A new nanocomposite catalyst based on clay-supported heteropolyacid for the green synthesis of 2,4,5-trisubstituted imidazoles

Article abstract of DOI:10.1002/aoc.5727

Intercalation of cetyltrimethylammonium (CTA⁺) cations within the nanolayers of montmorillonite (MMT) clay followed by reaction with Keggin-type phosphomolybdic acid (PMo) resulted in the synthesis of (CTA)₃PMo-MMT nanocomposite catalyst. The prepared nanocomposite catalyst was characterized using different physicochemical methods such as Fourier-transform infrared and inductively coupled plasma–optical emission spectroscopies, X-ray diffraction, and nitrogen adsorption–desorption (Brunauer–Emmett–Teller method) analyses. Characterization techniques demonstrated the intercalation of (CTA)₃PMo species into the nanolayers of MMT. The resulting (CTA)₃PMo-MMT nanocomposite catalyst efficiently catalyzed the synthesis of 2,4,5-trisubstituted imidazoles under solvent-free conditions. The efficiency is due to the fact that the presence of CTA⁺ species makes the nanocomposite catalyst hydrophobic and facilitates the accessibility of hydrophobic reactants to active sites in the course of the reaction. High activity and selectivity were achieved in the presence of the prepared nanocomposite catalyst. The nanocomposite catalyst was readily isolated from the reaction mixture using simple filtration, washed with ethanol, and recycled five times without a major loss of activity.

Full text of DOI:10.1002/aoc.5727

Received: 31 December 2019
DOI: 10.1002/aoc.5727
Revised: 19 March 2020
Accepted: 27 March 2020
F U L L P A P E R
A new nanocomposite catalyst based on clay-supported
heteropolyacid for the green synthesis of 2,4,5-trisubstituted
imidazoles
1
2
1
3
M. Masteri-Farahani
| A. Ezabadi | R. Mazarei | P. Ataeinia
|
1
2
S. Shahsavarifar | F. Mousavi
1
Faculty of Chemistry, Kharazmi
+
Intercalation of cetyltrimethylammonium (CTA ) cations within the nanolayers
of montmorillonite (MMT) clay followed by reaction with Keggin-type
University, Tehran, Iran
2
Department of Chemistry, Central
Tehran Branch, Islamic Azad University,
Tehran, Iran
phosphomolybdic acid (PMo) resulted in the synthesis of (CTA) PMo-MMT
3
nanocomposite catalyst. The prepared nanocomposite catalyst was characterized
using different physicochemical methods such as Fourier-transform infrared and
inductively coupled plasma–optical emission spectroscopies, X-ray diffraction,
and nitrogen adsorption–desorption (Brunauer–Emmett–Teller method)
analyses. Characterization techniques demonstrated the intercalation of
3
Faculty of Chemistry, Ardabil Branch,
Islamic Azad University, Ardabil, Iran
Correspondence
M. Masteri-Farahani, Faculty of
Chemistry, Kharazmi University, Tehran,
Iran.
(
CTA) PMo species into the nanolayers of MMT. The resulting (CTA) PMo-
3
3
Email: mfarahani@khu.ac.ir
MMT nanocomposite catalyst efficiently catalyzed the synthesis of 2,4,5-trisubsti-
tuted imidazoles under solvent-free conditions. The efficiency is due to the fact
+
that the presence of CTA species makes the nanocomposite catalyst
hydrophobic and facilitates the accessibility of hydrophobic reactants to active
sites in the course of the reaction. High activity and selectivity were achieved in
the presence of the prepared nanocomposite catalyst. The nanocomposite
catalyst was readily isolated from the reaction mixture using simple filtration,
washed with ethanol, and recycled five times without a major loss of activity.
K E Y W O R D S
heteropolyacid, imidazole, intercalation, montmorillonite, nanocomposite
[
6]
[7]
1
| INTRODUCTION
alkanes, epoxidation of olefins, oxidation of alco-
[
8]
[9]
hols, acetalization reactions, esterification of carbox-
ylic acids,
phosphomolybdic acid (H PMo O ) has been broadly
studied as a catalyst for many organic synthesis reactions
[
10]
[11]
Recently, the requirement of designing green processes
resulted in the development of solid acid catalysts. These
materials can replace hazardous and corrosive liquid
acids usually used in various industries. Various mate-
rials such as sulfated metal oxides and polyoxometalates
and heterocyclic synthesis.
Keggin-type
3
12 40
[
12–15]
and is used in various processes.
Separation of
POMs from the reaction mixtures is often difficult
because of their high solubility in various solvents. There-
fore, their immobilization on solid supports possessing
large surface areas helps their reusability in catalytic
reactions. Previously, a variety of solids such as silica,
alumina,
(POMs) have been used as solid acids. Among the solid
acids, POMs have attracted great interest as environ-
ment-friendly, efficient, and highly selective acid cata-
lysts for organic transformations.
[1–5]
[16]
Some of these
[
17]
[18]
[19]
applications include selective oxidation of light
active carbon,
TiO2,
acidic ion-
Appl Organomet Chem. 9999:e5727.
wileyonlinelibrary.com/journal/aoc
© 2020 John Wiley & Sons, Ltd.
1 of 12
https://doi.org/10.1002/aoc.5727

