Dual functions of N,N-dimethylethanolamnium-based ionic liquids for the Knoevenagel reactions at room temperature

Article abstract of DOI:10.1016/j.cattod.2012.06.006

In this work, the hydrogen bond formation ability of cation and anion of the ILs was determined by using the solvatochromic method and was found to be responsible for their catalytic activity in the Knoevenagel reactions. The enhancement in the hydrogen bond donor ability of the cations and the hydrogen bond acceptor ability of the anions can both lead to the increase in the catalytic activity of the ILs. From the proposed reaction mechanism, it was deduced that the cations of the ILs can form hydrogen bond with aldehyde to activate the CO bond as electrophile, and the anions of the ILs can promote active methylene compound to produce carboanion as nucleophile, showing dual function activation effect in the catalytic processes. In addition, the optimized N,N-dimethylethanolamnium acetate as dual function activator for the Koevenagel reactions benefits from wide substrates tolerance, ambient reaction temperature, easy work-up procedure, and easy reuse of the IL.

Full text of DOI:10.1016/j.cattod.2012.06.006

Catalysis Today 200 (2013) 17–23
Contents lists available at SciVerse ScienceDirect
Catalysis Today
journal homepage: www.elsevier.com/locate/cattod
Dual functions of N,N-dimethylethanolamnium-based ionic liquids for the
Knoevenagel reactions at room temperature
Anlian Zhu, Ruixia Liu, Lingjun Li, Liangyun Li, Lan Wang, Jianji Wang∗
School of Chemical and Environmental Sciences, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007,
PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
In this work, the hydrogen bond formation ability of cation and anion of the ILs was determined by using
the solvatochromic method and was found to be responsible for their catalytic activity in the Knoevenagel
reactions. The enhancement in the hydrogen bond donor ability of the cations and the hydrogen bond
acceptor ability of the anions can both lead to the increase in the catalytic activity of the ILs. From the
proposed reaction mechanism, it was deduced that the cations of the ILs can form hydrogen bond with
aldehyde to activate the C O bond as electrophile, and the anions of the ILs can promote active methylene
compound to produce carboanion as nucleophile, showing dual function activation effect in the catalytic
processes. In addition, the optimized N,N-dimethylethanolamnium acetate as dual function activator for
the Koevenagel reactions benefits from wide substrates tolerance, ambient reaction temperature, easy
work-up procedure, and easy reuse of the IL.
Received 19 March 2012
Received in revised form 27 May 2012
Accepted 8 June 2012
Available online 10 July 2012
Keywords:
Knoevenagel reaction
Ionic liquid
Hydrogen bond donor
Hydrogen bond acceptor
Catalytic activity
© 2012 Elsevier B.V. All rights reserved.
1. Introduction
cation and hydrogen bond acceptor property of the anion would be
essential for the catalytic potential of these ILs, and have been sub-
Ionic liquids (ILs) have attracted great interest in the area of
green chemistry due to their favorable properties such as negli-
gible vapor pressure, wide liquid range, excellent salvation ability
and feasible designablility [1]. As novel intriguing functional mate-
rials, they have been widely applied in organic synthesis and
catalysis [2–8], energy storage [9,10], extraction and separation
[11,12], biomass conversion and utilization [13,14] and among
others, and the applicable fields of ILs could be widened with
more and more new functional ILs being designed and synthe-
sized. However, rational design of ILs for a peculiar application
is still in its infancy, and thus the related studies on the rela-
tionship between the functions of ILs and their structures are in
a great necessary. It has been found that the cation and anion
of ILs have synergetic effect in catalyzing various organic reac-
tions [6,13–21]. For example, Chakraborti et al. [18–21] reported
the importance of both the cation and the anion of ILs in impart-
ing catalytic potential to 1-methyl-3-alkylimidizoluma-based ILs
in promoting various organic reactions. The role of the ILs has been
envisaged as cooperative “electrophile–nucleophile dual activa-
tion” through hydrogen-bonded networks. The results of various
spectroscopic studies, such as IR and 1H NMR, suggested that
hydrogen bond donor ability of C-2 hydrogen of the imidazolium
stantiated by identification of the hydrogen-bonded supramolec-
ular catalytic species through MALDI-TOf-TOF and ESI-MS
studies.
