2-hydroxyethylammonium formate ionic liquid grafted magnetic nanoparticle as a novel heterogeneous catalyst for the synthesis of substituted imidazoles

Article abstract of DOI:10.1002/aoc.4052

Catalytic one-pot condensation of benzil, aldehyde and ammonium acetate have been successfully carried out using 2-hydroxyethylammonium formate (HEAF) grafted on a magnetic nanoparticles as a new heterogeneous catalyst. The as-prepared catalyst was charac

Full text of DOI:10.1002/aoc.4052

Received: 20 May 2017
DOI: 10.1002/aoc.4052
Revised: 22 July 2017
Accepted: 23 July 2017
F U L L P A P E R
2‐hydroxyethylammonium formate ionic liquid grafted
magnetic nanoparticle as a novel heterogeneous catalyst for
the synthesis of substituted imidazoles
Maryam Rajabzadeh1 | Hossein Eshghi1
| Reza Khalifeh2
| Mehdi Bakavoli1
1 Department of Chemistry, Faculty of
Catalytic one‐pot condensation of benzil, aldehyde and ammonium acetate
have been successfully carried out using 2‐hydroxyethylammonium formate
(HEAF) grafted on a magnetic nanoparticles as a new heterogeneous catalyst.
The as‐prepared catalyst was characterized by FT‐IR, TEM, FESEM, VSM,
TGA and XRD. This catalyst indicated significant advantages, such as excellent
yields, shorter reaction time, reusability of the catalyst and easy workup
process.
Sciences, Ferdowsi University of Mashhad,
Mashhad 9177948974, Iran
2 Department of Chemistry, Shiraz
University of Technology, 71555‐313
Shiraz, Iran
Correspondence
Hossein Eshghi, Department of
Chemistry, Faculty of Sciences, Ferdowsi
University of Mashhad, Mashhad
9177948974, Iran.
Email: heshghi@um.ac.ir
Reza Khalifeh, Department of Chemistry,
Shiraz University of Technology, 71555‐
313, Shiraz, Iran.
Email: khalifeh@sutech.ac.ir
1 | INTRODUCTION
of expensive catalyst, tiresome work‐up, nonrecyclability
catalyst and long reaction times. Therefore, design and
Imidazole derivatives have been identified as important
chemical and biological active compounds.[1] Often
substituted imidazoles are also used as fungicides,[2] her-
bicides,[3] plant growth regulators[4] and therapeutic
agents.[5] In addition, the application of imidazole as ionic
liquids[6] and N‐heterocyclic carbenes[7] have expanded in
recent development green chemistry and organometallic
chemistry. Therefore, in recent times, the preparation of
this class of compounds has received significant attention.
The straightforward synthesis of these compounds
involves the one‐pot condensation of diketones,
aldehydes, and ammonium acetate in the presence of
protic acids[6–8] and Lewis acids[9–11] as catalysts.
Moreover, various methods have been designed to
synthesize substituted imidazoles using CAN,[12] L‐pro-
line,[13] L‐systeine,[14] N‐bromosuccinimide,[15] ytterbium
trifluoromethanesulfonate[10] and microwave irradia-
tion.[16] However, some of these methods show varying
drawbacks such as difficult reaction conditions, the use
utilization of recyclable catalytic systems for the clean
chemical synthesis of imidazoles is desirable. In this back-
ground, ionic liquids are perfect catalysts for chemical
reactions. In the context of green sustainable chemistry,
ionic liquids have attracted much attention due to their
interesting chemical and physical properties, such as high
catalytic activity and good selectivity, high ionic conduc-
tivity, negligible vapour pressure and good thermal stabil-
ity.[17] Currently, kinds of ionic liquids have been used in
various organic reactions such as N‐alkylation reac-
tion,[18] nitration,[19] Diels–Alder,[20] Michael addition,[21]
esterification,[22] aldol condensation[23] and MCRs.[24]
Although ionic liquids are widely used in organic reac-
tions, but suffered from some disadvantages such as high
viscosity, high cost, difficulty the separation of product
from ionic phas and catalyst recovery. Therefore, immobi-
lization of ionic liquids on the surface of numerous sup-
ports such as polymers,[25] graphene nanosheets,[26]
silica,[17b] magnetic materials[27] and inorganic
Appl Organometal Chem. 2017;e4052.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4052

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RAJABZADEH ET AL.
