Synthesis, characterization, and application of easily accessible resin-encapsulated nickel nanocatalyst for efficient reduction of functionalized nitroarenes under mild conditions

Article abstract of DOI:10.1007/s12039-018-1548-7

Abstract: A novel resin-encapsulated nickel nanocatalyst has been synthesized by a modified impregnation method using nickel acetate tetrahydrate in presence of sodium borohydride as a mild reducing agent. The synthesized nanocatalyst was characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The concentration of nickel nanoparticles encapsulated on resin was determined by inductively coupled plasma-mass spectroscopy (ICP-MS). Further, synthesized resin-encapsulated nickel nanocatalyst was found to be stable and efficient in micromolar concentrations, for the selective reduction of functionalized nitroarenes to corresponding amines in good to high yield, under mild reaction conditions. The nanocatalyst shows excellent reusability. Graphical Abstract: SYNOPSIS A novel resin-encapsulated nickel nanocatalyst (Ni@XAD-4) was synthesized using a modified impregnation method. The nanocatalyst exhibited excellent catalytic activity towards the selective reduction of functionalized nitroarenes in the presence of NaBH ₄ with reusability up to five cycles.[Figure not available: see fulltext.].

Full text of DOI:10.1007/s12039-018-1548-7

J. Chem. Sci.
(2018) 130:160
© Indian Academy of Sciences
https://doi.org/10.1007/s12039-018-1548-7
REGULAR ARTICLE
Synthesis, characterization, and application of easily accessible
resin-encapsulated nickel nanocatalyst for efficient reduction of
functionalized nitroarenes under mild conditions
POONAM RANI, KAMAL NAIN SINGH and AMARJIT KAUR∗
Department of Chemistry, Faculty of Science, Panjab University, Chandigarh 160014, India
E-mail: amarjitk@pu.ac.in
MS received 5 May 2018; revised 16 August 2018; accepted 25 August 2018
Abstract. A novel resin-encapsulated nickel nanocatalyst has been synthesized by a modified impregnation
method using nickel acetate tetrahydrate in presence of sodium borohydride as a mild reducing agent. The
synthesized nanocatalyst was characterized by field emission scanning electron microscopy (FESEM) and
transmission electron microscopy (TEM). The concentration of nickel nanoparticles encapsulated on resin
was determined by inductively coupled plasma-mass spectroscopy (ICP-MS). Further, synthesized resin-
encapsulated nickel nanocatalyst was found to be stable and efficient in micromolar concentrations, for the
selective reduction of functionalized nitroarenes to corresponding amines in good to high yield, under mild
reaction conditions. The nanocatalyst shows excellent reusability.
Keywords. Resin-encapsulated nickel nanocatalyst; impregnation; stability; recyclability; reduction;
nitroarenes; aromatic amines.
1. Introduction
amines so obtained are generally employed as the
important building blocks in the synthesis of drugs,
biologically active compounds, dyes, agrochemicals,
pharmaceuticals, polymers, corrosion inhibitors, surfac-
tant, herbicides, etc.7–9 Conventional methods for the
reduction of nitroarenes include certain drawbacks such
as long reaction time, use of toxic and carcinogenic sol-
vents, expensive noble metal complexes, generation of
a large amount of waste and non-reusability of the cat-
alysts, etc.10–12
The importance of amines in the above-mentioned
industries and efforts in surface science have led to
the discovery of new heterogeneous catalysts either
by impregnation of unsupported metal nanoparticles
or highly dispersed metal precursors to different sup-
ports for the reduction of nitroarenes using various
reducing agents such as H2, NaBH4, N2H4·H2O and
so on.13–15 Many support materials such as polymers,
dendrimers, carbonaceous porous materials, metal
oxide, etc., are in trend to arrest the agglomeration
and the high surface energy of metal nanoparticles.16–20
Nitroarenes are generally employed in a wide range
of industries for the synthesis of many valuable mate-
rials such as dyes, pesticides, explosives, polymers,
pharmaceuticals, etc. Excessive discharge of these
nitro compounds from industries into the wastewater
has led to environmental pollution.1 Their mutagenic
and carcinogenic nature affect extensively the entire
range of living organisms including humans as they
are heavily dependent on water and aquatic products
in everyday life. Moreover, these nitro compounds
have been declared as the second largest group of
organic environmental pollutants.2 Therefore, it is nec-
essary to eliminate these nitro compounds from the
waste water and land. Principles of green chemistry
endorse the replacement of hazardous chemicals by
using environment-friendly alternatives. Among the
various reported methods,3–6 the transformation of
nitroarenes to their corresponding amines is the most
significant and sustaining strategy that contributes to
the environmental fate of nitroarenes. The aromatic
*
For correspondence
Electronic supplementary material: The online version of this article (https://doi.org/10.1007/s12039-018-1548-7) contains
supplementary material, which is available to authorized users.