In the present work,
a series of ILs based on N,N-
dimethylethanolamnium (DMEA) moiety with different counter
anions have been synthesized, and the hydrogen bond donor ability
and the hydrogen bond acceptor ability of the ILs have been esti-
mated. The catalytic activity of these ILs on Knoevenagel reactions
has been investigated and the relationship between the catalytic
activity and the hydrogen bond formation ability of cation and
anion of the ILs has been discussed from the view-point of their
dual activation effect on electrophiles and nucleophiles. On the
other hand, this kind of ILs have shown excellent performance in
catalyzing Knoevenagel reactions with wide substrates tolerance,
easy separation and work-up procedures, feasible reutilization of
the ILs and benign reaction conditions.
2. Experimental
2.1. Chemicals and instruments
Acetic acid (Ac), propanoic acid (Pr), butanoic acid (Bu),
isobutanoic acid (i-Bu), and lactic acid (Lac) were all AR
grade and purchased from Aladdin Reagents Company. N,Nꢀ-
dimethylaminoethanol (AR grade) was obtained from Beijing
Chemical Reagent Company and distilled at reduced pressure
∗
Corresponding author. Tel.: +86 0373 3325805; fax: +86 0373 3329030.
E-mail address: jwang@henannu.edu.cn (J. Wang).
0920-5861/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.cattod.2012.06.006

18
A. Zhu et al. / Catalysis Today 200 (2013) 17–23
room temperature
OH
OH
NH
N
RCOOH
+
methanol
RCOO
R= CH3, CH3CH2, CH3CH2CH2, (CH3)2CH, CH3CHOH
(a)
(b)
OH
Anion exchange resin
OH
N
N
N
Cl
OH
OH
CH3COOH
CH3COO
C4H9
OH
OH
80oC
N
N
C4H9Cl
+
ethanol
Cl
Anion exchange resin
C4H9
OH
C4H9
OH
CH3COOH
N
N
OH
CH3COO
(c)
Scheme 1. Synthesis of protic N,Nꢀ-dimethylaminoethanol-based ionic liquids.
before use. Strong basic ion exchange resin (Ambersep
900 OH), 4-nitroaniline and N,N-diethyl-4-nitroaniline were
purchased from Alfa Aesar, and 2,6-dichloro-4-(2,4,6-triphenyl-
N-pyridino)phenolate (Reichardt’s dye 33) was obtained from
Aldrich. Aldehydes, ethyl cyanoacetate, malononitrile and
other reagents were analytical grade, and the water used
in this work was twice deionized. All of the commercially
available reagents were used as received unless indicated
otherwise.
(c)), the following produce was closely followed. Into a 100 ml
flask containing 0.1 mol N,Nꢀ-dimethylaminoethanol in ethanol at
80 ◦C, 0.11 mol chlorobutane was dropped under stirring through
a dropping funnel for 10 h to get [C4-choline][Cl], which was
ionic exchanged into [C4-choline][OH]. Then, [C4-choline][OH] was
neutralized with acetic acid to give [C4-choline][Ac]. Both of the
prepared ILs were pale yellow and viscous liquids at room temper-
ature. The purity for all of the ILs is higher than 99% as determined
by 1H NMR.
1H NMR spectra were recorded on a BRUKER AV-400 instrument
at room temperature by using TMS as internal standard. Melting
points were taken from a XRC-1 Microscopic Melting Point Mea-
surer (Sichuan University instrument factory) without correction.
The UV–vis spectra were determined by a TU-1021 spectrometer
(Beijing Persee Instrument Company) with a standard 5 mm cell,
and the temperature was controlled to 25.0 0.1 ◦C with a DC-
2006 low temperature thermostat (Shanghai Hengping Instrument
& Meter Factory, China).
2.3. General procedures for Knoevenagel reactions and
reutilization of the ILs
In a typical experiment, 0.5 mmol aldehyde, equivalent active
methylene compounds and a given amount of ILs were mixed in a
Table 1
Catalytic performance of different ILs for the Knoevenagel reactions.
