Ni-S-methylisothiourea complexes supported on boehmite nanoparticles and their application in the synthesis of 5-substituted tetrazoles

Article abstract of DOI:10.1039/c6ra08026j

Boehmite nanoparticles are aluminum oxide hydroxide (γ-AlOOH) particles, which were prepared by a simple and inexpensive procedure and immobilized further with nickel-S-methylisothiourea complexes (Ni-SMTU@boehmite), and characterized by FT-IR spectroscopy, TGA, XRD, ICP-OES, EDS, SEM and TEM techniques. Finally, we investigated the catalytic activity of Ni-SMTU@boehmite as a new, heterogeneous, stable and highly reusable nanocatalyst for the synthesis of 5-substituted 1H-tetrazole derivatives in PEG-400 as a green solvent. This catalyst was recovered by simple filtration and reused several times without significant loss of its catalytic efficiency or nickel leaching. The heterogeneity of this catalyst has been studied using hot filtration and ICP-OES technique.

Full text of DOI:10.1039/c6ra08026j

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Ni-S-methylisothiourea complex supported on
boehmite nanoparticles and its application in the
synthesis of 5-substituted tetrazoles
Cite this: DOI: 10.1039/x0xx00000x
∗
Arash GhorbaniꢀChoghamarani, Parisa Moradi and Bahman Tahmasbi
Received 00th January 2012,
Accepted 00th January 2012
Department of Chemistry, Faculty of Science, Ilam University, P. O. Box 69315516, Ilam, Iran.
DOI: 10.1039/x0xx00000x
Boehmite nanoparticles is an aluminum oxide hydroxide (ɤꢀAlOOH) particles, which were
prepared by simple and inexpensive procedure and immobilized further with nickel Sꢀ
methylisothiourea complex (NiꢀSMTU@boehmite), and characterized by FTꢀIR spectroscopy,
TGA, XRD, ICPꢀOES, EDS, SEM and TEM techniques. Finally, we investigated the catalytic
activity of NiꢀSMTU@boehmite as a new, heterogeneous, stable and high reusable
www.rsc.org/
nanocatalyst for the synthesis of 5ꢀsubstituted 1Hꢀtetrazole derivatives in PEGꢀ400 as green
solvent. This catalyst was recovered by simple filtration and reused several times without
significant loss of its catalytic efficiency or nickel leaching. Heterogeneity of this catalyst has
been studied using hot filtration and ICPꢀOES technique.
∗
Address correspondence to A. GhorbaniꢀChoghamarani, Department of Chemistry, Ilam University, P.O. Box
6
9315516, Ilam, Iran; Tel/Fax: +98 841 2227022; Eꢀmail address: arashghch58@yahoo.com or
a.ghorbani@mail.ilam.ac.ir
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starting material in the synthesis of alumina [32]. Meanwhile,
nanoboehmite has been rarely used as support for catalyst [34ꢀ
1
Introduction
3
6]. Therefore herein a Nickel Sꢀmethylisothiourea complex
Tetrazoles are an interesting class of nitrogenꢀrich heterocycles,
also have wide range of applications as drugs in
pharmaceuticals, in coordination chemistry as a ligand, in
synthetic organic chemistry, in catalysis technology, in
medicinal chemistry as stable surrogates for carboxylic acids, in
the photographic industry, in organometallic chemistry as
effective stabilizers of metallopeptide structures and in various
immobilized on boehmite nanoparticles (NiꢀSMTU@boehmite)
has been reported as organometallic nanocatalyst for the
synthesis of 5ꢀsubstituted 1
Hꢀtetrazole derivatives using nitriles
and sodium azide in PEGꢀ400.