0123456789().: V,-vol

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(2018) 130:160
Usually, heterogeneous catalysts including noble 2. Experimental
metals (palladium, platinum, gold, and silver) are the
2.1 Materials and methods
most widely sourced supported catalysts for the reduc-
tion of nitroarenes.21–25 The high price of these precious
noble metals limit their large-scale applications. Current
research activities in this area are mainly focused on the
development of the heterogeneous catalysts based on
base-metals (nickel, iron, copper, and cobalt) for effi-
cient and cost-effective catalytic selective reduction of
nitroarenes.26–29
Unless otherwise stated, all reactions were carried out without
taking precautions to exclude air and moisture. Nickel acetate
tetrahydrate (Ni(OAc)2·4H2O, 98%) was procured from Qua-
likems, India, sodium borohydride (NaBH4, >96%) from
Spectrochem, India, absolute ethanol (99.9%) from Chang-
shu chemicals, China, and amberlite XAD-4 resin (of high
purity) from Sigma-Aldrich, Germany, and used as received.
Hydrochloride acid (37%) and other solvents were of ana-
Many supported nickel nanocatalysts and their ver-
satile applications in the field of medical diagno- lytical grade and supplied by qualigens chemicals, India and
sis,30 supercapacitors,31 and catalysis32–35 especially
were used after purification by standard procedures. All reac-
tion temperatures refer to oil bath temperatures. Silica gel
for the reduction of nitroarenes are reported in the
(230–400 mesh) (of high purity grade) for column chro-
matography, was purchased from Fisher Scientific Ltd, India.
literature. Kalbasi and co-workers developed nickel
nanoparticles@polyvinylamine/SBA-15
composite
1H NMR and 13C NMR spectra were recorded on model
Avance-II (Bruker) 400 spectrometer operating at 400MHz
(1H) and 100MHz (13C). FESEM images were recorded
using HITACHI SU8010 field emission scanning electron
microscope. HR-TEM images and TEM-EDS analysis were
obtained using a TecnaiTM G2 20, 120kV transmission elec-
tron microscope with embedded CCD Camera. ICP-MS study
was done on Agilent’s 7700x, ICP-MS system. UV-Vis study
(PVAm/SBA-15), to be used in most of the solvents as
an efficient heterogeneous catalyst for hydrogenation
of aromatic nitro compounds to corresponding aro-
matic amino compounds in good yields by employing
sodium borohydride as a reducing agent.36 Figueiredo
et al. generated nickel nanoparticles by metal dis-
integration. These were stabilized on the top of the
filamentous carbon. This nanocomposite was tested as for reduction of functionalized nitroarenes was carried out
using UV-Visible spectrophotometer JASCO model V-530
using a 1cm path length quartz cell.
a catalyst for the reduction of nitrobenzene under 1.5
MPa hydrogen pressure at 120 ◦C with excellent perfor-
mance producing clean aniline (approx. 99% yield).37
Ranu and co-workers reported the excellent use of
Fe(0) nanoparticles stabilized by citric acid, for reduc-
tion of nitroarenes. The reaction was done using 3
equiv. nanoparticles per 1 equiv. of substrate in water
for 3–4h to obtain desired products in good yield.38
The commercially available amberlite XAD-4 resin
used as a solid support for nanoparticles has advan-
tages like easy to handle, non-reactive, easily available,
porous nature, thermal and chemical stability.39 This
has not been so far explored for the synthesis of nickel
nanoparticles.