Entry
IL (molar ratio of IL to substrate)
Time
Isolated yield (%)
2.2. Synthesis and characterization of the ILs
1
2
3
4
5
6
7
8
9
10
11
12
13
14a
[DMEA][Ac] (0.2:1)
[DMEA][Ac] (0.5:1)
[DMEA][Ac] (1:1)
[DMEA][Ac] (1.5:1)
[DMEA][Pr] (1:1)
[DMEA][Bu] (1:1)
[DMEA][i-Bu] (1:1)
[DMEA][Lac] (1:1)
[DMEA][Ac] (0.1:1)
[Choline][Ac] (0.1:1)
[C4-Choline][Ac] (0.1:1)
DMEA
1.5 h
85
97
99
99
90
85
85
60
80
85
99
70
60
98
40 min
25 min
25 min
25 min
25 min
25 min
25 min
6 h
6 h
5 h
3.5 h
3.5 h
Protic ILs were synthesized simply by neutralization of
N,Nꢀ-dimethylaminoethanol with corresponding carboxyl acids
(Scheme 1, path (a)). In
a
typical reaction, 0.1 mol N,Nꢀ-
dimethylaminoethanol dissolved in 10 ml methanol was put into
a 100 ml flask, and 0.1 mol carboxyl acid was slowly added under
stirring. The solution was stirred at room temperature for 24 h to
complete the reaction, and then the methanol was removed at 50 ◦C
under reduced pressure to give a pale yellow and viscous liquid.
[Choline][Ac] was synthesized by the neutralization reaction of
acetic acid with [Choline][OH] prepared from the ionic exchange
of [Choline][Cl] by strong basic ionic exchange resin (Scheme 1,
path (b)). For the preparation of [C4-choline][Ac] (Scheme 1, path
[AM][Ac]
[DMEA][Ac] (1:1)
25 min
a
The fifth reuse of the recovered ionic liquid.

A. Zhu et al. / Catalysis Today 200 (2013) 17–23
19
Table 2
flask and stirred for a desired time at room temperature. The reac-
The ˛ and ˇ values of the ILs at 25 ◦C.
tions were monitored by TLC. At the end of the reactions, water was
added to the mixtures. The ILs dissolved in water can be recycled for
at least five times without significant activity decrease after simple
drying process. Most of the products can be obtained from simple
filtration after the water was added to the reaction mixtures, and
no further purification was required. All of the products were pre-
Entry
IL
˛
ˇ
1
2
3
4
5
6
7
[DMEA][Ac]
[DMEA][Pr]
[DMEA][Lac]
1.08
0.99
0.82
1.14
1.11
0.57
0.53
0.71
0.82
0.64
0.61
0.65
0.75
0.96
[DMEA][Bu−
[DMEA][i-Bu−
[Choline][Ac]
]
]
viously reported, they were characterized by melting point and 1
NMR spectroscopy measurements.
H
[C4-choline][Ac]
the solvent parameters were calculated by using the following
equations [25,26]:
2.4. Determinations of the hydrogen bond donor and acceptor
parameters
1
ꢁdye
=
(1)
ꢀmax (dye) × 10−4
The hydrogen bond formation ability of the ILs was eval-
uated from the hydrogen bond donor ability and the hydro-
gen bond acceptor ability of the ILs by using the solva-
tochromic method established by Kamlet and Taft [22–24].
For this purpose, Reichardt’s dyes, 4-nitroaniline and N,N-
diethyl-4-nitroaniline were selected as a set of solvatochromic
ꢀ
ꢁ
28592
ET (30) = 0.9986
− 8.6878
(2)
ꢀ
ꢀmax (Reichardt s dye 33)
ꢂ∗ = 0.314(27.52 − ꢁ(N,N-diethyl−4−nitroaniline)
˛ = 0.0649 ET (30) − 2.03 − 0.72 ꢂ∗
)
(3)
(4)
probes.
A less basic probe, 2,6-dichloro-4-(2,4,6-triphenyl-1-
pyridinio)phenolate (Reichardt’s dye 33, pKa = 4.78), was used to
determine polarity of the ILs due to the strong acidity of these pro-
tic ILs. The procedure for the measurements of the Kamlet–Taft
parameters of the ionic liquids was as follows. To 2 ml ionic
liquid, each probe dye was added as a concentrated dry dichloro-
mentane solution, and the concentration of probe dyes in the
ILs was kept at about 1 × 10−4 mol l−1 for Reichardt’s dye 33,
and 5 × 10−5 mol l−1 for both N,N-diethyl-4-nitroaniline and 4-
nitroaniline to avoid aggregation of the dyes. The dichloromentane
was then carefully removed by vacuum drying at 40 ◦C for 8 h.