materials science applications [1ꢀ6]. Recently tetrazole moieties 2 Results and discussion
were widely used for binding aryl thiotetrazolylacetanilides
with HIVꢀ1 reverse transcriptase [7]. Also, tetrazoles and their 2.1 Catalyst preparation
derivatives have been reported as analgesic, antiviral, antiꢀ In order to prepare NiꢀSMTU@boehmite, initially the boehmite
inflammatory, antiꢀproliferative, antibacterial, potential anti nanoparticles was prepared according to new reported
HIV drug candidate, antifungal, herbicidal and anticancer procedure
[37],
then
modified
using
(3ꢀ
agents [8ꢀ12]. Valsartan and Losartan are two typical examples chloropropyl)trimethoxysilane (CPTES). In the next step, the
of the extensive application of these compounds as drugs, such terminal Cl was successfully replaced by Sꢀmethylisothiourea
as antiꢀhypertensive sartan family drugs [13]. Conventional hemisulfate salt (SMTU) through substation reaction, which
synthesis of 5ꢀsubstituted 1Hꢀtetrazoles is [3 + 2] cycloaddition SMTU has been supported on boehmite nanoparticles
of azide to the corresponding nitriles. Recently, many catalysts (SMTU@boehmite). Finally Nickel (II) particles have been
have attracted increasing interest in the context for synthesis of coordinated with SMTU@boehmite (Scheme 1). The prepared
tetrazole derivatives [1ꢀ12]. In order to combine the advantages catalyst has been characterized by FTꢀIR, XRD, TEM, SEM,
of both homogeneous and heterogeneous catalysis, EDS, TGA and ICPꢀOES analysis.
immobilization of homogeneous catalysts on heterogeneous
nanomaterials have been widely used as efficient and reusable
catalysts for synthesis of tetrazole derivatives [14]. However,
many supports such as Zeolite [3, 12], MCMꢀ41 [15], iron oxide
[
[
16], carbon nanotubes [17], graphene [18], heteropolyacids
19], ionic liquids [20] or some polymers [21] have been used
as catalyst supports, which most of this supports are expensive
or unstable. Also, synthesis of other nanoparticles requires inert
atmosphere or high temperature for calcination or preparation
[
22ꢀ25]. While, boehmite nanoparticles is not air or moisture
sensitive, more importance boehmite nanoparticles can be
prepared in water at room temperature using available materials
such as NaOH and Al(NO ) .9H O [25]. Boehmite is an
3
3
2
aluminum oxide hydroxide (γꢀAlOOH) particles including
double sheets of octahedral with aluminum ions at their centers
and the sheets themselves are composed of octahedral chains in
cubic orthorhombic structure. The surface of boehmite
nanoparticles are covered by many hydroxyl groups, which
makes possible the modification of the surface of boehmite
nanoparticles with other functional groups to supported
catalysts such as metal complexes. Boehmite nanoparticles
have several advantages such as nonꢀtoxicity, stability, high
Scheme 1. Synthesis of NiꢀSMTU@boehmite.
2
specific surface area (>120 m /g), ease of surface modification
due to many hydroxyl groups on its surface, inexpensive and
easily and readily availability [26ꢀ28]. Several methods such as
sol–gel [29], hydrothermal [30] and hydrolysis of aluminum 2.2 Catalyst characterizations
[
31] have been reported for preparation of boehmite
The XRD pattern of the boehmite nanoparticles, shows several peaks
at 2Ɵ values at 14.40 (0 2 0), 28.39 (1 2 0), 38.57 (0 3 1), 46.46 (1 3
nanoparticles; but, most of them have focused on the effect of
temperature, ultrasonic waves, time and Al/OH molar ratio on
morphologies, chemical and physical properties of the prepared
particles [33]. Also, Boehmite has been used as an optical
material, absorbent, composite reinforcement material in
ceramics, vaccine adjuvants, cosmetic products, coatings,
1
3
), 49.54 (0 5 1), 51.94 (2 0 0), 56.01 (1 5 1), 59.35 (0 8 0), 65.07 (2
1), 65.56 (0 0 2), 68.10 (1 7 1), and 72.38 (2 5 1) corresponded to
crystal planes of boehmite nanoparticles in orthorhombic unit cell
Figure 1) [34, 35].
(
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6
5
4
3
2
1
000
000
000
000
000
000
0
b
0
20
40
θ / degree
60
80
2
Figure 1. The XRD pattern of boehmite nanoparticles.
Scanning electron microscopy (SEM) was used to obtain direct
information about the size and morphology of the prepared boehmite
nanoparticles and NiꢀSMTU@boehmite nanoparticles. SEM images
show these nanoparticles was prepared with an average size about Figure 2. SEM images of boehmite nanoparticles (a) and Niꢀ
0ꢀ40 nm (Figure 2), were of uniform size, and showed good SMTU@boehmite (b).
2
dispersity. Also the size and morphology of NiꢀSMTU@boehmite
was studied by TEM technique. As shown in Figure 3, the unit cells
of NiꢀSMTU@boehmite was obtained in cubic orthorhombic
structures with about 20ꢀ40 nm of size.
a
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spectrum c, the existence of the grafted Sꢀmethylisothiourea groups
−1
has been proved by C=N vibration peak (1638 cm ) [38].
