Isocyanurate-based periodic mesoporous organosilica (PMO-ICS): A highly efficient and recoverable nanocatalyst for the one-pot synthesis of substituted imidazoles and benzimidazoles

Article abstract of DOI:10.1039/c6ra14550g

Isocyanurate bridging periodic mesoporous organosilica (PMO-ICS) was shown to be a highly active and efficient recyclable catalyst for the three-component synthesis of imidazole derivatives from benzoin, different aldehydes and ammonium acetate under mild reaction conditions in short reaction times and good to excellent yields in EtOH. Also, benzimidazole derivatives were efficiently prepared from o-phenylenediamine and different aldehydes in the presence of PMO-ICS. Moreover, the catalyst was also recovered and reused at least four times without a significant decrease in its activity. The PMO-ICS catalyst was characterized by Fourier transformer infrared (FTIR) spectroscopy, thermogravimetry analysis (TGA), powder X-ray diffraction (XRD) and nitrogen adsorption-desorption isotherm (NADI) techniques as well as field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Compared to the classical methodologies, this method illustrated significant advantages including low loading of the catalyst, avoiding the use of toxic transition metals or reactive reagents for modification of the catalytic activity, short reaction times, high to excellent yields, easy separation and purification of the products, and reusability of the catalyst.

Full text of DOI:10.1039/c6ra14550g

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: M. G. Dekamin, E.
Arefi and A. Yaghoubi, RSC Adv., 2016, DOI: 10.1039/C6RA14550G.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Please do not adjust margins
RSC Advances
Page 1 of 11
View Article Online
DOI: 10.1039/C6RA14550G
RSC Advances
ARTICLE
IsocyanurateꢀBased periodic mesoporous organosilica (PMOꢀ
ICS): a highly efficient and recoverable nanocatalyst for the
oneꢀpot synthesis of substituted imidazoles and benzimidazoles
Received 00th January 20xx,
Accepted 00th January 20xx
Mohammad G. Dekamin,* Elham Arefi and Amene Yaghoubi
DOI: 10.1039/x0xx00000x
www.rsc.org/
Isocyanurate bridging periodic mesoporous organosilica (PMOꢀICS) was shown to be a highly active and efficient
recyclable catalyst for threeꢀcomponent synthesis of imidazole derivatives from benzoin, different aldehydes and
ammonium acetate under mild reaction conditions in short reaction times and good to excellent yields in EtOH. Also,
benzimidazole derivatives were efficiently prepared from oꢀphenylenediamine and different aldehydes in the presence of
PMOꢀICS. Moreover, the catalyst was also recovered and reused at least four times without significant decrease in its
activity. The PMOꢀICS catalyst was characterizred by fourier transformer infrared (FTIR) spectroscopy, thermogravimetry
analysis (TGA), powder Xꢀray diffraction (XRD) and nitrogen adsorption–desorption isotherms (NADI) techniques as well
as field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Compared to the
classical methodologies, this method illustrated significant advantages including low loading of the catalyst, avoiding the
use of toxic transition metals or reactive reagents for modification of the catalytic activity, short reaction times, high
to excellent yields, easy separation and purification of the products, and reusability of the catalyst.
5
and often experimentally simple procedure. The imidazole and
Introduction
benzimidazole ring systems are one of the most important
heterocyclic moieties found in a large number of natural
The use of heterogeneous catalysts has become highly desirable
in recent years, because they incorporate many green chemistry
principles. In 1999, mesoporous organosilica hybrids were
products and pharmacologically active compounds. Hence,
6
,7
their role in biochemical processes is very significant.
In the recent years, a few methods have been described for
the oneꢀpot multicomponent synthesis of 2,4,5ꢀtrisubstituted
imidazole derivatives from benzoin in the presence of different
prepared from bridged organosilane precursors ((R
3
́O ) Si–R–
Si(OR ; R: organic bridging group, R: methyl or ethyl). Such
́)
3
́
mesoporous hybrids prepared from bridged organosilane
precursors have been classified as periodic mesoporous
8
catalysts. These include graphene oxide–chitosan composite,
9
10
1
,2
molecular iodine,
p
ꢀtoluenesulfonic acid (PTSA),
Nꢀmethylꢀ
organosilicas (PMOs). PMOs are very attractive as support
for heterogeneous catalysts in fine chemicals synthesis among
others. The large and tunable pore sizes (between 2 and 30
nm) and pore volumes, wellꢀdefined pore morphology, and
high surface areas of PMOs allow facile diffusion of bulky
reactants and products that are often involved in such reactions.
In addition, other unique properties of PMOs such as high
loading of uniform distribution of organic functional groups in
their framework, superior thermal stability, nonꢀtoxicity,
reusability, and stability against air and moisture make them an
attractive candidate for the widespread applications in catalysis,
chromatography, solidꢀphase extraction, electronic, sensor
1
1
12
2
ꢀpyrrolidonium hydrogen sulphate, PEGꢀ400 and 2,6ꢀ
dimethylpyridinium
DMPyH]C(NO2)3}. However, there are much more catalytic
methodologies starting from benzil. For example, catalysts such
trinitromethanide
{[2,6ꢀ
1
3
1
4
15
19
24
as KH PO ,
pꢀdodecylbenzenesulfonic acid (PDBSA),
2
4
1
6
17
18
glyoxalic acid,
KAl(SO ) , ZnCl , FeBr2, FeCl .6H O, nanoꢀIn O ,
NiCl .6H O/Al O ,
Lꢀproline,
Znꢀproline,
InCl ·3H O,
3 2
2
0
21
22
23
4
2
2
5
3
2
2
3
2
26
FeCl /SiO ,
WellsꢀDawson
2
2
2
3
3
2
2
7
heteropolyacid supported on silica (WD/SiO2), zirconium
modified silica gel, ZrO ꢀsupportedꢀβꢀcyclodextrin,
polyethylene glycol–Cu nanocomposite (Fe O –PEG–Cu),
2
8
Fe O –
3 4
2
2
9
3
4
n
30
3
,4
Fe O @SiO ꢀimidꢀPMA magnetic porous nanosphere, Silica
3
4
2
technology, gas storage, etc.
multicomponent reactions (MCRs) offer high atom economy
and bondꢀforming e ciency for the synthesis of diverse and
On the other hand,
coated
magnetic
NiFe O
nanoparticle
supported
2
4
3
1
phosphomolybdic acid, different fluoroboric acid (HBF )
derived catalyst systems, and ionic liquids.