These ionic liquids solutions were placed into quartz cells with
5 mm light-path length. Temperature of the quartz sample cell
was maintained at 25 ◦C by water circulation. From the wave-
length at the maximum absorption (ꢀmax) determined, values of
1.035ꢁ(N,N-diethyl-4-nitroaniline) + 2.64 − ꢁ(4−nitroaniline)
ˇ =
(5)
2.80
In these equations, ET (30), ꢂ*, ˛ and ˇ stand for polarity, dipo-
larity/polarizability, hydrogen bond donor ability (acidity) and
hydrogen bond acceptor ability (basicity) of the ILs, respectively.
3. Results and discussion
3.1. The catalytic activity of different ILs on the Knoevenagel
reactions
This work was originated from the discovery that ionic liq-
uid N,N-dimethylethanolamnium acetate is able to catalyze the
Fig. 1. The plausible reaction mechanism for [DMEA][Ac] promoted Knoevenagel reactions.

20
A. Zhu et al. / Catalysis Today 200 (2013) 17–23
Knoevenagel reaction between 4-nitrobenzaldehyde and ethyl
cyanoacetate, and its catalytic performance was affected by the
molar ratio of the IL to the substrates (Table 1, entries 1–4). It
was shown that catalytic activity of the IL increased with increas-
ing molar ratio of the IL to substrates from 0.2 to 1, but with the
further increase of the molar ratio, the catalytic performance was
kept at the same level. Then catalytic activity of the ILs with N,N-
dimethylethanolamnium cation but different carboxyl acid anions
for the Knoevenagel reaction between 4-nitrobenzaldehyde and
ethyl cyanoacetate was investigated at the mole ratio of 1:1 and
the results were also collected in Table 1 (Table 1, entries 5–8).
It was found that the catalytic performance of the ILs was signifi-
cantly affected by anions of the ILs, and the ILs with acetate anion
has the highest catalytic activity. Therefore, the ILs composed of
the same acetate anion but different cations were also investigated
for the catalysis of a model Knoevenagel reaction of benzaldehyde
with ethyl cyanoacetate (Table 1, entries 9–11) at the molar ratio
of 1:1. In the experiment, it was found that with the increase of
the carbon chain length linked on the nitrogen atom of cation of
the ILs, the reactions could be promoted significantly but suffered
from low isolated yields because of the low selectivity. However,
when the molar ratio of the ILs to substrates was decreased to 0.1:1,
[Choline][Ac] and [C4-Choline][Ac] could give satisfactory results,
especially [C4-Choline][Ac] could give almost quantitative isolated
yields within prolonged reaction time. This suggests that catalytic
activity of the ILs increases with the prolonged carbon chain length
of cations. However, the attempt to promote the same reaction was
not successful in N,N-dimethylethanolamnium because too many
side-reactions took place. This indicates that ionic nature of the IL
is also important for this reaction. In addition, under the cataly-
sis of ammonium acetate ([AM][Ac]), the same reaction gave only
60% conversion after 3 h, which suggests that introduce of hydroxyl
group in the cation benefits to the excellent performance of DMEA-
based ionic liquids.
The empirical Kamlet–Taft parameters including the hydrogen
bond donor acidity ˛ and hydrogen bond acceptor basicity ˇ deter-
mined experimentally were collected in Table 2 (entries 1–5). It
can be seen that for the ILs with the same cation of [DMEA], the ˛
Table 3
Knoevenagel reactions of different aldehydes with active methylene compounds.
O
CN
[DMEA][Ac]
R2
R1
+
R1
H
room temperature
R2
CN
1mmol
1mmol
.