2
of 12
MASTERI-FARAHANI ET AL.
[20]
[21]
[22]
exchange resins,
clays,
and molecular sieves
2.1 | Preparation of (CTA) PMo-MMT
3
were used as support materials for the immobilization of
POMs. The supported materials may retain the catalytic
properties of primary POMs. However, the weak interac-
tion of POMs with some support materials such as MCM-
nanocomposite catalyst
First, MMT clay was ion exchanged with sodium chloride
solution to remove other cations. In the next step, 1 g of
Na–MMT was dissolved in 30 ml of deionized water and
magnetically stirred at room temperature. Then, a solu-
tion of 2 mmol of cetyltrimethylammonium bromide
(CTAB) in 20 ml of deionized water was added to the clay
suspension, and the mixture was stirred for 24 h at room
temperature. The resulting mixture was filtered, and the
obtained solid (CTA–MMT) was washed thoroughly with
deionized water to remove the residue of CTAB species.
Finally, 1 g of CTA–MMT was added to an aqueous solu-
tion of 2 mmol of H PMo O in 50 ml of deionized
4
1 and SBA-15 leads to their partial leaching during the
[23,24]
catalytic reactions.
Montmorillonite (MMT), a low-cost and easily avail-
able solid with several excellent properties, is a natural,
layered clay possessing a large surface area as well as
high cation exchange capacity. It has been extensively
[25–27]
used in a variety of industries.
Because of its small
particle size, bearing constant negative charge on sur-
faces and sheet-like structures, MMT may be particularly
suitable to be used as a support for the immobilization of
3
12 40
[26–31]
cationic materials.
On the contrary, clay-supported
water, and the mixture was stirred for 24 h at room tem-
catalysts have been used in some organic reactions such
perature. The solid product, (CTA) PMo-MMT, was sepa-
rated by filtration and then Soxhlet extracted with water
to remove unreacted PMo.
3
[32]
[33]
as esterification reactions,
alkylation of aromatics,
oxidative desulfurization,
[
34]
[35]
dehydration of alcohols,
[
36]
and epoxidation of olefins.
Incorporation of cationic surfactants onto the clay has
also been a subject of special interest because of their
extensive use in various fields such as oil recovery, soil
2.2 | General procedure for the
preparation of imidazole derivatives
[37,38]
chemistry, and environmental issues.
Imidazole and its derivatives as an important class of
organic materials have a wide range of biological and
A mixture of benzil (1 mmol), aldehyde (1 mmol), ammo-
nium acetate (5 mmol), and (CTA) PMo-MMT (50 mg)
3
[39–41]
medical applications.
The most common method
was stirred at a given temperature in solvent-free condi-
tions. The progress of the reaction was monitored contin-
uously using thin layer chromatography. After the
reaction was completed, 5 ml of hot ethanol was added to
the reaction mixture, and the solid catalyst was separated
for the preparation of imidazole derivatives is the con-
densation of aldehydes with benzil and ammonium ace-
[42–48]
tate in the presence of acid catalysts.
However,
some of the current methods have some disadvantages,
such as environmental pollution caused by organic sol-
vents, long reaction times, harsh reaction conditions, and
by filtration. The (CTA) PMo-MMT catalyst was then
3
washed with ethanol and dried under vacuum overnight
for the recycling experiment. Pure products obtained
were analyzed after evaporation of the solvent from the
residual solution and recrystallization. All of the imidaz-
ole derivatives obtained are known compounds and iden-
[49,50]
complicated operations.
Therefore, the development
of clean, efficient, and environment-friendly approaches
is still desirable.
Here, we report the design and characterization of
MMT-supported (CTA) PMo O nanocomposite cata-
1
tified by H NMR and melting points in comparison with
3
12 40
1
lyst for the synthesis of 2,4,5-trisubstituted imidazoles
catalyzed under solvent-free conditions. To the best of
our knowledge, such nanocomposite catalysts have not
been used before for the synthesis of trisubstituted
imidazoles. Practically easy workup, low cost, ready
preparation of the catalyst, high-yielding reaction, and
avoidance of organic solvents make this procedure
superior to the earlier methods for the synthesis of
imidazoles.
the reported values. The melting points and H NMR
spectra of the products are provided in the Supplemen-
tary Information.
3 | RESULTS AND DISCUSSION
3.1 | Preparation of (CTA) PMo-MMT
3
nanocomposite catalyst
Intercalation of (CTA) PMo into the nanolayers of MMT
3
2
| EXPERIMENTAL
was performed using the strategy shown in Scheme 1.
+
The first step involved the ion exchange of Na cations of
+
Details of reagents used and instruments have been pro-
vided in Supplementary Information.
MMT with cetyltrimethylammonium (CTA ) cations to
obtain CTA–MMT nanocomposite. In the next step,