materials[28] can overcome these drawbacks. However,
there are serious drawbacks for most of these supports
like a complicated synthesis, hampered diffusion kinetics
or tedious separation via centrifugation.[29] Therefore,
magnetic nanoparticles are the best choice for catalyst
support due to their magnetic separation compare to con-
ventional techniques such as filtration or centrifugation
as it prevents loss of catalyst and increases the reusabil-
ity.[30,31] In continuation of our studies on the preparation
and applications of heterogeneous catalysts, in the syn-
thetic organic chemistry,[32] we wish introduce a new
strategy for synthesis of a 2‐hydroxyethyl ammonium for-
mate modified Fe3O4@SiO2 as a novel and magnetically
recyclable heterogeneous catalyst. The catalytic activity
of Fe3O4@SiO2‐EP‐HEAF has investigated for the one‐
pot synthesis of 2,4,5‐trisubstituted‐1H‐imidazole.
and morphology of the prepared catalyst were character-
ized by Fourier transform infrared spectroscopy (FT‐IR),
transmission electron microscopy (TEM), Field Emission
Scanning Electron Microscopy (FESEM), vibrating sam-
ple magnetometry (VSM), Thermo gravimetric analysis
(TGA) and X‐ray powder diffraction (XRD).
Figure 1 shows the FTIR spectra of the final catalyst
which was synthesized in 4 step. The characteristic
absorption peak of Fe3O4 magnetic nanoparticles is found
at 585 cm−1 is attributed to Fe–O vibrations (curve 1a). In
the case of Fe3O4@SiO2, the absorption peak of Fe–O
bond was also appeared around 580 cm−1. The character-
istic peaks around 805 cm−1 and 1098 cm−1 are assigned
to stretching vibration of Si–O and asymmetry stretching
vibration of Si–O–Si, respectively. Also, the peak at 465
2 | RESULT AND DISCUSSION
The immobilization of 2‐hydroxyethylammonium for-
mate (HEAF) onto magnetic nanoparticles was performed
in three steps (Scheme 1). In the first step, the
Fe3O4@SiO2 magnetic nanoparticles were synthesized
using the stober method.[33] In the next step, the substitu-
tion reaction of epichlorohydrin species was accom-
plished with hydroxyl groups of silica coated magnetic
nanoparticles.[32] Finally, Fe3O4@SiO2‐EP‐HEAF was
obtained by simple mixing of Fe3O4@SiO2‐EP and 2‐
hydroxyethylammonium formate in 60°C. The structure
FIGURE 1 FT‐IR spectra of (a) Fe3O4, (b) Fe3O4@SiO2, (c)
Fe3O4@SiO2‐EP, (d) Fe3O4@SiO2‐EP‐HEAF
OH
O
O
O
O
SiO
NH3 OOCH
NH3 OOCH
OH
Fe O
FeCl3
FeCl2
Fe3O4@SiO2-EP-HEAF
NH3OOCH
HO
60 oc
O
O
SiO
SiO
O
Fe O
Cl
Fe O
O
O
SCHEME 1 Preparation process of the
Fe3O4@SiO2‐EP‐HEAF catalyst
Fe3O4@SiO2
Fe3O4@SiO2-EP

RAJABZADEH ET AL.
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is attributed to bending vibration of Si–O and peaks at 940
and 1630 cm−1 are bending vibrations of Si–OH, which
indicates the silica coating of Fe3O4 MNPs (curve 1b).
The bands at 2950 and 2870 cm−1 are due to the stretching
vibration of aliphatic CH2 groups of epichlorohydrin.
Furthermore, the C‐O‐C vibration stretching around
1260 cm−1 which was covered by the broad band of
stretching vibration of Si–O–Si bonds confirms that silica
coated magnetic nanoparticles were modified with epichlo-
rohydrin (curve 1c). The broad band around 3000–3500 cm
−1
exhibits characteristic peaks of ammonium structure.
The carbonyl stretching and N–H plane bonding vibrations
are observed as a combined bond centered at 1600 cm−1
(curve 1d).
