Magnetically nano core–shell Fe3O4@Cu(OH)x: a highly efficient and reusable catalyst for rapid and green reduction of nitro compounds

Article abstract of DOI:10.1007/s13738-016-0962-3

Magnetically separable nano core–shell Fe₃O₄@Cu(OH)_x with 22?% Cu content was prepared by the addition of sodium hydroxide to a mixture of CuCl₂·2H₂O and nano Fe₃O₄ in water. Characterization of the impregnated copper hydroxide was carried out by X-ray fluorescence (XRF), X-ray diffraction (XRD) atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM), value stream mapping (VSM) and Brunauer–Emmett–Teller (BET) analysis. The core–shell nanocatalyst exhibited the excellent catalytic activity toward reduction of various nitro compounds to the corresponding amines with NaBH₄. All reactions were carried out in H₂O (55–60?°C) within 3–15?min to afford amines in high to excellent yields. Reusability of core–shell Cu(OH)_x catalyst was examined 9?times without significant loss of its catalytic activity.

Full text of DOI:10.1007/s13738-016-0962-3

J IRAN CHEM SOC
DOI 10.1007/s13738-016-0962-3
ORIGINAL PAPER
Magnetically nano core–shell Fe3O4@Cu(OH)x: a highly efficient
and reusable catalyst for rapid and green reduction of nitro
compounds
Zahra Shokri1 · Behzad Zeynizadeh1 · Seyed Ali Hosseini1 · Behrooz Azizi1
Received: 3 April 2016 / Accepted: 11 August 2016
© Iranian Chemical Society 2016
Abstract Magnetically separable nano core–shell Fe3O4@
Cu(OH)x with 22 % Cu content was prepared by the addi-
tion of sodium hydroxide to a mixture of CuCl2·2H2O and
nano Fe3O4 in water. Characterization of the impregnated
copper hydroxide was carried out by X-ray fluorescence
(XRF), X-ray diffraction (XRD) atomic absorption spec-
troscopy (AAS), scanning electron microscopy (SEM),
value stream mapping (VSM) and Brunauer–Emmett–
Teller (BET) analysis. The core–shell nanocatalyst exhib-
ited the excellent catalytic activity toward reduction of
various nitro compounds to the corresponding amines with
NaBH4. All reactions were carried out in H2O (55–60 °C)
within 3–15 min to afford amines in high to excellent
yields. Reusability of core–shell Cu(OH)x catalyst was
examined 9 times without significant loss of its catalytic
activity.
industrial purposes. Metal oxides [7], zeolites [8], hydrotal-
cites [9] ion-exchange resins [10], solid supports [11] and
polyoxometalates [12–14] are the kinds of heterogeneous
catalysts which are commonly used for functional group
transformations.
Recently, the design and synthesis of core–shell nano-
particles, because of their potential abilities to catalyze
organic reactions, has more attracted [15, 16]. The core–
shell composites containing the core of Fe3O4 are robust
and air-stable, and they can be separated by an external
magnet leading to avoid traditional filtration processes [17].
It has also demonstrated that nanostructural iron catalysts
are close in catalytic activity to the corresponding homo-
geneous catalysts. A literature review shows that impreg-
nation of different metallic salts such as TiO2 [18], MnO2
[19], Fe(OH)3 [20], Co(NO3)2 [21], Cu(OH)x [22, 23],
Ru(OH)x [24], Pd [25, 26], Pt [27] and Rh(III)-metallopor-
phyrin [28] has been carried out on nanomagnetic Fe3O4.
However, their applications in organic synthesis have quite
limited.