2.2 Synthesis of resin-encapsulated nickel
nanocatalyst
In a typical synthetic protocol, 5g of resin beads were added to
25mL of 5.0mmol nickel acetate tetrahydrate solution pre-
pared in ethanol and stirred at room temperature for 3–4h
–
followed by dropwise addition of 0.1M aq. NaBH4 solu-
tion (10mL). The addition of NaBH4 solution turns resin
beads black, indicating the formation of nickel nanoparticles.
The synthesized nanoparticles were first washed with distilled
water followed by ethanol to control surface oxidation. This
synthesized resin-encapsulated nickel nanocatalyst was then
We have synthesized the amberlite XAD-4 resin- stored in absolute ethanol and is referred to as resin stabilized
nickel nanocatalyst (Ni@XAD-4 nanocatalyst).
encapsulated nickel nanocatalyst by the chemical reduc-
tion of nickel acetate tetrahydrate (Ni(OAc)2·4H2O)
in ethanol. Further, we have investigated the reduction 2.3 General procedure for catalytic reduction
of functionalized nitroarenes by the resin-encapsulated
To an oven dried 50mL round bottom flask, charged with
nickel nanocatalyst as a heterogeneous catalyst, using
nitroarene (1.5mmol) and 10mL of methanol: water (3:7)
sodium borohydride as a reducing agent under mild
was added resin-encapsulated nickel nanocatalyst (300mg
reaction conditions. Thus, catalytic reduction of
of resin) (0.161mg of Ni ≈ 0.00275 mmol of Ni). The
nitroarenes by resin-encapsulated nickel nanocatalyst
solution was stirred at room temperature for 5–10min. To
may be of direct use in the treatment of waters con-
this solution, solid sodium borohydride (0.567g, 10 equiv.
taminated with nitroarenes if the resulting amines
15mmol) was added in small instalments and the reaction
◦
can be removed by subsequent treatment. The resin-
encapsulated nickel nanocatalyst was recycled five
times without any significant loss of its catalytic
activity.
mixture was heated at 50 C for the required time (almost
30 min) to complete the reaction as monitored by using TLC.
It was cooled to room temperature and then filtered. The
filtrate was extracted with ethyl acetate (3 × 10 mL). The

J. Chem. Sci.
(2018) 130:160
Page 3 of 9 160
combined organic extract was washed with brine (20mL),
dried over anhydrous Na2SO4 and concentrated under vac-
uum. The crude material so obtained was purified by column
chromatography.
TEM-EDS analysis reveals the presence of only
nickel metal and it is found to be 10.24 wt% in elemental
composition. The inset TEM shows the SAED pattern
of nickel nanocatalyst displayed with bright spots and
good ring pattern that specifies the crystallinity of nickel
nanoparticles.
3. Results and Discussion
3.1.2 Inductively Coupled Plasma-Mass Spectroscopy
(ICP-MS): The concentration of nickel nanoparticles
deposited on resin could be figured out by ICP-MS.
500mg of resin-encapsulated nanocatalyst was incin-
erated in a silica crucible for 4h at 550 ◦C, and then the
residue was dissolved in 1mL of Aqua-regia and diluted
up to 5mL with distilled water. The average concentra-
tion of nickel metal deposited on resin was calculated
as 0.00916mmol/g or 0.538mg/g of the resin in at least
three trials.