The TEM images of Fe3O4@SiO2 and ionic liquid
modified Fe3O4@SiO2 MNPs are illustrated in Figure 2.
The TEM image of Figure 2a and Figure 2b indicates that
catalysts have a core‐shell structure, which is consistent
with the results of XRD and FTIR analyzes. Figure 2b
show that after modification of Fe3O4@SiO2 with ionic
liquid the morphology of MNPs are retained. Based on
TEM images some shells of SiO2 were linked among the
particles (Figure 2). For further investigation of the mor-
phology of the ionic liquid modified Fe3O4@SiO2 MNPs
the SEM images was used. Figure 2c show a spherical
shape of final catalyst with aggregated structure.
The magnetic hysteresis loops of the Fe3O4,
Fe3O4@SiO2 and ionic liquid modified Fe3O4@SiO2
MNPs are displayed in Figure 3. The M–H curve of cata-
lyst indicates a ferromagnetic characteristic, which is
inherited from the Fe3O4 core. The magnetic saturation
(Ms) value of Fe3O4, Fe3O4@SiO2 and ionic liquid modi-
fied Fe3O4@SiO2 are 64.99, 35.13, and 25.90 emu g−1
,
respectively (Figures 3a, 3b and 3c). This decrease in the
Ms Value of final catalyst in comparison with bare
Fe3O4 MNPs is related to the silica shell with disordered
structure at interfaces and loading of epichlorohydrin/
ionic liquid as organic linker. These results demonstrate
that the core–shell particles possess magnetic properties.
To examine the thermal stability of the final catalyst,
thermal gravimetric analysis (TGA) was carried out
(Figure 4). The final catalyst show about 14.5% weight loss
in the region of 10–800 °C. The initial weight loss up to
200 °C is probably due to the removal of surface adsorbed
water and dehydration of the ionic liquid, while the weight
loss at 200–800 °C could be attributed to the evaporation of
the dehydration product, 2‐hydroxyethylammonium for-
mate or its decomposition products.[34]
The XRD patterns of Fe3O4@SiO2 MNPs and ionic liq-
uid modified Fe3O4@SiO2 MNPs were shown at Figure 5.
Figure 5a revealed six diffraction peaks located at 30.17°,
35.45°, 43.17°, 53.48°, 56.89° and 62.61° can be assigned
to the Fe3O4 crystal with inverse spinel structure from
FIGURE 2 TEM image of (a) Fe3O4@SiO2, (b) Fe3O4@SiO2‐EP‐
HEAF and FESEM image of (c) Fe3O4@SiO2‐EP‐HEAF

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RAJABZADEH ET AL.
FIGURE 3 Magnetization curves of (a)
Fe3O4, (b) Fe3O4@SiO2, (c) Fe3O4@SiO2‐
EP‐HEAF
crystallinity of Fe3O4@SiO2 persists after surface modifi-
cation. The average crystal size of the Fe3O4 cores from
the broadness of the (311) peak, obtained by calculation
of Sherrer's formula, is about 15.2 nm.
The efficiency of the prepared Fe3O4@SiO2‐EP‐HEAF
catalyst was examined for the synthesis of imidazole deriv-
atives. In order to optimize the reaction conditions, the
mixture of benzaldehyde, benzil and ammonium acetate
in the presence Fe3O4@SiO2‐EP‐HEAF was selected as a
model reaction (Scheme 2). Initially, the model reaction
in a various solvents such as H2O, CH3CN, PEG, toluene
and EtOH in the presence of 0.02 gr of the catalyst was
investigated. The product was obtained in 90, 40, 75, 40
and 95% yield, respectively (Table 1, Entry 1–5). Therefore,
ethanol was found to be the best solvent for this catalytic
system. To demonstrate the influence of the catalyst
amount, the model reaction was tested in the presence of
different amount of the catalyst in EtOH as solvent. The
results showed that the reaction yield was improved when
the amount of the catalyst increased from 0.002 to 0.02 gr.
No product was observed in the absence of the catalyst
(Table 1, Entry 6). We examined the effect of different tem-
peratures on the model reaction under solvent free condi-
tions. The reactions took a long time to achieve a low yield
of the desired product (Table 1, Entry 10, 11).