Figure 3. TEM images of NiꢀSMTU@boehmite.
In order to show the presence elements in catalyst, the EDS analysis
of NiꢀSMTU@boehmite was performed. The EDS patterns of Niꢀ
SMTU@boehmite is shown in Figure 4, that EDS spectrum of this
catalyst indicates the presence of Al, O, Si, C, S and N and Ni specie
in the catalyst.
Also, upon complexation of the modified boehmite nanoparticles
with Ni, the exact amount of loaded metal was determined by
inductively coupled plasma atomic emission spectroscopy (ICPꢀ
OES). Based on ICP, the nickel content of described catalyst was
ꢀ
3
ꢀ1
1
.64×10 mol g .
Figure 5. FTꢀIR spectra of boehmite nanoparticles (a), nClꢀ
Pr@boehmite (b), SMTU@boehmite (c) and NiꢀSMTU@boehmite
(d).
In order to indicate the bond formation between the boehmite
nanoparticles with the organic layers and Niꢀcomplex, the TGA
analysis was performed (Figure 6). The TGA curve of the Niꢀ
SMTU@boehmite shows the mass loss of the supported complex
and organic functional groups as it decompose upon heating. In the
all samples, the negligible weight loss below 200 °C is due to the
attached hydroxyl groups or adsorbed solvent molecules on the
surface of nanoparticles [24]. But organic spacers and Niꢀcomplex
have been reported to desorb at temperatures above 260 °C. Based
on TGA data, the weight losses of boehmite nanoparticles and
SMTU@boehmite from 200 to 600 °C are 15% and 30%,
respectively. While the weight loss of NiꢀSMTU@boehmite is 47%.
These results were confirmed that organic layers and Niꢀcomplex
have been anchored in the surface of boehmite nanoparticles.
Figure 4. EDX spectrum of NiꢀSMTU@boehmite.
Successful functionalization of Niꢀcomplex on boehmite
nanoparticles was confirmed by FTꢀIR technique (Figure 5). As
−1
shown in spectrum a, strong bands at 3086 and 3308 cm are
attributed to the symmetrical and asymmetrical modes of the
hydroxyl groups on the surface of boehmite nanoparticles [37, 38].
−1
In spectra aꢀd, several peaks at 480, 605 and 735 cm are related to
the AlꢀO bonds in boehmite structure [33]. Also, the nitrate impurity
and hydrogen bands (OH…OH) vibration are appeared at (1637) and
ꢀ
1
(
1164 and 1069) cm respectively [25, 32]. In spectrum b, the
modification of boehmite nanoparticles with
chloropropyltrimethoxysilane is authenticated by C–H stretching
−1
ꢀ1
vibrations (2955 cm ) and OꢀSi stretching vibration (1073 cm ). In
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Table 1. Optimization of reaction conditions for synthesis of 5ꢀ
substituted 1 ꢀtetrazole derivatives in the presence of Niꢀ
1
00
H
9
8
7
6
5
4
3
2
0
0
0
0
0
0
0
0
SMTU@boehmite.
a
b
c
Catalyst
NaN
(mmol)
3
Temperature Time
a
Entry
Solvent
Yield (%)
(
mg)
30
30
30
25
20
15
25
25
25
25
25
25
(ºC)
(min)
80
80
80
80
80
80
60
60
80
80
80
80
1
2
3
4
5
6
7
8
9
PEG
PEG
PEG
PEG
PEG
PEG
DMSO
DMF
1.2
1.3
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
120
60
73
93
94
69
52
89
90
64
40
72
44
120
120
120
120
0
200
400
Temperature( C)
600
800
◦
120
120
Figure 6. TGA diagram of boehmite nanoparticles (a),
SMTU@boehmite (b) and NiꢀSMTU@boehmite (c).
120
H
2
O
Reflux
Reflux
100
1
1
0
1
EtOH
PEG
PEG
2
.3 Catalytic study
12
80
a
Isolated yield.
We examined the activity of NiꢀSMTU@boehmite as an efficient,
stable, reusable and commercially available catalyst for the synthesis
of 5ꢀsubstituted 1Hꢀtetrazole derivatives.
