Green synthesis of thiiranes from epoxides catalyzed by magnetically separable CuFe2O4/Mg(OH)2 nanocomposite in water under benign conditions

Article abstract of DOI:10.1080/17415993.2019.1567728

The magnetically separable CuFe₂O₄/Mg(OH)₂ nanocomposite was prepared and characterized by FT-IR, XRD, SEM, EDS, and VSM techniques. The synthesized nanoparticles were used as a new and efficient heterogeneous catalyst for the conversion of various epoxides to the corresponding thiiranes with thiourea in water solvent at room temperature. The reactions were completed within 1–3.7 h to give thiiranes in 70–99% yields. The applied CuFe₂O₄/Mg(OH)₂ nanocomposite was separated easily using an external magnet and reused for several times without any considerable loss of activity.

Full text of DOI:10.1080/17415993.2019.1567728

Journal of Sulfur Chemistry
ISSN: 1741-5993 (Print) 1741-6000 (Online) Journal homepage: https://www.tandfonline.com/loi/gsrp20
Green synthesis of thiiranes from epoxides
catalyzed by magnetically separable CuFe2O4/
Mg(OH)2 nanocomposite in water under benign
conditions
Shadi Hassanzadeh, Ronak Eisavi & Mojtaba Abbasian
To cite this article: Shadi Hassanzadeh, Ronak Eisavi & Mojtaba Abbasian (2019):
Green synthesis of thiiranes from epoxides catalyzed by magnetically separable CuFe2O4/
Mg(OH)2 nanocomposite in water under benign conditions, Journal of Sulfur Chemistry, DOI:
10.1080/17415993.2019.1567728
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JOURNAL OF SULFUR CHEMISTRY
https://doi.org/10.1080/17415993.2019.1567728
Green synthesis of thiiranes from epoxides catalyzed by
magnetically separable CuFe2O4/Mg(OH)2 nanocomposite in
water under benign conditions
Shadi Hassanzadeh, Ronak Eisavi and Mojtaba Abbasian
Department of Chemistry, Payame Noor Universtiy, Tehran, Iran
ABSTRACT
ARTICLE HISTORY
Received 6 October 2018
Accepted 23 December 2018
The magnetically separable CuFe2O4/Mg(OH)2 nanocomposite was
prepared and characterized by FT-IR, XRD, SEM, EDS, and VSM tech-
niques. The synthesized nanoparticles were used as a new and effi-
cient heterogeneous catalyst for the conversion of various epoxides
to the corresponding thiiranes with thiourea in water solvent at room
temperature. The reactions were completed within 1–3.7 h to give
thiiranes in 70–99% yields. The applied CuFe2O4/Mg(OH)2 nanocom-
posite was separated easily using an external magnet and reused for
several times without any considerable loss of activity.
KEYWORDS
Epoxide; CuFe2O4/Mg(OH)2;
nanocomposite; thiirane;
thiourea
1. Introduction
Thiiranes, the simplest sulfur heterocycles, are used in polymer, pharmaceutical, pesti-
cide and herbicide industries [1] They are also the essential heterocyclic building blocks
of valuable biologically active compounds [2–5]. Transformation of epoxides to thiiranes
by an oxygen-sulfur replacement reaction is the most straightforward synthetic method
for the formation of thiiranes. The sulfur-transfer agents such as thiourea [6], inorganic
CONTACT Ronak Eisavi
roonak.isavi@gmail.com
Department of Chemistry, Payame Noor Universtiy, PO BOX
19395-3697, Tehran, Iran
This article makes reference to supplementary material available on the publisher’s website at
http://dx.doi.org/10.1080/17415993.2019.1567728
© 2019 Informa UK Limited, trading as Taylor & Francis Group