FIGURE 4 TGA analysis of the Fe3O4@SiO2‐EP‐HEAF
With this optimized reaction condition, we evaluated
the one‐pot condensation of benzil and ammonium acetate
with a variety of aldehydes in the presence Fe3O4@SiO2‐
EP‐HEAF to achieve the intended products (Table 2, Entry
1–14). The desired imidazole products were obtained in
FIGURE 5 XRD diagrams of (a) Fe3O4@SiO2, (b) Fe3O4@SiO2‐
EP‐HEAF
(220), (311), (400), (422), (511) and (440) crystal plane
which are agreed well with the standard diffraction card
JCPDS 19–0629. From Figure 5b, it is seen clearly that
ionic liquid modified Fe3O4@SiO2 MNPs exhibit diffrac-
tion patterns similar to that of Fe3O4@SiO2 MNPs which
indicates that the particles are single‐crystalline and the
SCHEME 2 One‐pot catalytic synthesis 2,4,5‐trisubstituted‐1H‐
imidazole

RAJABZADEH ET AL.
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TABLE 1 Optmization of reaction conditions for one‐pot con-
as anthracene‐9‐carbaldehyde also provided the corre-
sponding products in 75% yield (Table 2, Entry 14).
The recyclability of the desired catalyst was examined
for the synthesis of 2,4,5‐trisubstituted‐1H‐imidazole
under the optimized reaction conditions. The recycling
test result shows the Fe3O4@SiO2‐EP‐HEAF could be
recycled up to five run without loss of catalytic activity.
After the five cycle, the Fe3O4@SiO2‐EP‐HEAF was recov-
ered for further TEM and SEM characterization. Figure 6
shows the morphology of Fe3O4@SiO2‐EP‐HEAF is
almost unchanged after the five cycle.
densation of benzil, benzaldehyde, and ammonium acetatea
Amount
Time
Entry
Solvent
catalyst (gr)
Yeild (%)
(h: Min)
1
H2O
0.02
0.02
0.02
0.02
0.02
‐
90
04: 00
07: 00
05: 00
07: 00
00: 40
12: 00
03: 00
03: 00
01: 00
05; 00
07; 00
2
CH3CN
PEG
40
75
40
95
0
3
4
toluene
EtOH
EtOH
EtOH
EtOH
EtOH
‐
5
6
7
0.002
0.005
0.01
0.02
0.02
40
55
73
30
45
3 | EXPERIMENTAL
8
9
3.1 | General procedure for the
preparation 2‐hydroxyethylammonium
formate (ionic liquid)
b10
c11
‐
aReaction condition: benzil (1 mmol), benzaldehydes (1 mmol), ammonium
Into around‐bottom flask equipped with a dropping fun-
nel was placed Amino ethanol (0.2 mol) and the flask
was mounted in an ice bath. Under vigorous stirring
formic acid (0.2 mol) was added dropwise to the flask in
45 min. The reaction mixture was shaken for 24 h at room
temperature, to obtain a viscous clear liquid.[34]
acetate (2 mmol), Fe3O4@SiO2‐EP‐HEAF (0.02 g) and solvent (3 ml).
bReaction condition carried out at 80 °C
cReaction condition carried out at 100 °C
TABLE 2 Summarized catalytic results of the one‐pot condensa-
tion between various aldehydes, benzil and ammonium acetate
3.2 | General procedure for the
preparation Fe3O4@SiO2‐EP‐HEAF
Yiled
(%)
Time
(min)
Entry
Aldehyde
1
Benzaldehyde
95
92
95
85
90
87
90
92
90
95
90
90
83
75
40
45
45
60
40
60
60
45
45
40
40
60
120
180
Fe3O4@SiO2 MNPs were synthesized by the conventional
stober method.[33] To a solution of epichlorohydrin
(10 mmol, 1.36 g) in ethanol (3 ml), Fe3O4@SiO2 MNPs
(0.5 g) was added and the resulting mixture was stirred
for 5 h at 60°C. The precipitate was separated by a magnet
and washed with ethanol several times.[32] The formed
Fe3O4@SiO2‐EP (0.5 g) was dispersed in 3 ml 2‐
hydroxyethylammonium formate with ultrasonic for
120 min, then the mixture was vigorously stirred for 6 h
at 60°C. The precipitate was separated with using an exter-
nal magnet and washed with distilled water and with eth-
anol for three times, then dried at 60 °C for 6 h. The finally
obtained Fe3O4@SiO2‐EP‐HEAF product was employed as
nanocatalyst for the synthesis of imidazole derivatives.