In order to show the efficiency of NiꢀSMTU@boehmite than
corresponding homogeneous one, the homogeneous catalyst
without boehmite nanoparticles (nPrꢀSi(OMe) ꢀSMTUꢀNi) and
3
also Sꢀmethylisothiourea complex of Ni (SMTUꢀNi) has been
synthesized and their catalytic activity has been compared with
NiꢀSMTU@boehmite for the synthesis of 5ꢀ(2ꢀchlorophenyl)ꢀ
1
2
Hꢀtetrazole. The results of this comparison are shown in Table
. As shown in Table 2, catalytic activity of heterogeneous and
Scheme 2. Synthesis of 5ꢀsubstituted 1
the presence of NiꢀSMTU@boehmite.
Hꢀtetrazole derivatives in
reusable catalyst (NiꢀSMTU@boehmite) is comparable to their
corresponding homogeneous ones, because: 1) the boehmite
was formed in nanometerꢀsized particles (20ꢀ40 nm), which;
when the size of the support is decreased to the nanometer
scale, the surface area is substantially increased and the support
can be evenly dispersed in the reaction mixture, forming a
homogenous emulsion. 2) highꢀsurfaceꢀarea of boehmite
nanoparticles including many hydroxyl groups leads to high
catalyst loading capacity. Therefore, as shown in Table 2, these
heterogeneous catalyst showed the advantages of both
homogeneous (high catalytic activity) and heterogeneous (easy
and rapid recoverability and recyclability) catalyst. Also, it is
very important that the reaction did not proceed in the absence
of catalyst even after long time (Table 2, entry 1).
In order to optimize the reaction conditions, the reaction of
benzonitrile and sodium azide (NaN ) was selected as a model
3
reaction. The effect of various parameters such as temperature,
solvents, amount of catalyst and NaN were considered in the [2+3]
3
cycloaddition reaction of benzonitrile with NaN (Table 1). When,
3
1
5 mg of catalyst was used to catalyze the model reaction, the
product was obtained in 52% yield within 80 min at 120 °C.
Increasing the amount of catalyst from 20 to 25 mg was led to
increasing in yield of product from 69 to 94%. While, increasing the
amount of catalyst (from 25 to 30 mg) had no significant effect on
yield of product. In order to find the best solvent for this
transformation, the model reaction was studied in PEGꢀ400, DMSO,
DMF, H O and EtOH that the best results were obtained in PEGꢀ400
2
(
Table 1, entry 5). Also the effect of various amount of NaN were
3
Table 2. Comparison of NiꢀSMTU@boehmite with
corresponding homogeneous catalyst in the synthesis of 5ꢀ(2ꢀ
chlorophenyl)ꢀ1Hꢀtetrazole under optimized condition.
Time Yield
examined in the [2+3] cycloaddition reaction of benzonitrile with
NaN3 (Table 1) and 1.4 mmol of NaN3 was found to be for
completion of reaction within 80 min at 120 °C (Table 1, entry 5).
Also, we found that the reaction yields were susceptible to
temperature changes. Therefore, the effect of temperature were
described (Table 1, entries 10ꢀ12) and the best results were obtained
at 120 ºC. As shown in Table 1, 0.025 g of NiꢀSMTU@boehmite in
entry
Substrate
Catalyst
a
(min)
(%)
1
2
3
4
2ꢀchlorobenzonitrile
2ꢀchlorobenzonitrile
2ꢀchlorobenzonitrile nPrꢀSi(OMe)
ꢀ
80
55
60
60
Trace
91
92
SMTUꢀNi
3
ꢀSMTUꢀNi
2ꢀchlorobenzonitrile NiꢀSMTU@boehmite
90
PEGꢀ400 at 120 °C using 1.4 mmol of NaN was found to be ideal
the reaction conditions for the synthesis of 5ꢀsubstituted 1Hꢀtetrazole
3
a
Isolated yield.
derivatives.
After optimizing the reaction conditions, in order to explore the
generality and scope of this protocol, various nitriles with NaN3
were employed as substrates for the synthesis of 5ꢀsubstituted
1Hꢀtetrazole derivatives in the presence of Niꢀ
SMTU@boehmite. The results of this study are summarized in
Table 3. These results show that the reactions are equally facile
with both electronꢀdonating and electronꢀwithdrawing
substituents on the benzonitriles, resulting in goodꢀtoꢀhigh
yields of the corresponding tetrazoles.
