2-aminoethanesulfonic acid immobilized on epichlorohydrin functionalized Fe3O4@WO3 (Fe3O4@WO3-EAE-SO3H): A novel magnetically recyclable heterogeneous nanocatalyst for the green one-pot synthesis of 1-substituted-1H-1, 2, 3, 4-tetrazoles in water

Article abstract of DOI:10.1246/bcsj.20170148

In this research 2-aminoethanesulfonic acid immobilized on epichlorohydrin functionalized Fe₃O₄@WO₃ (Fe₃O₄@WO₃- EAE-SO3H) has been introduced as a novel and efficient magnetic nanocatalyst for appropriate and rapid synthesis of 1-substituted-1H-1, 2, 3, 4-tetrazoles. This new nanocatalyst was then characterized using FT-IR, XRD, TEM, EDS, TGA, FE-SEM, CHNS and VSM techniques. The above experimental results allowed determination of the composition of Fe₃O₄@WO₃-EAE-SO3H and clearly revealed that the nanoparticles are spherical in shape with particle size in the range of 723nm and superparamagnetic behavior. Fe₃O₄@WO₃- EAE-SO3H as an excellent replacement for Br?nsted acids was shown to be highly efficient in the rapid preparation of 1- substituted-1H-1, 2, 3, 4-tetrazoles through the cyclization reaction of various primary amines, triethyl orthoformate and 1- butyl-3-methylimidazolium azide ([bmim][N3]). Compared with conventional methods, the present protocol has considerable advantages such as short reaction time, mild reaction conditions, easy work-up, pure products with high yields, catalyst recovery using an external magnet and reuse of the catalyst several times without noticeable deterioration in catalytic activity. In addition to the aforementioned favourable properties, the remarkable feature of the present protocol is the use of water as environmentally benign solvent, which eliminates the use of toxic solvent.

Full text of DOI:10.1246/bcsj.20170148

Advance Publication Cover Page
2-Aminoethanesulfonic acid immobilized on epichlorohydrin functionalized
Fe3O4@WO3 (Fe3O4@WO3-EAE-SO3H): a novel magnetically recyclable
heterogeneous nanocatalyst for the green one-pot synthesis of
1-substituted-1H-1,2,3,4-tetrazoles in water
Maryam Sadat Ghasemzadeh and Batool Akhlaghinia*
Advance Publication on the web July 31, 2017
doi:10.1246/bcsj.20170148
© 2017 The Chemical Society of Japan

2-Aminoethanesulfonic acid immobilized on epichlorohydrin functionalized
Fe3O4@WO3 (Fe3O4@WO3-EAE-SO3H): a novel magnetically recyclable
heterogeneous nanocatalyst for the green one-pot synthesis of 1-substituted-
1H-1,2,3,4-tetrazoles in water
Maryam Sadat Ghasemzadeh and Batool Akhlaghinia*
Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, 9177948974 Mashhad, Iran
E-mail: akhlaghinia@um.ac.ir
Furthermore, tetrazoles played main roles in information
recording systems and photography.13-24 Recently, because
of the effective usefulness of this heterocyclic nucleus, the
synthesis of tetrazole frameworks is of much current
importance, and various preparative methods have been
developed. 1-Substituted-1H-1,2,3,4-tetrazoles as a special
category of tetrazoles have been reported since the last mid-
century and only a few methods for synthesis of this
compounds have been reported.14,17 One of the main routes
for the synthesis of 1-substituted-1H-1,2,3,4-tetrazoles,
involves acid-catalyzed cycloaddition between isocyanides
and hydrazoic acid or, trimethylsilyl azide.25-27 This method
often includes a number of steps and is insufficiently
effective. Another method (as the most promising method)
of 1-substituted-1H-1,2,3,4-tetrazoles synthesis is based on
the reaction of amines with ethyl orthoformate or
orthocarboxylic acid ester and sodium azide in the presence
of acetic acid, trifluoroacetic acid, PCl5, ionic liquid and
DMSO and ytterbium triflate in highly polar solvents.28-35
Unfortunately, some of the earlier reported methods for the
synthesis of 1-substituted-1H-1,2,3,4-tetrazoles have one or
more of the following drawbacks such as harsh reaction
conditions (the presence of excess amounts of hydrazoic
acid, which is highly toxic, explosive and volatile),
expensive and toxic metal catalysts and reagents, difficulty
in obtaining and/or preparing the starting materials, high
boiling solvents, refluxing for a prolonged period of time,
low yield and tedious work-up. As the lack of convenient
methods for the preparation of 1-substituted tetrazoles
should not restrict their potential applications, a continuing
interest for the formation of this class of heterocyclic
compounds is still challenging and demand at the forefront
of synthetic organic chemistry. In last decade, magnetic
nanoparticles have received a remarkable attention due to
their unique physicochemical properties and potential
applications in numerous areas.36 Iron oxides and other
iron-containing nanoparticles are the most widely studied
magnetic nanomaterials.37 To control the size, shape,
stability and dispersibility of the magnetic nanomaterials
(as a technological challenge) they have been coated with
organic or inorganic protective layers (to avoid the
Abstract
In this research 2-aminoethanesulfonic acid
immobilized on epichlorohydrin functionalized
Fe3O4@WO3 (Fe3O4@WO3-EAE-SO3H) has been
introduced as a novel and efficient magnetic nanocatalyst
for appropriate and rapid synthesis of 1-substituted-1H-
1,2,3,4-tetrazoles. This new nanocatalyst was then
characterized using FT-IR, XRD, TEM, EDS, TGA, FE-
SEM, CHNS and VSM techniques. The above
experimental results determined the composition of
Fe3O4@WO3-EAE-SO3H and clearly revealed that the
nanoparticles are spherical in shape with the particle size in
the range of 7–23 nm and superparamagnetic behavior.
Fe3O4@WO3-EAE-SO3H as an excellent instance to
replace Brønsted acids was shown to be highly efficient in
the rapid preparation of 1-substituted-1H-1,2,3,4-tetrazoles
through the cyclization reaction of various primary amines,
triethyl orthoformate and 1-butyl-3-methylimidazolium
azide ([bmim][N3]). Compared with conventional methods,
the present protocol has the considerable advantages such
as short reaction time, mild reaction conditions, easy work-
up, pure products with high yields, recovering the catalyst
using an external magnet and reusing the catalyst several
times without noticeable deterioration in catalytic activity.
In addition to the aforementioned favorable properties, the
remarkable feature of the present protocol is the use of
water as environmentally benign solvent, which eliminates
the use of toxic solvent.
1. Introduction
Nitrogen-containing compounds have always remained
a major source for therapeutic drugs and have received
significant attention.1 Among them nitrogen-containing
heterocycles such as tetrazoles have attracted considerable
interest because of their wide range of applications in
material sciences (including explosives and rocket
propellants), synthetic organic chemistry as analytical
reagents,2 and synthons for a variety of nitrogen containing
heterocycles.3-9 Tetrazoles have been successfully used in
coordination chemistry as ligands for many useful
transformations10,11 and in medicinal chemistry as a
surrogate for carboxylic acid functionalities which exhibit
favourable pharmacokinetic profit and metabolic stability.12