2
4‐methylbenzaldehyde
3
4‐methoxybenzaldehyde
4‐hydroxybenzaldehyde
3,4‐dimethoxybenzaldehyde
4‐hydroxy‐3‐methoxybenzaldehyde
4‐(dimethylamino)benzaldehyde
4‐Cyanobenzaldehyde
4
5
6
7
8
9
4‐chlorobenzaldehyde
10
11
12
13
14
2,4‐dichlorobenzaldehyde
2,6‐dichlorobenzaldehyde
furan‐2‐carbaldehyde
Cinnamaldehyde
anthracene‐9‐carbaldehyde
3.3 | General procedure for the synthesis
of 2,4,5‐trisubstituted‐1H‐imidazole
Fe3O4@SiO2‐EP‐HEAF (0.02 g) was added to a mixture of
benzil (1 mmol), aldehyde (1 mmol) and ammonium ace-
tate (2 mmol) in EtOH (3 ml), the reaction mixture was
refluxed at 80 °C for 40–180 min under stirring. After
completion of the reaction, the catalyst was removed with
using external magnet. The mixture reaction was allowed
to cool and the resulting precipitates were recrystallized
excellent yields for both electron rich (Table 2, Entry 2–7)
and electron poor (Table 2, Entry 8–11) aromatic aldehydes.
Heteroaromatic aldehydes such as furan‐2‐carbaldehyde
(Table 2, Entry 12) and allylic aldehydes such as
cinnamaldehyde (Table 2, Entry 13) were also converted
in high yields to the desired products. Other aldehyde such

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RAJABZADEH ET AL.
(75 MHz, DMSO‐d6): δ = 125.6, 126.9, 127.5, 128.2,
128.7, 128.9, 129.2, 130.8, 131.6, 135.6, 137.5, 145.9.
3.3.2 | 4,5‐diphenyl‐2‐p‐tolyl‐1H‐imidazole
(Table 2, Entry 2)
Mp: 228–229 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 2.33 (s,
3H), 7.26 (d, 4H, J = 7.8 Hz), 7.41–7.49 (m, 8H), 7.95 (d, 2H,
J = 7.5 Hz), 12.58 (s, 1H). 13C NMR (75 MHz, DMSO‐d6):
δ = 21.4, 125.6, 127.5, 128.1, 128.9, 129.7, 131.6, 138.2, 146.1.
3.3.3 | 2(4‐methoxyphenyl)‐4,5‐diphenyl‐
1H‐imidazole (Table 2, Entry 3)
Mp: 220–222 °C, 1H NMR (250 MHz, DMSO‐d6): δ = 3.82
(s, 3H), 6.90–6.94 (m, 2H), 7.24–7.28 (m, 6H), 7.51 (s, 4H),
7.78–7.82 (m, 2H), 9.69 (s, 1H). 13C NMR (62.5 MHz,
DMSO‐d6): δ = 55.3, 112.1, 114.1, 115.5, 122.8, 126.9,
127.2, 127.9, 128.4, 146.4, 148.9, 151.1, 163.9.
3.3.4 | 4‐(4,5‐diphenyl‐1H‐imidazole‐2‐yl)
phenol (Table 2, Entry 4)
Mp: 256–257 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 6.83
(d, 2H, J = 8.1 Hz), 7.19 (d, 1H, J = 6.6 Hz), 7.27 (t, 2H,
J = 7.8 Hz), 7.34 (d, 1H, J = 6.9 Hz), 7.38–7.52 (m, 6H),
7.87 (d, 2H, J = 8.1 Hz), 9.69 (s, 1H), 12.39 (s, 1H). 13C
NMR (75 MHz, DMSO‐d6): δ = 115.8, 122.1, 126.8,
127.3, 127.5, 127.8, 128.0, 128.6, 128.8, 129.1, 131.8,
135.9, 137.0, 146.5, 158.2.