3.1 Characterization of resin-encapsulated nickel
nanocatalyst
3.1.1 Field emission Scanning Electron Microscopy
(FESEM) and High-Resolution Transmission Electron
Microscopy (HR-TEM): FESEM was carried out to
study topography and elemental information of the
surface of resin beads encapsulated with nickel nanopar-
ticles. FESEM images depict the smooth dispersion of
nickel nanoparticles into the matrix and on the surface of
beads. FESEM images show no obvious contamination
or agglomeration of metal nanoparticles on the surface
of the resin beads (Figure 1).
3.2 Optimization of the reaction conditions for the
reduction of nitroarenes
The resin beads were immersed in ethanol that
developed the nanopores in microporous resins. The The catalytic performance of resin-encapsulated nickel
nanopores of the microporous XAD-4 resin can control nanocatalyst has been investigated in the reduction of
the growth of metal nanoparticles resulting in con- nitroarenes. For the optimization of the reaction condi-
cise distribution in the size of nickel nanoparticles. tions, a series of experiments were carried out, involving
Figure 2 depicts the HR-TEM images of synthesized the variation in reducing agent, amount of resin-
nickel nanocatalyst. HR-TEM analysis was used to encapsulated nickel nanocatalyst, temperature, and sol-
know the morphology and dimension of nickel nanopar- vent combinations. The reduction of 4-nitrotoluene
ticles embedded in the matrix of resin. Resin beads (0.205g, 1.5mmol) was chosen as the model reaction
were dispersed in ethanol through sonication. The anal- to give the 4-aminotoluene. Increasing the amount of
ysis was done by putting a drop of this dispersion on sodium borohydride from 5 equivalents to 10 equiva-
carbon-coated copper grids. The typical TEM images lents for 4-nitrotoluene, the yield of the desired product
of freshly prepared nickel nanocatalyst show uniform increased from 70 to 95% (Table 1, entries 2–4). Further
and well-dispersed spherical nickel nanoparticles with increase in the amount of sodium borohydride did not
a dimension between 5 and 8nm (average size 6.7
3.03 nm) as revealed through particle size distribution Decreasing the amount of nickel nanocatalyst resulted
TEM-histogram (Figure 2c). in the decrease in the yield of the product. However,
result in any increase in the yield (Table 1, entry 12).
Figure 1. FESEM images of resin bead with nickel nanoparticles (1–2).

160 Page 4 of 9
J. Chem. Sci.
(2018) 130:160
Figure 2. HR-TEM images (a–b), particle size distribution histogram (c), SAED pattern (d) and TEM-EDS images (e) of
freshly prepared resin-encapsulated nickel nanocatalyst.
the yield did not improve on increasing the amount of 3.3 General scope of the reaction
nickel nanocatalyst (from 300 to 350mg) under similar
conditions (Table 1, entries 5, 8–11).
With the optimized reaction conditions in hand,
The effect of solvent on the yield and time of the resin-encapsulated nickel nanocatalyst was further eval-
reaction was also examined. Water and methanol were uated for the reduction of different functionalized
more efficient compared to other solvents like ethanol, nitroarenes. The synthesized resin-encapsulated
DCM and THF (Table 1, entries 5, 13, and 15–19). nickel nanocatalyst was found to be compatible with
The best yield was obtained using a combination of arenes having electron-donating as well as electron-
◦
methanol: water (v/v = 3/7) at 50 C. Even when the withdrawing substituents at any position (Table 2).
reaction was carried out in water only, the desired prod- Amino, methoxy, and methyl substituted nitroarenes
uct 4-aminotoluene (Table 1, entry 17) was obtained were reduced to corresponding amines in good yield.
in good yield (68%). When the reduction was carried
It was found that both 4-chloro and 4-bromo sub-
out at room temperature, the product was obtained in a stituted nitroarenes were reduced to their correspond-
lower yield (Table 1, entry 14). However, no reaction ing amines without any dehalogenation taking place
occurred in the absence of either catalyst or reduc- (Table 2, entries 8, 9). The 4-chloroaniline so obtained is
ing agent (Table 1, entries 1, 20). The best results an important ingredient for the synthesis of antimalarial
were obtained using 4-nitrotoluene (0.205g, 1.5mmol), drug paludrine. The nitro group in the heterocyclic
300mg resin-encapsulated nickel nanocatalyst with system was reduced to give the corresponding amine in
sodium borohydride (0.567g, 10 equiv. ◦15mmol) in good yield (Table 2, entries 11, 15). 8-Aminoquinoline
10mL of CH3OH : H2O (3:7) at 50 C (Table 1, (2k) is an important ingredient for the synthesis of anti-
entry 5).
malarial drugs primaquine and pamaquine.