4
ffi
3
2
11,33
However,
complex molecules especially heterocyclic compounds in a fast
Many of the reported synthetic protocols for the synthesis of
imidazoles have limitations in terms of the use of excess
amounts of expensive or toxic catalysts, formation of
byproducts and unsatisfactory yields, lengthy reaction times,
difficult workꢀup, unavoidable metal pollution, significant
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 1-8 | 1
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 2 of 11
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
RSC Advances
amounts of waste materials, and low selectivity. Therefore, field emission scanning electron microscopy (FESEM),
development of new methodologies and introducing green transmission electron microscopy (TEM), and thermal
catalysts to overcome aforementioned disadvantages is still gravimetric analysis (TGA). The IR spectrum of PMOꢀICS (
desirable and is in demand. shows the presence of organic functional groups in the material
The heteroaromatic isocyanurate ring in the structure of framework (See ESI). Indeed, the bands observed at 2935 and
1)
ꢀ1
isocyanurateꢀbased periodic mesoporous organosilica (PMOꢀ 2850 cm are assigned to C–H stretching of aliphatic moieties.
ꢀ1
ICS) contains three nonpolar propyl groups and is well known Moreover, the signals appeared at 1689 and 1471cm are
2
b,34
for its binding ability to transition metals.
Furthermore, it is attributed to the stretching vibrations of the isocyanurate ring.
) showed bands at 1120, 1070
properties of a wide variety of polyurethanes and other coating and 935 cm corresponding to asymmetric and symmetric
thermally very stable and used to enhance the physical On the other hand, PMOꢀICS (
1
ꢀ1
3
5
materials such as polyureas in commercial systems. These vibrations of Si–O–Si (siloxane) bonds, respectively. The
unique properties as well as other useful properties associated strong and broad signal appeared about 3334 cm is attributed
with PMOs make isocyanurateꢀbased periodic mesoporous to O–H bonds of silanol groups.
ꢀ1
organosilica (PMOꢀICS) a promising support or catalyst
The transmission electron microscopy (TEM) images
depending on the used conditions compared to modified demonstrated that the mesostructure PMOꢀICS (
mesoporous silica materials (M41S family) or even other ordered hexagonal structure (Fig 1).
members of PMOs family having two aryl or alkyl groups in
1) exhibits
their structures. In continuation of our interest to develop mild
3
6
and efficient catalysts for different MCRs, we herein wish to
report the catalytic application of an isocyanurateꢀbased
periodic mesoporous organosilica (PMOꢀICS, 1) nanomaterial
without any postꢀmodification with active Bronsted or Lewis
acid centres, as an efficient and recoverable catalyst, for the
synthesis of 2,4,5ꢀtrisubstituted imidazoles
benzoimidazoles ( ) in EtOH under reflux conditions (Scheme
). To the best of our knowledge, there is no report on the use
(
5)
and
7
1
of PMOs for the synthesis of imidazole or benzimidazole Fig 1. TEM image of PMOꢀICS (1) nanocatalyst
.
derivatives.
Furthermore, BET analysis of PMOꢀICS (1) showed specific
2
surface area close to 570 m /g, pore size ≈ 4.1 and volume pore ≈ 5
nm (Fig 2). On the other hand, thermogravimetric analysis (TGA)
of PMOꢀICS (1) showed the thermal stability about 470 °C for
the isocyanurate bridging containing organics which have been
incorporated into the silica framework (Fig 3).
Scheme 1
different aldehydes
aldehydes with 1,2ꢀphenylenediamine (
.
(a) Oneꢀpot threeꢀcomponet reaction of benzoin (
2) and
3
with NH OAc ( ); (b) Condensation of different
4
4
3
6
)
.
Fig 2. BET analysis of the PMOꢀICS (1) nanocatalyst.
Results and discussion
PMOꢀICS (1) was prepared through a known procedure
3
4
described by Jaroniec and his coꢀworkers. The catalyst was
then characterized using techniques including Fourier transform
infrared (FTIR) spectroscopy, Xꢀray powder di
ffraction (XRD),
2
| RSC Adv., 2016, 2016, 6, 1-10
This journal is © The Royal Society of Chemistry 2016
Please do not adjust margins

Page 3 of 11
PleaseRd So Cn oA t da vd aj un s ct ems argins
View Article Online
DOI: 10.1039/C6RA14550G
RSC Advances
ARTICLE
2
.5 mmol) was investigated as the model reaction. The reaction
conditions were optimized with regard to the best catalyst
loading, different solvents and temperature for the synthesis of
desired product of 2ꢀ(4ꢀchlorophenyl)ꢀ4,5ꢀdiphenylꢀ1
imidazole (5a). The results are summarized in Table . It is
noteworthy that only a trace amount of the desired product 5a
was obtained in the absence of PMOꢀICS ( ) at room
temperature after 4 h in EtOH (Table , entry 1). On the other
hand, the yield of trisubstituted imidazole 5a was improved to
Hꢀ
1
1
1
4
1
0% under similar reaction conditions in refluxing EtOH (Table
, entry 2). The effect of catalyst loading on the completion of
the reaction was examined in next experiments (Table
1, entries
3
ꢀ5). Interestingly, after addition of 15 mg of the catalyst (1)
the yield of the desired product 5a was increased significantly
under similar reaction conditions in refluxing EtOH compared
to catalystꢀfree conditions. Furthermore, 20 mg loading of
Fig 3. Thermal gravimetric analysis (TGA) of the fresh PMOꢀICS (1)
(■) and recycled PMOꢀICS (1) (
▲
) nanocatalyst.