MASTERI-FARAHANI ET AL.
3 of 12
SCHEME 1 Schematic synthesis procedure
of (CTA) PMo-MMT nanocomposite catalyst
3
treatment of CTA–MMT nanocomposite with pho-
sphomolybdic acid yielded (CTA) PMo-MMT
attributed to the stretching vibrations of C–H groups
and strongly confirm the existence of CTA cations in
+
3
nanocomposite catalyst through the electrostatic interac-
the intercalated materials. In the FT-IR spectrum of
+
tion of intercalated CTA cations with phospho-
(CTA) PMo-MMT (Figure 1b), four main peaks of the
3
[
51]
−1
molybdate anions. Based on the literature report,
the
Keggin-type PMo anions were observed at 1059 cm
−1
organic cation salts of POMs were insoluble in water and
(ν ), 956 cm (νMo = O), 879 (νas corner-sharing Mo–O–
P–O
), and 798 cm− (νas edge-sharing Mo–O–Mo), confirming
1
many organic solvents. Thus, the (CTA) PMo species
3
Mo
formed were immobilized in the nanolayers of MMT and
could not be leached out from the nanolayers of MMT
during the Soxhlet extraction of the solid product, which
was performed subsequently to remove the unreacted
species.
the Keggin structure of (CTA) PMo in the final product
3
[
21]
(Figure 1c).
In comparison with the FT-IR spectrum
of the neat PMo (Figure 1d), the νas corner-sharing Mo–O–Mo
and νas edge-sharing Mo–O–Mo peaks in (CTA) PMo-MMT
3
shifted from 869 to 879 cm− and 787 to 798 cm ,
1
−1
respectively. The observed blue shift in these peaks
+
+
indicated the substitution of H cations by CTA
3
.2 | Characterization of (CTA) PMo-
cations with stronger interactions. It has been shown
that the H cations in the heteropoly acids are
connected to the bridging oxygen atoms rather than to
3
+
MMT nanocomposite catalyst
[
53]
To carry out the successful intercalation of (CTA) PMo
the terminal oxygen atoms.
Therefore, the replace-
3
+
+
species into the MMT nanolayers, the Fourier-transform
infrared (FT-IR) spectra of the prepared materials were
obtained (Figure 1). The FT-IR spectra exhibited two
ment of H cations with CTA cations mainly affects
the vibrations involving the bridging oxygen atoms, that
is, corner-sharing Mo–O–Mo and edge-sharing Mo–O–
Mo asymmetric stretching vibrations.
−1
bands in the range of 3400–3700 cm related to OH
stretching vibrations in pristine MMT. The relatively
The elemental analysis also confirmed the intercala-
−1
+
sharp band at ~3622 cm
vibrations of OH groups bonded to octahedral Al cat-
is due to the stretching
tion of the CTA cations and (CTA) PMo species into the
3
3+
nanolayers of MMT. The nitrogen contents of CTA–MMT
−
1
−1
ions, and the band at ~3421 cm can be attributed to
the stretching vibrations of physisorbed interlayer
and (CTA) PMo samples were 0.17 and 0.12 mmol g ,
3
respectively. Also, the amount of (CTA) PMo species
3
[
52]
−1
water.
1
The strong and broad band at ~1000–
intercalated into MMT clay was 0.03 mmol g based on
100 cm− is due to the Si–O–Si stretching vibrations.
1
the P and Mo elemental analysis performed by induc-
tively coupled plasma–optical emission (ICP–OES)
analysis.
−
1
The observed peaks at ~2853 and 2925 cm in the FT-
IR spectra of CTA–MMT and (CTA) PMo-MMT can be
3