2
S. HASSANZADEH ET AL.
thiocyanates [7], dimethylthioforamide [8], phosphine sulfide [9] silica-gel supported
KSCN [10] Dowx-50WX8- supported thiourea [11] have been employed for this purpose.
Although there are numerous protocols for the preparation of thiiranes in the literature,
most of them suffer from disadvantages such as high temperatures, long reaction times, low
yield of products, the use of unsafe reagents and solvents, the formation of by-products,
tedious work-up procedures, and the use of irrecoverable catalysts.
The combination systems of different protic or Lewis acids such as TiO(TFA)2
[12], TiCl3(OTf) [12], Mg(HSO4)2 [13], RuCl3 [14], InBr3 [15], BiCl3 [16], 2,4,6-
trichloro-1,3,5-triazine [17], Bi(TFA)3 [18], Bi(OTf)3 [18], TiO2 [19], Al(DS)3·3H2O [20],
Sn(TTP)(OTf)2 [21], Sn(TTP)(BF4)2 [22], SiO2-HBF4 [23], SbCl3 [24], polymeric cosol-
vents [25], etidronic acid [26], montmorillonite K-10 [27], (NH4)8[CeW10O36]·20H2O
[28], LiBF4 [29], LiClO4 [30], I2 [31], oxalic acid [32], CAN [33], [bmim]PF6 [34], β-
cyclodextrin [35], poly(4-vinylpyridine)-supported Ce(OTf)4 [36], polystyrene supported
AlCl3 [37], (R)-TRIP [38], graphite oxide [39], and microwave irradiation [40] with
thiourea or NH4SCN have also been reported for transformation of epoxides to thiiranes.
In organic synthesis, the use of eco-friendly solvents and recyclable magnetic nanocata-
lysts under mild conditions facilitates the achievement of green chemistry goals. In recent
years, magnetic nano-ferrites due to their amazing properties such as chemical stability
[41], the large surface area to volume ratio and high catalytic activity [42], easy separa-
tion using a simple magnet without need for filtration [43], and recyclability have received
great consideration in organic transformations. Nevertheless, these nano-ferrites often suf-
fer from adsorption difficulties, because of their high tendency of self-aggregation and lack
of sufficient functional groups on the surface [44,45]. Nanocomposites containing cores
of magnetic ferrites with a functionalized shell provide a helpful solution for efficiency
improvement of nano-ferrites [46].
As a part of our research program on the synthesis of thiiranes [47–49] and in con-
nection with our work on nano-ferrites [50–53], we wish to introduce an efficient and
eco-friendly method for the conversion of various epoxides to the corresponding thiiranes
using thiourea in the presence of CuFe2O4/Mg(OH)2 nanocomposite as an active and
recyclable catalyst in water solvent at room temperature in high to excellent yields.
2. Results and discussions
2.1. Synthesis and characterization of CuFe2O4/Mg(OH)2 nanocomposite
Recently, we have used CuFe2O4 as a magnetic nanocatalyst for the preparation of thiiranes
from epoxides with thiourea in refluxing ethanol [50]. However, conversion of epoxides to
thiiranes catalyzed by CuFe2O4/Mg(OH)2 nanocomposite in water at room temperature,
compared to the use of bare copper nanoferrite under reflux in ethanol, is preferred. The
presence of hydroxyl functional groups on the surface of nano-ferrite not only increases
the catalytic activity, but can also reduce the self-aggregation of nanoparticles. Avoiding
the use of high temperatures and organic solvents are the other advantages of the present
method.
CuFe2O4/Mg(OH)2 nanocomposite was synthesized in a two steps procedure. In the
first step, nano-CuFe2O4 was prepared by a solid-state reaction of inorganic salts of CuSO4,
Fe(NO3)3·9H2O, NaCl and NaOH (Scheme 1) [54]. Then, the obtained CuFe2O4 was