Keywords Amine · Fe3O4@Cu(OH)x · NaBH4 ·
Nanomagnetic · Nitro · Reduction
Reduction of nitroarenes to arylamines is one of the
most important organic transformations, since arylamines
are versatile intermediates and precursors in the prepara-
tion of dyes, pharmaceuticals, pigments, agrochemicals and
polymers [29–32]. This process is complicated when the
reduction of nitro group leads to the formation of hydroxy-
lamine or hydrazine as a side product [33, 34]. Therefore,
a complete reduction of nitro group to amine is a subject
of interest and various reducing agents and protocols have
been introduced for this achievement [35–38]. It is known
that the alone NaBH4 does not reduce nitro compounds
under ordinary conditions. However, the reducing power of
this reagent undergoes a drastic change toward the reduc-
tion of nitro groups by a combination with metal halides
or salts [39]. Although most of the reported protocols are
Introduction
Heterogeneous catalysis has become a sustainable and
powerful tool for a great variety of organic transformations
[1–6]. In homogeneous catalysis, however, the reagents/
catalysts are often expensive and difficult to easily remove
from the mixture of reactions. Therefore, their applica-
tions encounter with some rustications in academic and
* Behzad Zeynizadeh
bzeynizadeh@gmail.com
1
Faculty of Chemistry, Urmia University, Urmia 5756151818,
Iran
1 3

J IRAN CHEM SOC
NaBH4/Fe3O4@Cu(OH)x
H2O, 55-60 oC
RNO2
RNH2
R: Ar, alkyl
Scheme 1 Reduction of nitro compounds with NaBH4/nano Fe3O4@
Cu(OH)x system
Scheme 2 Synthesis of nanomagnetic Fe3O4
efficient and provide a useful synthetic method, however,
they generally suffers from the prolonged reaction times,
using expensive organic solvents, formation of side prod-
ucts and inability to reuse the applied catalyst.
In line with the outlined strategies, herein, we wish to
introduce nanomagnetic core–shell Fe3O4@Cu(OH)x with
22 % Cu content as a highly efficient and reusable cata-
lyst for NaBH4 reduction of nitro compounds to amines in
water as an easily available and eco-friendly safe solvent
(Scheme 1).
The morphology and size distribution of the pre-
pared core–shell Fe3O4@Cu(OH)x was then inves-
tigated by scanning electron microscopy. The SEM
image indicates that the catalyst is as granule nano-
particles with the size distribution ranged from 13 to
30 nm. The SEM approved the nanostructure of the
catalyst. The particles are agglomerated to some extent
(Fig. 1).
The composition percentage of Cu in nano Fe3O4@
Cu(OH)x NPs was then determined by atomic absorp-
tion (AAS) and X-ray fluorescence (XRF) analyses. Both
techniques exhibited that the Cu content in nanocatalyst
was 22 %. Characterization of the core–shell nanocatalyst
was more carried out by X-ray diffraction (XRD) analy-
sis. The XRD patterns of superparamagnetic Fe3O4 and
Fe3O4@Cu(OH)x NPs are shown in Fig. 2. In XRD pattern
of Fe3O4, the peaks at 30.2°, 35.5°, 43.3°, 53.7°, 57.2° and
62.9° are attributed to the (220), (311), (400), (422), (511)
and (440) crystal planes of a pure Fe3O4 with a spinal struc-
ture (JCPDS card no. 65-3107) [45, 46]. These peaks are
corresponded to a cubic unit cell, characteristic of a cubic
spinel structure. In the case of XRD pattern of Fe3O4@
Cu(OH)2, all the peaks of Fe3O4 are observed. The peaks at
16.5°, 23.6°, 34°, 38°, 39.6°, 54.1°, 62.9°, 63.5°, 67.3° and
72.4° are corresponded to orthorhombic copper hydroxide
which is in good agreement with standard card of JCPDS
No. (35-0505) [47]. The peaks at 35.8° and 53.06° for cop-
per hydroxide overlap with the 35.5° and 53.7° peaks of
Fe3O4.
The plots of magnetization versus applied magnetic field
(VSM) for Fe3O4 and Fe3O4@Cu(OH)x NPs were also
illustrated in Fig. 3. The plots show that these two kind of
nanoparticles exhibited superparamagnetism and no obvi-
ous remanence or coercivity was recorded when the applied
magnetic field was removed. The magnetization saturation
(MS) values of Fe3O4 and Fe3O4@Cu(OH)x were 66.976
and 39.891 emu g−1, respectively. The high magnetiza-
tion represents the fast responsivity of the nanocatalysts in
the magnetic separation. After the coating process, the Ms
value of the nano Fe3O4 was reduced clearly which indi-
cates the coating of copper hydroxide layer. By comparing
the Ms values before and after coating of Cu(OH)x, the Cu
content in nano Fe3O4@Cu(OH)x was estimated to be 27 %
[48].
