakakura, J.-C. Choi, H. Yasuda, Chem. Rev. 107 (2007) 2365–2387;
(b) M. Mikkelsen, M. Jørgensen, F.C. Krebs, Energy Environ. Sci. 3 (2010)
43–81.
[3] (a) M. Cokoja, C. Bruckmeier, B. Rieger, W.A. Herrmann, F.E. Kühn, Angew.
Chem. Int. Ed. 5 (2011) 8510–8537;
(b) C. Maeda, Y. Miyazaki, T. Ema, Catal. Sci. Technol. 4 (2014) 1482–1497;
(c) H. Takeda, C. Cometto, O. Ishitani, M. Robert, ACS Catal. 7 (2017) 70–88.
[4] (a) D.B. Dell’Amico, F. Calderazzo, L. Labella, F. Marchetti, G. Pampaloni, Chem.
Rev. 103 (2003) 3857–3897;
(b) C. Liu, J. Ye, J. Jiang, Y. Pan, ChemCatChem 3 (2011) 529–541;
(c) G.A. Olah, G.K.S. Prakash, A. Goeppert, J. Am. Chem. Soc. 133 (2011)
12881–12898;
(d) W. Wang, S. Wang, X. Ma, J. Gong, Chem. Soc. Rev. 40 (2011) 3703–3727;
(e) K. Li, B. Peng, T. Peng, ACS Catal. 6 (2016) 7485–7527.
[5] (a) T. Sakakura, K. Kohnoa, Chem. Commun. (2009) 1312–1330;
(b) M. North, R. Pasquale, C. Young, Green Chem. 12 (2010) 1514–1539;
(c) M. Cokoja, M.E. Wilhelm, M.H. Anthofer, W.A. Herrmann, F.E. Kühn,
ChemSusChem 8 (2015) 2436–2454.
(d) B. Wang, S. Yang, L. Min, Y. Gu, Y. Zhang, X. Wu, L. Zhang, E.H.M. Elageed, S.

130
L. Ji et al. / Molecular Catalysis 446 (2018) 124–130
Wu, G. Gao, Adv. Synth. Catal. 356 (2014) 3125–3134;
(e) B. Wang, E.H.M. Elageed, D. Zhang, S. Yang, S. Wu, G. Zhang, G. Gao,
ChemCatChem 6 (2014) 278–283;
(f) E.H.M. Elageed, B. Chen, B. Wang, Y. Zhang, S. Wu, X. Liu, G. Gao, Eur. J. Org.
Chem. (2016) 3650–3656;
(g) Y. Zhang, B. Wang, E.H.M. Elageed, L. Qin, B. Ni, X. Liu, G. Gao, ACS Macro
Lett. 5 (2016) 435–438;
(c) Z.J. Dijkstra, A.R. Doornbos, H. Weyten, J.M. Ernsting, C.J. Elsevier, J.T.F.
Keurentjes, J. Supercrit. Fluids 41 (2007) 109–114;
(d) R. Vijayaraghavan, D.R. MacFarlane, ACS Sustain. Chem. Eng. 2 (2014)
1724–1728.
[19] (a) C.S. Srikanth, S.S.C. Chuang, J. Phys. Chem. C 117 (2013) 9196–9205;
(b) Y. Wang, J. Zhang, J. Liu, C. Zhang, Z. Zhang, J. Xu, S. Xu, F. Wang, F. Wang,
ChemSusChem 8 (2015) 2066–2072.
(h) Z. Luo, B. Wang, Y. Liu, G. Gao, F. Xia, Phys. Chem. Chem. Phys. 18 (2016)
27951–27957.
[17] (a) J. Song, B. Zhang, P. Zhang, J. Ma, J. Liu, H. Fan, T. Jiang, B. Han, Catal. Today
183 (2012) 130–135;
(b) J. Shi, J. Song, J. Ma, Z. Zhang, H. Fan, B. Han, Pure Appl. Chem. 85 (2013)
1633–1641.
[18] (a) E.M. Hampe, D.M. Rudkevich, Tetrahedron 59 (2003) 9619–9625;
(b) U.P. Kreher, A.E. Rosamilia, C.L. Raston, J.L. Scott, C.R. Strauss, Molecules 9
(2004) 387–393;
[20] (a) C. Hisatsune, Can. J. Chem. 62 (1984) 945–948;
(b) D.J. Heldebrant, P.K. Koech, M.T.C. Ang, C. Liang, J.E. Rainbolt, C.R. Yonker,
P.G. Jessop, Green Chem. 12 (2010) 713–721;
(c) A.-H. Liu, R. Ma, C. Song, Z.-Z. Yang, A. Yu, Y. Cai, L.-N. He, Y.-N. Zhao, B. Yu,
Q.-W. Song, Angew. Chem. Int. Ed. 51 (2012) 11306–11310.
[21] D.J. Heldebrant, P.G. Jessop, C.A. Thomas, C.A. Eckert, C.L. Liotta, J. Org. Chem.
70 (2005) 5335–5338.