PMOꢀICS (
1) afforded higher yield of the desired product 5a in
shorter reaction time in refluxing EtOH (Table
1
, entry 4). In
the next step, the effect of other solvents such as H O and THF
2
Table 1. Optimization of conditions in the reaction of benzoin (
2
), 4ꢀ
on the model reaction was investigated. Both of solvents
chlorobenzaldehyde (3a) and NH
4
OAc under different conditionsa
afforded lower yield of the desired product 5a (Table
1
, entries
6
ꢀ7). Furthermore, product 5a was obtained in the presence 20
mg loading of PMOꢀICS (1) in lower yield at room temperature
after 3 h (Table
obtained in lower yield and longer reaction time at 100
under solventꢀfree conditions compared to reflux conditions in
EtOH (Table , entries 4 and 9). On the other hand, when
MCMꢀ41, as pure silica, or trisubstituted isocyanurates were
used under same catalyst loadings, the desired product 5a was
obtained in lower yields and longer reaction times (entries 4,
1, entry 8). Finally, the desired product 5a was
˚
C
1
Solvent
b
Entry
Catalyst 1
loading ( mg)
Temp.
C)
Time
(min)
Yield
(%)
(
̊
ꢀ
ꢀ
EtOH
EtOH
EtOH
r.t
1
2
3
240
240
35
Trace
40
1
0ꢀ12). These findings clearly show the synergic effects of both
silica and isocyanurate moieties on the catalytic activity of
PMOꢀICS ( ). Consequently, 20 mg PMOꢀICS ( ) loading in
reflux
reflux
1
2
2
2
5
0
5
0
88
1
1
EtOH under reflux conditions was selected as the optimized
conditions in the next experiments.
In order to demonstrate the scope of this protocol, the
optimized reaction conditions were developed to other
aromatic, heterocyclic or aliphatic aldehydes 3aꢀt. The results
EtOH
EtOH
4
5
6
reflux
reflux
reflux
25
25
97
93
45
2
H O
120
2
2
0
0
THF
are summarized in Table 2. After completion of the reaction
7
8
reflux
r.t
100
180
80
70
EtOH
(monitored by TLC), EtOH was added and the catalyst was
easily isolated from the reaction mixture by simple filtration
during recrystallization of the products. As it can be seen, high
to quantitative yields were obtained under the optimized
2
0
ꢀ
9
100
55
84
85
c
d
e
20
20
20
EtOH
10
reflux
360
EtOH
EtOH
conditions in short reaction times for the desired products 5aꢀt.
11
reflux
reflux
360
360
58
44
Both aromatic carbocyclic and heterocyclic aldehydes
containing electronꢀwithdrawing and electronꢀdonating groups
involved in the optimized conditions to afford corresponding
trisubstituted imidazoles 5aꢀt. In general, the nature of the
substituents on the phenyl ring has a significant influence on
the reaction rate. Indeed, aromatic aldehydes with electronꢀ
withdrawing groups often afforded the desired imidazole
derivatives 5aꢀt in higher yields and shorter reaction times
11
a
Reaction conditions: Benzoin (
2
, 1 mmol), 4ꢀChlorobenzaldehyde (3a, 1
mmol), and NH OAc (4, 2.5 mmol) in the presence of 20 mg PMOꢀICS
4
b
c
d
(
1
). Isolated Yields. MCMꢀ41 was used as catalyst. 1,3,5ꢀ
e
tripropyl isocuanurate was used as catalyst.
isocuanurate was used as catalyst.
1,3,5ꢀtriphenyl
compared to electronꢀdonating groups (Table
stage, the reaction between 1,2ꢀphenylenediamine (
various aldehydes 3aꢀu was investigated. The results are
summarized in Table . In all studied cases, the reactions
2
). In the next
To show the e
PMOꢀICS,
imidazoles (
ffi
ciency of periodic mesoporous organosilica
for the synthesis of 2,4,5ꢀtrisubstituted
), the reaction of benzoin ( , 1 mmol), 4ꢀ
6) and
(
1)
5
2
3
chlorobenzaldehyde (3a, 1 mmol) and ammonium acetate (4,
proceeded e
fficiently under the optimized conditions to afford
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 1-10 | 3
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 4 of 11
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
RSC Advances
corresponding products 7aꢀs in high to excellent yields within
very short reaction times.
Scheme 2. Plausible mechanism for oneꢀpot synthesis of 2,4,5ꢀtrisubstituted imidazoles (5 or 7) catalyzed by PMOꢀICS (1) through three
component reaction.