Results and discussions
Synthesis and characterizations of nano core–shell iron
oxide@copper hydroxide
Nowadays, nanoparticles (NPs) exhibit high catalytic activ-
ity and chemical selectivity under mild conditions. The
extreme small-sized particles maximize the surface area
and allow more reactions to occur at the same time. In this
context, nanomagnetic Fe3O4 due to nanosized particles,
high reactivity, magnetic specification and reusability has
been found in some useful applications in organic synthe-
sis [17]. The literature review shows that though the syn-
thesis and application of impregnated copper hydroxide,
Cu(OH)x, on nanomagnetic Fe3O4 with 1.37–1.62 % Cu
content have been reported for addition of alkoxy diboranes
to alkenes [22] and preparation of propargylamines [23],
however, synthesis of this type of nanocatalyst with 22 %
Cu content as well as its application in organic transfor-
mations has not been investigated yet. These subjects and
continuation of our research program directed to NaBH4
reduction of nitro compounds to amines [39–44] prompted
us to prepare nano core–shell Fe3O4@Cu(OH)x with 22 %
Cu content. In addition, we encouraged to investigate the
catalytic activity and reusability of the prepared NPs to the
titled transformation under green reaction conditions.
Synthesis of Fe3O4@Cu(OH)x NPs with 22 % Cu con-
tent was carried out in a two step procedure: 1) prepara-
tion of nanomagnetic Fe3O4 by a chemical co-precipita-
tion of FeCl3·6H2O and FeCl2·4H2O in aqueous ammonia
(Scheme 2) and 2) addition of nano Fe3O4 to aqueous solu-
tion of CuCl2·2H2O followed by alkali-making (pH ~ 13)
the resulting suspension with NaOH (Scheme 3).
1 3

J IRAN CHEM SOC
Scheme 3 Synthesis of nanomagnetic Fe3O4@Cu(OH)x
Fig. 2 XRD patterns of a Fe3O4 and b Fe3O4@Cu(OH)x NPs
Fig. 1 SEM image of nano Fe3O4@Cu(OH)x
Brunauer–Emmett–Teller (BET)
Nitrogen sorption was used to study the pore prop-
erties of the synthesized microspheres. The calcu-
lated specific surface area using the BET for Fe3O4@
Cu(OH)x NPs was 68.059 m2 g−1. The pore volume was
0.349 cm3 g−1 (Fig. 4). The corresponding pore size
distributions of the nanocatalyst were determined to be
20.559 nm using the Barrett–Joyner–Halenda (BJH),
indicating that nano Fe3O4@Cu(OH)x is mesoporous
(2 < Dv < 50 nm).
Fig. 3 Hysteresis loops of nano a Fe3O4 and b Fe3O4@Cu(OH)x
1 3

J IRAN CHEM SOC
efficient. However, using H2O as the sole solvent dramati-
cally accelerated the rate of reduction (entries 3–5). These
observations revealed that H2O was the best solvent of
choice, and the molar equivalents of 1:2:0.06 for PhNO2,
NaBH4 and Fe3O4@Cu(OH)x were the requirements to
complete reduction of nitrobenzene. Subsequently, aniline
was obtained as a sole product within 3 min at 55–60 °C
(Table 1, entry 5). The scope and generality of this syn-
thetic protocol was then studied with the reduction of vari-
ous aromatic nitro compounds at the optimized conditions
(Table 2).
The summarized results in Table 2 show that reduction
of nitroarenes having electron-releasing or withdrawing
functionalities was carried out successfully using 2–3 molar
equivalents of NaBH4 and 6–15 mol % Fe3O4@Cu(OH)x
within 3–12 min (H2O, 55–60 °C) (entries 1–15). It is also
noteworthy that in the case of nitroarenes containing formyl
group, both of nitro and formyl groups were reduced with
the same reactivity. Subsequently, higher molar equiva-
lents of NaBH4 and the nanocatalyst were required to com-
plete reduction of nitroaldehydes to their amino alcohols
(Table 2, entries 16–18). In the case of nitro compounds
containing ketone functionality, a perfect chemoselectivity
was observed when the controlled amounts of NaBH4 were
supplied in reduction reactions: with the molar equivalents
of 2:0.2 for NaBH4/nano Fe3O4@Cu(OH)x, the reduction
of nitro group was carried out in a perfect selectivity. How-
ever, the successful reduction of both functional groups can
be obtained when four molar equivalents of NaBH4 were
used in reduction reactions (entries 19–22). It means that
the current protocol reduces nitro groups in high reactiv-
ity and chemoselectivity versus ketone functionality.