aggregation/oxidation and serves as the catalyst platform)
such as polymer,38 silica,39 zeolite,40 carbon,41
hydroxyapatite 42 and metal oxides.43 Tungsten is one of the
most important economical and environmentally well-
suited metal in our globe.44 Interest in tungsten oxides
(WOx) can be dated back to the 17th century.45 Tungsten
trioxide (WO3) with wide range of applications in everyday
life and in several research fields (from condensedmatter
physics to solid-state chemistry) is commercially
available.44 As nanostructured WO3 is exceptionally
versatile and offers unique characteristics, the synthesis and
analysis of WO3 nanostructures have become increasingly
prominent. So far, different heterogeneous catalysts based
on WO3 nanoparticles have been reported in some organic
reactions such as oxidation of primary amines to oximes
using WO3/Al2O3,46 oxidation of olefins, sulfides and cyclic
ketones by WO3 /MCM-48,47 synthesis of 1,8-dioxo-
companies and were used as received without further
purification. The purity determinations of the products were
accomplished by TLC on silica gel polygram STL G/UV
254 plates. The melting points of the products were
determined with an Electrothermal Type 9100 melting
point apparatus. The FT-IR spectra were recorded on an
Avatar 370 FT-IR Therma Nicolet spectrometer. Elemental
analyses were performed using a Thermo Finnegan Flash
EA 1112 Series instrument. The NMR spectra were
obtained in Brucker Avance 300 MHz instruments in
CDCl3 or DMSO-d6. Mass spectra were recorded with a
CH7A Varianmat Bremem instrument at 70 eV electron
impact ionization, in m/z (rel %). TGA analysis was carried
out on a Shimadzu Thermogravimetric Analyzer (TG-50) in
the temperature range of 25–600 °C at a heating rate of 10
°C min-1 under air atmosphere. Transmission electron
microscopy (TEM) was performed with a Leo 912 AB
microscope (Zeiss, Germany) with an accelerating voltage
of 120 kV. Elemental compositions were determined with a
Leo 1450 VP scanning electron microscope equipped with
an SC7620 energy dispersive spectrometer (SEM-EDS)
presenting a 133 eV resolution at 20 kV. FE-SEM images
were recorded using a TESCAN, Model: MIRA3 scanning
electron microscope operating at an acceleration voltage of
30.0 kV and resolution of about 200 and 500 nm
(manufactured by Czech Republic). The crystal structure of
catalyst was analyzed by XRD using Model Explorer
Company: GNR (Italy) diffractometer Dectvis operated at
40 kV and 30 mA utilizing Cu Kα radiation (λ= 0.154 A°).
The magnetic property of catalyst was measured using a
vibrating sample magnetometer (VSM, Magnetic Danesh
Pajoh Inst.). All yields refer to isolated products after
purification by recrystallization.
octahydroxanthene,
tetrahydrobenzoxanthene
and
benzimidazolo quinazolinone derivatives in the presence of
WO3-SO3H (WSA),44 synthesis of alkyl levulinates from
levulinic acid using WO3-SBA-16,48 preparation of
WO3@PdO core-shell nanospheres as a reusable catalyst in
Mizoroki–Heck reaction 49 and synthesis of Fe3O4/WO3 as a
high-performance
and
recyclable
visible-light
photocatalyst.50 In continuing of our interests in developing
51-64
new
heterogeneous
catalysts
in
organic
transformations, herein we wish to design 2-
aminoethanesulfonic acid immobilized on epichlorohydrin
functionalized Fe3O4@WO3 (Fe3O4@WO3-EAE-SO3H), as
a novel and magnetically recyclable heterogeneous acidic
catalyst (Scheme 1). The Fe3O4 MNPs were prepared by
65
the method described in the literature which consists of
coprecipitation of Fe(III) and Fe(II) in alkaline solution.
Given the aforementioned advantages of WO3, Fe3O4
MNPs were then coated by WO3 shell through the reaction
with WCl6 and subsequent oxidation which leads to
formation of Fe3O4@WO3 (I). Suspension of I in pure
epichlorohydrin at 60 ºC with vigorous stirring results
2.2 Preparation of Magnetite Nanoparticles (Fe3O4
NPs). FeCl2.4H2O (10mmol, 1.99 g) and FeCl3.6H2O
(12mmol, 3.25 g) were dissolved in deionized water (30
mL) under N2 atmosphere at room temperature. NH4OH
solution (0.6 M, 200 mL) was then added drop wise to the
stirring mixture at room temperature to reach the reaction
pH to 11. The resulting black dispersion was continuously
stirred for 1 h at room temperature, and heated to reflux for
1 h to yield a brown dispersion. The magnetic nanoparticles
were subsequently separated by a magnetic bar and washed
with deionized water until it was neutralized. Fe3O4 NPs
was then dried at ambient temperature for 24 h.
epichlorohydrin
functionalized
Fe3O4@WO3
(Fe3O4@WO3-E) (II). Afterwards, Fe3O4@WO3-EAE-
SO3H (III) was obtained by treating of II with 2-
aminoethanesulfonic acid (taurine) as
organic molecule that has both –SO3H and –NH2 groups. It
can be used as surface modification agent. 2-
a bifunctional
a
Aminoethanesulfonic acid (taurine) as a ''conditionally
essential'' amino acid was found throughout the body
particularly in the brain, eyes, heart and muscles.66 Body
can produce some amount of taurine, and it is also found in
some foods such as meat, fish and dairy.67
2.3 Preparation of Fe3O4@WO3 core-shell (I).50
WCl6 (0.5mmol, 0.198 g), ethylene glycol (20 mL) and
Fe3O4 magnetic nanoparticle (1.5mmol, 0.346g) were
added to absolute ethanol (80 mL) under mild stirring. The
resulting black suspension was loaded into a Teflon-lined
autoclave, which was then sealed, heated to 180°C for 24 h,
and then allowed to cool to room temperature. The final
product was rinsed by absolute ethanol, and then dried at
2. Experimental
2.1 General. All chemical reagents and solvents were
purchased from Merck and Sigma-Aldrich chemical