4
| RSC Adv., 2016, 2016, 6, 1-10
This journal is © The Royal Society of Chemistry 2016
Please do not adjust margins

Page 5 of 11
PleaseRd So Cn oA t da vd aj un s ct ems argins
View Article Online
DOI: 10.1039/C6RA14550G
RSC Advances
ARTICLE
Table 2. Isocyanurate bridging periodic mesoporous organosilica (PMOꢀICS, 1) catalyzed oneꢀpot threeꢀcomponet synthesis of 2,4,5ꢀtrisubstituted
a
imidazoles
5
from benzoin (2), different aldehydes
3
4
with NH OAc (
4) under the optimized conditions
b,c
Entry
Aldehyde 3
Product 5
Time (min)
Yield (%)
1
2
3
4
5
6
7
8
4ꢀChlorobenzaldehyde (3a)
2ꢀChlorobenzaldehyde (3b)
2ꢀNitrobenzaldehyde (3c)
4ꢀNitrobenzaldehyde (3d)
3ꢀNitrobenzaldehyde (3e)
4ꢀCyanobenzaldehyde (3f)
5a
5b
5c
5d
5e
5f
25
35
30
35
45
55
45
42
97
81
85
94
92
98
95
98
2,4ꢀDichlorobenzaldehyde (3g)
4ꢀBoromobenzaldehyde (3h)
5g
5h
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 1-10 | 5
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 6 of 11
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
RSC Advances
9
Benzaldehyde (3i)
5i
5j
5k
5l
60
75
60
70
60
60
81
80
74
84
78
90
1
1
1
1
1
0
1
2
3
4
4ꢀMethylbenzaldehyde (3j)
4ꢀMethoxybenzaldehyde (3k)
4ꢀHydroxybenzaldehyde (3l)
2ꢀHydroxybenzaldehyde (3m)
Vanillin (3n)
5m
5n
1
5
4ꢀDimethylaminobenzaldehyde (3o)
5o
55
75
1
1
1
1
2
6
7
8
9
0
Furfural (3p)
5p
5q
5r
5s
5t
50
45
55
60
60
93
97
96
90
94
Thiopheneꢀ2ꢀcarbaldehyde (3q)
4ꢀPyridincarbaldehyde (3r)
Formaldehyde (3s)
3ꢀPhenylpropionaldehyde (3t)
a
b
7
4
Reaction conditions: Benzoin (2, 1 mmol), 4ꢀchlorobenzaldehyde (3a, 1 mmol ), and NH OAc (4, 2.5 mmol) in the presence of 20 mg PMOꢀICS (1) and EtOH (2 mL).
c
Isolated Yields.
All compounds are known compounds and were identified by comparison of their physical and spectroscopic data with authentic samples
b,11,13,37,38,39,40,41
6
| RSC Adv., 2016, 2016, 6, 1-10
This journal is © The Royal Society of Chemistry 2016
Please do not adjust margins

Page 7 of 11
RSC Advances
PleaseRd So Cn oA t da vd aj un s ct ems argins
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
Table 3. Isocyanurate bridging periodic mesoporous organosilica (PMOꢀICS, 1) catalyzed condensation of 1,2ꢀphenylenediamine (
6
) with diverse
a
aldehydes
3
under
the
optimized
conditions
b
Entry
Aldehyde 3
Product 7
Time (min)
Yield (%)
1
2
3
4
5
6
7
8
9
4ꢀChlorobenzaldehyde (3a)
2ꢀChlorobenzaldehyde (3b)
2ꢀNitrobenzaldehyde (3c)
4ꢀNitrobenzaldehyde (3d)
3ꢀNitrobenzaldehyde (3e)
4ꢀCyanobenzaldehyde (3f)
4ꢀBoromobenzaldehyde (3h)
Benzaldehyde (3i)
7a
7b
7c
7d
7e
7f
30
30
45
50
35
45
45
40
65
60
93
90
99
87
88
95
96
92
88
90
7g
7h
7i
4ꢀMethylbenzaldehyde (3j)
4ꢀMethoxybenzaldehyde (3k)
1
0
1
7j
1
4ꢀHydroxybenzaldehyde (3l)
7k
65
85
1
1
1
1
1
1
1
1
a
2
3
4
5
6
7
8
9
2ꢀHydroxybenzaldehyde (3m)
4ꢀDimethylaminobenzaldehyde (3o)
Furfural (3p)
7l
7m
7n
7o
7p
7q
7r
70
67
65
65
65
60
60
50
88
93
90
97
98
92
92
83
Thiopheneꢀ2ꢀcarbaldehyde (3q)
4ꢀPyridincarbaldehyde (3r)
2ꢀPyridincarbaldehyde (3u)
Formaldehyde (3s)
3ꢀPhenylpropionaldehyde (3t)
7s
b
Reaction conditions: 4ꢀChlorobenzaldehyde (3a, 1 mmol) with 1,2ꢀphenylenediamine (6, 1 mmol) in the presence of 20 mg PMOꢀICS (1) and EtOH (2 mL).
c
Isolated Yields.
All compounds are known compounds and were identified by comparison of their physical and spectroscopic data with authentic
1
6,37,40b,42,43
samples.
intermediate V affords desired products
5 or 7, respectively. It
A probable mechanistic pathway for the formation of is noteworthy that the byproducts of this tandem MCR reaction
2
,4,5ꢀtrisubstituted imidazoles (5) and benzimidazoles are mainly water molecules which can be sorbed on the surface
analogues (7) is outlined in Scheme 2. According to the of PMOꢀICS (1) physically by the silanols or chemically by
mechanism, it can be proposed that the enormous hydroxyl siloxane functional groups. Higher catalytic activity of PMOꢀ
groups on the surface of PMOꢀICS (1) are responsible for the ICS (1) compared to MCMꢀ41 can be attributed to both fineꢀ
initial activation of the carbonyl group of aldehydes 3 to tuning of the polarity of inorganic silica moiety by the organic
facilitate nucleophilic addition of ammonia or 1,2ꢀ 1,3,5ꢀtripropyl isocuanurate functionality and sizeꢀexclusion
3
a
phenylenediamine (6) on the intermediate I to afford aminal (sieve) effect.