3.3.5 | 2‐(3,4‐dimethoxyphenyl)‐4,5‐
diphenyl‐1H‐imidazole (Table 2, Entry 5)
Mp: 216–217 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 3.79
(s, 3H), 3.83 (s, 3H),7.04 (d, 1H, J = 8.7 Hz), 7.20 (d, 1H,
J = 6.9 Hz), 7.25–7.30 (m, 2H), 7.36(d, 1H, J = 6.0 Hz),
7.40–7.54 (m, 6H), 7.62–7.65 (m, 2H), 12.51 (s, 1H). 13C
NMR (75 MHz, DMSO‐d6): δ = 55.9, 56.0, 109.2, 112.2,
118.4, 123.7, 126.9, 127.5, 128.1, 128.6, 128.9, 129.1,
131.7, 135.7, 137.2, 146.2, 149.2, 149.5.
FIGURE 6 SEM (a) and TEM (b) image of Fe3O4@SiO2‐EP‐
HEAF after five times reuse
from EtOH/H2O to give pure imidazole derivatives. All
the products were confirmed by the spectroscopic method
3.3.6 | 4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)‐2‐
methoxyphenol (Table 2, Entry 6)
1
using H and 13C NMR.
Mp: 200–202 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 3.83
(s, 3H), 6.83 (d, 1H, J = 8.1 Hz), 7.19 (d, 1H, J = 6.6 Hz),
7.27 (t, 2H, J = 7.5 Hz), 7.35 (d, 2H, J = 6.6 Hz), 7.39–
7.50 (m, 6H), 7.60 (s, 1H), 9.25 (s, 1H), 12.40 (s, 1H). 13C
NMR (75 MHz, DMSO‐d6): δ = 56.1, 109.7, 116.0, 118.8,
122.4, 126.8, 127.5, 127.9, 128.1, 128.6, 128.8, 129.1,
131.8, 135.8, 146.5, 147.3, 147.5, 148.1.
3.3.1 | 2,4,5‐triphenyl‐1H‐imidazole
(Table 2, Entry 1)
Mp: 264–266 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 7.22–
7.33 (m, 3H), 7.36 (d, 2H, J = 6.9 Hz), 7.43–7.51 (m, 8H),
8.06 (d, 2H, J = 7.5 Hz), 12.68 (s, 1H). 13C NMR

RAJABZADEH ET AL.
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3.3.7 | 4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)‐N,
N‐dimethylbenzenamine (Table 2, Entry 7)
3.3.12 | 2‐(furan‐2‐yl)‐4,5‐diphenyl‐1H‐
imidazole (Table 2, Entry 12)
1
Mp: 262–264 °C, H NMR (300 MHz, DMSO‐d6): δ = 2.9
Mp: 234–235 °C, 1H NMR (250 MHz, DMSO‐d6): δ = 6.50–
6.53 (m, 1H), 9.98 (d, 1H, J = 3.2 Hz), 7.26–7.33 (m, 7H),
7.45–7.52 (m, 4H), 9.68 (s, 1H). 13C NMR (75 MHz,
DMSO‐d6): δ = 107.9, 112.3, 127.7, 128.2, 128.9, 139.0,
143.6, 146.1.
(s, 6H), 6.77 (d, 2H, J = 8.4 Hz), 7.18 (d, 1H, J = 6.9 Hz),
7.27 (t, 2H, J = 7.5 Hz), 7.32 (d, 1H, J = 6.6 Hz), 7.37–
7.40 (m, 3H), 7.45 (t, 2H, J = 7.5 Hz), 7.50–7.52 (m, 1H),
7.88 (d, 2H, J = 8.7 Hz), 12.3 (s, 1H). 13C NMR (75 MHz,
DMSO‐d6): δ = 112.4, 118.8, 126.7, 127.5, 127.9, 128.6,
128.7, 129.1, 131.9, 135.9, 136.9, 146.9, 150.7.