70°C for 1 h. Afterwards the resulting Fe3O4/W18O49
precursor was heated at 420°C for 6 h to produce
Fe3O4@WO3 (I).
SO3H) (III). Fe3O4@WO3-EAE-SO3H (III) (0.01g) was
added to a solution of aniline (0.093 g, 1.0 mmol), triethyl
orthoformate (0.177g, 1.2 mmol) and 1-butyl-3-
methylimidazolium azide (0.216 g, 1.2 mmol) in water (5
mL). The reaction mixture was allowed to stir magnetically
at 60 ºC for 30 min. After completion of the reaction (as
monitored by TLC), the reaction mixture was cooled to
room temperature and the catalyst was separated by an
external magnet. Then the resulting solution was extracted
with EtOAc (3 ×15 mL). The organic layer was washed
with brine, dried over anhydrous Na2SO4 and evaporated
under reduced pressure. The crude product was
recrystallized from ethylacetate/n-hexane (1/9 v/v) to afford
the pure 1-phenyl-1H-tetrazole (1.48 g, 95 %). The
recovered catalyst was washed with hot ethyl acetate, dried
at 60 ºC for 2 h and reused for subsequent cycle.
2.4 Preparation of epichlorohydrin functionalized
Fe3O4@WO3 (Fe3O4@WO3-E) (II). Fe3O4@WO3 (0.7 g)
was dispersed in 6 mL pure epichlorohydrin by sonication
for 30 min. The resultant suspension was heated at 60º C
with vigorous stirring. After 24 h the epichlorohydrin-
functionalized Fe3O4@WO3 was separated by an external
magnet and washed with MeOH (5×10 mL) until removing
additional amount of epichlorohydrine. Then Fe3O4@WO3-
E (II) was dried at 40°C under vacuum for 14 h.
2.5 Preparation of 2-aminoethanesulfonic acid
immobilized
on
epichlorohydrin
functionalized
Fe3O4@WO3 (Fe3O4@WO3-EAE-SO3H) (III). To
a
solution of 2-aminoethanesulfonic acid (5mmol, 0.7 g) in
refluxing NaOH (0.04 M, 30 mL), Fe3O4@WO3-E (II) (0.5
g) was added with stirring under N2 atmosphere. After 8 h,
the resulting Fe3O4@WO3-EAE-SO3H (III) as a dark
brown precipitate was separated with a magnet and washed
to pH <7.5 by distilled water and then dried under vacuum
at 60 °C overnight.
3. Results and Discussion
3.1 Characterization of Catalyst. The Fe3O4@WO3-
EAE-SO3H (III) as
a
magnetically heterogeneous
nanocatalyst was prepared according to the pathway shown
in Scheme 1. The composition of the newly synthesized
nanocatalyst was fully characterized by some technical
methods such as Fourier transform infrared (FT-IR)
spectroscopy, X-ray diffraction (XRD), transmission
electron microscopy (TEM), energy-dispersive X-ray
spectroscopy (EDX), thermogravimetric analysis (TGA)
field emission scanning electron microscopy (FE-SEM),
CHNS and vibrating sample magnetometry (VSM). The
obtained results confirmed the successful preparation of the
new nanocatalyst. Figure 1 illustrates the FT-IR spectra of
(a) Fe3O4 nanoparticles; (b) Fe3O4@WO3 core-shell (I); (c)
epichlorohydrin functionalized Fe3O4@WO3 (Fe3O4@WO3
-E) (II) and (d) 2-aminoethanesulfonic acid immobilized on
epichlorohydrin functionalized Fe3O4@WO3 (Fe3O4@WO3
-EAE-SO3H) (III). As can be seen, FT-IR spectrum of
Fe3O4 (Figure 1a) showed broad bands at around 650-580
cm-1, which was attributed to Fe–O vibration. The
stretching vibration of W–O bond in WO3 was assigned at
around 851-770 cm-1 (Figure 1b). Furthermore, the
absorption bands at 1619 cm-1 and 3500–3100 cm-1 were
attributed to the bending and stretching vibrational modes
of the physisorbed water and attached hydroxyl groups on
the surface of Fe3O4@WO3 (I). The epoxy ring which was
grafted to the of Fe3O4@WO3 framework was recognized
by the methylene C–H stretching and bending vibration
bands at 2872-2920 and 1450 cm-1, respectively (Figure
1c). An absorption band at 1110 cm-1 was attributed to C–
O–C vibrational stretching. These results indicated that the
Fe3O4@WO3 surface has been immobilized by covalent
bonded organic epoxy rings. Ring opening of epoxy ring
with 2-aminoethanesulfonic acid was asserted by the
2.6 Synthesis of 1-butyl-3-methylimidazolium
chloride. 1-Chlorobutane (10.8 g, 0.8 mol) was added to 1-
methyimidizole (8.2 g, 0.1 mol) in a round bottomed flask
equipped with a reflux condenser. The mixture was stirred
at 70 ºC for 48 h. After formation of two phases, the top
layer which contains unreacted starting material was
decanted. Then ethyl acetate (30 mL) was added with entire
mixing followed by its decantation and this step was
repeated three times. After the third decanting of ethyl
acetate, remaining solvent was removed by heating at 70
ºC. The obtained pale yellow liquid was vacuum distilled
and the resulting 1-butyl-3-methylimidazolium chloride
was placed for vacuum drying at 80 ºC in a vacuum drying
oven.68
2.7 Synthesis of 1-butyl-3-methylimidazolium azide.
Freshly prepared 1-butyl-3-methylimidazolium chloride
(3.49 g, 20 mmol) and NaN3 (1.30 g, 20 mmol) were added
into 25 mL deionized water, and the mixture was stirred for
24 h at room temperature. The solvent was removed under
reduced pressure at 50 ºC. To separate 1-butyl-3-
methylimidazolium azide from the crude product (which
contains azide ionic liquid and NaCl), the resulting mixture
was washed with acetonitrile (3 × 10 mL). The remaining
acetonitrile was removed under high vacuum to yield
yellow transparent liquid that became more viscous upon
extensive drying. Isolated yield was 92% (3.33 g).69
2.8 Typical procedure for synthesis of 1-phenyl-1H-
tetrazole in the presence of the Fe3O4@WO3-EAE-

Scheme 1. Preparation of 2-aminoethanesulfonic acid immobilized on epichlorohydrin functionalized Fe3O4@WO3
(Fe3O4@WO3-EAE-SO3H) (III).
appearance of absorption bands around 3402 and 1624 cm-
corresponding to the stretching and bending vibrations of
33.1°, 34.0°, 41.3°, 52.8°and 61.7° corresponding to (0 0
1), (1 1 0), (1 1 1), (2 0 0), (2 0 1), (1 1 2), (2 1 2) and (4 0
0) crystallographic faces, could be assigned to tetragonal
structure of WO3 (JCPDS 01-085-0807).71 The average
crystallite size, d, of Fe3O4@WO3 MNPs calculated using
the Debye–Scherrer equation d= K λ/β cos θ is about 15.5
nm. The morphology and size distribution of Fe3O4@WO3-
EAE-SO3H (III) was further determined using transmission
electron microscopy (TEM), as shown in Figure 3. TEM
analysis showed that morphology of the most prepared
nanoparticles is spherical in shape and also the size of
particles is in the range of 7–23 nm. Moreover, as can be
seen the synthesized MNPs have core-shell structure.
Furthermore, distribution histogram of Fe3O4@WO3-EAE-
SO3H (III) revealed that the average diameter of
nanoparticles is 15 nm, which is in a good agreement with
1
hydroxyl groups, respectively (Figure 1d). Absorption
bands at 1220 and 1159 cm-1 related to stretching vibrations
of both asymmetric and symmetric modes of S=O bond.
Also, the band was depicted at 1044 cm-1 in the spectrum of
Fe3O4@WO3-EAE-SO3H (III) related to C–N stretching
vibration frequency.
XRD measurement was used to identify the crystalline
structure of Fe3O4@WO3 MNPs. As shown in Figure 2, the
XRD pattern exhibited reflection peaks at 2Θ= 18.9°, 31.2°,
36.8°, 38.5°, 55.6° and 65.1° which can be indexed to (1 1
1), (2 2 0), (3 1 1), (2 2 2), (4 2 2) and (4 4 0) reflections of
the cubic structure of Fe3O4 (JCPDS 19–0629).70 In
addition, diffraction peaks appeared at 2Θ= 22.7°, 24.0°,