intermediates II or III΄, respectively. It is noteworthy that
ammonia itself is produced in situ by decomposition of
Another important aspect of this active, efficient, nonꢀ
ammonium acetate (4) in the presence of catalyst 1. In the toxic, and ecoꢀfriendly heterogeneous nanocatalyst is its high
case of 2,4,5ꢀtrisubstituted imidazoles (5), aminal degree of recyclability. In this part of our study, it has been
intermediates II is condensed with benzoin (2) to produce shown that the PMOꢀICS (1) could be recovered and reused at
corresponding 4,5ꢀdihydroimidazole intermediate IV through least four times in the subsequent runs for the model reaction
intermediate III. Air oxidation of the intermediates IV or IV΄ using the same recovered catalyst without a considerable loss
and subsequent [1,5]ꢀsigmatropic hydrogen shift of the of its catalytic activity (Fig 4).
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 1-10 | 7
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 8 of 11
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
00
RSC Advances
9
7
94
9
2
92
9
0
benzimidazole derivatives, it has been compared with some of
the previously reported and published procedures. Results are
1
90
80
70
60
50
40
30
20
10
0
summarized in Table
4. Obviously, the present protocol is
indeed superior to several of the others in terms of catalyst
loading, avoiding the use of toxic transition metals or reactive
reagents for modification of the catalytic activity, product yield,
reaction time and using a green solvent.
1
2
3
Run
4
5
Fig 4. Reusability of PMOꢀICS (1) nanocatalyst for the synthesis of 2ꢀ(4ꢀ
chlorophenyl)ꢀ4,5ꢀdiphenylꢀ1Hꢀimidazole (5a).
To demonstrate the efficiency and capability of the present
protocol for the synthesis of substituted imidazole and
a
b
Table 4. Comparison of the catalytic efficiency of PMOꢀICS (1) with other heterogeneous or homogeneous catalysts for the synthesis of of 5a and 7a .
°
Entry
Catalyst
Catalyst loading
170 mg
Solvent
EtOH
Temp ( C)
r.t
Time (min)
90
Yield (%)
96
Ref
a
b
1
[EMIM] OAc
33
a`
a
2
Poly (AMPSꢀcoꢀAA)
30 mg
Solventꢀfree
110
Reflux
80
25
70
95
98
92
84
88
91
94
97
93
98
37
a
Ceric (IV) ammonium
nitrate
3
55 mg
EtOHꢀWater (1:1)
38
a
MoO
ZrCl
Benzotriazole
NH VO
3
/SiO
2
20 mol%
CH
3
CN
CN
a
4
120
240
720
45
39
a
4
47 mg
5 mol%
10 mol%
20 wt%
20 mg
CH
3
5
r.t
40
41
a
nꢀButanol
EtOH
6
80
a
4
3
b
7
Reflux
Reflux
Reflux
Reflux
37
a
AlN/Al
PMOꢀICS
Lꢀproline
EtOH
b
8
45
39
a
EtOH
9
35
This Work
b
10 mol%
EtOH
1
1
0
1
125
360
17
42
b
Yb(OPf)
[pmim]BF
PMOꢀICS
3
Perfluorodecalin
Solventꢀfree
67 mg
90
r.t
b
b
4
1
1
2
3
178 mg
20 mg
340
30
92
96
43
EtOH
Reflux
This Work
are low catalyst loading, avoiding the use of toxic transition
metals or reactive reagents for modification of the catalytic
activity, short reaction times, high yields, elimination of toxic
organic solvents, reusability and reꢀactivity of the catalyst and
simple procedure.
Conclusions
In summary, the catalytic application of isocyanurate
bridging periodic mesoporous organosilica (PMOꢀICS) for the
synthesis of a wide range of trisubstituted imidazole and
benzimidazole derivatives has been demonstrated. The
Experimental
progress of reaction was significantly a
loading, reaction temperature and solvent. The catalyst
illustrated high e ciency for the oneꢀpot threeꢀcomponent used as received except for benzaldehyde which a fresh
ff
ected by catalyst General
All chemicals were purchased from Merck or Aldrich and
ffi
synthesis of substituted imidazole derivatives using a variety distilled sample was used. Field emission scanning electron
of aldehydes and 1,2ꢀphenylenediamine or benzoin and microscopy (FESEM) images was obtained using Sigma
ammonium acetate in EtOH under reflux conditions. In instrument of Zeiss company, Germany. The BET specific
addition, the catalyst could be recovered and reused at least surface area of the catalyst was obtained using an equipment
TM
four times with no significant decrease in its activity and ASAP 2020
micromeritics. Thermal gravimetric analysis
selectivity. Therefore, the attractive features of this procedure (TGA) was performed by means of Bahr company STA 504
8
| RSC Adv., 2016, 2016, 6, 1-10
This journal is © The Royal Society of Chemistry 2016
Please do not adjust margins

Page 9 of 11
RSC Advances
PleaseRd So Cn oA t da vd aj un s ct ems argins
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
o
instrument. Transmission electron microscopy (TEM) images dropwise to the filtrate at 50 C to give pure crystals of the
were recorded using EM10Cꢀ100 KV of Zeiss company, desired products 7aꢀs in 83–99% yields based on the starting
Germany. XRD analysis was performed using STOEꢀThataꢀ aldehyde. The separated catalyst was suspended in EtOAc (1mL)
Thata. FTIR spectra were recorded as KBr pellets on a for 30 min and the filtered. The obtained white powder was
o
Shimadzu FT IRꢀ8400S spectrometer. Melting points were heated in an oven at 70 C for 1 h and reused for successive runs.
determined using an Electrothermal 9100 apparatus and are
1
uncorrected. H NMR (500 MHz) spectra were obtained using a
3
Bruker DRXꢀ500 AVANCE spectrometer in CDCl at ambient
Acknowledgements
temperature. Analytical TLC was carried out using Merck 0.2
mm silica gel 60 Fꢀ254 Alꢀplates. All the products are known
compounds and were identified by comparison of their physical
and spectroscopic and analytical data with authentic samples.