J. Chem. Sci.
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Page 5 of 9 160
Table 1. Optimization of reaction conditions for reduction of 4-nitrotoluene.
Entry Substrate
1a (mmol)
NaBH4 (equiv.) Amount of resin (mg)
Solvent
Temp. (◦C) Time (h) Yielda (%)
1.
2.
3.
4.
5.
6.
7.
8.
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
5
5
7
0
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O(3 : 7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (3:7)
CH3OH : H2O (1:1)
CH3OH : H2O (3:7)
CH3OH
50
50
50
50
50
50
50
50
50
50
50
50
50
25
50
50
50
50
50
50
1
2
2
0
70
85
95
95
90
95
95
80
70
50
95
85
60
65
50
68
30
Trace
0
300
300
300
300
300
300
350
250
200
100
300
300
300
300
300
300
300
300
300
10
10
10
10
10
10
10
10
12
10
10
10
10
10
10
10
-
1
0.5
0.35
1
1
1
1
1
0.5
1
2
1
1
1
1
1
1
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
EtOH
H2O
DCM
THF
CH3OH : H2O (3:7)
aIsolated yield.
Table 2. Reduction of nitroarenes using resin-encapsulated nickel nanocatalyst and NaBH4 as mild reducing agenta.
Resin-encapsulated nickel nanocatalyst
NO2
NH2
(300 mg), NaBH4 (10 eq.)
R
R
CH3OH: H2O (3:7), 50 °C
2
1
Entry no.
Reactant 1
Product 2
Time (h)
Yieldb (%)
1.
2.
3.
4.
5.
6.
7.
8.
4-Nitrotoluene (1a)
3-Nitrotoluene (1b)
Nitrobenzene (1c)
4-Nitrophenol (1d)
4-Methoxynitrobenzene (1e)
3-Methoxynitrobenzne (1f)
4-Nitrobenzaldehyde (1g)
4-Chloronitrobenzene (1h)
4-Bromonitrobenzene (1i)
1-Nitronaphthalene (1j)
8-Nitroquinoline (1k)
4-Aminotoluene (2a)
3-Aminotoluene (2b)
Aniline (2c)
0.5
2
1
0.5
1
2
2
2
2
2
2
1
2
2
95
82
90
80
90
86
82
88
80
90
80
93
79
92
80
4-Aminophenol (2d)
4-Methoxyaniline (2e)
3-Methoxyaniline (2f)
4-Aminobenzylalcohol (2g)
4-Aminochlorobenzene (2h)
4-Aminobromobenzene (2i)
1-Aminonaphthalene (2j)
8-Aminoquinoline (2k)
1,4-Diaminobenzene (2l)
1,3-Diaminobenzene (2m)
1,2-Diaminobenzene (2n)
2-Aminopyridine (2o)
9.
10.
11.
12.
13.
14.
15.
4-Aminonitrobenzene (1l)
3-Aminonitrobenzene (1m)
2-Aminonitrobenzene (1n)
2-Nitropyridine (1o)
2
aReaction conditions: 1a (1.5mmol), Resin-encapsulated nickel nanocatalyst (300mg of resin ≈ 0.00275 mmol of Ni), NaBH4
(0.567g, 10 equiv., 15mmol) at 0 ◦C, CH3OH : H2O (3:7), 50 ◦C. bisolated yield after column chromatography.
