Experimental and theoretical study for CO2 activation and chemical fixation with epoxides

Article abstract of DOI:10.1039/c8ra10475a

The synthesis of five-membered cyclic carbonates via catalytic cycloaddition reaction of CO₂ with epoxides is considered to be an effective technology for alleviation of the energy crisis and global warming. Various commercial organic bases and ionic salts were used as catalysts, while the relationship of catalytic activity and compound structure has been seldom explored. Herein, a facilely obtained binary catalytic system based on triethylamine/NBu₄Br was developed for CO₂ activation and chemical fixation. The highly efficient catalytic system showed outstanding conversion and above 99% selectivity under metal-free mild reaction conditions (100 °C, 1 atm) in one hour. The detailed process of CO₂ activation and chemical fixation was investigated at the molecular level by a series of experiments and theoretical calculation, which provided a mode for the design and synthesis of a highly efficient catalytic system for conversion of CO₂ under mild conditions.

Full text of DOI:10.1039/c8ra10475a

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Experimental and theoretical study for CO2
activation and chemical fixation with epoxides†
Cite this: RSC Adv., 2019, 9, 13122
ab
b
b
b
Jinwei Gao,
Yaqiong Gong,
Liuyi Li,
Caiyan Cui, Muhammad Asad Ziaee,
a
c
ab
Rongjian Sa* and Hong Zhong*
2
The synthesis of five-membered cyclic carbonates via catalytic cycloaddition reaction of CO with epoxides
is considered to be an effective technology for alleviation of the energy crisis and global warming. Various
commercial organic bases and ionic salts were used as catalysts, while the relationship of catalytic activity
and compound structure has been seldom explored. Herein, a facilely obtained binary catalytic system
4 2
based on triethylamine/NBu Br was developed for CO activation and chemical fixation. The highly
efficient catalytic system showed outstanding conversion and above 99% selectivity under metal-free
Received 21st December 2018
Accepted 24th April 2019
ꢀ
mild reaction conditions (100 C, 1 atm) in one hour. The detailed process of CO
2
activation and
chemical fixation was investigated at the molecular level by a series of experiments and theoretical
calculation, which provided a mode for the design and synthesis of a highly efficient catalytic system for
DOI: 10.1039/c8ra10475a
rsc.li/rsc-advances
2
conversion of CO under mild conditions.
23–32
zeolites, ionic liquids, carbon nitride and so on.
most catalysts were used to activate epoxide by a metal ion or
) excessive emission is a main component hydrogen bond center, the effect of CO activity on the reaction
of greenhouse gases in the atmosphere. Its conversion to efficiency has rarely been studied deeply.
value-added products has offered one promising way to alleviate
CO is the highest oxidation state of carbon, and it is ther-
Though
Introduction
Carbon dioxide (CO
2
2
1–3
2
4–7
the energy crisis and global warming. As an economical and modynamically stable and kinetically inert, which will conse-
abundant C source, CO is renewable, inexpensive and non- quently hinder the development of efficient catalysts that achieve
1
2
8
–11
23,33,34
toxic,
applicability as a raw material in industry. The catalytic the activation of CO
synthesis of cyclic carbonate from epoxides and CO
is introduce/use of Lewis basic species and transition metal system
considered to be one of the most promising pathways to CO
but its chemical inertness is still the bottleneck for its CO
2
activation and subsequently its functionalization.
Thus
is pivotal for its effective conversion. The
2
2
have been highly considered, while the detailed CO
2
activation
2
1
2–14
35–38
utilization.
Cyclic carbonates have wide applications as process was unclear,
so developing a catalytic system that
green polar aprotic solvents, fuel additives, and chemical provides molecular level insight for CO
2
activation process is still
The chemical xations of CO2 into cyclic highly desired. Taking the aforementioned concerns into
carbonates are relatively simple from a chemical reactivity point account, we propose to explore a new catalytic system that can
of view, while in fact, the high temperature, high pressure, high activate and convert CO with epoxides under mild conditions,
catalyst loading, or a combination of these are required to make and serve as an ideal mold for providing a detailed mechanistic
the reaction effective, which is not economically suitable and understanding of CO activation and xation process.
Herein, a simple and efficient binary catalytic system based
conditions, a great variety of catalysts for the synthesis of cyclic on organobase/NBu Br was developed for CO cycloaddition
15–18
intermediates.