the results deduced from the XRD. Field emission scanning
electron microscopy (FE-SEM) is used to visualize very
small topographic details on the surface or fractioned
objects. Biology, chemistry and physics applied this
technique to observe structures that may be as small as 1
nanometer (= billion of a millimeter). So in order to
investigate the surface morphology of Fe3O4@WO3-EAE-
SO3H (III), we used the field emission scanning electron
microscopy. FE-SEM images of Fe3O4@WO3-EAE-SO3H
(III) reveals that the nanoparticles have spherical shape
with the average particle sizes of about 15-20 nm (Figure
4). The energy dispersive spectum (EDS) of the catalyst
indicates all of the expected elements of Fe3O4@WO3-
EAE-SO3H (III) (C, O, Fe, W and S) as shown in Figure 5.
It is clear that 2-aminoethanesulfonic acid was successfully
Figure 3. (a) TEM of Fe3O4@WO3-EAE-SO3H (III) and
(b) particle size distribution histogram of Fe3O4@WO3-
EAE-SO3H (III).
immobilized
on
epichlorohydrin
functionalized
Fe3O4@WO3 (Fe3O4@WO3-E) (II). Also no extra peaks
related to any impurity are identified in the nanocatalyst
structure. The thermal stability of Fe3O4@WO3-EAE-SO3H
(III) was investigated by thermogravimetric analysis
(TGA) (Figure 6). TGA thermogram of Fe3O4@WO3-EAE-
SO3H (III) showed two main weight losses. The first one is
related to the adsorbed water molecules on the support
Figure 4. The FE-SEM images of Fe3O4@WO3-EAE-
SO3H (III).
Figure 1. FT-IR spectra of (a) Fe3O4 nanoparticles, (b)
Fe3O4@WO3 core-shell (I), (c) Fe3O4@WO3-E (II), (d)
Fe3O4@WO3-EAE-SO3H (III), (e) 7th recovered
Fe3O4@WO3-EAE-SO3H (III).
Figure 5. The EDS analysis of Fe3O4@WO3-EAE-SO3H
(III).
(weight loss 0.78% at 131–219°C). The second one which
occurs at 219–540°C (weight loss 3.49%) is corresponded
to the decomposition of organic parts supported on the
Fe3O4@WO3 MNPs surface. According to the TGA, the
amount of organic segments supported on Fe3O4@WO3
MNPs is estimated to be 0.215 mmol g-1
.
According the elemental analysis data, the loading
amount of organic segments supported on Fe3O4@WO3 (I)
was 0.2 mmol g-1 based on carbon, nitrogen and sulfur
content (C=1.62%, N=0.31% and S=0.75%). To determine
the number of acidic sites in Fe3O4@WO3-EAE-SO3H
Figure 2. XRD pattern of Fe3O4@WO3 MNPs.

(III), back-titration analysis was performed on the catalyst.
The prepared catalyst (100 mg) was suspended in an
aqueous NaOH solution (0.1 M, 15 mL), and maintained at
room temperature overnight under stirring. Afterwards the
suspension was filtered. The filtrate was neutralized by a
standard solution of HCl (0.1 M). The amount of loaded -
NHCH2CH2SO3H per 1.000 g of Fe3O4@WO3-EAE-SO3H
(III) was determined by the consumed volume of HCl
(14.25 mL) (0.225 mmol of -NHCH2CH2SO3H per 1.000 g
of catalyst). This result is in good agreement with those
obtained from TGA and elemental analysis. The
magnetization curve of Fe3O4@WO3-EAE-SO3H (III) was
measured at ambient temperature by a vibrating sample
magnetometry (VSM). As illustrated in Figure 7, the value
of saturation magnetic moments of Fe3O4@WO3-EAE-
SO3H (III) is Ms= 43.60 emu g-1 which was lower than the
reference value for Fe3O4 particles Ms= 73 emu g-1.72
Decreasing in the saturation magnetization of
Fe3O4@WO3-EAE-SO3H(III) after surface grafting, can be
attributed to the contribution of the non-magnetic materials.
yields. As proved by control experiments, a considerable
increase in the reaction yield was observed using
Fe3O4@WO3-EAE-SO3H (III) at 110 ºC (Table 1, entry
5), while low conversion was obtained when the model
reaction was performed at 100 ºC (Table 1, entry 6). In
an effort to develop better reaction conditions and in
continuation of our interest in exploring the utility of
60,64,74
green solvents in organic synthesis,
by applying
1:1.2:1 molar ratio of PhNH2: HC(OEt)3: [bmim]N3, the
model reaction was carried out in H2O at different
temperatures (Table 1, entries 7-9). In comparison, in
aqueous media the reaction proceeded more efficiently
(a reasonable yield of the desired product was obtained
at lower temperature) than in solvent free condition. In
view of safety, economic and handling considerations,
H2O was chosen as the best solvent for further
experiments. Also, by considering the yield and reaction
rate, 60 ºC was preferred as the optimal reaction
temperature for all of the reactions. Decrease in molar
ratio of HC(OEt)3 reduced the reaction rate obviously,
while a further increase in molar ratio of HC(OEt)3 did
not show any further increase in the yield of the product
(Table 1, compare entry 10 with entry 12).
3.2 Catalytic synthesis of 1-substituted-1H-
1,2,3,4-tetrazoles. As a part of our growing interest in
the development of new methods for 5-substituted-1H-
tetrazoles synthesis 51,52,54,57,73 and according to the green
101
100
99
chemistry legislations, we decided to perform
systematic investigation on the synthesis of 1-
substituted-1H-1,2,3,4-tetrazole derivatives under
a
98
significantly milder conditions using Fe3O4@WO3-EAE-
SO3H (III) as a new green magnetically separable and
efficient heterogeneous nanocatalyst (Scheme 2). Initial
experiments were carried out in order to determine the
best reaction conditions. Very recently 54,57 we found that
using 1-butyl-3-methylimidazolium azide ([bmim][N3])
ionic liquid as an azide ion source in place of the highly
toxic reagents such as NaN3 or TMSN3 predominantly
supports the movement toward the green chemistry.
Therefore, at the first stage, we probed the optimized
reaction conditions including molar ratios of reactants as
well as loading of the catalyst, the effect of temperature
and solvents in terms of time and yield on the reaction of
aniline, triethyl orthoformate and [bmim]N3 in the
97
96
95
94
25
225
425
625
Temperature (°C)
Figure 6. TGA thermogram of Fe3O4@WO3-EAE-SO3H
(III).
60
40
20
presence of Fe3O4@WO3-EAE-SO3H
(III). The
0
obtained results are summarized in Table 1. For the
further understanding of the role of Fe3O4@WO3-EAE-
SO3H (III) in preparation of 1-phenyl-1H-tetrazole, in a
set of experiments the model reaction was conducted in
the absence of catalyst as well as in the presence of
-20
-40
-60
Fe3O4 NPs, Fe3O4@WO3
(I) NPs, and Fe3O4@WO3-E
-20000
-10000
0
10000
20000
(
II) respectively (Table 1, entries 1-4). As it was shown
Field (G)
in Table 1, when the reaction was attempted without the
addition of catalyst, no desired product was obtained and
Figure 7. Magnetization curve of Fe3O4@WO3-EAE-SO3H
(III).
Fe3O4 NPs, Fe3O4@WO3
(I) NPs and Fe3O4@WO3-E
(
II) provided the target compound with not satisfactory