4
of 12
MASTERI-FARAHANI ET AL.
FIGURE 1 Fourier-transform infrared
spectra of (a) MMT, (b) CTA–MMT,
(
3
c) (CTA) PMo-MMT, and (d) neat PMo
Nitrogen
adsorption–desorption
isotherms
of
The X-ray diffraction (XRD) patterns of (CTA) PMo-
3
(
CTA) PMo-MMT and MMT are shown in Figure 2.
MMT and MMT samples are shown in Figure 3. The
3
These isotherms belong to type IV, and the observation
of type H4 hysteresis loop (according to the IUPAC classi-
fication) endorses the presence of mesoporosity in the
materials. The observed hysteresis loop of type H4 in the
XRD patterns of (CTA) PMo-MMT and MMT exhibit
3
ꢀ
001 reflections at around 2θ
=
7.0 and 8.8 ,
corresponding to a d001 basal spacing of 12.52 and
10.03 Å, respectively. Other reflections appear in similar
[54,55]
isotherms is related to narrow slit pores.
The specific
positions in both pristine MMT and (CTA) PMo-MMT.
3
surface areas and the pore volumes of the materials are
provided in Table 1. As a result of the intercalation of
However, the d-spacing value increases after intercala-
tion of (CTA) PMo species. The similarity between the
3
(
CTA) PMo species, the surface area and pore volume of
XRD patterns of the pristine MMT and those of
3
(
CTA) PMo-MMT decreased in comparison with pristine
(CTA) PMo-MMT clearly indicates that the laminar
3
3
MMT.
structure of the MMT is retained during the intercalation
of (CTA) PMo species. This situation has been
3
mentioned previously for Mn(III) salen complexes
[
56]
immobilized between the clay layers of K10 MMT.
+
The monovalent Na cations are replaced easily by
CTA ions, and when the clay is treated with PMo solu-
+
tion, the d-spacing shifts from 10.03 to 12.52 Å, indicat-
ing the intercalation of (CTA) PMo species into the
3
MMT interlayers. Moreover, (CTA) PMo-MMT catalyst
3
does not show any peaks corresponding to PMo, indicat-
ing the absence of PMo impurity in the catalyst.
Scanning electron microscopy (SEM) and transmis-
sion electron microscopy (TEM) analyses were used to
obtain more information about the morphology and
microstructure of the MMT and (CTA) PMo-MMT cata-
3
lysts as well as the effect of the modification steps on the
structure of MMT (Figure 4). The two-dimensional and
layered structure of MMT support can be observed in the
FIGURE 2 Nitrogen adsorption–desorption isotherms of
MMT and (CTA) PMo-MMT
3

MASTERI-FARAHANI ET AL.
5 of 12
TABLE 1
Elemental analysis and texture parameters of the samples obtained from nitrogen sorption studies
CTA content (mmol g−1)
a
PMo content (mmol g−1)
b
S
BET (m g−1)
2
T
V )
(ml g−1
c
Sample
MMT
–
–
222
135
0.11
0.07
(
CTA)
3
PMo-MMT
0.12
0.031
a
Determined from nitrogen content according to CHN elemental analysis.
Determined from P and Mo content according to inductively coupled plasma–optical emission chemical analysis.
b
c
0
Total pore volume at p/p = 0.98.
FIGURE 3 X-ray diffraction patterns of
MMT and (CTA) PMo-MMT
3
FIGURE 4 Scanning electron microscopy
(
(
top) and transmission electron microscopy
bottom) images of MMT and (CTA) PMo-MMT
3
SEM and TEM images, indicating the preservation of
MMT-layered structure during the modification steps.
exhibited the presence of PMo species. But it is not clear
whether the PMo species is distributed on the surface or
within the layers of the MMT.
The TEM image of (CTA) PMo-MMT catalyst also
3