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Table 3. Synthesis of 5ꢀsubstituted 1Hꢀtetrazole derivatives in the presence of NiꢀSMTU@boehmite.
a
Melting Point
ºC)
Entry
1
Nitrile
Product
Time (h) Yield (%)
(
1.33
21
94
96
212ꢀ214
218ꢀ220
2
3
4
5
24
4
94
92
96
173ꢀ175
260ꢀ262
132ꢀ133
1.5
6
1
90
181ꢀ183
7
8
9
0.33
3.15
9
97
89
87
95
224ꢀ226
253
149ꢀ151
242ꢀ245
1
1
0
1
20
18
1
80
80
168ꢀ170
1
2
163ꢀ166
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1
1
3
4
24
77
92
120ꢀ123
210ꢀ212
0.66
1
1
5
6
1.75
4.5
90
69
115ꢀ116
190ꢀ192
1
1
1
7
8
9
2.75
5
93
86
64
230ꢀ232
262ꢀ265
229ꢀ230
28
2
2
0
1
24
20
75
70
164ꢀ148
244ꢀ246
a
Isolated yield.
A plausible mechanism for the synthesis of tetrazole derivatives separation. As shown in Table 4, many previously reported
catalyzed by NiꢀSMTU@boehmite is shown in Scheme 3 [38, catalysts have some drawbacks or limitations such as use of
3
9]. Initially, catalyst reacts with nitrile to produce the homogeneous catalysts that its separation is difficult from the
intermediate ; the [3+2] cycloaddition reaction between azide reaction mixture, hazardous organic solvents and long reaction
and form the intermediate II; protonation of complex II HCl times. While, synthesis of tetrazoles in the presence of Niꢀ
gives III, which rearranges to produce more stable desired SMTU@boehmite has been carried out in PEG as green solvent
I
I
product IV
.
with short reaction time. Also some of the previously reported
catalysts are more expensive, requires high temperature or inert
atmosphere, a lot of time and tedious conditions to prepare.
While, boehmite nanoparticles was synthesized in water
without inert atmosphere using commercially available
materials. In addition, the number recycling of Niꢀ
SMTU@boehmite is more than other catalysts. As shown in
Figure 7, NiꢀSMTU@boehmite was reused over 10 runs in
synthesis of 2ꢀ(1Hꢀtetrazolꢀ5ꢀyl)phenol without any significant
loss of its catalytic activity or nickel leaching, which clearly
demonstrates the practical reusability of this catalyst. Nickel
leaching of NiꢀSMTU@boehmite was studied by ICPꢀPEIS
analysis and hot filtration test. Based on the obtained results
from ICPꢀOES analysis, the amount of Ni in fresh catalyst and
Scheme 3. Plausible mechanism for the synthesis of tetrazoles
catalyzed by NiꢀSMTU@boehmite.
ꢀ1
the recycled catalyst after 10 times recycling is 1.64 mmol g
ꢀ1
and 1.31 mmol g , respectively, which indicated that Ni
leaching of this catalyst was very low. In order to examine
leaching of nickel in reaction mixture and heterogeneity of this
catalyst, we performed hot filtration in the reaction of 2ꢀ
In order to examine the efficiency of these procedures, we
compared the results of the model reaction ([2+3] cycloaddition
of benzonitrile with NaN ) with the previously reported
3
chlorobenzonitrile with NaN . In this study we found the yield
3
methods in the literatures (Table 4). This catalyst showed short
reaction time and good yield than other reported catalysts in
literatures. Also NiꢀSMTU@boehmite is outstanding in terms
of simple preparation, nonꢀtoxicity, price, stability and easy
of product in the half time of the reaction was 46%. Then the
reaction was repeated and in half time of the reaction, the
catalyst recovered and allowed the filtrate to react further. The
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yield of reaction in this stage was 50% that confirmed the any significant loss of its catalytic activity. Heterogeneity of this
leaching of nickel hasn’t been occurred.
catalyst has been studied using hot filtration and ICPꢀOES
techniques. This catalyst showed excellent catalytic activity, high
reusability and air or moisture stability for synthesis of 5ꢀsubstituted
1
Hꢀtetrazole derivatives in PEGꢀ400. Additionally, allylic, aliphatic
and aromatic nitriles can also be used to synthesis tetrazoles using
this catalyst. Thus, this methodology is effective for a wide range of
nitriles for the synthesis of 5ꢀsubstituted 1Hꢀtetrazoles.
Table 4. Comparison results of NiꢀSMTU@boehmite with other
catalysts for synthesis of 5ꢀphenylꢀ1Hꢀtetrazole.
Time Yield
Entry Catalyst
Condition
Ref.