However, this chemoselectivity between nitro and formyl
Fig. 4 BET-plot for Fe3O4@Cu(OH)x NPs (adsorption temperature
77 [K])
Reduction of nitro compounds with NaBH4/Nano
Fe3O4@Cu(OH)x system
After synthesis and characterization of Fe3O4@Cu(OH)x
NPs, we turned our attention to study the influence of nano-
catalyst on reducing capability of NaBH4 toward the reduc-
tion of nitro compounds. In order to optimize reaction con-
ditions, reduction of nitrobenzene with NaBH4 as a model
reaction was examined under different reaction conditions.
The illustrated results in Table 1 shows that reduction
of nitrobenzene with NaBH4 in the presence of Fe3O4@
Cu(OH)x NPs in protic and aprotic solvents was not
Table 1 Optimization experiments for reduction of nitrobenzene to aniline with NaBH4/nano Fe3O4@Cu(OH)x system under different condi-
tions
Entry
NaBH4 (mmol)
Fe3O4@Cu(OH)x (mmol)
Solvent (mL)
Condition
Time (min)
Conversion (%)
1
2
–
2
2
2
2
2
2
2
2
2
2
2
–
H2O
55–60 °C
55–60 °C
rt
300
300
40
30
10
90
95
95
50
75
50
75
0
2
1
H2O
3
0.5
0.1
0.06
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
H2O
4
H2O
55–60 °C
55–60 °C
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
3
5
H2O
3
6
MeOH
MeOH–H2O
EtOH
120
120
120
120
120
120
120
120
7
8
9
EtOH–H2O
CH3CN
CH3CN–H2O
THF
10
11
12
13
50
50
75
THF–H2O
All reactions were carried out with 1 mmol of nitrobenzene in 3 mL solvent
1 3

J IRAN CHEM SOC
Table 2 Reduction of nitro compounds with NaBH4/nano Fe3O4@Cu(OH)x system
Molar ratio
Time Yield
Entry
1
Substrate
NO2
Product
NH2
subs./NaBH4/cat . (min) (%)a
1:2:0.06
1:2:0.06
3
4
95
92
H2N
NO2
H2N
NH2
2
3
NO2
NH2
1:2:0.1
1:2:0.1
5
94
91
H2N
H2N
NO2
NH2
NH2
NH2
4
5
NO2
NH2
5
6
7
1:2:0.1
1:2:0.06
1:2:0.06
6
4
6
93
91
91
HOH2C
HOCH2
HOH2C
HOCH2
NO2
NH2
NO2
NH2
CH2OH
CH2OH
NO2
OH
NH2
OH
8
9
1:3:0.1
1:3:0.15
1:2:0.06
5
12
6
91
89
95
NO2
NH2
NHNH2
NHNH2
NO2
CH3
NH2
CH3
10
NO2
NH2
11
12
13
1:2:0.06
1:2:0.06
1:2:0.06
5
4
4
95
94
93
H3C
H3C
H3C
H3C
NO2
NH2
NO2
CH3
CH3
NO2
CH3
NH2
CH3
CH3
NH2
CH3
H3C
H3C
14
1:2:0.06
1:2:0.06
1:4:0.2
7
7
93
95
91
H3C
H3C
H3C
H3C
NO2
NO2
NH2
15
16
NH2
15
HOH2C
OHC
1 3

J IRAN CHEM SOC
Table 2 continued
OHC
NO2
HOH2C
HOH2C
NH2
1:3.5:0.15
1:3.5:0.15
12
12
93
92
17
18
Cl
Cl
NH2
NO2
OHC
CH(OH)CH3
COCH3
COCH3
COCH3
1:4:0.2
1:2:0.2
12
12
94
94
19
20
H2N
O2N
O2N
H2N
O2N
COCH3
COCH3
NO2
H2N
CH(OH)CH3
COCH3
NH2
1:4:0.2
1:2:0.2
15
12
89
94
21
22
O2N
H2N
1:3.5:0.2
12
92
23
O2N
H2N
24
25
1-Nitrohexane
2-Nitroheptane
1-Hexylamine
1:2:0.2
1:2:0.2
8
8
89
91
2-Aminoheptane
All reactions were carried out in H2O (3 mL, 55–60 °C)
a
Yields refer to isolated pure products
functionality cannot accessible. A more examination exhib-
ited that the present method was also efficient for reduc-
tion of dinitro compounds using the molar equivalents of
3.5:0.2 for NaBH4/nano Fe3O4@Cu(OH)x system in H2O
(Table 2, entry 23).