3.4 UV-Vis study of the reduction reaction
potential of metal nanocatalyst is located in between
the potential of BH−4 and nitroarenes. Bordbar et al.,40
The reduction of nitroarenes can be effectively have described the reduction of 4-nitrophenol (4-NP)
catalyzed by metal nanocatalyst only when the to 4-aminophenol (4-AP) using borohydride ion in the

160 Page 6 of 9
J. Chem. Sci.
(2018) 130:160
presence of immobilized nickel nanoparticles on spectrum of the aqueous solution of 4-nitrophenol and
polymer/mesoporous composite. Also, Song and the resin-encapsulated nickel nanocatalyst showed an
coworkers41 reported the catalytic activity of Ru absorption peak at 317nm. On the addition of NaBH4
nanoparticles as an efficient catalyst for the reduc- into the 4-nitrophenol solution, the absorption peak
tion of 4-nitrophenol to 4-aminophenol using NaBH4. shifted to 400nm, with a change in the color from
We have also studied the catalytic activity of syn- original light yellow to intense yellow (Figure S4
thesized resin-encapsulated nickel nanocatalyst by the (A–E), Supplementary Information). This is due to the
selective reduction of 4-nitrophenol to 4-aminophenol transformation of 4-nitrophenol to the 4-nitrophenolate
using NaBH4 as a mild reducing agent. This reac- anion. The progress of the catalytic reduction of the
tion is easy to follow using UV-Visible spectroscopy.42 4-nitrophenol to 4-aminophenol was monitored by the
The reaction was started by dissolving 4-nitrophenol change in the intensity of the absorbance peak at 317nm
(0.208g, 1.5mmol) in 10mL of CH3OH : H2O (3:7), in the UV-Visible spectrum. The time-dependent UV–
followed by addition of nickel nanocatalyst (300mg) Visible absorption spectra of 4-nitrophenol and NaBH4
and NaBH4 (0.567g, 10 equiv. 15mmol). The reac- solution in the presence of as-prepared nickel nanocata-
◦
tion mixture was heated to 50 C and then subjected lyst is shown in Figure S5, Supplementary Information.
to UV-Visible study by taking 0.3mL aliquot, from It has been observed that with the progress of the
the reaction mixture at regular intervals and diluting reaction, the intensity of the absorption peak of 4-
it to 5mL with 10% HCl. Dilute HCl was used to nitrophenol at 317nm decreased gradually and finally
decompose the excess amount of NaBH4 present in disappeared and a new peak at 295nm appeared, sig-
the sample aliquot. The UV-Visible absorption nifying that 4-nitrophenol gradually converted to the
Figure 3. HR-TEM images, particle size distribution histogram, SAED pattern and TEM-EDS images (a–e) of resin-en-
capsulated nickel nanocatalyst after fifth recycle for reduction of 4-nitrotoluene.

J. Chem. Sci.
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Page 7 of 9 160
Table 3. Comparison of catalytic activity of present nanocatalyst with the earlier reported results
Entry no.
1.
Nanocatalyst
Time
8h
Conditions
Reusability
Reference
Ni@organic modifier
0.8MPa pressure,
100 ◦C, anhydrous
ethanol
Up to four cycles
43
2.
Ni@ p(4-VP) cryogels
60min
Nitro compound
(0.01 M), NaBH4
(0.4 M), 30 ◦C,
800 rpm
Up to four cycles
44
3.
4.
Ni@ carbon filaments
12–24h
10 min
1.5 MPa of H2, 120 ◦C
Single time
45
45
Nanosized Nickel
decorated sisal fibers
Substrate (1.0 mmol),
NaBH4 (100 mmol)
catalyst (3.39%)
Up to seven cycles
5.
6.
7.
Ni/Carbide-Ni/carbon
nanofibers
nanocomposite
Fe(0) nps
2.5h
2.0 MPa of H2, 140 ◦C
Up to five cycles
Single time
46
38
3–4h
80–96%, Substrate
(1.0 mmol), catalyst
(3 equiv.)