2
2
19–22
poses safety concerns as well.
To optimize the reaction
4
2
carbonates have been developed so far, including alkali-metal reaction with epoxides under metal-free mild conditions. It was
halides, metal complexes, metal oxides, cellulose, MOFs, found that the synergistic effect between two components in
this new catalytic system promote the cycloaddition reaction
occur under atmospheric pressure during a short time period of
a
College of Science, North University of China, Taiyuan, Shanxi 030051, P. R. China
1
hour. Moreover, the relationship of catalytic activity and
b
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the
catalyst structure was investigated at molecular level by a series
of experiments and theoretical calculation, which could not
only offer in-depth understanding of the reaction mechanism
Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
E-mail: zhonghong@irsm.ac.cn
c
Institute of Oceanography, Ocean College, Fujian Provincial Key Laboratory of
Information Processing and Intelligent Control, Minjiang University, Fuzhou, Fujian but also provide a theoretical basis for the effect of triethyl-
3
†
1
50108, China. E-mail: rjsa@mju.edu.cn
amine (NEt
process.
2
) in activating CO and promoting the reaction
3
Electronic supplementary information (ESI) available. See DOI:
0.1039/c8ra10475a
13122 | RSC Adv., 2019, 9, 13122–13127
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
Results and discussion
To understand the effects of the counter anions on the catalytic
activity, the catalytic cycloaddition reaction of CO
were initially investigated in the presence of 0.5 mL NEt
shown in Table 1, NBu Br afforded a full conversion of 2-(chlor-
2
with epoxides
3
. As
4
omethyl)oxirane to 4-(chloromethyl)-1,3-dioxolan-2-one under 1.0
ꢀ
atm. CO at 100 C for 1.0 h (entry 1), and the catalytic conversion
2
showed unconspicuous change when the NBu Br was replaced by
4
NBu Cl, NBu I, respectively (entries 2–3). Notably, the yield of 2-
4
4
(
chloromethyl)oxirane to 4-(chloromethyl)-1,3-dioxolan-2-one
decreased signicantly when NBu PF was used under the
same condition, which is probably due to the weakest nucleo-
4
6
ꢁ ꢁ
ꢁ
ꢁ
ꢁ
philicity of PF
counter anions play a dominant role in cycloaddition reaction of
6
in selected Cl , Br , I , and PF , suggesting the
6
39
CO with epoxides. When the common organic base NEt was
2
3
used alone under the same condition, 36% yield of 2-(chlor-
omethyl)oxirane to 4-(chloromethyl)-1,3-dioxolan-2-one was ob-
3 2
tained (entry 6), indicating that NEt can activate CO in this
reaction. Based on the above results, the high efficiency of the
binary system is probably attributed to a synergistic effect
40
Fig. 1 Organic bases structures (a); the effect of organic bases on the
yield of cyclic carbonate (b). pKa value of the conjugated acid in water
which was obtained from the U.S. National Library of Medicine data-
between NBu
4
Br and NEt
3
during the catalytic conversion of CO
2
base.42 Reaction conditions: 2-(chloromethyl)oxirane (12.8 mmol),
ꢀ
with epoxides to cyclic carbonates.
4
NBu Br (0.06 mmol), organic base (0.5 mL), CO
2
(1 atm), 100 C, 1 h.
The possibility of by-product was 3-chloro-1,2-propanediol.
Additionally, the inuence of the basicity on the conversion
of 2-(chloromethyl)oxirane was investigated in the presence of
ꢀ
NBu Br with various organic bases at 100 C for 1 h (Fig. 1a and
4
2
The dependence of the cycloaddition reaction of CO and 2-
chloromethyl)oxirane on temperature is shown in Fig. 2a. The
b). As shown in Fig. 1b, the yield of 4-(chloromethyl)-1,3-
dioxolan-2-one greatly related to the basicity of organic bases,
(
results indicated that the activity of this catalytic system is
highly dependent on the reaction temperature. In the lower
temperature region (25 to 50 C), the yield of 4-(chloromethyl)-
3
and NEt gave rise to the highest conversion of 2-(chloromethyl)
oxirane to corresponding product due to its strongest alkalinity
and minimum steric hindrance. The activities of organic bases
decreased sharply from 99% to 92 and 63% when the pKa
decrease from 18.8 to 10.2, respectively. As reported previously,
ꢀ
41
the base was weaker, the DG of this reaction was lower, so the
basicity order might be DIPEA > NEt > TBA > TMEDA > MIm >
3
Py > DMBA. However, the catalytic activity order of the organic
bases is not in strict accordance with the established pKa, that
was NEt > TBA > Py > TMEDA > MIm > DIPEA > DMBA, which
3
indicates that the basicity of the organic bases is one important
factor for promoting catalytic activity, but the steric-hindrance
23
also play a role in this catalytic reaction.