The reducing capability of NaBH4/nano Fe3O4@
Cu(OH)x system toward reduction of aliphatic nitro com-
pounds was also studied by the reduction of 1-nitrohexane
and 2-nitroheptane with 2:0.02 molar equivalents of NaBH4
and Fe3O4@Cu(OH)x NPs in H2O at 55–60 °C. The results
showed that as aromatic nitro compounds, this protocol was
also efficient and the corresponding aliphatic amines were
obtained successfully in 90–94 % yields within 10–15 min
(Table 2, entries 24 and 25).
Fig. 5 Separation of Fe3O4@Cu(OH)x NPs by external magnet
For practical purposes, the ability to easy recycle the cat-
alyst is highly desirable. To investigate this issue, the reus-
ability of Fe3O4@Cu(OH)x NPs was examined in NaBH4
reduction of nitrobenzene. The obtained results exhibited
that the nanocatalyst has remarkable reusability. After com-
pletion of the reaction, the nanocatalyst was separated from
the reaction by an external magnet (Fig. 5). The core–shell
nanocatalyst was then washed with diethyl ether to remove
residual contaminants. The vessel of reaction was again
charged with fresh nitrobenzene, NaBH4 and water to run
the reduction reaction for a second time. The examina-
tions showed that the nanocatalyst can be reused severally
without significant loss of its catalytic activity (Fig. 6).
1 3

J IRAN CHEM SOC
of its catalytic activity. Remarkable reusability and easy
separation of the nanocatalyst, high yields and mild reac-
tion conditions as well as the benefits of using water as a
green solvent are the advantages which make this protocol
a perfect choice for reduction of nitro compounds.
Experimental
General
Fig. 6 Reduction of nitrobenzene with NaBH4/recycled nano
Fe3O4@Cu(OH)x system
All reagents and substrates were purchased from commercial
sources in high purity, and they were used without further
purification. 1H, 13C NMR and FT-IR spectra were recorded
on Bruker Avance 300 MHz and Thermo Nicolet Nexus 670
spectrometers. The products are known, and they were char-
acterized by their 1H, 13C NMR and FT-IR spectra followed
by comparison with authentic data. TLC was applied for the
purity determination of substrates, products and reaction
monitoring over silica gel 60 F254 aluminum sheet. X-ray
diffraction (XRD) measurements were performed with a
X’PertPro. The X-ray wavelength was 1.54 Å, and the dif-
fraction patterns were recorded in the 2θ range (10°–80°).
The particle morphology was examined by measuring SEM
using FESEM-TESCAN MIRA3. Magnetic properties of
the samples were measured using a vibration sample mag-
netometer (VSM, model MDKFT) under magnetic fields up
to 20 kOe. The N2 adsorption–desorption isotherms were
tested on Belsorp-max, BEL Japan. The specific surface area
of samples was determined using the Brunauer–Emmett–
Teller (BET) method. The pore volume and pore size dis-
tribution were derived from the desorption profiles of the
isotherms using the Barrett–Joyner–Halanda (BJH) method.
The elemental analysis of the nanocatalyst was carried out
by atomic adsorption spectroscopy (Shimadzu AA670) and
X-ray fluorescence (Philips 2404, Holland).
Although we reused the nanocatalyst for nine reduction
cycles, however, we believe that due to fantastic catalytic
activity of the core–shell nanocatalyst, it can be reused
for too much reduction cycles of nitrobenzene and conse-
quently other nitro compounds.