Entry
R1
R2
Reaction time
Isolated yield (%)
mp (◦C)
158
80–81
101–102
188
Lit. mp (◦C)
1a
2b
4-NO2C6H4
C6H5
3-NO2C6H4
4-OHC6H4
4-OHC6H4
4-ClC6H4
4-ClC6H4
4-FC6H4
C6H4CH CH
C6H4CH CH
CH3OC6H4
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
20 min
1 min
20 min
2 min
2 min
30 min
30 min
2 min
30 min
30 min
1 h
97
97
92
99
93
95
65
99
83
70
97
157 [27]
80–81 [28]
100–102 [29]
188 [30]
188 [30]
160–161 [27]
160–161 [27]
–
3a
4a
5b
188
6a
159–160
159–160
–
114–115
114–115
114
7b
8b
9a
–
–
10b
11b
113–114 [27]
O
12b
13b
14b
15b
CN
CN
CN
CN
2 min
20 min
3 min
5 min
98
94.2
95
65–66
159–160
–
70[28]
2-OHC6H4
–
–
–
C6H13
4-(OH)C6H3-3-(OCH3)
90
138
N
16b
17a
18b
19a
20a
21b
CN
2 min
95
95
99
98
99
94
214
–
4-NO2C6H4
C6H5
COOC2H5
COOC2H5
COOC2H5
COOC2H5
COOC2H5
25 min
30 min
30 min
20 min
30 min
167–168
44–46
127–128
90
168 [28]
47–48 [28]
130–131 [28]
92–94 [31]
94–96 [28]
3-NO2C6H4
4-ClC6H4
4-FC6H4
98
O
22b
23b
24b
25a
26a
COOC2H5
COOC2H5
COOC2H5
COOC2H5
COOC2H5
5 min
5 min
30 min
5 min
30 min
95
98
95
91
80
88
111–112
–
167–168
98
84∼86[28]
C6H4CH CH
2-OHC6H4
4-OHC6H4
4-(OH)C6H3-3-(OCH3)
–
–
169–171 [28]
–
N
27a
COOC2H5
2 min
95
97–98
–
a
The ratio of the IL to the substrates is 1:1.
The ratio of the IL to the substrates is 0.2:1.
b

A. Zhu et al. / Catalysis Today 200 (2013) 17–23
21
values decrease in the sequence: Bu > i-Bu > Ac > Pr > Lac, suggesting
that the hydrogen bond donor ability of such ILs can be modu-
lated by the nature of the anions, although the relationship between
the ˛ values and the catalytic performance of the ILs is not clear.
The other parameter hydrogen bond acceptor basicity ˇ is found
to decrease in the order: Pr > Ac > i-Bu ≈ Lac > Bu. This sequence is
almost the same as the sequence of the catalytic activity of the
ILs for the Knoevenagel reactions except those with Ac and Pr as
the anions, indicating that the increase in hydrogen bond accep-
tor ability of the anions would lead to the increase in catalytic
activity. The irregular behavior of Ac and Pr anions in the catalytic
performance suggests that the hydrogen bond acceptor ability of
the anions is not the only factor influencing the Knoevenagel reac-
tions, and the hydrogen bond donor ability of the cations should
have synergetic effect on the catalytic reactions because the ˛ val-
ues of [DMEA][Ac] is larger than that of [DMEA][Pr], which may be
the reason for the higher catalytic activity of the former IL. Fur-
thermore, the Kamlet–Taft parameters of the ILs with the same
Ac anion but different cations have also been determined and the
results are collected in Table 2 (entries 1, 6 and 7). It was found that
the ˛ and ˇ values can be influenced by the change of the cations,
and the ˛ values decrease in the sequence of DMEA > Choline > C4-
Choline, which is not in accordance with the catalytic activity.
However, the ˇ values increase in the same sequence of the cat-
alytic activity, which indicates that the hydrogen bond acceptor
ability of the ILs is the main factor controlling their catalytic
activities.
reactions involving various aldehydes, including aromatic aldehy-
des with electro-donating groups as well as electro-withdrawing
groups, allyl aldehydes, and aliphatic aldehydes could all give
satisfactory isolated yields within 1 h. The reactions involving
heterocyclic aldehydes also showed excellent reaction activity in
this system such as furaldehyde and pyridine-4-carboxaldehyde,
and almost quantitative isolated yields were obtained within
5 min for their reactions with malononitrile and ethyl
cyanoacetate.