Table 1 Catalyst screening for the conversion of CO
omethyl)oxirane
2
with 2-(chlor-
a
b
b
Entry
Catalyst
Time (h)
Yield (%)
Select. (%)
1
2
3
4
5
6
NBu
NBu
NBu
NBu
NBu
4
4
4
4
4
Br + NEt
Cl + NEt
I + NEt
3
1
1
1
1
1
1
99
97
96
43
34
36
>99
>99
>99
>99
>99
>99
3
Fig. 2 Effects of different reaction parameters. (a) Effects of reaction
temperature, conditions: 2-(chloromethyl)oxirane (12.8 mmol),
NBu Br (0.06 mmol), NEt (0.5 mL), CO (1 atm), 1 h. (b) Effects of
4 3 2
reaction time, conditions: 2-(chloromethyl)oxirane (12.8 mmol),
3
PF + NEt
6 3
Br
NEt
3
ꢀ
NBu
CO
4
Br (0.06 mmol), NEt
3
(0.5 mL), CO
2
(1 atm), 100 C. (c) Effects of
a
2
pressure, conditions: 2-(chloromethyl)oxirane (12.8 mmol),
NBu Br (0.06 mmol), NEt (0.5 mL), 100 C, 1 h. (d) Effects of mass ratio
Reaction conditions: 2-(chloromethyl)oxirane (12.8 mmol), NBu
4
X (X
ꢀ
ꢁ
ꢁ
ꢁ
ꢁ
ꢀ
4
3
¼
Br , Cl , I , PF
6
) (0.06 mmol), NEt
3
(0.5 mL), CO
2
(1 atm), 100 C.
b
1
of NEt
3
/NBu
4
Br, conditions: 2-(chloromethyl)oxirane (12.8 mmol),
Yield was determined by GC and H NMR. The possibility of by-
product was 3-chloro-1,2-propanediol.
ꢀ
4
NBu Br (0.06 mmol), CO
2
(1 atm), 100 C, 1 h. The possibility of by-
product was 3-chloro-1,2-propanediol.
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 13122–13127 | 13123

View Article Online
RSC Advances
Paper
1
,3-dioxolan-2-one increases slowly with increasing tempera- compared to the reactants. This is consistent with the ineffi-
ꢀ
ture. A further increase in temperature from 50 to 100 C has cient reaction under the mild experimental conditions.
signicant effects on the 2-(chloromethyl)oxirane conversion,
and gave the target product in 99% GC yield at 100 C for 1 h. NEt is introduced as the catalyst in addition to the system. To
The efficiency of the reaction is promoted signicantly when
ꢀ
3
2
The kinetic curve for catalytic conversion of CO into cyclic gain further insight into the synergetic catalytic role played by
carbonates was also investigated in the presence of NEt
3
/
3 4
NEt and NBu Br, more detailed calculations were carried out.
ꢀ
NBu
4
Br at 100 C. As shown in Fig. 2b, the yield of 4-
(chloromethyl)-1,3-dioxolan-2-one increased rapidly in the rst
4
2
0 min and then went up slowly. The complete consumption of Table 2 Cycloaddition of CO2 to various expoxides catalyzed by
-(chloromethyl)oxirane and synchronous formation of the triethylamine/NBu Br
4
a
desired product was achieved in 1 h. It should mentioned that
the selectivity remains above 99% in the entire catalytic process.