6
of 12
MASTERI-FARAHANI ET AL.
ꢀ
Phosphorus (P) and molybdenum (Mo) elemental
on heating from room temperature to 700 C under air
mapping along with energy-dispersive X-ray (EDX) spec-
flow (Figure 6a). The first weight loss from room tem-
perature to 200 C is due to the removal of surface-
ꢀ
trum of (CTA) PMo-MMT catalyst indicated the uniform
3
distribution of these elements in the catalyst (Figure 5).
Moreover, the EDX spectrum completely shows the
intended elements, confirming the presence of PMo spe-
cies in catalyst structure.
adsorbed water. The corresponding endothermic DTA
peak approves this interpretation. The second weight
ꢀ
ꢀ
loss from 200 C to 450 C, which is absent in the
TGA–DTA curves of neat PMo (Figure 6b), accounts
for the combustion of organic cations intercalated in
the MMT nanolayers. The observation of the exother-
mic DTA peak in this region confirms this explanation.
Thermogravimetric analysis (TGA) was performed
to monitor the decomposition profiles of (CTA) PMo-
3
MMT and neat PMo for comparison. (CTA) PMo-MMT
3
ꢀ
shows three distinct steps of weight losses in the com-
The third weight loss at about 500 C according to our
bined TGA–DTA (differential thermal analysis) curves
earlier study is due to the collapse of intercalated PMo
3
FIGURE 5 Phosphorus (P) and molybdenum (Mo) elemental mapping along with energy-dispersive X-ray spectrum of (CTA) PMo-
MMT catalyst
FIGURE 6 Thermogravimetric analysis–
derivative thermogravimetry–differential
thermal analysis curves of (a) (CTA)
and (b) neat PMo
3
PMo-MMT

MASTERI-FARAHANI ET AL.
7 of 12
TABLE 2
Synthesis of trisubstituted imidazoles in solvent-free conditions
Diketone Aldehyde Product Time (h:min)
Entry
Yield (%)
Turnover frequency (h−
1 a
)
1
85
567
1:00
2
93
827
0:45
3
89
593
1
1
0
0
:00
:00
:45
:45
4
86
573
5
90
800
6
95
844
(
Continues)

8
of 12
MASTERI-FARAHANI ET AL.
TABLE 2 (Continued)
Turnover frequency (h−
)
1 a
Entry
Diketone
Aldehyde
Product
Time (h:min)
Yield (%)
7
96
853
0
1
1
1
1
2
:45
:30
:00
:00
:00
:00
8
80
355
9
96
640
1
1
1
0
1
2
90
93
85
600
620
283

MASTERI-FARAHANI ET AL.
9 of 12
TABLE 2 (Continued)
1 a
Entry
13
Diketone
Aldehyde
Product
Time (h:min)
:00
Yield (%)
Turnover frequency (h−
)
85
567
1
1
4
2:00
97
323
ꢀ
Note: Reaction conditions: 1,2-diketone (1 mmol), aldehyde (1 mmol), ammonium acetate (5 mmol), catalyst (50 mg), 100 C.
Turnover frequency: Determined as millimoles of product per millimoles of PMo in catalyst per time.
a
species and transformation to the corresponding metal
5–7). Moreover, the relatively bulky 2-naphthaldehyde
showed a low yield (85%) even after 2 h (entry 12) in
comparison with other aldehydes.
At the end of the catalytic reaction, the
nanocomposite catalyst was separated from the reaction
mixture by the addition of methanol, centrifuged, and
washed thoroughly with methanol. The recovered
[1]
oxide and phosphorous oxide.
The corresponding
DTA peak is exothermic because of the decomposition
of PMo species. Interestingly, the decomposition tem-
perature of the supported PMo species was increased
ꢀ
compared with neat PMo (decomposed at 450 C)
+
because of the stabilization effect of CTA cations and
MMT support.
3
.3 | Catalytic activity of (CTA) PMo-
3
MMT nanocomposite catalyst
Solvent-free synthesis of trisubstituted imidazoles via the
condensation of benzil, benzaldehyde, and ammonium
acetate was performed to investigate the catalytic perfor-
mance of (CTA) PMo-MMT nanocomposite catalyst, and
3
the results are summarized in Table 2. To elucidate the
essential role of the catalyst, a catalyst-free reaction was
prepared as a control test in which no reaction progress
was detected even after 48 h.
Interestingly, (CTA) PMo-MMT nanocomposite cata-
3
lyst was efficient for the preparation of trisubstituted
imidazoles in short reaction times. The efficiency is due
+
to the fact that the presence of CTA species makes the
FIGURE 7 The reusability of (CTA)
nanocomposite catalyst in the solvent-free synthesis of
,4,5-triphenyl imidazole. Reaction conditions: benzil (1 mmol),
3
PMo-MMT
nanocomposite catalyst hydrophobic and facilitates the
accessibility of hydrophobic reactants to active sites in
the course of the reaction. As can be seen in Table 2, the
steric hindrance near the carbonyl group decreases the
reactivity of the corresponding aldehyde (see, e.g., entries
2
benzaldehyde (1 mmol), ammonium acetate (5 mmol), catalyst
ꢀ
(50 mg), 100 C. The numbers above the columns show the amount
–1
(mmol g ) of PMo species after recovery of the catalyst