4. Conclusion
A series of ionic liquids based on N,N-dimethylethanolamnium
moiety were synthesized and found to be efficient for the pro-
motion of Knoevenagel reactions at ambient temperature, and the
substrates tolerance was considerably wide because aromatic alde-
hydes with electro-donating groups as well as electro-withdrawing
groups, allyl aldehydes, aliphatic aldehydes and heterocyclic alde-
hydes can all react with malononitrile and ethyl cyanoacetate
fluently and give good to excellent isolated yields. This reac-
tion system also benefit from the ambient reaction temperature,
easy preparation procedure, and the reuse of the ILs. Further-
more, it was found that the catalytic activity of the ILs was
relevant to the hydrogen bond forming ability of the ILs, and
the increase in the hydrogen bond donor ability of the cations
would increase the catalytic activity of the ILs. However, the
hydrogen bond acceptor ability of the anions played a more impor-
tant role in the catalytic activity of the ILs compared with the
hydrogen bond donor ability of the cations. These findings would
be useful for the better understanding of the synergetic effect
of ILs in catalytic reactions and for the rational design of the
ILs for the particular reactions from structure–activity relationships
of the ILs.
3.2. Plausible catalytic mechanism
Based on the different catalytic activities observed for the
studied ILs on the Knoevenagel reactions and their relationship
with the hydrogen bond forming ability of the ILs, a plausible
reaction mechanism was proposed and illustrated in Fig. 1. It
was deduced that the reaction was originated from the dehy-
drogenation of the active methylene compounds to form the
carboanion attacked by the anion of the ILs, and then the car-
boanion attacked the C O bond which was activated by the
formation of hydrogen bond with cation of the ILs to give the
intermediate ␣-cyano-alcohols, which was then attacked by the
anions of the ILs to form the dehydration productions. In this
catalytic procedure, anions of the ILs act as an activator for the
nucleophiles to produce carboanions, and cations of the ILs act
as an activator for the electrophiles to increase the polariza-
tion of C O bond. Therefore, it is reasonable to state that the
increased hydrogen bond acceptor ability of the anions will bene-
fit to the production of the carboanion and thus to the increased
catalytic activity. The increased hydrogen bond donor ability of
the cations would increase the polarization of C O bonds which
become easy to be attacked by the carboaions. As a result, the
increased hydrogen bond formation ability of the cations and the
anions results in the dual functions for the activation of the sub-
strates and contributes to the increased catalytic activities of the
ILs.
Acknowledgements
This work was supported by the National Natural Sci-
ence Foundation of China (Grant 20903037), the Research
Fund for the Doctoral Program of Higher Education of China
(20094104120003), and the Foundation of Henan Educational
Committee (2009B150014).
Appendix A.
Selected data for typical compounds are given below:
[DMEA][Ac]: 1H NMR (400 MHz; D2O): 1.729(s, 3H, CH3COO−),
2.683(s, 6H, (CH3)2N), 3.039–3.066 (q, 2H), 3.645–3.671
(q, 2H);
[Choline][Ac]: 1H NMR (400 MHz; D2O): 1.700(s, 3H, CH3COO−),
2.989(s, 9H, (CH3)3N), 3.294–3.319(q, 2H), 3.829–3.859(q, 2H);
[C4-Choline][Ac]: 1H NMR (D2O, 25 ◦C): 0.8(t, 3H,
CH3 (CH2)3 N); 1.22(m, 2H, CH3 CH2 (CH2)2 N); 1.60(m,
2H, CH3 CH2 CH2 CH2 N); 1.75(s, 3H, CH3 COO−);2.97(s,
3.3. Knoevenagel reactions between different aldehydes and
active methylene compounds
6H, CH3
N
CH3); 3.22(t, 2H, C3H7 CH2 N); 3.32(t, 2H,
CH2 CH2 OH); 4.678(s,
N
CH2 CH2 OH); 3.874(m, 2H,
As discussed above, [C4-Choline][Ac] has the highest catalytic
activity for the Knoevenagel reactions. However, considering
the fact that its preparation procedure is tedious and then
the cost is much higher, the Knoevenagel reactions of differ-
ent aldehydes with active methylene compounds were further
investigated by using [DMEA][Ac] as promotor. As the ratio
of the IL to the substrates is kept at 1:1 for the solid alde-
hydes and at 0.2:1 for the liquid aldehydes (see Table 3), the
1H, CH2 CH2 OH).