It could be obviously seen that the reaction pressure showed
a great effect on the cycloaddition reaction (Fig. 2c). With the
b
Entry
Epoxide
Product
Time (h)
1
Yield (%)
Sel. (%)
>99
1
98
increase of CO
dioxolan-2-one yield increases from 20 to 99%. A further
increase in the CO pressure from 1 to 1.5 atm results in a same
2
from 0.25 to 1 atm, the 4-(chloromethyl)-1,3-
2
1
7
level in 2-(chloromethyl)oxirane conversion. A similar effect of
2
3
4
5
10
59
98
>99
>99
>99
>99
20
CO pressure on catalytic activity was observed in other related
2
43,44
catalytic systems.
The inuence of NEt
3
4
to NBu Br ratio on the yield of 4-
(
1
chloromethyl)-1,3-dioxolan-2-one was also investigated at
1
8
1
17
82
98
ꢀ
00 C for 1 h with xed NBu
4
Br (0.06 mmol). As shown in
to NBu Br increases from 1.6 to
8.2, the 4-(chloromethyl)-1,3-dioxolan-2-one yield increased
2
Fig. 2d, when the ratio of NEt
1
3
4
rapidly. Then the 2-(chloromethyl)oxirane conversion stayed
almost constant when ratio of NEt to NBu Br increased further.
3
4
1
4
8
16
85
99
The excellent catalytic activity encouraged us to further explore
the generality of the catalytic system, and several expoxides with
different steric and electronic characters were tested. The results
show that the various diverse epoxides were converted to the cor-
responding cyclic carbonates in high yields and excellent selective
by this effective catalytic system (Table 2). The complete conver-
sion of 2-(chloromethyl)oxirane is attributed to the presence of
1
10
11
66
99
20
electron-withdrawing –CH Cl group (entry 1), which facilitates
2
nucleophilic attack of halide anions during the ring opening of the
45,46
epoxide.
The catalytic system is still effective for the epoxides
with long alkyl carbon chain, such as 2-butyloxirane, 2-(ethox-
ymethyl)oxirane and 2-((allyloxy)methyl)oxirane (entries 2–4). The
reactivity of epoxides with aromatic substituent is similar to that of
long alkyl carbon chain (entries 5, 6). Interestingly, the complete
1
4
6
17
95
99
6
>99
0
conversion of 2,2 -(((propane-2,2-diylbis(4,1-phenylene))bis(oxy))
0
bis(methylene))bis(oxirane) into 4,4 -(((propane-2,2-diylbis(4,1-
phenylene))bis(oxy))bis(methylene))bis(1,3-dioxolan-2-one) could
be achieved in 18 h (entry 7).
To further understand the underlying principles of CO
2
activation, the computation by the DFT (M06-2X) calculations
1
8
1
21
79
99
was studied. Preliminary calculations indicated no involvement
+
7
>99
of NBu
4
cation (Fig. S1 in ESI†), which was consequently
8
47
neglected from the elaborate calculations reported herein.
With bromide as catalyst (Fig. 3), the ring opening through the
attack of a nucleophile on epoxide and CO addition takes place
2
a
simultaneously in TS1, which is considered to be the rate-
determining step with a free energy of 22.3 kcal mol . Subse-
quently, this reaction tended to undergo the carbonate ring-
ꢁ
1
a
Reaction conditions: epoxide (12.8 mmol), NBu
4
Br (0.06 mmol), NEt
3
ꢀ
b
1
(0.5 mL), CO
2
(1 atm), 100 C. Yield was determined by GC and
H
a
ꢁ1
closure step ( TS2) has the energy of 10.8 kcal mol
NMR. The possibility of by-products were corresponding diols.
13124 | RSC Adv., 2019, 9, 13122–13127
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
a solvent but also inuences the course of the reaction. Thus,
the mechanism when NEt participation tends to a bromine and
3
NEt3 jointly catalyzed process (blue prole shown in Fig. 4),
a new intermediate C appears, resulting from the CO addition
1
2
upon interaction with NEt
3
and bromine. This rate-determining
step presented no transition states and has an energy of
ꢁ
1
ꢁ1
1
7.5 kcal mol the above reactants, 4.8 kcal mol energy
favorable than pure bromine-catalyzed process in gas-phase,
ꢁ
1
1
3.8 kcal mol decrease than bromine-catalyzed procedure in
NEt solvent, which allows the reaction to be performed under
3
mild conditions. A potential energy surfaces scan calculation
based on C1 intermediate validates transition states non-
existent (Fig. S3 in ESI†). It is conceivable that the ring-
opening of epoxide and CO
2
addition might undergo synchro-
nously with two catalysts. Aerwards, ring-closure takes place
Fig. 3 Free energy profiles for carbonate formation with bromine as
catalyst in gas-phase.