10 of 12
MASTERI-FARAHANI ET AL.
catalyst was dried in vacuum overnight and reused in the
next catalytic run under the same reaction conditions.
Figure 7 shows the results of the reusability of
(
CTA) PMo-MMT nanocomposite catalyst in the solvent-
3
free synthesis of 2,4,5-triphenyl imidazole. It can be seen
that the catalyst can be reused for up to five times with
no considerable loss of activity, which demonstrates its
excellent stability.
Further evidence of the stability of (CTA) PMo-MMT
3
nanocomposite catalyst was provided by FT-IR spectrum
of the fifth recovered catalyst (Figure 1S). No significant
change in catalyst structure was seen even after reusing
the catalyst five times. Also, the results of ICP–OES anal-
ysis of the recovered catalysts after each recycling experi-
ment showed that PMo leaching during the catalytic
reaction is negligible (Figure 7). These observations con-
firmed that the catalyst is stable during the catalytic reac-
tion conditions.
SCHEME 2 Plausible reaction mechanism for the formation
of 2,4,5-trisubstituted imidazoles in the presence of (CTA)
MMT nanocomposite catalyst
3
PMo-
A
comparison of the catalytic activities of
(
CTA) PMo-MMT nanocomposite catalyst with those of
comparable or better catalytic efficiency in comparison
with other reported catalysts. These observations imply
that our prepared catalyst can be used in various organic
reactions with good catalytic performance.
3
some earlier catalysts used in the synthesis of trisubsti-
tuted imidazoles is shown in Table 3. As can be observed,
the prepared (CTA) PMo-MMT catalyst (entry 14) shows
3
TABLE 3
3
Comparison of the efficiency (yield and reaction time) of various catalysts with (CTA) PMo-MMT in the synthesis of the
2
,4,5-trisubstituted imidazoles
Number
Catalyst
InCl .3H
SnCl .2H
CoCl .2H
NiCl .2H
AlCl .6H
BO
Mg(OAc)
MoO /SiO
MCS-GT@Co (II)
CoFe nanoparticles
CuCl .2H
SA-MNPs
Supported Mo(IV) salen complex
(CTA) PMo-MMT
Conditions
Time (h)
Yield (%)
Reference
1
2
3
4
5
6
7
8
9
3
2
O
MeOH, room temperature
MeOH, room temperature
MeOH, room temperature
MeOH, room temperature
MeOH, room temperature
MeOH, room temperature
8.3
18
18
18
18
18
18
2.2
0.5
0.5
24
0.5
1
82
48
39
41
38
34
51
95
97
95
87
86
94
85
43
2
2
O
43
2
2
O
O
O
43
2
2
43
3
2
43
H
3
3
43
2
.2H
2
O
MeOH, room temperature
43
ꢀ
3
2
CH
3
CN, 80 C
42
EtOH, reflux
44
10
11
12
13
14
2
O
4
EtOH, ultrasound
45
ꢀ
2
2
O
Dimethylformamide, 50 C
EtOH, ultrasound
46
47
ꢀ
EtOH, 50 C
48
ꢀ
3
100 C, solvent free
1
This work