(h) (%)a
1
2
3
CoY Zeolite
Cu–Zn alloy nanopowder
B(C
CAN supported HYꢀ
zeolite
DMF, 120 ºC
DMF, 135 ºC
DMF, 120 ºC
14
10
8
90
95
94
[3]
[4]
[9]
6 5 3
F )
4 Experimental
4
DMF, 110 ºC
4
93 [12]
5
6
7
8
9
(NH
4
)Ce(NO
3
)
6
DMF, 110 ºC
DMF, 120 ºC
DMF, 120 ºC
DMF, 120 ºC
DMF, 120 ºC
6
7
97 [13]
90 [16]
4
.1. Preparation of the Ni-SMTU@boehmite
Fe
Fe
3
O
O
4
2
@SiO /Salen Cu(II)
/ZnS HNSs
24 81.1 [41]
36
5
The boehmite nanoparticles was synthesized according to our
recently reported procedure via addition of aqueous NaOH solution
to aqueous solution of Al(NO ) .9H O as drop to drop under
3
4
Mesoporous ZnS
AgNO
86 [42]
83 [43]
3
3
3
2
NH4OAc (15 mg),
DMF/MeOH (9/1),
vigorous stirring [36]. The obtained boehmite nanoparticles (1.5 g)
was dispersed in 50 mL toluene by sonication for 30 min, and then
1
0
LiB(N
3
)
4
8
86 [44]
1
20 ºC
2
.5 mL of (3ꢀcholoropropyl)triethoxysilane (CPTES) was added to
1
1
1
1
1
2
3
4
Cu(OAc)
CuFe
FeCl
Nano ZnO/Co
2
DMF, 120 ºC
DMF, 120 ºC
DMF, 120 ºC
12
12
12
12
98 [45]
82 [46]
79 [47]
90 [48]
This
mixture. The reaction mixture was stirred at 40 ºC for 24 h. Then,
the prepared nanoparticles (nClꢀPr@boehmite) was filtered, washed
with ethanol and dried at room temperature. The obtained nClꢀ
Pr@boehmite (1g) were dispersed in 50 mL ethanol for 20 min, and
then Sꢀmethylisothiourea hemisulfate salt (2.5 mmol) and potassium
carbonate (2.5 mmol) were added to the reaction mixture and stirred
2
O
4
3
–SiO
2
3
O
4
DMF, 120ꢀ130 ºC
1
5
NiꢀSMTU@boehmite
PEG, 120 ºC
1.33 94
work
a
Isolated yield.
for 28
h
at 80 ºC. Then, the resulting nanoparticles
(SMTU@boehmite) was filtered, washed with ethanol and dried at
room temperature. The obtained SMTU@boehmite (0.5 g) was
dispersed in 25 mL ethanol by sonication for 20 min, and then
Ni(NO ) .6H O (1 mmol) was added to the reaction mixture. The
1
00
3
2
2
reaction mixture was stirred at 80 ºC for 20 h. The final product (Niꢀ
SMTU@boehmite) was filtered, washed by ethanol and dried at
room temperature.
8
6
4
2
0
0
0
0
0
4.2 General procedure for the synthesis of 5-substituted 1H-
tetrazoles
A mixture of sodium azide (1.4 mmol) and nitrile (1 mmol) in the
presence of 0.025 g of NiꢀSMTU@boehmite, was stirred at 120 °C
in PEGꢀ400; after completion of the reaction (observed by TLC), the
reaction mixture was cooled down, and catalyst was isolated by
simple filtration and HCl (4 N, 10 mL) was added to the filtrated
solution. The products extracted with ethyl acetate (2×10 mL). The
organic solvent was dried over anhydrous sodium sulfate, and
concentrated to give the crude solid product.
1
2
3
4
5
6
7
8
9
10
Run number
Figure 7. Recyclability of NiꢀSMTU@boehmite in the synthesis of
ꢀ(1Hꢀtetrazolꢀ5ꢀyl)phenol.
2
3
Conclusions
4
.3 Selected spectral data
In summary, NiꢀSMTU@boehmite as a novel type of recoverable
nanocatalyst was prepared by grafting of nickel on modified 5-Phenyl-1H-tetrazole (Table 2, Entry 1): White solid, m.p. 212ꢀ
1
boehmite nanoparticles by very simple and inexpensive procedure 214 ºC, FTIR (KBr): νmax/cm : 3436, 2920, 1610, 1559, 1474,
1
without inert atmosphere. This catalyst was synthesized from
inexpensive and commercially available starting materials. This
catalyst has been characterized by FTꢀIR spectroscopy, TGA, XRD,
ICPꢀOES, EDS, SEM and TEM techniques. The advantages of this
protocol are the use of an ecoꢀfriendly, chemically stable and
commercially available materials, the operational simplicity and
good to high yields. More important, nanoboehmite is new support
for heterogenization of homogeneous catalysts, which has several
advantages such as high surface area, high stability, ease of surface
modification, easy and inexpensive procedure of preparation. Also in
this protocol, catalyst was reused for 10 times without Ni leaching or
1
405, 1252, 1159, 1051, 987, 784, 689, 492. H NMR (400 MHz,
DMSO, ppm) δ = 7.65ꢀ7.59 (m, 3H), 8.08ꢀ8.04 (m, 2H).