reported the 1H NMR, 13C NMR and FT-IR spectral data
of some selected synthesized 1-substituted-1H-1,2,3,4-
tetrazoles.
Completion of the reaction was established by the
disappearance of amine and formation of desired product
on TLC. The Fourier transform infrared (FTIR) spectra
of synthesized compounds showed the absence of the –
NH2 absorption bands and appearance a group of bands
at around 3150-3007, 833-710 cm-1 due to stretching and
scissoring bending of =C–H ,1691-1596 cm-1 and 1286–
1204 cm-1 owing to C=N and N-N=N of tetrazole ring
Scheme 2. Synthesis of different structurally 1-substituted-
1H-1,2,3,4-tetrazoles using Fe3O4@WO3-EAE-SO3H (III)
in water
However, the increase in molar ratio of [bmim]N3 up to
1:1.2:1.2 has a profound effect on the yield of the product
during the course of reaction (Table 1, compare entry 11
with entry 13). To achieve the optimum amount of the
catalyst, the model reaction was investigated at different
quantities of Fe3O4@WO3-EAE-SO3H (III) at 60 ºC in
H2O. The usage of higher amounts of catalyst did not
increase the yield significantly, while decreasing the
amount of catalyst reduced the yield (Table 1, entries 14-
15). To study the efficacy of [bmim]N3, when NaN3 was
used as the source of azide ion in the model reaction under
the optimized reaction conditions (Table 1, entry 11), the
reaction rate was slowed down along with obtaining low
yield of product (Table 1, entry 16). To further improve the
product yield, the effect of other solvents such as EtOH,
PEG, DMF, DMSO, CH3CN, 1,4-dioxane and THF have
been checked on model reaction. Considering the economic
and environmental factors and also based on the results of
Table 1, water was chosen as the best solvent for synthesis
of 1-substituted-1H-1,2,3,4-tetrazoles (Table 1, entry 17-
23).
Next, after optimizing the reaction conditions, we
attempted to broaden the applicability of the above-
described approach using several amines, triethyl
orthoformate and [bmim]N3. The results are summarized
in Table 2. Under similar conditions, it was observed
that amines carrying different functional groups
(containing electron-withdrawing as well as electron-
donating groups) such as methyl, hydroxyl, bromo,
chloro and nitro underwent the conversion in short
reaction times and in all cases high yields of the desired
products were achieved by heating the reaction mixture
at 60°C. In comparison the para-substituted anilines
gave good results than the ortho-substituted anilines,
because of more steric hindrance for the ortho-position
anilines on product formation than the para-position
anilines (entries 6 and 10 vs. entry 5 and 9).The present
catalytic system also worked well with heterocyclic and
aliphatic amines such as 2-amino pyridine and
benzylamine to generate the corresponding products
with good yields of 95% and 90% respectively (entries
12 and 13). The structural elucidation of the all
synthesized 1-substituted-1H-1,2,3,4-tetrazoles has been
established on the basis of their melting points and mass
spectral studies which were in good corroboration with
literature and the proposed structures. We have also
respectively. 1H NMR spectra displayed
a singlet
resonating signal at around 9.94-8.96 ppm, due to =C-H of
the tetrazole ring. In the 13C NMR spectral study, the
signal of the sp2 hybridized carbon of the tetrazole ring
was observed in the expected region around 159-140.4
ppm, which signifies the formation of tetrazole ring.
Comprehensive characteristic spectral data for the
different synthesized 1-substituted-1H-1,2,3,4-tetrazoles
have been discussed in the experimental section and
"Supporting Information " file.
The reusability of the catalyst is an important property
especially for commercial application which it reduces the
cost of process. So, to satisfy the green chemistry criteria,
the recovery and reusability of Fe3O4@WO3-EAE-SO3H
(III) as a magnetic nanocatalyst was examined on the
model reaction under the optimized reaction conditions.
After completion of the model reaction, the catalyst was
recovered from the reaction mixture simply by a magnetic
field. Then the recovered catalyst was washed with hot
ethyl acetate, dried at 60 ºC for 2 h and reused up to seven
more reaction cycles. The results demonstrate that the
recycled and reused catalyst showed the same activity as a
fresh catalyst and a minimal decrease in yields was
observed (the product was obtained in 95%, 95%,
95%,95%, 95%, 90%, 85% isolated yields after successive
cycles). So, the magnetic nanocatalyst can be reused as
such without a significant deterioration in catalytic activity
(Figure. 8). To ascertain the variation in chemical structure
of functional groups and the hydrogen bonding network of
the recovered catalyst, the FT-IR spectrum of the 7th
recovered Fe3O4@WO3-EAE-SO3H (III) was recorded
(Figure. 1e). It was found that no significant changes were
happened in the shape and intensities of the representative
absorption bands (Figures 1d vs.1e). Thus, the catalytic
system is almost consistent with the fresh catalyst after
repeated cycles of the reaction as compared to the fresh
catalyst. The activity and selectivity of heterogeneous
catalysts may change during the reactions. The activity
usually decreases due to either chemical or physical reasons
or a combination of both factors. Therefore, a reduction in
the activity of Fe3O4@WO3-EAE-SO3H (III) might be due
to the chemisorption of species on catalytic sites which