The usefulness and capability of NaBH4/nano Fe3O4@
Cu(OH)x system in reduction of nitroarenes were high-
lighted by comparison of the obtained result for nitroben-
zene with other reported systems (Table 3). A case study
shows that in viewpoints of reusability of the nanocatalyst,
amounts of reducing agent, reaction time and yield of the
product, the present protocol shows a more or comparable
efficiency than the other systems.
Conclusions
In this paper, the impregnation of copper hydroxide on
nanomagnetic Fe3O4 with 22 % Cu content was carried out
successfully. The prepared nano Fe3O4@Cu(OH)x was then
characterized with XRD, XRF, AAS, VSM, SEM and BET
analyses. The core–shell nanocatalyst exhibited the excel-
lent catalytic activity and reusability in NaBH4 reduction
of various nitro compounds. All reactions were carried out
in water (55–60 °C) within 3–15 min to afford amines in
high to excellent yields. In addition, the nanocatalyst can
be reused for nine catalytic cycles without significant loss
Preparation of nanomagnetic Fe3O4
Magnetically nano Fe3O4 was prepared by chemical co-
precipitation of chloride salts of Fe3+ and Fe2+ [53, 54].
Table 3 Comparison of the reduction of nitrobenzene with NaBH4/nano Fe3O4@Cu(OH)x and other reported systems
Entry
Catalyst
Reductant
Time (min)
Yield (%)
Condition
Reusability (times)
Refs.
1
2
3
4
5
6
Fe3O4@Cu(OH)x (20 mg)
Fe3O4@Ni (33 mg)
Fe3O4@Ni (50 mg)
Nano Ni (11 mg)
NaBH4 (2 mmol)
3
25
95
95
94
99
50
96
55–60 °C
9
30
8
*
NaBH4 (4 mmol)
rt
[49]
[50]
[51]
[51]
[52]
Glycerol/KOH (2 mmol)
N2H4·2H2O (0.2 mL)
N2H4·2H2O (0.2 mL)
Formic acid (3.5 mmol)
180
75
80 °C
rt
5
Nano Co (11 mg)
300
15 h
rt
5
Co3O4–NGr/C (20 mg)
100 °C
6
* Current protocol
1 3

J IRAN CHEM SOC
Typically, in a two-neck round-bottom flask, a solution
of FeCl3·6H2O (5.838 g, 0.0216 mol) and FeCl2·4H2O
(2.147 g, 0.0108 mol) in distilled water (100 mL) was
prepared. The solution was stirred vigorously by mechan-
ical stirrer at 85 °C under N2 atmosphere for 10 min.
Aqueous NH4OH (25 %, 10 mL) was quickly added
in one portion to the prepared solution of iron salts at
85 °C. Upon the addition, the black Fe3O4 nanoparticles
were immediately precipitated. The resulting mixture
was continued to stirring at 85 °C for 30 min followed by
cooling to the room temperature. The nanoparticles were
then separated from the reaction mixture (by an external
magnet) and washed doubly with distilled water followed
by a solution of NaCl (0.02 M). Drying under air atmos-
phere affords the pure nanomagnetic Fe3O4 (size of nano-
particles: 13–30 nm).
References
1. S.M. George, Chem. Rev. 95, 475 (1995)
2. H. Hattori, Chem. Rev. 95, 537 (1995)
3. M. Boudart, Chem. Rev. 95, 661 (1995)
4. N. Mizuno, M. Misono, Chem. Rev. 98, 199 (1998)
5. M. Heitbaum, F. Glorius, I. Escher, Angew. Chem. Int. Ed. Engl.
45, 4732 (2006)
6. A. Corma, H. Garcia, F.X. Llabres i Xamena, Chem. Rev. 110,
4606 (2010)
7. M.B. Gawande, R.K. Pandey, R.V. Jayaram, Catal. Sci. Technol.
2, 1113 (2012)