JOURNAL OF SULFUR CHEMISTRY
3
Scheme 1. Synthesis of CuFe2O4 nanoparticles.
Scheme 2. Synthesis of CuFe2O4/Mg(OH)2 nanocomposite.
added to the aqueous solution of Mg(NO3)2·6H2O followed by dropwise addition of NaOH
solution with stirring (Scheme 2). The CuFe2O4/Mg(OH)2 nanocomposite was collected
as a dark brown powder and characterized by FT-IR, X-ray diffraction (XRD), scanning
electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), and vibration
sample magnetometer (VSM) analyses.
2.1.1. X-ray diffraction (XRD)
The XRD patterns of nano-Mg(OH)2, CuFe2O4 nanoparticles and CuFe2O4/Mg(OH)2
nanocomposite are shown in Figure 1. The lines (220), (311), (222), (400), (422), (511), and
(440) related to 2ꢀ = 30.04, 34.96, 37.26, 43.92, 55.81, 58.01, and 63.84 respectively, are
assigned to the diffraction of CuFe2O4 crystals and indicate that the synthesized CuFe2O4
nanoparticles are pure and highly crystalline. This pattern is in agreement with the pure
spinel CuFe2O4 in the standard data ((JCPDS card No. 34-0425) [54]. In the XRD pattern
of CuFe2O4/Mg(OH)2, all the peaks of CuFe2O4 and Mg(OH)2 are observed. The lines
(001), (101), (102), (110), (103), and (201) related to the sharp peaks at 2ꢀ = 18.49, 38.21,
50.99, 58.85, 68.37, and 75.08 respectively, are corresponded to hexagonal phase of magne-
sium hydroxide crystal, which are very close to standard card of (JCPDS No. 84-2164) [53].
The peak at 62.47 for magnesium hydroxide overlaps with the 63.84 peak of CuFe2O4. The
average crystallite size of the sample was calculated using the Scherrer equation (24 nm).

4
S. HASSANZADEH ET AL.
Figure 1. The X-ray diffraction patterns of (a) nano-Mg(OH)2, (b) nano-CuFe2O4 and (c)
CuFe2O4/Mg(OH)2 nanocomposite.
Figure 2. Magnetization curves of CuFe2O4 (a) and (b) CuFe2O4/Mg(OH)2.
2.1.2. Vibration sample magnetometer (VSM)
Figure 2 shows magnetization curves of CuFe2O4 nanoparticles and CuFe2O4/Mg(OH)2
nanocomposite at room temperature. The CuFe2O4/Mg(OH)2 nanocomposite showed
the same ferromagnetic behavior, but the incorporation of Mg(OH)2 with copper ferrite
led to decrease the saturation magnetization and coercivity. The decrease in saturation
magnetization can be explained by the presence of nonmagnetic Mg(OH)2 in the sample.
2.1.3. Scanning electron microscopy (SEM)
The morphology of as-prepared CuFe2O4 and CuFe2O4/Mg(OH)2 nanoparticles has been
analyzed by the SEM technique (Figure 3). CuFe2O4 nanoparticles are in tetragonal crys-
talline shapes with uniform distribution in the sample. The nanoparticles of Mg(OH)2 with

JOURNAL OF SULFUR CHEMISTRY
5
Figure 3. SEM images of (a) CuFe2O4 and (b) CuFe2O4/Mg(OH)2 nanoparticles.

6
S. HASSANZADEH ET AL.
Figure 4. FT-IR (KBr) spectrum of (a) CuFe2O4/Mg(OH)2, (b) CuFe2O4 and (c) Mg(OH)2.
hexagonal shape are regularly immobilized on the whole surfaces of CuFe2O4 nanoparti-
cles. These images show that particle lies in the range of 16–65 nm. The obtained results
are in good agreement with XRD data.
2.1.4. Fourier transform infra-red (FT-IR) spectrum
Figure 4 shows the FT-IR spectrum of CuFe2O4, Mg(OH)2 and CuFe2O4/Mg(OH)2. The
sharp and strong absorption band at 3681 cm−1 is related to the O–H stretching vibra-
tions in the crystal structure of Mg(OH)2 [53]. The broad absorption peaks at 3492 and
1610 cm−1 correspond to the stretching and bending modes of hydroxyl group in surface
absorbed water, respectively. A broad peak at 1400 cm−1 is assigned to the O-H bent vibra-
tions in Mg(OH)2. The formation of tetrahedral-octahedral structures of the metal oxide
(Fe-O and Cu-O) is confirmed by the absorption bands at around 400–600 cm−1 [50].
2.1.5. Electron dispersive spectroscopy (EDS)
The chemical combination of nano-CuFe2O4/Mg(OH)2 was determined with EDS analy-
sis. In the EDS spectrum, Fe, O, Cu, and Mg signals are observed (Figure 5).
2.2. Conversion of epoxides to thiiranes catalyzed by CuFe2O4/Mg(OH)2
nanocomposite
In order to optimize the reaction conditions, the conversion of styrene oxide to styrene
episulfide using thiourea in the presence of catalytic amount of CuFe2O4/Mg(OH)2
nanocomposite was studied (Scheme 3). According to a literature survey, the catalyst and
reactant quantities, reaction temperature, time, and solvents were investigated as optimiza-
tion factors. The optimization experiments are summarized in Table 1. The best result