c
through TS1. NEt
which reverts to A
3
then dissociates from the reacting system,
a
1
and evolves to product through TS2 with
ꢁ
1
a free energy of 27.7 kcal mol
calculated rate constant is 1.850 ꢂ 10
corresponding half-life is ten minute, which accord with the
experimental data. The intermediate of A with C were selected
to compare the structure changes in reaction, the C–O bond of
CO change slightly as shown in Fig. S4,† while the C–O bond
between C atom of CO moiety and O atom of epoxide moiety
above the reactants. The
ꢁ3
ꢁ1
s
at 373 K. Then the
When the reaction was calculated in NEt
3
solution, there
different mechanisms were revealed (Fig. 4). The bromide-
catalyzed process (black energy prole shown in Fig. 4) in
1
1
NEt solution shows the same transition states and intermedi-
3
2
ates as in gas-phase. But the energy barrier of rate-determining
ꢁ
1
ꢁ1
2
step is 31.1 kcal mol , which is 8.8 kcal mol larger this
˚
˚
decreases from 1.46 A to 1.43 A, then the interaction between
CO and epoxide moieties enhanced with NEt as solution and
procedure without NEt
3
solvent. Also the carbonate ring-closure
a
ꢁ1
2
3
step ( TS2) in NEt
3
solution has an energy of 18.2 kcal mol
,
ꢁ
1
catalyst. Moreover, the Mulliken charge of carbon atom of CO2
moiety decreases from 0.3 to 0.07 when compared C with A
which is 7.4 kcal mol larger than bromide-catalyzed process
in gas. For comparison, we also calculated the reaction with
1
1.
Therefore, the bond length and charge analysis suggest that the
NEt as catalyst in the absence of bromide (red prole). The
3
lone pair electron of nitrogen in NEt
C and TS1.
1
3
stabilized the formation of
NEt -catalyzed epoxide ring-opening procedure has a high
3
c
b
ꢁ1
energy barrier ( TS1, 42.4 kcal mol , red prole in Fig. 4),
which is 11.3 kcal mol larger than bromide-catalyzed transi-
ꢁ1
Overall, a plausible mechanism for triethylamine-promoted
catalytic conversion of CO into cyclic carbonates has been
2
tion state in NEt
3
solution. Aerwards, the CO
2
addition step to
b
ꢁ1
proposed based on the aforementioned results (Fig. 5). First, the
epoxide ring opens through nucleophilic attack on the less
form TS2 has an energy of 46.0 kcal mol relative to the energy
of the reactants. Finally, this mechanism of ring-closure process
ꢁ
b
sterically hindered b-carbon atom by Br to produce an alkoxide
may undergo a TS3 transition states, which has an energy of
ꢁ
1
ion, and simultaneously CO is activated by NEt via electrostatic
2
3
4
4.7 kcal mol above the reactants. However, the energy barrier
ꢁ
1
interaction to form the carbamate salt. Then a new intermediate
is produced resulting from the nucleophilic attack on carba-
mate salt by alkoxide ion. Finally, cyclic carbonate is produced by
following intramolecular ring-closure reaction of C
of 42.4 kcal mol is quite high and consistent with a sluggish
reaction and unable to take place under mild experimental
conditions, indicating that NEt
C
1
48
3
does not merely act as
1
.
Fig. 5 Proposed reaction pathway for cyclic carbonate formation
catalyzed by NEt and NBu Br.
Fig. 4 Free energy profiles of three different mechanisms in NEt
3
.
3
4
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 13122–13127 | 13125

View Article Online
RSC Advances
Paper
50
were performed in this work. The continuum SMD model was
Conclusions
51
applied. The Gaussian 09 package was used for all of our
solvent.
An efficient binary catalytic system containing triethylamine calculations in NEt
and NBu Br was screened for catalytic conversion of CO and
epoxides into cyclic carbonates under metal-free mild condi-
3
4
2
Conflicts of interest
tions. Especially, NEt
3 2
could activate CO via electrostatic
interaction and remarkably reduce the reaction energy to
promote the reaction in the catalytic system. This work not only
There are no conicts to declare.
presents a simple and useful route for CO chemical xation
2
into high-value chemicals, but provides a detailed mechanistic Acknowledgements
2
understanding of CO activation and xation process.