8. A. Corma, J. Catal. 216, 298 (2003)
9. M.R. Othman, Z. Helwani, Martunus, W.J.N. Fernando, Appl.
Organomet. Chem. 23, 335 (2009)
10. G. Gelbard, Ind. Eng. Chem. Res. 44, 8468 (2005)
11. K. Smith, Solid Supports and Catalysts in Organic Synthesis
(Ellis Horwood, New York, 1992)
12. D.E. Katsoulis, Chem. Rev. 98, 359 (1998)
13. M. Ammam, J. Mater. Chem. A 1, 6291 (2013)
14. Y. Ren, M. Wang, X. Chen, B. Yue, H. He, Materials 8, 1545
(2015)
Synthesis of Fe3O4@Cu(OH)x NPs with 22 % Cu content
15. K. Bakhmutsky, N.L. Wieder, M. Cargnello, B. Galloway, P. For-
nasiero, R.J. Gorte, Chem. Sus. Chem. 5, 140 (2012)
16. R.G. Chaudhuri, S. Paria, Chem. Rev. 112, 2373 (2012)
17. V. Polshettiwar, R. Luque, A. Fihri, H. Zhu, M. Bouhrara, J.-M.
Basset, Chem. Rev. 111, 3036 (2011)
To a solution of CuCl2·2H2O (0.852 g, 5 mmol) in distilled
water (30 mL), nano Fe3O4 (1 g, 4.31 mmol) was added
and the mixture was vigorously stirred for 10 min at room
temperature. The mixture was then slowly basified with
NaOH (1 M) up to pH ~ 13. The resulting basified mix-
ture was stirred at room temperature for 24 h, and then the
nanoparticles were separated from the reaction mixture via
magnetic decantation. Collected Fe3O4@Cu(OH)x NPs was
washed with distilled water and then dried under air atmos-
phere within 2 days. Atomic absorption and X-ray fluores-
cence analyses resulted 22 % Cu content for the prepared
nanocatalyst.
18. S. Xuan, W. Jiang, X. Gong, Y. Hu, Z. Chen, J. Phys. Chem. C
113, 553 (2009)
19. Z. Shu, S. Wang, J. Nanomater. (2009), ID 340217 http://dx.doi.
org/10.1155/2009/340217
20. F. Niu, L. Zhang, S.-Z. Luo, W.-G. Song, Chem. Commun. 46,
1109 (2010)
21. A. Uheida, G. Salazar-Alvarez, E. Björkman, Z. Yu, M.
Muhammed, J. Colloid Interface Sci. 298, 501 (2006)
22. R. Cano, D.J. Ramón, M. Yus, J. Org. Chem. 75, 3458 (2010)
23. M.J. Aliaga, D.J. Ramón, M. Yus, Org. Biomol. Chem. 8, 43
(2010)
24. M. Kotani, T. Koike, K. Yamaguchi, N. Mizuno, Green Chem. 8,
735 (2006)
25. K.V. Ranganath, J. Kloesges, A.H. Schäfer, F. Glorius, Angew.
A typical procedure for reduction of nitrobenzene to aniline
with NaBH4/Nano Fe3O4@Cu(OH)x system
Chem. Int. Ed. Engl. 49, 7786 (2010)
26. J. Liu, X. Peng, W. Sun, Y. Zhao, C. Xia, Org. Lett. 10, 3933
(2008)
27. M. Ma, J. Xie, Y. Zhang, Z. Chen, N. Gu, Mater. Lett. 105, 36
(2013)
In a round-bottom flask (10 mL) equipped with a mag-
netic stirrer, a mixture of nitrobenzene (0.123 g, 1 mmol)
and H2O (3 mL) was prepared. Nano Fe3O4@Cu(OH)x
(20 mg, 0.06 mmol, x = 2) was then added, and the result-
ing mixture was stirred for 5 min. Next, NaBH4 (0.076 g,
2 mmol) was added and the reaction mixture was contin-
ued to stirring for 3 min at 55–60 °C. TLC monitored the
progress of the reaction (eluent, n-hexane/EtOAc: 5/2).
After completion of the reaction, the nanocatalyst was
separated by an external magnet and the reaction mixture
was extracted with EtOAc (2 × 5 mL). Drying organic
layer over anhydrous Na2SO4 and then evaporation of
the solvent affords the pure liquid aniline in 95 % yield
(0.088 g, Table 2, entry 1).