Products data
H
C
CN
C
CN
O2N
1.

22
A. Zhu et al. / Catalysis Today 200 (2013) 17–23
1H NMR (400 MHz, CDCl3): 7.878(s, 1H), 8.065–8.087(d, 2H),
H
C
O2N
CN
8.382–8.404(d, 2H); mp 158 ◦C, ref. 160–162 ◦C.
C
H
CN
C
C
COOCH2CH3
9.
CN
1H NMR (400 MHz, CDCl3): 1.408–1.443(t, 3H), 4.400–4.454(q,
2H), 7.720–7.761(m, 1H), 8.310(s, 1H), 8.395–8.431(d, 2H), 8.700(s,
1H); mp 127–128 ◦C, ref. 131–133 ◦C.
2.
1H NMR (400 MHz, CDCl3): 7.530–7.568(t, 2H), 7.621–7.659(t,
H
1H), 7.783(s, 1H), 7.905–7.923(d, 2H); mp 80–81 ◦C, ref. 82 ◦C.
C
CN
C
H
CN
C
C
COOCH2CH3
10
CN
1H NMR (400 MHz, CDCl3): 1.389–1.425(t, 3H), 4.367–4.420(q,
2H), 7.492–7.585(m, 3H), 7.988–8.006(d, 2H), 8.259(s, 1H); mp
Cl
3.
1HNMR (400 MHz, CDCl3): 7.515–7.536(d, 2H), 7.731(s, 1H),
46 ◦C, ref. 49 ◦C.
7.848–7.870(d, 2H); mp 158–160 ◦C, ref. 160–161 ◦C
H
C
CN
H
CN
C
C
C
COOCH2CH3
CN
11. Cl
HO
4.
1H NMR (400 MHz, CDCl3): 1.386–1.422(t, 3H), 4.366–4.419(q,
2H), 7.474–7.496(d, 2H), 7.928–7.950(d, 2H), 8.201(s, 1H); mp
1H NMR (400 MHz, CDCl3): 6.954–6.975(d, 2H), 7.651(s, 1H),
7.869–7.891(d, 2H); mp 188 ◦C, ref. 188 ◦C.
90 ◦C.
H
H
C
Cl
CN
C
C
C
CN
5. H C
3
COOCH CH
2
3
O
12. HO
1H NMR (400 MHz, CDCl3): 3.918(s, 3H), 7.006–7.028(d, 2H),
1H NMR (400 MHz, CDCl3): 1.381–1.417(t, 3H), 4.353–4.406(q,
2H), 6.093–6.130(m, 1H), 6.966–6.987(d, 2H), 7.954–7.976(d, 2H),
8.195(s, 1H); mp 167–168 ◦C, ref. 169–171 ◦C.
NC
7.654(s, 1H), 7.904–7.927(d, 2H); mp 113–114 ◦C, ref. 115–116 ◦C.
NC
C
CN
C
C
H
COOCH CH
2
3
6.
O
C
H
O
13.
1HNMR (400 MHz, CDCl3): 6.715–6.724(t, 1H), 7.364–7.373(s,
1H), 7.513(s, 1H), 7.805–7.808(d, 1H).
1H NMR (400 MHz, CDCl3): 1.367–1.402(t, 3H), 4.335–4.389(q,
2H), 6.657–6.666(t, 1H), 7.392–7.401(d, 1H), 7.751–7.753(d, 1H),
8.020(s, 1H); mp 88 ◦C, ref. 83 ◦C.
OH
CN
H
CN
C
C
COOCH2CH3
CN
7.
14.
1H NMR (400 MHz, CDCl3): 1.520–1.556(t, 3H), 4.479–4.533(q,
2H), 7.422–7.457(d, 2H), 7.580–7.590(t, 3H), 7.741–7.765(d, 2H),
1H NMR (400 MHz, CDCl3): 7.078–7.099(d, 1H), 7.148–7.166(t,
1H), 7.307–7.327(d, 1H), 7.443–7.478(t, 1H), 7.697(s, 1H); mp
158–160 ◦C.
8.155–8.182(m, 1H); mp 111–112 ◦C.
H
CN
C
H
C
CN
C
C
COOCH2CH3
COOCH CH
2
3
HO
O N
8.