This work was nancially supported by the National Natural
Science Foundation of China (21603228 and 21671039) and
Natural Science Foundation of Fujian Province (2015J01038),
State Key Laboratory of Structural Chemistry and Program for
Innovative Research Team in Science and Technology in Fujian
Province University (IRTSTFJ) and the Open Project Program of
the State Key Laboratory of Photocatalysis on Energy and
Environment (SKLPEE-KF201813).
Experimental
General
Chemicals including NEt , NBu Br, NBu Cl, NBu I, NBu PF ,
3
4
4
4
4
6
epoxides and CO are commercially available and used directly
2
without further purication. Gas chromatography (GC) was
performed on a Shimadzu GC-2014 equipped with a capillary
column (RTX-5, 30 m ꢂ 0.25 mm) using a ame ionization
detector.
Notes and references
1
F. D. Bobbink, D. Vasilyev, M. Hulla, S. Chamam, F. Menoud,
G. Laurenczy, S. Katsyuba and P. J. Dyson, ACS Catal., 2018,
Typical catalytic reaction
The cycloaddition reaction was carried out by magnetic stirring,
8
, 2589–2594.
trimethylamine (0.5 ml), NBu
omethyl)oxirane (12.8 mmol) were added into a reactor at room
temperature. Then, the reactor was sealed and purged with CO
to remove air. CO was introduced into the reactor and the
4
Br (0.06 mmol) and 2-(chlor-
2
3
B. B. Lu, W. Jiang, J. Yang, Y. Y. Liu and J. F. Ma, ACS Appl.
Mater. Interfaces, 2017, 9, 39441–39449.
A. Buonerba, A. D. Nisi, A. Grassi, S. Milione,
C. Capacchione, S. Vagin and B. Rieger, Catal. Sci. Technol.,
2
2
pressure was adjusted to 1 atm at room temperature. The
reactor was placed into pre-heated oil bath and temperature was
2
015, 5, 118–123.
Q. L. Qian, J. J. Zhang, M. Cui and B. X. Han, Nat. Commun.,
016, 7, 11481.
4
5
ꢀ
maintained at 100 C. Aer the reaction was completed, the
2
ꢀ
reactor was cooled to 0 C in ice-water bath, and then the excess
L. G. Ding, B. J. Yao, W. L. Jiang, J. T. Li, Q. J. Fu, Y. A. Li,
Z. H. Liu, J. P. Ma and Y. B. Dong, Inorg. Chem., 2017, 56,
2
of CO was carefully vented. The mixture was diluted with ethyl
acetate. The conversion of epoxide and yield of cyclic carbonate
were determined by gas chromatography (Shimadzu GC-2014,
2337–2344.
6
7
C. Feng, X. L. Cao, L. G. Zhang, C. Y. Guo, N. Akram and
J. D. Wang, RSC Adv., 2018, 8, 9192–9201.
E. Fazekas, G. S. Nichol, M. P. Shaver and J. A. Garden, Dalton
Trans., 2018, 47, 13106–13112.
1
a ame ionization detector) and H NMR.
Computational details
49
The M06-2X functional was employed in this article to perform
all the calculations. Our structure optimizations were as
8 D. H. Lan, H. T. Wang, L. Chen, C. T. Au and S. F. Yin,
Carbon, 2016, 100, 81–89.
follows. In NBu
tions were performed. For carbonate formation with bromine as
catalyst, the structures were rstly optimized base on the level of
4
Br involved reaction, only gas-phase calcula-
9 L. Wang, R. L. Zhang, Q. X. Han, C. Xu, W. M. Chen, H. Yang,
G. S. Gao, W. W. Qin and W. S. Liu, Green Chem., 2018, 20,
5311–5317.