Table 1. Optimization of various reaction parameters for the synthesis of 1-phenyl-1H-tetrazole in the presence of Fe3O4@WO3-
EAE-SO3H (III).
Entry
Temperature
(ºC)
110
110
110
110
110
100
reflux
60
Time
(min)
24 (h)
24 (h)
24 (h)
24 (h)
30
Molar ratio of
PhNH2/HC(OEt)3/[bmim]N3
Amount of
catalyst (g)
Isolated
Yield (%)
Solvent
1
2a
1:1.2:1
1:1.2:1
-
-
-
-
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.012
0.008
0.01
0.01
0.01
0.01
0.01
0.01
5
3b
4c
1:1.2:1
-
10
10
95
90
90
90
85
80
95
95
95
95
90
80
80
70
75
40
55
1:1.2:1
-
5
1:1.2:1
-
6
1:1.2:1
-
40
7
1:1.2:1
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
EtOH
PEG
DMF
DMSO
CH3CN
25
8
1:1.2:1
40
9
1:1.2:1
50
55
10
11
12
13
14
15
16d
17
18
19
20
21
22
1:1:1
60
45
1:1.2:1.2
1:1.5:1.2
1:1.2:1.5
1:1.2:1.2
1:1.2:1.2
1:1.2:1.2
1:1.2:1.2
1:1.2:1.2
1:1.2:1.2
1:1.2:1.2
1:1.2:1.2
60
30
60
30
60
30
60
30
60
55
60
55
60
24 (h)
24 (h)
24 (h)
24 (h)
24 (h)
60
60
60
60
1,4-
Dioxane
1:1.2:1.2
1:1.2:1.2
0.01
0.01
60
60
24 (h)
24 (h)
40
30
23
THF
a The reaction was performed in the presence of Fe3O4 NPs. b The reaction was performed in the presence of Fe3O4@WO3 NPs (I).
c The reaction was performed in the presence of Fe3O4@WO3-E (II). d The reaction was performed by using NaN3.

Table 2. Synthesis of different structurally 1-substituted-
1H-1,2,3,4-tetrazoles in the presence of Fe3O4@WO3-EAE-
SO3H (III).
NPs/bentonite, ZnS nanoparticles and HClO4-SiO2, was
completed at higher temperature (100-120 °C) by taking
prolonged time period as well (50-360 min). However,
nano ZnS/US and immobilized AlCl3 on Al2O3 afforded the
desired product quickly at lower temperature but by using
DMF as solvent (Table 3, entries 6-7). Quick route to 1-
phenyl-1H-tetrazole was obtained using [Hbim]BF4,
Fe3O4@SiO2/Salen Cu(II) and Fe3O4@silica sulfonic acid
as catalyst but at higher temperature (Table 3, entries 10-
12). It is clear that Fe3O4@WO3-EAE-SO3H (III) worked
remarkably well, as the desired product was produced at 60
ºC within 30 min in H2O along with easy separation using
an external magnet. Then Fe3O4@WO3-EAE-SO3H (III)
can be the catalyst of choice for the present synthetic
method.
Time
(min)
Isolated Yield
(%)
Entry
R
C6H5
1a
1
2
30
20
25
40
25
60
35
55
40
95
50
35
45
95
95
90
90
95
95
90
90
90
90
90
95
90
4-Me-C6H4
1b
3-Me-C6H4
3
1c
3,4-Me2-C6H3
4
1d
4-HO-C6H4
5
1e
2-HO-C6H4
6
1f
4-Br-C6H4
7
1g
Figure 8. Synthesis of 1-phenyl-1H-tetrazole in the
presence of reused Fe3O4@WO3-EAE-SO3H (III).
3-Br-C6H4
8
1h
4. Conclusion
4-Cl-C6H4
In summary, a convenient, eco-friendly and scalable
approach for the synthesis of 1-substituted-1H-1,2,3,4-
tetrazoles using Fe3O4@WO3-EAE-SO3H (III) as a catalyst
was reported. Fe3O4@WO3-EAE-SO3H (III) as a novel
heterogeneous nanocatalyst was prepared and characterized
by FT-IR, XRD, TEM, FE-SEM, EDS, TGA, CHNS and
VSM techniques. Characterization results validate that
magnetic nanocatalyst Fe3O4@WO3-EAE- SO3H (III) with
spherical shape and mean diameters of 7–23 nm was
successfully synthesized. Subsequently, the new
synthesized nanocatalyst has been used for the synthesis of
structurally different 1-substituted-1H-1,2,3,4-tetrazoles via
the cyclization reaction of various primary amines, triethyl
orthoformate and 1-butyl-3-methylimidazolium azide
([bmim][N3]) under benign reaction conditions.
9
1i
2-OMe-4-Cl-
10
11
12
13
C6H3
1j
4-NO2-C6H4
1k
2-C5H4N
1l
C6H5CH2
1m
blocks the sites of nanocatalyst. Also the deactivation of
catalyst might be caused by the physical deposit of
reactants onto the catalyst surface or in the catalyst pores.86
In subsequent experiments, to show the superiority of
Fe3O4@WO3-EAE-SO3H (III) over a variety of the
reported catalysts in the literature, a comparative study was
conducted on model reaction (Table 3). As shown in Table
3 (entries 1-5 and entries 8-9), the model reaction in the
presence of In(OTf)3, natrolite zeolite, SSA, Cu
The noteworthy features of this green synthetic protocol are
enhanced reaction rate, mild reaction conditions,
operational simplicity, excellent yield, high purity, clean
reaction profile, using magnetic separation technique and
the potential reusability of the catalyst. Moreover, the
present synthetic method eliminates the use of harmful