2
1H NMR (400 MHz, CDCl3): 1.407–1.442(t, 3H), 4.299–4.454(q,
2H), 7.713–7.751(m, 1H), 8.123–8.365(m, 4H); mp 167–168 ◦C, ref.
168 ◦C.
O
CH3
15.

A. Zhu et al. / Catalysis Today 200 (2013) 17–23
23
1HNMR (400 MHz, CDCl3): 1.377–1.413(t, 3H), 3.987(s,
3H), 4.347–4.401(q, 2H), 6.212(s, 1H), 6.993–7.013(d, 1H),
[7] A. Sarkar, S.R. Roy, N. Parikh, A.K. Chakraborti, Journal of Organic Chemistry 76
(2011) 7132.
[8] S.R. Roy, P.S. Jadhavar, K. Seth, K.K. Sharma, A.K. Chakraborti, Synthesis (2011)
2261.
[9] J.L. Bideau, J.B. Ducros, P. Soudan, D. Guyomard, Advanced Functional Materials
21 (2011) 4073.
7.384–7.409(m, 1H), 7.854–7.858(d, 1H), 8.145(s, 1H); mp 98 ◦C.
COOCH2CH3
[10] B. Scrosati, J. Garche, Journal of Power Sources 195 (2010) 2419.
[11] L. Vidal, M.-L. Riekkola, A. Canals, Analytica Chimica Acta 715 (2012) 19.
[12] P.S. Kulkarni, C.A.M. Afonaso, Green Chemistry 12 (2010) 1139.
[13] S.S.Y. Tan, D.R. MacFarlane, Topics in Current Chemistry 290 (2009) 311.
[14] R.P. Swatloski, S.K. Spear, J.D. Holbrey, R.D. Rogers, Journal of the American
Chemical Society 124 (2002) 4974.
NC
CH
[15] A.L. Zhu, T. Jiang, B.X. Han, J.C. Zhang, Y. Xie, X.M. Ma, Green Chemistry 9 (2007)
169.
[16] L.F. Zhang, X.L. Fu, G.H. Gao, ChemCatChem 3 (2011) 1359.
[17] J. Sun, W.G. Cheng, W. Fan, Y.H. Wang, Z.Y. Meng, S.J. Zhang, Catalysis Today
148 (2009) 361.
[18] A.K. Chakraborti, S.R. Roy, Journal of the American Chemical Society 131 (2009)
6902.
N
16.
1HNMR (400 MHz, CDCl3): 1.555–1.591(t, 3H), 4.547–4.601(q,
2H), 7.902–7.917(d, 2H), 8.350(s, 1H) 8.969–8.984(d, 2H), mp
97–98 ◦C.
[19] K. Chakraborti, S.R. Roy, D. Kumar, P. Chopra, Green Chemistry 10 (2008) 1111.
[20] S.R. Roy, A.K. Chakraborti, Organic Letters 12 (2010) 3866.
[21] A. Sarkar, S.R. Roy, A.K. Chakraborti, Chemical Communications 47 (2011) 4538.
[22] M.J. Kamlet, R.W. Taft, Journal of the American Chemical Society 98 (1976) 377.
[23] R.W. Taft, M.J. Kamlet, Journal of the American Chemical Society 98 (1976)
2886.
[24] M.J. Kamlet, J.L. Addoud, R.W. Taft, Journal of the American Chemical Society
99 (1977) 6027.
[25] Y. Fukaya, K. Hayashi, M. Wada, H. Ohno, Green Chemistry 10 (2008) 44.
[26] C. Reichardt, Green Chemistry 7 (2005) 339.
[27] H.R. Shaterian, M. Arman, F. Rigi, Journal of Molecular Liquids 158 (2011) 145.
[28] G.W. Li, J. Xiao, W.Q. Zhang, Green Chemistry 13 (2011) 1828.
[29] M. Seifi, H. Sheibani, Catalysis Letters 126 (2008) 275.
[30] M.L. Deb, P.J. Bhuyan, Tetrahedron Letters 46 (2005) 6453.
[31] C.B. Yue, A.Q. Mao, Y.Y. Wei, M.J. Lu, Catalysis Communications 9 (2008) 1571.
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