We are grateful for the financial support from The Research
Council of Iran University of Science and Technology (IUST),
Tehran, Iran (Grant No 160/347). We would also like to
acknowledge the support of Iran Nanotechnology Initiative
Council (INIC), Iran.
General procedure for the synthesis of PMOꢀICS (1)
The synthesis of PMOꢀICS (1) has been achieved using
3
5
known procedure described by Jaroniec and his coꢀworkers. In Notes and references
a typical experiment, 2.0 g of Pluronic P123 (Aldrich, average
Mw 5800 Dalton) was dissolved in a mixture of 15 mL of
deionized water and 60 g of 2 M HCl solution. Then, 0.01 mol
3.08 g) of tris [3ꢀtrimethoxysilyl) propyl] isocyanurate (ICS,
Aldrich) and 0.03 mol tetraethoxysilane (TEOS, 3.12 g)) was
added dropwise into that solution. The obtained mixture was
stirred at the constant rate and room temperature for 20 h. The
mixture was aged at 100 °C for 48 h without stirring. The solid
1
(a) P. V. D. Voort, D. Esquivel, E. D. Canck, F. Goethals, I.
V. Driessche and F. J. RomeroꢀSalguero, Chem. Soc. Rev.
013, 42, 3913ꢀ3955; (b) N. Mizoshita, T. Tani and Sh.
Inagaki, Chem. Soc. Rev., 2011, 40, 789ꢀ800; (c) R. J. White,
R. Luque, V. L. Budarin, J. H. Clark and D. J. Macquarrie,
Chem. Soc. Rev., 2009, 38, 481ꢀ494
(a) B. Hatton, K. Landskron, W. Whitnall, D. Perovic and G.
A. Ozin, Acc. Chem. Res., 2005, 38, 305ꢀ312; (b) W. J.
Hunks and G. A. Ozin, J. Mater. Chem., 2005, 15, 3716ꢀ
≅
,
2
(
2
3
3
724; (c) K. Nakajima, I. Tomita, M. Hara, S. Hayashi, K.
2
was filtered off and washed thoroughly with hot EtOH/H O (60
Domen and J. N. Kondo, Adv. Mater., 2005, 17, 1839ꢀ1842.
(a) F. Hoffmann and Michael Fröba, Chem. Soc. Rev., 2011,
mL of EtOH 96% and 2 mL of 12 M HCl) using a soxhelet
apparatus for 72 h to remove the surfactant molecules. The
obtained white powder was dried in air at 100 ºC overnight.
4
0, 608–620; (b) W. Whitnall, L. Cademartiri and G. A. Ozin,
J. Am. Chem. Soc., 2007, 129, 15644; (c) S. Abedi, B.
Karimi, F. Kazemi, M. Bostina, and H. Vali, Org. Biomol.
Chem., 2013, 11, 416ꢀ419; (d) M. N. Esfahani, D. Elhamifar,
T. Amadeha and B. Karimi, RSC Adv., 2015, 5, 13087ꢀ13094.
J. A. Melero, R. V. Grieken and G. Morales, Chem. Rev.,
General procedure for synthesis of 2,4,5ꢀtrisubstituted
imidazole derivatives (5aꢀt)
4
2
006, 106, 3790ꢀ3812.
In a 5 mL roundꢀbottomed flask, benzoin (2, 1 mmol),
aldehyde 3 (1 mmol), ammonium acetate (4, 2.5 mmol) and 20
mg PMOꢀICS (1) were added to EtOH 96% (2 mL). The obtained
mixture was stirred at reflux conditions for times indicated in
Table 2. After completion of the reaction monitored by TLC
5
(a) V. Estevez, M. Villacampa and J. C. Menendez, Chem.
Soc. Rev., 2014, 43, 4633ꢀ4657; (b) K. R. Reddy, K.
Rajgopal, C. U. Maheswari and M. L. Kantam, New J. Chem.,
2
006, 30, 1549ꢀ1552.
6
7
(a) S. S. K. Boominathan, C. Y. Chen, R. J. Hou, P. J. Huang
and J. J. Wang, New J. Chem., 2015, 39, 6914ꢀ6918; (b) E.
Gopi, T. Kumar, R. F. S. MennaꢀBarreto, W. O. Valenca, E.
N. da Silva Junior and I. N. N. Namboothiri, Org. Biomol.
Chem., 2015, 13, 9862ꢀ9871.
(eluent: EtOAc: nꢀhexane), EtOH (3 mL) was added and the
obtained mixture was heated and filtered off to separate the solid
o
catalyst 1. Water was added dropwise to the filtrate at 50 C to
(a) A. Patel, S. Y. Sharp, K. Hall, W. Lewis, M. F. G.
give pure crystals of the desired products 5aꢀt in 74–98% yields
based on the starting aldehyde. The separated catalyst was
suspended in EtOAc (1mL) for 30 min and the filtered. The
Stevens, P. Workman and C. J. Moody, Org. Biomol. Chem.
,
2
016, 14, 3889ꢀ3905; (b) H. Naeimi and D.
Aghaseyedkarimi, New J. Chem., 2015, 39, 9415ꢀ9421.