MASTERI-FARAHANI ET AL.
11 of 12
A probable mechanism for the condensation of
benzil, benzaldehyde, and ammonium acetate in the
[11] M. M. Heravi, F. Derikvand, F. F. Bamoharram, J. Mol. Catal.
A: Chem. 2007, 263, 112.
[12] V. B. Kumar, I. N. Pulidindi, R. K. Mishra, A. Gedanken,
Energy Fuels 2016, 30, 10583.
presence of (CTA) PMo-MMT nanocomposite catalyst for
3
the synthesis of trisubstituted imidazoles was proposed
[13] J. She, Z. Fu, J. Li, B. Zeng, S. Tang, W. Wu, H. Zhao, D. Yin,
S. R. Kirk, Appl. Catal. B Environ. 2016, 182, 392.
[57]
based on the literature report,
as shown in Scheme 2.
Initially, (CTA) PMo-MMT induced the polarization of
3
[14] J. Safari, M. Tavakoli, M. A. Ghasemzadeh, Appl. Organomet.
Chem. 2019, e4748.
[15] S. Farhadi, M. Hakimi, M. Maleki, RSC Adv. 2018, 8, 6768.
carbonyl group because of the interaction of the carbonyl
oxygen atoms of aldehyde and benzil with the molybde-
num center. Then, the nucleophilic attack of the lone
pair of ammonia, produced from ammonium acetate, on
activated carbonyl resulted in the formation of
intermediate A. The subsequent reaction followed by
intramolecular interaction led to cyclization. The formed
intermediate B was dehydrated and deprotonated to
obtain 2,4,5-trisubstituted imidazole D in excellent yield.
[
[
[
[
[
16] O. Makrygenni, D. Brouri, A. Proust, F. Launay,
R. Villanneau, Micropor. Mesopor. Mat. 2019, 278, 314.
17] L. Hong, P. Win, X. Zhang, W. Chen, H. N. Miras, Y.-F. Song,
Chem. – Eur., J. 2016, 22, 11232.
18] N. García-Bosch, B. Bachiller-Baeza, I. Rodríguez-Ramos,
A. Guerrero-Ruiz, ChemCatChem 2018, 10, 3746.
19] S. Xun, D. Zheng, S. Yin, Y. Qin, M. Zhang, W. Jiang, W. Zhu,
H. Li, RSC Adv. 2016, 6, 42402.
20] G. Yan, X. Feng, S. U. Khan, L. Xiao, W. Xi, H. Tan, Y. Ma,
L. Zhang, Y. Li, Chem. – Asian J. 2018, 13, 158.
[
[
21] V. V. Bokade, G. D. Yadav, Appl. Clay Sci. 2011, 53, 263.
22] X. Yang, J. A. Wang, L. Chen, S. P. R. Sebastian,
A. M. Robledo, Catal. Comm. 2012, 28, 202.
4
| CONCLUSION
An efficient nanocomposite catalyst was successfully pre-
pared by immobilizing H PMo O onto
[
[
23] Z. Zhu, W. Yang, J. Phys, Chem. C 2009, 113, 17025.
24] T. Pinto, P. Arquilliere, G. P. Niccolai, F. Lefebvre, V. Dufaud,
New J. Chem 2015, 39, 5300.
3
12 40
cetyltrimethylammonium-modified MMT. The prepared
nanocomposite catalyst exhibited excellent catalytic activ-
ity for the synthesis of 2,4,5-trisubstituted imidazoles in
solvent-free conditions. The catalyst can also be easily
recovered from the reaction mixture and reused several
times without a significant loss of activity. These advan-
[25] P. Biswas, N. A. Hoque, P. Thakur, M. M. Saikh, S. Roy,
F. Khatun, B. Bagchi, S. Das, ACS Sustainable Chem. Eng.
2019, 7, 4801.
[26] N. Wang, F. Xiao, J. Zhang, H. Zhou, Y. Qin, D. Pan, Appl.
Clay Sci. 2019, 174, 146.
[
27] X. Zhang, M. Liu, W. Qiu, J. Evans, M. Kaur, J. P. Jasinski,
W. Zhang, ACS Sustainable Chem. Eng. 2018, 6, 5574.
28] M. Asgari, U. Sundararaj, Appl. Clay Sci. 2018, 153, 228.
29] M. Asgari, A. Abouelmagd, U. Sundararaj, Appl. Clay Sci.
tages make (CTA) PMo-MMT a green and promising
nanocomposite catalyst for other organic reactions.
3
[
[
2
017, 146, 439.
ORCID
[
[
[
30] D. F. Montano, H. Casanova, W. I. Cardona, L. F. Giraldo,
Mater. Chem. Phys. 2017, 198, 386.
31] N. Greesh, R. Sanderson, P. C. Hartmann, Appl. Clay Sci.
M. Masteri-Farahani https://orcid.org/0000-0001-9770-
9
566
2014, 93-94, 38.
REFERENCES
32] D. Zhou, Z. Zhang, J. Tang, F. Wang, L. Liao, Appl. Clay Sci.
2016, 121-122, 1.
[33] G. Wang, Y. Miao, Z. Sun, S. Zheng, J. Colloid Interface Sci.
2018, 511, 67.
[34] S. Shobana, P. Subramaniam, J. Dharmaraja, A. Narayan,
Spectrochim. Acta a. 2014, 126, 242.
[35] A. S. Gurjar, M. N. Darekar, K. Y. Yeong, L. Ooi, Med. Chem.
2018, 26, 1511.
[36] S. C. Bete, C. Wurtele, M. Otte, Chem. Commun. 2019, 55,
4427.
[37] S. V. Bhosale, M. B. Kalyankar, S. V. Nalage, D. S. Bhosale,
S. L. Pandhare, T. V. Kotbagi, S. B. Umbarkar, M. K. Dongare,
Synth. Commun. 2011, 41, 762.
[38] S. K. Bhorodwaj, D. K. Dutta, Appl. Clay Sci. 2011, 53, 347.
[39] G. D. Yadav, S. R. More, Appl. Clay Sci. 2011, 53, 254.
[40] V. V. Bokade, G. D. Yadav, Appl. Clay Sci. 2011, 53, 263.
[41] B. Li, Z. Liu, C. Han, W. Ma, S. Zhao, J. Colloid Interf. Sci.
2012, 377, 334.
[
1] M. Masteri-Farahani, M. Modarres, J. Mol. Catal. Chem. 2016,
17, 81.
2] M. Masteri-Farahani, M. Ghorbani, Mater. Res. Bull. 2016,
6, 332.
4
[
7
[
[
[
3] W. Xie, F. Wan, Chem. Eng. J. 2019, 365, 40.
4] A. A. Shatalov, Carbohydr. Polym. 2019, 206, 80.
5] L. Hao, L. Sun, T. Su, D. Hao, W. Liao, C. Deng, W. Ren,
Y. Zhang, H. Lü, Chem. Eng. J. 2019, 358, 419.
[
[
[
[
6] M. Sun, J. Zhang, P. Putaj, V. Caps, F. Lefebvre, J. Pelletier,
J.-M. Basset, Chem. Rev. 2014, 114, 981.
7] M. Najafi, A. Abbasi, M. Masteri-Farahani, V. H. Rodrigues,
Inorg. Chem. Commun. 2014, 46, 251.
8] S. Abednatanzi, A. Abbasi, M. Masteri-Farahani, Catal.
Commun. 2017, 96, 6.
9] M. S. Hosseini, M. Masteri-Farahani, Chem. – Asian J. 2019,
1
4, 1076.
[
10] C. F. Oliveira, L. M. Dezaneti, F. A. C. Garcia, J. L. de Macedo,
J. A. Dias, S. C. L. Dias, K. S. P. Alvim, Appl. Catal. A: Gen.
[42] M. Farias, M. Martinelli, G. K. Rolim, Appl. Catal. A: Gen.
2011, 403, 119.
2
010, 372, 153.