5
-(4-Nitrophenyl)-1H-tetrazole (Table 2, Entry 2): Yellow solid,
m.p. 218ꢀ220 ºC, FTIR (KBr): νmax/cm : 3508, 3101, 2967, 2919,
854, 2755, 2547, 1646, 1608, 1521, 1439, 1346, 1156, 1101, 1024,
51, 854, 721, 696, 494. H NMR (400 MHz, DMSO, ppm) δ =
1
2
9
8
1
.43ꢀ8.41 (d, J= 8.8 Hz, 2H), 8.31ꢀ8.29 (d, J= 8.8 Hz, 2H).
1
-(4-(1H-tetrazol-5-yl)phenyl)ethanone (Table 2, entry 3): white
1
solid, m.p. 173ꢀ175 ºC, FT.IR (KBr): νmax/cm : 3432, 3144, 3079,
3
011, 2969, 2921, 2858, 2719, 2625, 2472, 1680, 1570, 1431, 1365,
This journal is © The Royal Society of Chemistry 2013
J. Name., 2013, 00, 1-3 | 8

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DOI: 10.1039/C6RA08026J
ARTICLE
1
4
271, 1156, 1120, 1081, 1058, 997, 982, 961, 841, 752, 704, 589,
91. H NMR (400 MHz, DMSO, ppm) δ =8.20ꢀ8.14 (m, 4H), 2.64
1
1
5. A. Najafi Chermahini, M. Azadi, E. Tafakori, A. Teimouri, M.
Sabzalian, J. Porous Mater. 2016, 23, 441.
1
(s, 3H).
6. N. Razavi, B. Akhlaghinia, RSC Adv. 2015, 5, 12372.
5
-(4-Bromophenyl)-1H-tetrazole (Table 2, Entry 4): white solid,
17. H. Sharghi, S. Ebrahimpourmoghaddam, M. M. Doroodmand, J.
Organometal. Chem. 2013, 738, 41.
1
m.p. 260ꢀ262 ºC, FTIR (KBr): νmax/cm : 3443, 2956, 2923, 2861,
2
NMR (400 MHz, DMSO, ppm) δ = 8.00ꢀ7.97 (m, 2H), 7.84ꢀ7.81 (m,
2
1
766, 2627, 1601, 1423, 1317, 1152, 1055, 998, 842, 734, 562. H
1
1
8. G. Qi, W. Zhang, Y. Dai, Res. Chem. Intermed 2015, 41, 1149.
9. A. Fazeli, H. A. Oskooie, Y. S. Beheshtiha, M. M. Heravi, H.
Valizadeh, F. F. Bamoharram, Monatsh Chem 2013, 144, 1407.
0. J. Chen, W. Su, H. Wu, M. Liu, C. Jin, Green. Chem. 2007, 9, 972.
1. X. Liu, X. Zhao, M. Lu, J. Organometal. Chem. 2014, 768, 23.
H).
5
-(3-Chlorophenyl)-1H-tetrazole) (Table 2, Entry 5): white solid,
2
2
1
m.p. 132ꢀ133 ºC, FTIR (KBr): νmax/cm : 3454, 3241, 3063, 2972,
2
7
1
894, 2605, 1972, 1651, 1473, 1445, 1360, 1300, 1246, 1094, 1002,
1
22. M. Nikoorazm, A. GhorbaniꢀChoghamarani, N. Noori, Appl.
Organometal. Chem. 2015, 29, 328.
72, 675, 576. H NMR (400 MHz, DMSO, ppm) δ = 8.09ꢀ8.00 (m,
H), 8.04ꢀ8.01 (m, 1H), 7.69ꢀ7.63 (m, 2H).
2
3. A. GhorbaniꢀChoghamarani, B. Tahmasbi, P. Moradi, Appl.
Organometal. Chem. 2016, 30, 422.