A. Maleki and R. Paydar, RSC Adv., 2015, 5, 33177ꢀ33184.
M. Kidwai, P. Mothsra, V. Bansal, R. K. Somvanshi, A. S.
Ethayathulla, S. Dey and T. P. Singh, J. Mol. Catal. A:
Chem., 2007, 265, 177ꢀ182.
o
8
9
obtained white powder was heated in an oven at 70 C for 1 h and
reused for successive runs.
1
0 M. Afzal Pasha and A. Nizam, J. Saudi Chem. Soc., 2011, 15,
5
General procedure for synthesis of Benzimidazole Derivatives
5–58.
11 H. R. Shaterian and M. Ranjbar, J. Mol. Liq., 2011, 160, 40ꢀ
9.
(7aꢀs)
4
In a 5 mL roundꢀbottomed flask, 1,2ꢀphenylenediamine (6, 1
1
2 (a) X. C. Wang, H. P. Gong, Z. J. Quan, L. Li and H. L. Ye,
Chin. Chem. Lett., 2009, 20, 44; (b) B. Das, C. Sudhakar and
Y. Srinivas, Synth. Commun., 2010, 40, 2667–2675.
3 M. A. Zolfigol, S. Baghery, A. R. MoosaviꢀZare and S. M.
Vahdat, RSC Adv., 2015, 5, 32933–32940.
mmol), aldehyde 3 (1 mmol), and PMOꢀICS (1, 20 mg) were
added to EtOH 96% (2 mL). The obtained mixture was stirred at
reflux conditions for times indicated in Table 3. After completion
of the reaction, monitored by TLC (eluent: EtOAc: nꢀhexane)
EtOH (3 mL) was added and the obtained mixture was heated
and filtered off to separate the solid catalyst 1. Water was added
1
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 1-10 | 9
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 10 of 11
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
RSC Advances
1
4 R. G. Jacob, L. G. Dutra, C. S. Radatz, S. R. Mendes, G.
Perin and E. J. Lenardao, Tetrahedron Lett., 2009, 50, 1495ꢀ
M. G. Dekamin and M. Farhadnia, Monatsh. Chem., 2016,
DOI: 10.1007/s00706ꢀ016ꢀ1666ꢀ1.
1
497.
5 H. H. Kung and M. C. Kung, Catal. Today, 2004, 97, 219ꢀ
24.
37 (a) A. Mohammdi, H. Keshvari, R. Sandaroos, H. Rouhi, Z.
1
1
1
1
1
2
2
Sepehr, J. Chem. Sci., 2012, 124, 717–722; (b) K. S.
Niralwad, B. B. Shingate and M. S. Shingare, J. Heterocycl.
Chem., 2011, 48, 742ꢀ745.
2
6 S. S. Pawar, D. V. Dekhane, M. S. Shingare and S. N. Thore,
Chin. Chem. Lett., 2008, 19, 1055ꢀ1058.
7 R. Varala, A. Nasreen, R. Enugala and S. R. Adapa,
Tetrahedron Lett., 2007, 48, 69ꢀ72.
8 R. Varala, R. Enugala, V. Kotra and S. R. Adapa, Chem.
Pharm. Bull., 2007, 55, 1254ꢀ1257.
38 J. N. Sangshetti, N. D. Kokare, S. A. Kotharkara and D. B.
Shinde, J. Chem. Sci., 2008, 120, 463ꢀ467.
39 (a) S. V. Bhosale, M. B. Kalyankar, S. V. Nalage, D. S.
Bhosale, S. L. Pandhare, T. V. Kotbagi, S. B. Umbarkar and
M. K. Dongare, Synth. Commun., 2011, 41, 762ꢀ769; (b) N.
S. Kanhe, S. U. Tekale, N. V. Kulkarni, A. B. Nawale, A. K.
Das, S. V. Bhoraskar, R. D. Ingle and R. P. Pawar, J. Iran
Chem. Soc., 2013, 10, 243–249.
9 S. D. Sharma, P. Hazarika and D. Konwar, Tetrahedron Lett.,
2008, 49, 2216ꢀ2220.
0 M. M. Heravi, F. Derikvand and F. Bamoharram, J. Mol.
Catal., 2007, 263, 112ꢀ114.
1 R. G. Jacob, L. G. Dutra, C. S. Radatz, S. R. Mendes, G.
40 G. V. M. Sharma, Y. Jyothi and P. S. Lakshmi, Synth.
Commun., 2006, 36, 2991ꢀ3000.
Perin and E. J. Lenardao, Tetrahedron Lett., 2009, 50, 1495ꢀ 41 F. Xu, N. Wang, Y. Tian, and G. Li, J. Heterocycl. Chem.
,
1497.
2013, 50, 668ꢀ670.
2
2
2 M. Shen and T. G. Driver, Org. Lett., 2008, 10, 3367ꢀ3370.
3 M. M. Heravi, F. Derikvand, M. Haghighi, Monatsch Chem.,
42 (a) M. G. Shen and C. Cai, J. Fluorine Chem., 2007, 128,
232ꢀ235; (b) H. Sharghi, O. Asemani and R. Khalifeh, Synth.
Commun., 2008, 38, 1128ꢀ1136.
2008, 139, 1, 31ꢀ33.
2
2
2
2
2
4 S. Santra, A. Majee and A. Hajra, Tetrahedron Lett., 2012, 43 P. Ghosh and A. Mandal, Tetrahedron Lett., 2012, 53, 6483ꢀ
53, 1974ꢀ1977.
6488.
5 M. M. Heravi, K. Bakhtiari, H. A. Oskooie and S. Taheri, J.
Mol. Catal. A: Chem., 2007, 263, 279ꢀ281.