6-31+G(d,p) in gas-phase, then the solvent structure optimiza- 10 M. H. Anthofer, M. E. Wilhelm, M. Cokoja, M. Drees,
tions were carried out based on gas-phase results. As for the rest
of other structure optimizations, the calculations were per-
W. A. Herrmann and F. E. K u¨ hn, ChemCatChem, 2015, 7,
94–98.
formed in solvent. Vibrational frequency analyses at the same 11 L. Martinez-Rodriguez, J. Otalora Garmilla and A. W. Kleij,
basis sets were used on all optimized structures in order to ChemSusChem, 2016, 9, 749–755.
characterize stationary points as local minima or transition 12 J. K. Qiu, Y. L. Zhao, Z. Y. Li, H. Y. Wang, M. H. Fan and
states. Furthermore, the intrinsic reaction coordinate (IRC) J. J. Wang, ChemSusChem, 2017, 10, 1120–1127.
calculations at the same level have been applied to validate that 13 Z. J. Guo, Q. W. Jiang, Y. M. Shi, J. Li, X. N. Yang, W. Hou,
transition states connect appropriate reactants and products. Y. Zhou and J. Wang, ACS Catal., 2017, 7, 6770–6780.
The Gibbs free energy were further calculated by single-point 14 M. R. Li, M. C. Zhang, T. J. Yue, X. B. Lu and W. M. Ren, RSC
energy calculations using M02-2X/6-311+G(d,p) method on Adv., 2018, 8, 39182–39186.
previously 6-31+G(d,p) structures and thermal corrections at 15 L. Wang, G. Y. Zhang, K. Kodama and T. Hirose, Green
98.15 K and 1 atm. No conformational sampling calculations Chem., 2016, 18, 1229–1233.
2
13126 | RSC Adv., 2019, 9, 13122–13127
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
1
1
1
1
6 C. Maeda, T. Taniguchi, K. Ogawa and T. Ema, Angew. Chem., 38 B. Sarmah and R. Srivastava, Ind. Eng. Chem. Res., 2017, 56,
Int. Ed., 2015, 54, 134–138. 8202–8215.
7 H. L. Parker, J. Sherwood, A. J. Hunt and J. H. Clark, ACS 39 H. Zhong, Y. Q. Su, X. W. Chen, X. J. Li and R. H. Wang,
Sustainable Chem. Eng., 2014, 2, 1739–1742. ChemSusChem, 2017, 10, 4855–4863.
8 A. H. Tamboli, A. A. Chaugule and H. Kim, Fuel, 2016, 184, 40 L. Wang, G. Zhang, K. Kodama and T. Hirose, Green Chem.,
33–241. 2016, 18, 1229–1233.
9 Z. Z. Yang, L. N. He, Y. N. Zhao, B. Li and B. Yu, Energy 41 D. J. Heldebrant, C. R. Yonker, P. G. Jessopc and L. Phan,
Environ. Sci., 2011, 4, 3971–3975. Energy Environ. Sci., 2008, 1, 487–493.
0 J. Q. Wang and Y. G. Zhang, ACS Catal., 2016, 6, 4871–4876. 42 L. Gong and J. S. McCullagh, Rapid Commun. Mass Spectrom.,
2
2
2
1 L. Guo, L. L. Deng, X. C. Jin, Y. R. Wang and H. Z. Wang, RSC
Adv., 2018, 8, 26554–26562.
2014, 28, 339–350.
43 J. Q. Wang, W. G. Cheng, J. Sun, T. Y. Shi, X. P. Zhang and
S. J. Zhang, RSC Adv., 2014, 4, 2360–2367.
2
2
2
2
2 C. K. Johannes Steinbauer, R. Ludwig and T. Werner, ACS
Sustainable Chem. Eng., 2018, 6, 10778–10788.
44 M. S. Liu, L. Liang, X. Li, X. X. Gao and J. M. Sun, Green
Chem., 2016, 18, 2851–2863.
3 J. Sun, W. G. Cheng, Z. F. Yang, J. Q. Wang, T. T. Xu, J. Y. Xin
and S. J. Zhang, Green Chem., 2014, 16, 3071–3078.
4 R. C. Luo, Z. Yang, W. Y. Zhang, X. T. Zhou and H. B. Ji, Sci.
China: Chem., 2017, 60, 979–989.
45 Z. Z. Yang, Y. F. Zhao, G. P. Ji, H. Y. Zhang, B. Yu, X. Gao and
Z. M. Liu, Green Chem., 2014, 16, 3724–3728.
46 J. Liang, R. P. Chen, X. Y. Wang, T. T. Liu, X. S. Wang,
Y. B. Huang and R. Cao, Chem. Sci., 2017, 8, 1570–1575.
5 T. Berestok, P. Guardia, R. F. Du, J. B. Portals, M. Colombo,
S. Estrade, F. Peiro, S. L. Brock and A. Cabot, ACS Appl. Mater. 47 C. J. Whiteoak, A. Nova, F. Maseras and A. W. Kleij,
Interfaces, 2018, 10, 16041–16048. ChemSusChem, 2012, 5, 2032–2038.