2
2
2
8
-(1H-tetrazol-5-yl)phenol (Table 2, Entry 7): white solid, m.p.
24ꢀ226 ºC, FTIR (KBr): νmax/cm : 3253, 3059, 2933, 2709, 2566,
1
2
4. A. GhorbaniꢀChoghamarani, B. Tahmasbi, F. Arghand, S. Faryadi,
RSC Adv. 2015, 5, 92174.
359, 1610, 1545, 1475, 1393, 1358, 1294, 1230, 1115, 1068, 946,
1
08, 742, 680, 541. H NMR (400 MHz, DMSO, ppm) δ = 8.02ꢀ8.00
(m, 1H), 7.44ꢀ7.40 (m, 1H), 7.11ꢀ7.08 (m, 1H), 7.03ꢀ6.99 (m, 1H),
25. V. Vatanpour, S.S. Madaenia, L. Rajabi, S. Zinadini, A.A.
1
1.10 (br, 1H), 15.73 (br, 1H).
Derakhshan, J. Membr. Sci. 2012, 401-402, 132.
2
6. M. Mirzaee, B. Bahramian, A. Amoli, Appl. Organometal. Chem.
2015, 29, 593.
4
-(1H-tetrazol-5-yl)benzonitrile (Table 2, entry 8): white solid,
1
m.p. 253 ºC, FT.IR (KBr): νmax/cm : 3476, 3150, 3090, 3018, 2923,
2
1
859, 2724, 2624, 2566, 2485, 2232, 1620, 1566, 1494, 1431, 1364,
275, 1153, 1067, 1028, 847, 749, 695, 552. H NMR (400MHz,
27. Z. Wu, Y. Mao, M. Song, X. Yin, M. Zhang, Catal. Commun. 2013,
2, 52.
1
3
DMSO, ppm) δ = 8.24ꢀ8.21 (m, 2H), 8.12ꢀ8.09 (m, 2H).
2
8. S. M. Kim, Y.J. Lee, K.W. Jun, J.Y. Park, H.S. Potdar, Mater. Chem.
Phys. 2007, 104, 56.
5
-(3-Nitrophenyl)-1H-tetrazole (Table 2, Entry 9): White solid,
1
m.p. 149ꢀ151 ºC, FTIR (KBr): νmax/cm : 3852, 3308, 3085, 2975,
29. X.Y. Chen, H.S. Huh, S.W. Lee. Nanotechnology 2007, 18, 285608.
2
8
8
894, 2822, 2752, 1621, 1524, 1348, 1243, 1156, 1076, 1011, 912,
3
0. M. Thiruchitrambalam, V.R. Palkar, V. Gopinathan, Mater. Lett.
004, 58, 3063.
1
19, 727, 453. H NMR (400 MHz, DMSO, ppm) δ = 8.85 (s, 1H),
2
.50ꢀ8.43 (m, 2H), 7.94ꢀ7.90 (m, 1H).
3
3
1. L. Rajabi, A.A. Derakhshan, Sci. Adv. Mater. 2010, 2, 163.
2. A. GhorbaniꢀChoghamarani, B. Tahmasbi, New J. Chem. 2016, 40,
1
205.
Acknowledgements
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3. H. Liu, J. Deng, W. Li, Catal. Lett. 2010, 137, 261.
4. K. Bahrami, M.M. Khodaei, M. Roostaei, New J. Chem. 2014, 38,
This work was supported by the research facilities of Ilam
University, Ilam, Iran.
5
515.
3
3
3
3
3
4
5. E. Carbonell, E. DelgadoꢀPinar, J. PitarchꢀJarque, J. Alarcón, E.
GarcíaꢀEspañ, J. Phys. Chem. 2013, 117, 14325.
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DOI: 10.1039/C6RA08026J
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This journal is © The Royal Society of Chemistry 2013
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Graphical Abstract
Ni-S-methylisothiourea complex supported on boehmite nanoparticles
and its application in the synthesis of 5-substituted tetrazoles
Arash Ghorbani-Choghamarani, Parisa Moradi and Bahman Tahmasbi
CN
R
Ni
Ni
Ni
Ni
Ni
Ni
NaN3
PEG
Ni
Ni
Ni
N
Ni
N
N
Ni
Ni
N
H
O
R
O
Si
N
S
O
Ni
HN
Catalyst = Ni-SMTU@boehmite
H3C
Boehmite nanoparticles were immobilized with a new type of nickel complex and applied for the synthesis of 5-
substituted 1H-tetrazole derivatives in PEG-400.