JOURNAL OF SULFUR CHEMISTRY
7
Figure 5. EDS of CuFe2O4/Mg(OH)2 nanocomposite.
was obtained using styrene oxide (1 mmol) and thiourea (1 mmol) in the presence of
CuFe2O4/Mg(OH)2 (0.05 g, 0.17 mmol) in water at room temperature (Table 1, entry 4).
The use of catalytic amount of nanocomposite was necessary to perform the reaction, and
epoxide transformation did not proceed without catalyst even after 3 h (Table 1, entry 1).
Various amounts of CuFe2O4/Mg(OH)2 (0.03, 0.04 and 0.05 g) were applied, and the most
satisfying outcome was achieved using 0.05 g of catalyst (Table 1, entry 4). The enhance-
ment of catalyst quantity from 0.03 to 0.05 g not only accelerated the reaction rate, but
also increased the product yield effectively (Table 1, entries 2–4). More amounts of nano-
CuFe2O4/Mg(OH)2 did not improve the yield of product (Table 1, entry 5). The more
amounts of thiourea (2 and 3 mmol) were also examined in the conversion of styrene oxide
to styrene episulfide. The reaction time and product yield were similar to results obtained
using 1 mmol of thiourea (entries 6 and 7). The effect of solvent, was considered by com-
paring results from reactions carried out in water and other solvents such as acetonitrile,
chloroform, ethyl acetate and ethanol (Table 1, entries 8–11). Water as a green and eco-
friendly solvent was chosen as the best option for this transformation. Furthermore, H2O
with hydrogen bonding capability facilitates the ring opening of epoxides by nucleophilic
reagents in the presence of catalyst. In comparison with water, the reaction times were
longer and the product yields were lower in all other solvents. In addition, the model reac-
tion was also considered under solvent-free conditions. The reaction was not accomplished
in the absence of solvent even under grinding condition (Table 1, entries 12 and 13).
In order to study the influence of temperature on the reaction, the conversion of styrene
oxide to corresponding thiirane was carried out at different temperatures (Table 1, entries
14 and 15). Increasing the temperature and performing the reaction in refluxing water
raised the reaction rate but it did not significantly affect the product yield. In order to apply
mild conditions, room temperature was selected as the best option.