solvents and hazardous materials thus provides a better
scope for the synthesis of 1-substituted-1H-1,2,3,4-
tetrazoles. This notable and valuable feature of this
methodology makes it a more helpful and practical
alternative to the other existing methods for synthesizing
this class of compounds in organic chemistry and also in
medicinal chemistry.
The authors gratefully acknowledge the partial support
of this study by Ferdowsi University of Mashhad Research
Council (Grant no. p/3/43366).
Supporting Information
The Supporting Information contains characterization
data of all compounds. This material is available on
http://dx.doi.org/
Table 3 Comparison between efficiency of Fe3O4@WO3-EAE-SO3H (III) and some other catalysts for the synthesis of 1-phenyl-
1H-tetrazole.
Temperature
(°C)
Yield
(%)
Entry
Catalyst
Solvent
Time (min)
Ref.
1
2
In(OTf)3
Natrolite zeolite
SSA
-
100
120
120
120
100
r.t
120
240
300
180
360
20
90
94
95
93
85
92
75
76
77
78
30
79
-
3*
4
-
Cu NPs/bentonite
Yb(OTf)3
-
5
CH3OC2H4OH
DMF
6
Nano ZnS/U.S
Immobilized AlCl3 on
Al2O3
7
DMF
-
50
60
94
80
8
ZnS nanoparticles
HClO4-SiO2
130
120
100
100
100
270
240
25
78
89
89
96
97
81
82
83
84
85
9
10
11
12
[Hbim]BF4
-
-
-
Fe3O4@SiO2/Salen Cu(II)
Fe3O4@silica sulfonic acid
60
50
Fe3O4@WO3-EAE-SO3H
Present
study
13
H2O
60
30
95
(III)
* Silica Sulfuric Acid.
6
6857.
7
L. A. Flippin, Tetrahedron Lett. 1991, 32,
P. Rhonnstad, D. Wensbo, Tetrahedron Lett.
References
1
B. Jawabrah Al-Hourani, W. Al-Awaida, K. Z.
2002, 43, 3137.
Matalka, M. I. El-Barghouthi, F. Alsoubani, F. Wuest,
Bioorg. Med. Chem. Lett. 2016, 26, 4757.
8
R. E. Ford, P. Knowles, E. Lunt, S. M.
Marshall, A. J. Penrose, C. A. Ramsden, A. J. H.
Summers, J. L. Walker, D. E.Wright, J. Med. Chem.
1986, 29, 538.
2
L. B. Moskvin, A. V. Bulatov, G. L.
Griogorjev, G. I. Koldobkij, J. Flow Injection Anal.
2003, 20, 53-58.
9
N. P. Peet, L. E. Baugh, S. Sundler, J. E.
3
4
A. Burger, Prog. Drug Res. 1991, 37, 287.
A. R. Modarresi-Alam, F. Khamooshi, M.
Lewis, E. H. Matthews, E. L. Olberding, D. N. Shah, J.
Med. Chem. 1986, 29, 2403.
Rostamizadeh, H. Keykha, M. Nasrollahzadeh, H. R.
10 V. V. Nikulin, T. V. Artamonova, G. I.
Koldobskii, Russ. J. Org. Chem. 2003, 39, 1525.
11 V. V. Nikulin, T. V. Artamonova, G. I.
Koldobskii, Russ. J. Org. Chem. 2005, 41, 444.
Bijanzadeh, E. Kleinpeter, J. Mol. Struct. 2007, 841, 61.
5
F. Ek, L. G. Wistrand, T. Frejd, Tetrahedron
2003, 59, 6759.

12 L. V. Myznikov, A. Hrabalek, G. I.
Koldobskii, Chem. Heterocycl. Compd. 2007, 43, 1.
13 R. N. Butler, A. R. Katritzky, C. W. Rees, E. F.
V. Scriven, Comprehensive Heterocyclic Chemistry II,
Pergamon Oxford 1996, 4, 621.
38 B. Liu, W. Zhang, F. Yang, H. Feng, X. Yang,
J. Phys. Chem. C 2011, 115, 15875.
39 Y. S. Li, J. S. Church, A. L. Woodhead, F.
Moussa, Spectrochim. Acta Mol. Biomol. Spectrosc.
2010, 76, 484.
14 H. Singh, A. S. Chawla, V. K. Kapoor, D.
Paul, R. K. Malhotra, Prog. Med. Chem. 1980, 17, 151.
15 V. A. Ostrovskii, M. S. Pevzner, T. P. Kofmna,
M. B. Sheherbinin, I. V. Tselinskii, Targets Heterocycl.
Syst. 1999, 3, 467.
16 M. Hiskey, D. E. Chavez, D. L. Naud, S. F.
Son, H. L. Berghout, C. A. Bome, Proc. Int. Pyrotech.
Semin. 2000, 27, 3.
17 M. J. Genin, D. A. Allwine, D. J. Anderson, M.
R. Barbachyn, D. E. Emmert, S. A. Garmon, D. R.
Graber, K. C. Grega, J. S. Hester, D. K. Hutchinson, J.
Morris, R. J. Reischer, C.W. Ford, G. E. Zurenko, J. C.
Hamel, R. D. Schaadt, D. Stapert, B. H. Yagi, J. Med.
Chem. 2000, 43, 953.
40 Y. Deng, C. Deng, D. Qi, C. Liu, J. Liu, X.
Zhang, D. Zhao, Adv. Mater. 2009, 21, 1377.
41 Y. Dong, M. Hu, R. Ma, H. Cheng, S. Yang,
Y. Y. Li, J. A. Zapien, CrystEngComm 2013, 15, 1324.
42 W. Xie, X. Zang, Food Chem. 2017, 227, 397.
43 Y. Li, X. Xu, D. Qi, C. Deng, P. Yang, X.
Zhang, J. Proteome Res. 2008, 7, 2526.
44 A. Amoozadeh, S. Rahmani, J. Mol. Catal. A:
Chem. 2015, 396, 96.
45 H. Zheng, J. Z. Ou, M. S. Strano, R. B. Kaner,
A. Mitchell, K. Kalantar-zadeh, Adv. Funct. Mater.
2011, 21, 2175.
46 K. Suzuki, T. Watanabe, S. I. Murahashi, J.
Org. Chem. 2013, 78, 2301.
18 R. N. Butler, Adv. Heterocycl. Chem. 1977, 21,
47 D. H. Koo, M. Kim, S. Chang, Org. Lett. 2005
,
323.
7, 5015.
19 F.R. Benson, Chem. Rev. 1947, 47, 1.
20 P. K. Kadaba, Synthesis 1973, 71.
21 S. J. Wittenberger, Org. Prep. Proced. Int.
1994, 26, 499.
22 A. R. Katritzky, B. V. Rogovoy, K. V.
Kovalenko, J. Org. Chem. 2003, 68, 4941.
23 M. L. Kantam, K. B. S. Kumar, K. P. Raja, J.
Mol. Catal. A: Chem. 2006, 247, 186.
48 S. S. Enumula, V. R. B. Gurram, R. R. Chada, D.
R. Burri, S. R. R. Kamaraju, J. Mol. Catal. A: Chem.
2017, 426, 30.
49 M. Amini, A. Yousefi, Reac. Kinet. Mech. Cat.
2016, 119, 207.
50 G. Xi, B. Yue, J. Cao, J. Ye, Chem. Eur. J.
2011, 17, 5145.
51 N. Razavi, B. Akhlaghinia, RSC Adv. 2015, 5,
24 R. J. Herr, Bioorg. Med. Chem. 2002, 10, 3379.
25 D. M. Zimmerman, R. A. Olofson,
Tetrahedron Lett. 1969, 10, 5081.
12372.
52 S. S. E. Ghodsinia, B. Akhlaghinia, RSC Adv.
2015, 5, 49849.
26 T. Jin, S. Kamijo, Y. Yamamoto, Tetrahedron
Lett. 2004, 45, 9435.
53 M. Zarghani, B. Akhlaghinia,
Organomet. Chem. 2015, 29, 683.
Appl.
27 F. G. Fallon, R. M. Herbst, J. Org. Chem.
54 R. Jahanshahi, B. Akhlaghinia, RSC Adv. 2015
,
1957, 22, 933.
28 Y. Satoh, N. Marcopulos, Tetrahedron Lett.
1995, 36, 1759.
5, 104087.
55 N. Y. Siavashi, B. Akhlaghinia, M. Zarghani,
Res. Chem. Intermed. 2016, 42, 5789.
29 A. K. Gupta, C. H. Oh, Tetrahedron Lett. 2004
45, 4113.
30 W. Su, Z. Hong, W. Shan, X. Zhang, Eur. J.
Org. Chem. 2006, 2723.
31 S. N. Dighe, K. S. Jain, K. V. Srinivasan,
Tetrahedron Lett. 2009, 50, 6139.
,
56 R. Jahanshahi, B. Akhlaghinia, RSC Adv. 2016
6, 29210.
57 M. Zarghani, B. Akhlaghinia, RSC Adv. 2016
6, 31850.
58 M. Zarghani, B. Akhlaghinia, RSC Adv. 2016
6, 38592.
,
,
,
32 S. V. Voitekhovich, A. N. Vorob’ev, P. N.
Gaponik, O. A. Ivashkevich, Chem. Heterocycl. Compd.
2005, 41, 999.
33 A. K. Gupta, C. Y. Rim, C. H. Oh, Synlett
2004, 2227.
59 S. M. Masjed, B. Akhlaghinia, M. Zarghani, N.
Razavi, Aust. J. Chem. 2017, 70, 33.
60 S. S. E. Ghodsinia, B. Akhlaghinia, R.
Jahanshahi, RSC Adv. 2016, 6, 63613.
61 M. Zarghani, B. Akhlaghinia, Bull. Chem. Soc.
Jpn. 2016, 89, 1192.
34 A. K. Gupta, C. H. Song, C. H. Oh,
Tetrahedron Lett. 2004, 45, 4113.
35 N. T. Pokhodylo, V. S. Matiychuk, M. D.
Obushak, Tetrahedron 2008, 64, 1430.
62 Z. Zarei, B. Akhlaghinia, RSC Adv. 2016, 6,
106473.
63 N. Razavi, B. Akhlaghinia, R. Jahanshahi,
36 a) T. Zeng, W. W. Chen, C. M. Cirtiu, A.
Moores, G. Song, C. J. Li, Green Chem. 2010, 12, 570,
b) V. Polshettiwar, R. Luque, A. Fihri, H. Zhu, M.
Bouhrara, J. M. Basset, Chem. Rev. 2011, 111, 3036, c) D.
Wang, D. Astruc, Chem. Rev. 2014, 114, 6949, d) C. W.
Lim, I. S. Lee, Nano Today 2010, 5, 412, e) M. B.
Gawande, P. S. Branco, R. S. Varma, Chem. Soc. Rev.
2013, 42, 3371.
Catal. Lett. 2017, 147, 360.
64 N. Razavi, B. Akhlaghinia, New J. Chem.
2016, 40, 447.
65 S. Sobhani, M. S. Ghasemzadeh, M.
Honarmand, F. Zarifi, RSC Adv. 2014, 4, 44166.
66 H. Ripps, W. Shen, Mol. Vis. 2012, 18, 2673.
67 F. Shirini, N. Daneshvar, RSC Adv. 2016, 6,
110190.
37 A. Ali, H. Zafar, M. Zia, I. ul Haq, A. R. Phull,
J. S. Ali, A. Hussain, Nanotechnol. Sci. Appl. 2016, 9,
49.
68 P. N. Tshibangu, S. N. Ndwandwe, E. D.
Dikio, Int. J. Electrochem. Sci. 2011, 6, 2201.