3.3.13 | (E)‐4,5‐diphenyl‐2‐styryl‐1H‐imid-
azole (Table 2, Entry 13)
Mp: 254–256 °C, 1H NMR (250 MHz, DMSO‐d6): δ = 7.25–
7.26 (m, 2H), 7.33 (d, 4H, J = 6.5 Hz), 7.37–7.45 (m, 5H),
7.48–7.56 (m, 4H), 7.91 (d, 2H, J = 7.75 Hz), 9.42 (s, 1H).
13C NMR (75 MHz, DMSO‐d6): δ = 125.7, 127.0, 127.5,
128.3, 128.7, 128.9, 129.2, 130.8, 131.6, 135.6, 137.6, 146.0.
3.3.8 | 4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)
benzonitrile (Table 2, Entry 8)
Mp: 232–233 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 7.22–
7.30 (m, 3H), 7.42–7.54 (m, 7H), 7.93 (d, 2H, J = 7.8 Hz),
8.23 (d, 2H, J = 8.1 Hz), 13.01 (s, 1H). 13C NMR
(75 MHz, DMSO‐d6): δ = 110.6, 119.4, 126.0, 127.3,
127.6, 128.6, 128.7, 129.0, 129.2, 130.1, 131.1, 133.3,
134.7, 135.1, 138.5, 144.2.
3.3.14 | 2‐(anthracen‐10‐yl)‐4,5‐diphenyl‐
1H‐imidazole (Table 2, Entry 14)
Mp: 165–167 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 7.24–
7.41 (m, 6H), 7.55–7.63 (m, 8H), 7.90–7.91 (m, 2H), 8.15–
8.17 (m, 2H), 8.78 (s, 1H), 12.94 (s, 1H). 13C NMR
(75 MHz, DMSO‐d6): δ = 126.1, 126.5, 127.1, 127.8,
128.0, 128.2, 128.4, 128.8, 128.9, 129.2, 131.3, 131.6,
135.9, 137.4, 143.7.
3.3.9 | 2‐(4–chlorophenyl)‐4,5‐diphenyl‐
1H‐imidazole (Table 2, Entry 9)
Mp: 267–268 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 7.22
(d, 1H, J = 6.6 Hz), 7.28 (t, 2H, J = 7.5 Hz), 7.36–7.47 (m,
7H), 7.53 (d, 2H, J = 7.5 Hz), 8.08 (d, 2H, J = 8.4 Hz),
12.77 (s, 1H). 13C NMR (75 MHz, DMSO‐d6) δ = 127.1,
127.3, 127.5, 128.3, 128.7, 128.9, 129.0, 129.1, 129.2,
129.7, 131.4, 133.2, 135.5, 137.8, 144.9.
4 | CONCLUSION
In summary, we have developed a facile approach to fab-
ricate Fe3O4@SiO2‐EP‐HEAF as a high performance cata-
lyst. Fe3O4@SiO2‐EP‐HEAF was used as an efficient
catalyst for synthesis of 2,4,5‐trisubstituted‐1H‐imidazole
via one‐pot condensation of benzil, aldehydes and ammo-
nium acetate. This catalyst was simply separated from the
reaction mixture by external magnet and reused several
times without a significant loss of its activity.
3.3.10 | 2‐(2,4‐dichlorophenyl)‐4,5‐
diphenyl‐1H‐imidazole (Table 2, Entry 10)
Mp: 170–173 °C, 1H NMR (300 MHz, DMSO‐d6): δ = 7.22
(d, 1H, J = 6.9 Hz), 7.26–7.31 (m, 2H), 7.35–7.56 (m, 8H),
7.77–7.83 (m, 2H), 12.70 (s, 1H). 13C NMR (75 MHz,
DMSO‐d6): δ = 127.1, 127.6, 127.9, 128.3, 128.7, 129.2,
129.3, 130.2, 131.2, 132.9, 133.1, 134.3, 135.4, 137.5, 142.8.
ORCID
Hossein Eshghi http://orcid.org/0000-0002-8417-220X
Reza Khalifeh http://orcid.org/0000-0003-3060-5556
3.3.11 | 2‐(2,6‐dichlorophenyl)‐4,5‐
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How to cite this article: Rajabzadeh M, Eshghi
H, Khalifeh R, Bakavoli M. 2‐
hydroxyethylammonium formate ionic liquid
grafted magnetic nanoparticle as a novel
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