6 J. Zhu, P. M. Usov, W. Q. Xu, P. J. Celis-Salazar, S. Y. Lin, 48 W. Cho, M. S. Shin, S. Hwang, H. Kim, M. Kim, J. G. Kim and
M. C. Kessinger, C. Landaverde-Alvarado, M. Cai, Y. Kim, J. Ind. Eng. Chem., 2016, 44, 210–215.
A. M. May, C. Slebodnick, D. Zhu, S. D. Senanayake and 49 Y. Zhao and D. G. Truhlar, Theor. Chem. Acc., 2008, 120, 215–
A. J. Morris, J. Am. Chem. Soc., 2018, 140, 993–1003. 241.
7 K. Zhou, B. Mousavi, Z. X. Luo, S. Phatanasri, 50 A. V. Marenich, C. J. Cramer and D. G. Truhlar, J. Phys. Chem.
2
2
S. Chaemchuen and F. Verpoort, J. Mater. Chem. A, 2017, 5,
52–957.
8 J. Y. Hu, J. Ma, H. Z. Liu, Q. L. Qian, C. Xie and B. X. Han,
Green Chem., 2018, 20, 2990–2994.
9 X. H. Song, Y. F. Wu, D. H. Pan, F. F. Cai and G. M. Xiao, Mol.
Catal., 2017, 436, 228–236.
0 J. Liang, Y. Q. Xie, Q. Wu, X. Y. Wang, T. T. Liu, H. F. Li,
Y. B. Huang and R. Cao, Inorg. Chem., 2018, 57, 2584–2593.
1 J. J. Zhu, T. T. Diao, W. Y. Wang, X. L. Xu, X. Y. Sun,
S. A. C. Carabineiro and Z. Zhao, Appl. Catal., B, 2017, 219,
B, 2009, 113, 6378–6396.
9
51 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
G. A. Petersson, H. Nakatsuji, X. Li, M. Caricato,
A. Marenich, J. Bloino, B. G. Janesko, R. Gomperts,
B. Mennucci, H. P. Hratchian, J. V. Ortiz, A. F. Izmaylov,
J. L. Sonnenberg, D. Williams-Young, F. Ding, F. Lipparini,
F. Egidi, J. Goings, B. Peng, A. Petrone, T. Henderson,
D. Ranasinghe, V. G. Zakrzewski, J. Gao, N. Rega,
G. Zheng, W. Liang, M. Hada, M. Ehara, K. Toyota,
R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, T. Vreven, K. Throssell,
J. A. Montgomery Jr, J. E. Peralta, F. Ogliaro, M. Bearpark,
J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov,
T. Keith, R. Kobayashi, J. Normand, K. Raghavachari,
A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi,
J. M. Millam, M. Klene, C. Adamo, R. Cammi,
J. W. Ochterski, R. L. Martin, K. Morokuma, O. Farkas,
J. B. Foresman, and D. J. Fox, Gaussian 09, Revision E.01,
Gaussian, Inc., Wallingford CT, 2016.
2
2
3
3
92–100.
3
3
3
3
2 A.-L. Girard, N. Simon, M. Zanatta, S. Marmitt, P. Gonçalves
and J. Dupont, Green Chem., 2014, 16, 2815–2825.
3 Q. Liu, L. P. Wu, R. Jackstell and M. Beller, Nat. Commun.,
2
015, 6, 5933.
4 S. Marmitt and P. F. Goncalves, J. Comput. Chem., 2015, 36,
322–1333.
1
5 S. Hayashi, S. Yamazoe, K. Koyasu and T. Tsukuda, Chem.–
Asian J., 2017, 12, 1635–1640.
6 X. D. Lang and L. N. He, Chem. Rec., 2016, 16, 1337–1352.
7 X. F. Liu, Q. W. Song, S. Zhang and L. N. He, Catal. Today,
3
3
2016, 263, 69–74.
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 13122–13127 | 13127