Fe- containing ionic liquid supported on nanosized MCM-41: An efficient and reusable catalyst in the synthesis of 2-Aryl Benzimidazole derivatives

Article abstract of DOI:10.13005/ojc/320438

In this study, an efficient method for the synthesis of 2-Aryl Benzimidazole derivatives has been developed. The synthesis was performed by condensation aromatic benzaldehydes and 1.2 phenylenediamin using [bmim][FeCl₄]/MCM-41 as a heterogeneous catalyst under reflux conditions and at 60 C. The advantages of this method are easy work-up procedure, clean and neutral reaction conditions. The separation and reuse of the catalyst were simple and could be reused without a significant loss of catalytic activity. Moreover, the products were achieved in good yields (70-83%).

Full text of DOI:10.13005/ojc/320438

ISSN: 0970-020 X
CODEN: OJCHEG
2016, Vol. 32, No. (4):
Pg. 2101-2106
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Free Access, Peer Reviewed Research Journal
www.orientjchem.org
Fe- Containing Ionic liquid Supported on Nanosized
MCM-41: An Efficient and Reusable Catalyst in the
Synthesis of 2-Aryl Benzimidazole Derivatives
ESMAT IZADPANAH1 and SOHEIL SAYYAHI2*
1Department of Chemistry, Omidiyeh Branch, Islamic Azad University, Omidiyeh, Iran.
2Department of Chemistry, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran.
*Corresponding author E-mail: sayyahi.soheil@gmail.com
http://dx.doi.org/10.13005/ojc/320438
(Received: June 26, 2016; Accepted: August 04, 2016)
ABSTRACT
In this study, an efficient method for the synthesis of 2-Aryl Benzimidazole derivatives has been
developed. The synthesis was performed by condensation aromatic benzaldehydes and 1.2
phenylenediamin using [bmim][FeCl4]/MCM-41 as a heterogeneous catalyst under reflux conditions
and at 60 C.The advantages of this method are easy work-up procedure, clean and neutral reaction
conditions. The separation and reuse of the catalyst were simple and could be reused without a
significant loss of catalytic activity. Moreover, the products were achieved in good yields (70-83%).
Keywords: Magnetic ionic liquid, MCM-41, Banzimidazoles.
silica, MCM-41 exhibits a highly ordered hexagonal
array of one dimensional mesoporous with a pore
diameter of 15–100 Å, high surface area (>1000 m2
g 1) and high thermal stability (ca. 900 °C)2.
INTRODUCTION
Mesoporous silica nanoparticles with
uniform pore size and a long-range ordered pore
structure were first reported in the early 1990s
using surfactants as structure-directing agents
(SDAs). Now, rapid progress has been achieved in
the synthesis and application of ordered MSNs in
catalysis, adsorption, separation, sensing, and drug
delivery1. Among the various types of mesoporous
Magnetic ionic liquids (MILs) 3 incorporated
withinorganicororganicparamagneticionsareanew
type of ionic materials having high ionic conductivity,
magnetic responsiveness and sometimes integrated
with luminescence activity4.