6 Q. Dang, B. S. Brown and M. D. Erion, Tetrahedron Lett.,
2000, 41, 6559ꢀ6562.
7 A. R. Karimi, Z. Alimohammadi and M. M. Amini, Mol.
Divers., 2010, 14, 635ꢀ641.
8 (a) S. Balalaie and A. Arabanian, Green Chem., 2002, 2, 274ꢀ
2
77; (b) Y. R. Girish, K. S. Sharath Kumar, K. N.
Thimmaiah, K. S. Rangappa and S. Shashikanth, RSC Adv.
015, 5, 75533ꢀ75546.
9 Z. Zarnegar and J. Safari, New J. Chem., 2014, 38, 4555ꢀ
565.
0 M. Esmaeilpour, J. Javidi and Maryam Zandi, New J. Chem.,
015, 39, 3388ꢀ3398.
,
2
2
3
3
4
2
1 B. Maleki, H. Eshghi, A. Khojastehnezhad, R. Tayebee, S.
Sedigh Ashrafi, G. Esmailian Kahoo and F. Moeinpour, RSC
Adv., 2015, 5, 64850ꢀ64857.
32 D. Kumar, D. N. Kommi, N. Bollineni, A. R. Patel and A. K.
Chakraborti, Green Chem., 2012, 14, 2038ꢀ2049.
33 (a) S. A. Siddiqui, U. C. Narkhede, S. S. Palimkar, T. Daniel,
R. J. Lahoti and K. V. Srinivasan, Tetrahedron Lett., 2005,
6
1, 3539ꢀ3546; (b) H. Zang, Q. Su, Y. Mo, B. W. Cheng and
S. Jun, Ultrason. Sonochem., 2010, 17, 749ꢀ751.
3
4 O. Olkhovyk and M. Jaroniec, J. Am. Chem. Soc., 2005, 127,
1, 60ꢀ61.
3
5 (a) M. F. Sonnenschein, Polyurethanes
:
Science, Technology,
Markets, and Trends, Wiley; First Ed., 2014; (b) M. G.
Dekamin, M. Ghanbari, M. R. Moghbeli, M. Barikani and S.
Javanshir, Polym-Plast Technol., 2013, 52, 1127ꢀ1132; (c) M.
G. Dekamin, K. Varmira, M. Farahmand, S. SaghebꢀAsl and
Z. Karimi, Catal. Commun., 2010, 12, 226ꢀ230; (d) M. G.
Dekamin, M. F. Moghaddam, H. Saeidian and S. Mallakpour,
Monatsh. Chem., 2006, 137, 1591ꢀ1595.
3
6 M. G. Dekamin, M. Azimoshan and L. Ramezani, Green
Chem., 2013, 15, 811ꢀ820; (b) M. G. Dekamin and M.
Eslami, Green Chem., 2014, 16, 4914ꢀ4921; (c) M. G.
Dekamin, S. Ilkhanizadeh, Z. Latifidoost, H. Daemi, Z.
Karimi and M. Barikani, RSC Adv., 2014, 4, 56658ꢀ56664; (d)
M. G. Dekamin, S. Z. Peyman, Z. Karimi, S. Javanshir, M. R.
NaimiꢀJamal and M. Barikani, Int. J. Biol. Macromol., 2016,
8
7, 172ꢀ179; (e) M. G. Dekamin, M. Eslami and A. Maleki,
Tetrahedron, 2013, 69, 1074ꢀ1085; (f) M. G. Dekamin, M.
Alikhani and S. Javanshir, Green Chem. Lett. Rev., 2016, 9,
9
6ꢀ105; (g) M. G. Dekamin and S. Z. Peyman, Monatsh.
Chem., 2016, 147, 445ꢀ450; (h) M. Yarhosseini, S. Javanshir,
1
0 | RSC Adv., 2016, 2016, 6, 1-10
This journal is © The Royal Society of Chemistry 2016
Please do not adjust margins

Page 11 of 11
RSC Advances
PleaseRd So Cn oA t da vd aj un s ct ems argins
View Article Online
DOI: 10.1039/C6RA14550G
ARTICLE
IsocyanurateꢀBased periodic
mesoporous organosilica (PMOꢀICS): a
highly efficient and recoverable
nanocatalyst for the oneꢀpot synthesis of
substituted imidazoles and
benzimidazoles
Mohammad G. Dekamin,* Elham Arefi and Amene
Yaghoubi
Isocyanurate bridging periodic mesoporous organosilica (PMOꢀICS)
was shown to be a highly active and efficient recyclable catalyst for
threeꢀcomponent synthesis of imidazole derivatives from benzoin,
different aldehydes and ammonium acetate under mild reaction
conditions in short reaction times and good to excellent yields in
EtOH. Also, benzimidazole derivatives were efficiently prepared
from 1,2ꢀphenylenediamine and different aldehydes in the presence of
PMOꢀICS. Moreover, the catalyst was also recovered and reused at
least four times without significant decrease in its reactivity. The
PMOꢀICS catalyst was characterizred by Fourier transformer infrared
(
FTIR) spectroscopy, thermogravimetry analysis (TGA), Xꢀray
powder diffraction (XRD) and nitrogen adsorption–desorption
isotherms (NADI) techniques as well as scanning electron
microscopy (SEM) and transmission electron microscopy (TEM).
Compared to the classical methodologies, this method illustrated the
advantages including low loading of the catalyst, avoiding the use of
toxic transition metals or reactive reagents for modification of the
catalytic activity, short reaction times, high to excellent yields, easy
separation and purification of the products, and reusability of the
catalyst.
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 1-10 | 11
Please do not adjust margins