8
S. HASSANZADEH ET AL.
Scheme 3. Conversion of epoxides to thiiranes with thiourea catalyzed by CuFe2O4/Mg(OH)2 nanocom-
posite.
Table 1. Optimization experiments for conversion of styrene oxide to styrene episulfide with thiourea
a
catalyzed by nano-CuFe2O4/Mg(OH)2 .
NH2CSNH2
(mmol)
CuFe2O4/Mg(OH)2
(g)
Entry
Conditions
Time (h)
Conversion (%)b
Yield (%)c
1
2
3
4
5
6
7
8
1
1
1
1
1
2
3
1
1
1
1
1
1
1
1
1
1
–
H2O/r.t.
H2O/r.t.
H2O/r.t.
H2O/r.t.
H2O/r.t.
H2O/r.t
H2O/r.t
CH3CN /r.t.
CHCl3 /r.t.
EtOAc /r.t.
EtOH /r.t.
Solvent-free /r.t.
Solvent-free/r.t./grinding
Solvent-free/oil bath (75°C)
H2O/reflux
H2O/r.t.
H2O/r.t.
3
0
100
100
100
100
100
100
60
50
20
90
60
60
70
100
50
50
0
80
85
90
90
90
90
50
45
Trace
70
50
50
65
91
40
42
0.03
0.04
0.05
0.06
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
3.5
2.7
2.3
2.3
2.3
2.3
6
4.7
6
4
4
0.5
4
1
2.3
2.3
9
10
11
12
13
14
15
16d
17e
aAll reactions were carried out with 1 mmol of styrene oxide.
bConversion of less than 100% was determined on the basis of the recovered epoxide.
cIsolated yields.
dCatalysed by CuFe2O4.
eCatalysed by Mg(OH)2.
Conversion of styrene oxide to styrene episulfide was also investigated using bare
CuFe2O4 and Mg(OH)2 nanoparticles under the same reaction condition (entries 16
and 17). The reactions were not complete and results showed that the interactions
between the Mg(OH)2 and CuFe2O4 nanoparticles may increase the catalytic activity of
CuFe2O4/Mg(OH)2 composite.
The generality of the presented procedure in the preparation of thiiranes from epox-
ides was established by reaction of various epoxides bearing either electron-donating
or -withdrawing substituents, and cyclic epoxides with thiourea in the presence of
CuFe2O4/Mg(OH)2 nanocomposite under the optimized conditions. The results are sum-
marized in Table 2. All reactions were carried out successfully within 1–3.7 h to give
thiiranes in 70–99% yields.
2.3. Recycling of CuFe2O4/Mg(OH)2 nanocomposite
The recycling of the nanocatalyst was investigated under optimized reaction conditions
(Table 2, entry 1). The nanoparticles were easily collected using a simple magnet, washed

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9
a
Table 2. Conversion of epoxides to thiiranes with thiourea catalyzed by nano-CuFe2O4/Mg(OH)2 .
Entry
1
Epoxide (a)
thiiranes (b)
Time (h)
2.3
Yield (%)b
Ref.
[51]
90
2
3
4
5
2.2
3.7
3.5
3.2
88
99
95
90
[51]
[51]
[34]
[51]
6
7
8
3.7
1
98
80
75
[34]
[51]
[51]
1.5
9
2.1
2
91
75
[34]
[34]
10
11
3
82
[51]
12
13
2.5
2
90
75
[34]
[51]
14
15
2
70
79
[51]
[51]
2.1
aAll reactions were carried out with 1 mmol of epoxide in the presence of thiourea (1 mmol) and nano-CuFe2O4/Mg(OH)2
(0.05 g) in water at room temperature.
bYields refer to isolated pure products.
with distilled water and after drying reused under the same reaction conditions. In order to
have a logical comparison, the reaction time was kept constant in all cycles. The obtained
results showed that the nanocatalyst could be recycled four times without significant

10
S. HASSANZADEH ET AL.
Figure 6. Recycling of CuFe2O4/Mg(OH)2 nanocatalyst in the conversion of styrene oxide to styrene
episulfide.
activity loss, and even after five runs the yields remained still high (Figure 6). The slowly
decreasing activity in five consecutive cycles, might be attributed to the slight loss of catalyst
during the reaction and recovery processes.
The hot filtration test was used for confirming the heterogeneity of as-prepared catalyst.
Accordingly, the filtration of the catalyst was carried out after 30 min at 100°C and the
filtrate was allowed to react for additional 2 hours, but the reaction due to the absence of
catalyst did not take place, and no transformation was observed. Further, the extent of Cu,
Fe and Mg leaching during the catalytic reaction was studied by ICP-OES analysis of the
supernatant liquid after removal of catalyst and the result showed no presence of Cu, Fe or
Mg in supernatant liquid.
2.4. Proposed mechanism for conversion of epoxides to thiiranes with thiourea
catalyzed by CuFe2O4@Mg(OH)2 nanocomposite
The exact mechanism of this transformation is not clear at present. However, a possible
mechanism is shown in Scheme 4. The immobilized Mg(OH)2 shell on the surface of
CuFe2O4 reduced the self-aggregation tendency of copper ferrite nanoparticles and also
increased the quantity of hydroxyl functional groups on the catalyst surface which led to
an enhancement of its activity. The hydroxyl groups facilitate the ring opening of oxirane
through the formation of hydrogen bonds with oxygen. On the other hand, the coordina-
tion of oxygen in epoxide with copper and magnesium also catalyzes the opening of the
oxirane ring especially in water as a protic and polar solvent.
2.5. Comparison of catalytic activities of CuFe2O4/Mg(OH)2 and other catalysts
The advantages of the presented method were demonstrated by comparison of styrene
oxide transformation to styrene episulfide with other methods reported in the literature
(Table 3). Our procedure due to the mild and eco-friendly conditions such as recoverabil-
ity and reusability, easy preparation and separation of magnetic nanocatalyst, performing
the reaction at low temperature, and the use of water as a green solvent is preferred. The