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IzADPANAH & SAyyAHI, Orient. J. Chem., Vol. 32(4), 2101-2106 (2016)
The MILs are primarily based on high- tetrachloro ferrate(III) was dried under vacuum at
spin d5 Fe (III) in the form of tetrachloroor 80 ºC overnight.
tetrabromoferrate(III) with various counter cations.
Owing to the high single-ion magnetic moments, Synthesis of MCM-41
these MILs exhibited a strong response to magnetic
The source of silicon was tetraethyl
fields 5. Since then, much attention has been paid to orthosilicate (TEOS, 98%). The structure-directing
the design and synthesis of this new class of ILs 6–10
.
agent was cetyltrimethylammonium bromide (CTAB).
Moreover, the catalytic activities of MILs have been A typical synthesis gel was prepared by adding
studied in Friedel Crafts acylation 11, aryl grignard 5.78 g of TEOS to an aqueous solution containing
cross coupling of alkyl halides 12, preparation of 1.01 g of CTAB and 0.34 g of NaOH and 30 ml of
1,2-azidoalcohols 13, glycolysis of poly(ethylene deionized water. After further stirring for about 1 h
terephthalate) 14, “liquid fixed-bed” catalysts in flow at room temperature, the resulting homogeneous
application 15, oxidative desulfurization of fuels 16 and mixture was crystallized under static hydrothermal
multi-component synthesis of 1- and 5-substituted conditions at 383 K in a Teûon lined autoclave for
1H-tetrazoles 17 and quinazoline derivatives 18
.
96 h.The molar composition of the initial gel mixture
was 1.0:0.10:0.30:60 TEOS/CTAB/NaOH/ H2O.The
Recently, we introduced new sustainable solid product was obtained by ûltration, washed with
synthetic methods using Fe-containing ionic liquids deionized water, dried in air at 353 K and calcined in
19-21. In the present work we report the catalytic air at 813 K for 24 h.
application of nanosized MCM-41 supported n-
1-butyl-3-methylimidazolium tetrachloroferrate(III), as The preparation of [bmim][FeCl4]/MCM-41
catalyst in the synthesis of benzimidazole derivatives
A suspensions of the MCM-41(0.1g) and
via condensation of different benzaldehydes and [bmim][FeCl4] (1mmol) in acetone (5mmol) were
o-phenylenediamine.
EXPERIMENTAL
stirred vigorously for 12 h. It was then centrifuged
and the solid washed many times with acetone and
then dried under vacuum at 40 C.
General
General procedure for the synthesis of
All compounds were purchased from Aldrich benzimidazoles in the presence of [bmim][FeCl4]/
and Merck companies and used as received without MCM-41(MIL/MCM-41)
further purification. The purity of the products and
A mixture of 1.2 phenylenediamin(1 mmol),
reaction monitoring were followed by thin layer aryl aldehyde (1 mmol), [bmim][FeCl4]/MCM-41 (0.05
chromatography on Merck DC-Alufolien plates gr) and ethanol (5 mL) was placed in a round bottom
pre-coated with silica gel F254. IR spectra were flask and refluxed for the given times recorded in
recorded on a Perkin-Elmer RX1 FTIR spectrometer. Table 2.After completion of the reaction observed by
SEM images were obtained from a Philips XL30 TLC (using n-hexane/ ethylacetate (1:2) as eluent),
instrument.
the mixture was cooled to room temperature, the
precipitate was filtered and washed with (hot ethanol)
for several times. The resultant product purified
Synthesis of MIL[bmim][FeCl4]
The magnetic ionic liquid was synthesized by column chromatography and characterized by
following the same way remarked in literature. 5 comparison of their physical data with benzimidazole
mmol [bmim]Cl (0.870g) and 5 mmol FeCl3 (0.825g) derivatives reported in literature.
were added to a round bottom flask and stirred
with a magnet for 15 minutes. The resulting ionic
liquid was dissolved in ethyl acetate (10 mL) and
the solution was centrifuged after filtration in order
RESULTS AND DISCUSSIONS
First of all, FT IR spectroscopy and
to separate any possible residue of inorganic salts. Scanning electron microscopy (SEM) were employed
Afterwards, ethylacetate was evaporated and the to confirm the successful immobilization of [bmim]
obtained dark brown liquid, butyl methyl imidazolium [FeCl4] onto the MCM-41. The FT IR spectrum and

IzADPANAH & SAyyAHI, Orient. J. Chem., Vol. 32(4), 2101-2106 (2016)
2103
SEM image of [bmim][FeCl4]/MCM-41 is shown in
Fig. 1
Then, it was decided to evaluate the
catalytic activity of the catalyst for the preparation
of 2-Aryl Benzimidazoles and the results showed a
highly effective performance of the catalyst (Scheme
1, Table 2).
In order to investigate the catalytic ability
of the MIL/MCM-41, the condensation of 1-2
phenylenediamin with 4-nitrobenzaldehyde was
chosen as the model reaction in different conditions.
As seen in Table 1, the most appropriate condition
among the candidate ones giving excellent yield in
a proper time is the 8th process using ethanol as
solvent under reflux condition.
With the optimal reaction conditions in
hand, consisting of a 1:1 molar ratios of aldehyde and
o-phenylenediamine with 0.05 g loading of [bmim]
[FeCl4]/MCM-41 and ethanol as solvent under reflux
conditions, the generality and synthetic scope of this
coupling protocol were demonstrated through the
Fig. 1:The FT-IR spectrum (upper) and SEM image (lower) of [bmim][FeCl4]/MCM-41