28. T. Poursaberi, V. Akbar, S.M.R. Shoja, Iran. J. Chem. Chem.
Eng. 34, 41 (2015)
29. A.M. Tafesh, J. Weiguny, Chem. Rev. 96, 2035 (1996)
30. T.C. Nugent, Chiral Amine Synthesis: Methods, Developments
and Applications (Wiley-VCH, Weinheim, 2010)
31. T. Farooqui, A.A. Farooqui, Biogenic Amines: Pharmacological,
Neurochemical and Molecular Aspects in the CNS (Nova Sci-
ence, New York, 2010)
32. S.A. Lawrence, Amines: Synthesis, Properties and Applications
(Cambridge University Press, Cambridge, 2004)
33. C. Yu, B. Liu, L. Hu, J. Org. Chem. 66, 919 (2001)
34. A.K. Shil, P. Das, Green Chem. 15, 3421 (2013)
35. P.G. Andersson, I.J. Munslow, Modern Reduction Methods
(Wiley-VCH, New York, 2008)
36. J. Seyden-Penne, Reductions by the Alumino and Borohydrides
in Organic Synthesis, 2nd edn. (Wiley-VCH, New York, 1997)
37. A.F. Abdel-Magid, Reductions in Organic Synthesis, vol. 641
(ACS Symposium Series, 1996)
Acknowledgments The financial support of this work was gratefully
acknowledged by the Research Council of Urmia University.
1 3

J IRAN CHEM SOC
38. M. Hudlicky, Reductions in Organic Chemistry (Ellis Horwood,
Chichester, 1984)
48. W. Li, Q. Deng, G. Fang, Y. Chen, J. Zhan, S. Wang, J. Mater.
Chem. B 1, 1947 (2013)
39. B. Zeynizadeh, M. Zabihzadeh, J. Iran. Chem. Soc. 12, 1221
(2015)
49. P.S. Rathore, R. Patidar, T. Shripathi, S. Thakore, Catal. Sci.
Technol. 5, 286 (2015)
40. B. Zeynizadeh, K. Zahmatkesh, J. Chin. Chem. Soc. 50, 267
(2003)
41. B. Zeynizadeh, H. Ghasemi, J. Chem. Res. 542 (2006)
42. B. Zeynizadeh, D. Setamdideh, Synth. Commun. 36, 2699
(2006)
50. M.B. Gawande, A.K. Rathi, P.S. Branco, I.D. Nogueira, A. Vel-
hinho, J.J. Shrikhande, U.U. Indulkar, R.V. Jayaram, C.A.A.
Ghumman, N. Bundaleski, O.M.N.D. Teodoro, Chem. Eur. J. 18,
12628 (2012)
51. R.K. Rai, A. Mahata, S. Mukhopadhyay, S. Gupta, P.-Z. Li, K.T.
Nguyen, Y. Zhao, B. Pathak, S.K. Singh, Inorg. Chem. 53, 2904
(2014)
43. B. Zeynizadeh, S. Zarrin, S. Ashuri, Org. Chem. Indian J. 9, 313
(2013)
44. N. Hassanloie, B. Zeynizadeh, S. Ashuri, F. Hassanloie, Org.
Chem. Indian J. 10, 59 (2014)
45. G.L. Li, Y.R. Jiang, K.L. Huang, P. Ding, I.I. Yao, J. Colloid
52. R.V. Jagadeesh, D. Banerjee, P.B. Arockiam, H. Junge, K. Junge,
M.-M. Pohl, J. Radnik, A. Brückner, M. Beller, Green Chem. 17,
898 (2015)
Interface Sci. A320, 11 (2008)
53. X. Ma, L. Cui, G. Xu, Appl. Mech. Mater. 271–272, 320 (2013)
54. X. Liu, Z. Ma, J. Xing, H. Liu, J. Magn. Magn. Mater. 270, 1
(2004)
46. J.A. Lopez, F. González, F.A. Bonilla, G. Zambrano, M.E.
Gómez, Rev. Latinoam. Metal. Mater. 30, 60 (2010)
47. D.P. Singh, A.K. Ojha, O.N. Srivastava, J. Phys. Chem. C 113,
3409 (2009)
1 3