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11
Scheme 4. Proposed mechanism for conversion of epoxides to thiiranes with thiourea catalyzed by
nano-CuFe2O4/Mg(OH)2
proposed procedure was also compared to other literature methods in terms of reaction
time and yield of products, and it showed a more or comparable efficiency towards the
other protocols.
Comparison of the catalytic effects of bare CuFe2O4 and CuFe2O4/Mg(OH)2 nanocom-
posite indicated that the properties of the coated copper nanoferrite were amazingly
different from the CuFe2O4 particles (Table 3, entries 1 and 7). The new synthesized
CuFe2O4/Mg(OH)2 nanocomposite takes advantage of both magnetic core and function-
alized surface, which make the present procedure more efficient than the other methods
that use the bare nanoferrites. Conversion of styrene oxide to styrene episulfide was not
accomplished using CuFe2O4 catalyst in water at room temperature even after long times
[50], while CuFe2O4/Mg(OH)2 nanocomposite easily catalyzed this reaction in water
under mild conditions. The eco-friendly solvent and low temperature are very impor-
tant factors in organic synthesis. On the other hand, the bare CuFe2O4 particles often
suffer from agglomeration problem. So, minimizing the aggregation of nanoparticles was
the other remarkable advantage of CuFe2O4/Mg(OH)2 nanocomposite, which increased
the dispersibility of nanoparticles and facilitated the recovering and recycling of cata-
lyst. In addition, the presence of large amounts of hydroxyl groups on the surface of

12
S. HASSANZADEH ET AL.
Table 3. Comparison of the conversion of styrene oxide to styrene episulfide catalyzed by
CuFe2O4/Mg(OH)2 and other reported methodsa.
Entry
Reagent
Catalyst
Condition
Time (min)
Yield (%)b
Ref.
1
2
3
4
5
6
7
8
NH2CSNH2
NH2CSNH2
NH2CSNH2
NH2CSNH2
NH2CSNH2
NH2CSNH2
NH2CSNH2
NH4SCN
NH4SCN
KSCN
KSCN
KSCN
CuFe2O4/Mg(OH)2
Ps-AlCl3
Mg(HSO4)2
SnIV(tpp)(OTf)2
SnIV(tpp)(BF4)2
SiO2-AlCl3
Nano CuFe2O4
Nano NiFe2O4
Nano MgFe2O4
InCl3
H2O/r.t.
138
90
150
60
50
84
40
20
25
270
300
150
15
90
85
80
98
98
85
92
94
92
89
89
87
65
This work
[37]
[13]
[21]
[22]
[55]
[50]
[51]
[51]
[15]
[34]
[56]
[6]
CH3CN/reflux
CH3CN/reflux
CH3CN/reflux
CH3CN/reflux
CH3CN/45°C
EtOH/reflux
Solvent-free/oil bath 60°C
Solvent-free/oil bath 60°C
CH3CN/reflux
H2O/r.t.
H2O/r.t.
Solvent-free/120°C
9
10
11
12
13
[bmim]BF4·H2O
BTPBDC
NH2CSNH2
–
aAll reactions were carried out using 1 mmol of styrene oxide.
bYields refer to isolated pure products.
nanocomposite increased the catalytic activity through hydrogen bond formation with
oxygen atom of oxirane which helps to the ring opening of epoxide.
3. Conclusions
In summary, in this research, we have reported the synthesis and characterization of
CuFe2O4/Mg(OH)2 nanocomposite and evaluated its potential as a novel and green mag-
netic nanocatalyst in the conversion of structurally different epoxides to corresponding
thiiranes with thiourea in water at room temperature. The recoverability, reusability and
simple separation of magnetic catalyst from the reaction mixture, low temperature, short
reaction times, high to excellent product yields, the use of green solvent, and easy work-up
are among the remarkable advantageous of the presented method.
4. Experimental
4.1. Instruments and materials
All materials were purchased from the Merck and Aldrich Chemical Companies with
the best quality and they were used without further purification. The synthesized
nanocomposite was characterized by XRD on a Bruker D8-Advanced diffractometer with
graphite-monochromatized Cu Kα radiation (λ = 1.54056 Å) at room temperature. Mag-
netic property of synthesized nanocatalyst was measured using a VSM (Meghnatis Daghigh
Kavir Co., Kashan Kavir, Iran) at room temperature. The energy dispersive X-ray spec-
trometer (EDS) analysis was taken on a MIRA3 FE-SEM microscope (TESCAN, Czech
Republic) equipped with an EDS detector (Oxford Instruments, UK). SEM images were
1
determined using FESEM-TESCAN. IR and H/13C NMR spectra were recorded on
Thermo Nicolet Nexus 670 FT-IR and 300 MHz Bruker Avance spectrometers, respec-
tively. The products were characterized by their spectra and comparison with the authentic
data in the literature. All yields refer to isolated pure products.