12 of 12
MASTERI-FARAHANI ET AL.
[
43] S. D. Sharma, P. Hazarika, D. Konwar, Tetrahedron Lett. 2008,
9, 2216.
[56] Y. Zidane, A. Ourari, T. Bataille, P. Hapiot, D. Hauchard,
J. Electroanal. Chem. 2010, 641, 64.
4
[
[
44] H. Singh, J. K. Rajput, Appl. Organometal. Chem. 2017, e3989.
45] E. Eidi, M. Z. Kassaee, Z. Nasresfahani, Appl. Organometal.
Chem. 2016, 30, 561.
[57] M. V. Chary, N. C. Keerthysri, S. V. N. Vupallapati,
N. Lingaiah, S. Kantevari, Catal. Comm. 2008, 9, 2013.
[
[
[
46] J. Jayram, V. Jeena, Green Chem. 2017, 19, 5841.
47] J. Safari, Z. Zarnegar, Ultrason. Sonochem. 2013, 20, 740.
48] H. Sharghi, M. Aberi, M. M. Doroodmand, Mol. Diversity 2015,
SUPPORTING INFORMATION
Additional supporting information may be found online
in the Supporting Information section at the end of this
article.
1
9, 77.
[
[
49] A. Akbari, Tetrahedron Lett. 2016, 57, 431.
50] K. Niknam, A. Deris, F. Naeimi, F. Majleci, Tetrahedron Lett.
2
011, 52, 4642.
[
[
51] P. Yin, D. Li, T. Liu, Chem. Soc. Rev. 2012, 41, 7368.
52] S. Chen, W. Zhou, Y. Cao, C. Xue, C. Lu, J. Phys. Chem. C
How to cite this article: Masteri-Farahani M,
Ezabadi A, Mazarei R, Ataeinia P, Shahsavarifar S,
Mousavi F. A new nanocomposite catalyst based
on clay-supported heteropolyacid for the green
synthesis of 2,4,5-trisubstituted imidazoles. Appl
Organomet Chem. 2020;e5727. https://doi.org/10.
1002/aoc.5727
2
014, 118, 2851.
[
53] S. Ganapathy, M. Fournier, J. F. Paul, L. Delevoye,
M. Guelton, J. P. Amoureux, J. Am. Chem. Soc. 2002, 124,
7
821.
54] I. A. Shabtai, Y. G. Mishael, ACS Appl. Mater. Interfaces 2018,
0, 27088.
55] Y. Xu, M. A. Khan, F. Wang, M. Xia, W. Lei, Appl. Clay Sci.
018, 162, 204.
[
[
1
2