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IzADPANAH & SAyyAHI, Orient. J. Chem., Vol. 32(4), 2101-2106 (2016)
synthesis of a series of 2-Aryl Benzimidazoles (Table was well tolerated under the optimized reaction
2). Pleasingly, a wide range of aromatic aldehydes conditions. Also, postulated catalytic activity of the
with electron donating or electron withdrawing groups catalyst is shown (Scheme 2).
Table 1:The one-pot condensation reaction of 1-2 phenylenediamin (1
mmol) and 4-nitrobenzaldehyde (1 mmol) under different condition
Entry Catalyst Solvent
(mmol)
Temperature
(ºC)
Time
(min)
Result
1
2
3
4
5
6
7
8
9
0.05
0.05
0.05
0.05
0.05
0.05
0.02
0.05
0.05
-
-
60
r.t
120
120
120
120
120
120
120
30
No Reaction
No Reaction
No Reaction
Uncompleted
Uncompleted
Uncompleted
Uncompleted
Completed
H2O
reflux
reflux
reflux
reflux
reflux
reflux
r.t
n-hexane
CHCl3
CH3CN
EtOH
EtOH
EtOH
120
Uncompleted
CHO
NH2
N
bmim[FeCl4]/MCM-41
EtOH, reflux
R
NH
NH2
R
Scheme 1: Synthesis of 2-Aryl Benzimidazoles
O
+
NH2
[bmim][FeCL 4]/MCM-41
Ar
H
+
a
NH2
e
..
NH2
H
air oxidation
N
H
N
Ar
Ar
H
N
N
Ar
H
b
d
N
c
Scheme 2: Schematic illustration of the reaction

IzADPANAH & SAyyAHI, Orient. J. Chem., Vol. 32(4), 2101-2106 (2016)
2105
Table 2: Synthesis of 2-Aryl Benzimidazoles and catalyzed
by [bmim][FeCl4]/MCM-41 (MIL/MCM-41)
Entry
Aldehyde
Product
Time (min)
Yield (%)
M.p. (ºC) (Lit.)
Ref
CHO
N
289-291
1
70
75
(294-293)
22
N
H
CHO
290-288
N
2
3
4
5
30
55
30
60
72
74
83
72
(292-290)
24
23
22
22
Cl
N
H
Cl
CHO
263-261
(263.5-(261.5
N
Br
N
H
Br
319-317
(320-318)
CHO
N
NO2
N
H
NO2
260-258
(262-260)
CHO
N
Me
N
H
Me
178-176
CHO
6
7
8
9
40
40
75
73
81
70
(182-180)
24
23
N
OMe
N
H
OMe
CHO
235-232
(233-231)
N
Cl
N
H
Cl
CHO
N
Me
75
45
295-290
N
Me
N
H
N
Me
Me
CHO
242-240
-248
N
24
F
N
H
F

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IzADPANAH & SAyyAHI, Orient. J. Chem., Vol. 32(4), 2101-2106 (2016)
CONCLUSION
several advantages including easy workup, green
condition, good yield and simple purification.
We have developed a facile and
environmentally friendly protocol for the syntheses of
2-Aryl Benzimidazoles derivatives in the presence of
[bmim][FeCl4]/ MCM-41 as a novel environmentally
safe heterogeneous catalyst. This method offers
ACKNOWLEDGMENTS
We are sincerely grateful to the Omidiyeh
Branch, Islamic Azad University for the financial
support of this project.
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