JOURNAL OF SULFUR CHEMISTRY
13
4.2. Preparation of CuFe2O4 nanoparticles
CuFe2O4 nanoparticles were synthesized through a solid-state method. Briefly, in an agate
mortar, CuSO4, Fe(NO3)3·9H2O, NaOH, and NaCl were mixed in a molar ratio (1:2:8:2)
and ground together for 50 min. The exothermic reaction started and was accompanied by
changing the color of pasty mixture from blue to brown after 4 min. The obtained mixture
was washed with distilled water for several times and then was dried at 80°C for 2 h. In order
to remove the additional salts completely, the generated powder was calcined at 900°C for
2 h to give the final CuFe2O4 nano-ferrite.
4.3. Synthesis of CuFe2O4/Mg(OH)2 nanocomposite
To a solution of Mg(NO3)2·6H2O (1.28 g, 5 mmol) in distilled water (30 mL), CuFe2O4
(1.03 g, 4.3 mmol) was added. The mixture was stirred vigorously for 15 min at room tem-
perature. Next, the resulting mixture was slowly basified by dropping of NaOH solution
(2 M) up to pH∼12. The stirring of the mixture was continued at room temperature for
24 h. The dark brown CuFe2O4/Mg(OH)2 nanoparticles were separated using a magnet,
washed with distilled water and then dried under air atmosphere during 2 days.
4.4. Conversion of epoxides to thiiranes using thiourea catalyzed by
CuFe2O4/Mg(OH)2 nanocomposite: a general procedure
In a round-bottomed flask equipped with a magnetic stirrer, a mixture of epoxide (1 mmol),
thiourea (0.47 g, 3 mmol) and CuFe2O4/Mg(OH)2 nanoparticles (0.05 g, 0.17 mmol) in
H2O (2 mL) was prepared and stirred at room temperature for 1−3.5 h. The progress
of the reaction was monitored by TLC using n-hexane: EtOAc (10:4) as an eluent.
After completion of the reaction, CuFe2O4/Mg(OH)2 nanoparticles were recovered
with an external magnet, washed with ethyl acetate, and used for subsequent cycles
after drying under vacuum. The reaction mixture was extracted by CH2Cl2 (3 × 5 mL)
and then dried over anhydrous Na2SO4. The organic solvent was evaporated to give
crude thiirane for further purification by a short-column chromatography over silica
gel (70–99% yield) (Table 2). All products are known compounds and were charac-
1
terized by comparison of their spectra ((FT-IR, H NMR and 13C NMR)) with those
of valid samples; [34,51] these data are presented in the supplementary information
(http://dx.doi.org/10.1080/17415993.2019.1567728).
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
The financial support of this work was gratefully acknowledged by the Research Council of Payame
Noor University.
ORCID
Ronak Eisavi http://orcid.org/0000-0003-2851-9536

14
S. HASSANZADEH ET AL.
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