69 H. Valizadeh, M. Amiri, E. Khalili, Mol.
Diversity 2012, 16, 319.
70 M. Esmaeilpour, A. R. Sardarian, J. Javidi,
Appl Catal A: Gen 2012, 445–446, 359.
71 W. L. Kehl, R. G. Hay, D. Wahl, J. Appl. Phys.
1952, 23, 212.
78 A. Rostami-Vartooni, M. Alizadeh, M.
Bagherzadeh, Beilstein. J. Nanotechnol. 2015, 6, 2300.
79 H. Naeimi, F. Kiani, Ultrason. Sonochem.
2015, 27, 408.
80 H. M. Nanjundaswamy, H. Abrahamse,
Heterocycles 2014, 89, 2137.
72 S. Li, H. Bai, J. Wang, X. Jing, Q. Liu, M.
81 H. Naeimi, F. Kiani, M. Moradian, J.
Nanopart. Res. 2014, 16, 2590.
Zhang, R. Chen, L. Liu, C. Jiao, Chem. Eng. J. 2012
,
193–194, 372.
73 B. Akhlaghinia, S. Rezazadeh, J. Braz. Chem.
Soc. 2012, 23, 2197.
74 S. Rezazadeh, B. Akhlaghinia, E. K.
Goharshadi, H. Sarvari, J. Chin. Chem. Soc. 2014, 61,
1108.
82 S. Bahari, A. Rezaei, Lett. Org. Chem. 2014
11, 55.
83 T. M. Potewar, S. A. Siddiqui, R. J. Lahoti, K.
V. Srinivasan, Tetrahedron Lett. 2007, 48, 1721.
84 F. Dehghani, A. R. Sardarian, M. Esmaeilpour,
J. Organomet. Chem. 2013, 743, 87.
,
75 D. Kundu, A. Majee, A. Hajra, Tetrahedron
Lett. 2009, 50, 2668.
85 H. Naeimi, S. Mohamadabadi, Dalton Trans.
2014, 43, 12967.
76 D. Habibi, M. Nasrollahzadeh, T. A. Kamali,
86 M. D. Argyle, C. H. Bartholomew, Catalysts
Green Chem. 2011, 13, 3499.
2015, 5, 145.
77 D. Habibi, H. Nabavi, M. Nasrollahzadeh, J.
Chem. 2013, 4.

Graphical Abstract
2-Aminoethanesulfonic acid immobilized on epichlorohydrin functionalized Fe3O4@WO3 (Fe3O4@WO3-EAE-SO3H): a
novel magnetically recyclable heterogeneous nanocatalyst for the green one-pot synthesis of 1-substituted-1H-1,2,3,4-
tetrazoles in water
Maryam Sadat Ghasemzadeh and Batool Akhlaghinia*
A novel method for preparing 1-substituted-1H-1,2,3,4-tetrazoles with high yield of products using Fe3O4@WO3-EAE-SO3H
(III) as a magnetic nanocatalyst, was investigated. This new methodology is cost-effective and offers several advantages such as
excellent yields of products, mild reaction conditions, minimization of chemical waste, broad substrate scope, simple work-up
procedure and magnetic separation of the nanocatalyst, make this protocol very attractive for the synthesis of a variety of 1-
substituted-1H-1,2,3,4-tetrazoles.