95–80%, 0.00275 mmol
nanocatalyst for
Ni@XAD-4 nanocatalyst
20–80min
Up to five cycles
Present
work
1.5 mmol of substrate,
NaBH4 (10 equiv.)
corresponding 4-aminophenol. This was accompanied 3.6 Comparison of catalytic activity of present
by the change in color from yellow to colorless.
nanocatalyst with the earlier reported nickel and other
nanocatalysts towards reduction of nitroarenes
3.5 Recyclability of resin-encapsulated nickel
This section features Table 3.
nanocatalyst
The recyclability and reusability of resin-encapsulated
nickel nanocatalyst was demonstrated in the reduc-
tion of 4-nitrotoluene. The reaction was carried out
with 4-nitrotoluene (0.205g, 1.5mmol) and nickel-
encapsulated nickel nanocatalyst (300mg) in 10mL of
CH3OH : H2O (3:7) at 0 ◦C and followed by the addition
of NaBH4 (0.567g, 10 equiv.) in small instalments. The
reaction mixture was heated to 50 ◦C and stirred at the
same temperature for 30min. After completion of the
reaction, as monitored by TLC nickel nanocatalyst was
recovered by filtration, and washed with distilled water,
followed by ethanol and reused as such in the next reac-
tion. The nanocatalyst was successfully recycled and
reused up to five cycles without a significant decrease
in its catalytic efficiency (95%, 95%, 94%, 90% and
90%) as shown in Figure S6 (Supplementary Informa-
tion). The characterization of used nickel nanocatalyst
through HR-TEM analysis shows that the morphology
and size of nickel nanocatalyst remains almost the same
(spherical and average size 8.1 2.55 nm) after use for
the fifth cycle. Slight variation in the concentration of
nickel impregnation is there as revealed by the HR-TEM
images and TEM-EDS analysis (Figure 3).
4. Conclusions
In conclusion, an inexpensive and recyclable
resin-encapsulated nickel nanocatalyst has been syn-
thesized using a modified impregnation method and
characterized by using FESEM, HR-TEM, TEM-EDS,
andICP-MStechniques. Thisprotocoloffersadvantages
such as easy accessibility, easy product isolation, eco-
friendly, and recyclability of the nanocatalyst for the
reduction of nitroarenes.
Supplementary Information (SI)
The synthesized resin-encapsulated nickel nanocatalyst is
characterized by FESEM, HR-TEM, TEM-EDS, and ICP-MS
techniques. FESEM and HR-TEM, particle size distribution
histogram, and TEM-EDS images of the synthesized resin-
encapsulated nickel nanocatalyst are given in SI (Figures
S1, S2 and S3). The H NMR and 13C NMR spectral data
1
and spectra of aromatic amines obtained on the reduction of
nitroarenes with resin-encapsulated nickel nanocatalyst are
given in Appendix A of Supplementary Information, avail-
able at www.ias.ac.in/chemsci.

160 Page 8 of 9
J. Chem. Sci.
(2018) 130:160
Acknowledgements
14. Blanita G and Lazar M D 2013 Review of graphene-
supported metal nanoparticles as new and efficient het-
erogeneous catalysts Micro Nanosyst. 5 138
15. Segobia D, Trasarti A and Apesteguia C 2012 Hydro-
genation of nitriles to primary amines on metal-
supported catalysts: Highly selective conversion of
butyronitrile to n-butylamine Appl. Catal. A 445
69
The authors acknowledge the financial support from Sci-
ence and Engineering Research Board (SERB)-DST, New
Delhi, through Scheme number EEQ/2016/000574, CRF, IIT
Delhi for HR-TEM and TEM-EDS analysis, PBTI, Mohali
for ICP-MS characterization and SAIF, Punjab University for
1H NMR and 13C NMR and other characteristic techniques.
16. Tumma M and Srivastava R 2013 Transition metal
nanoparticles supported on mesoporous polyaniline cat-
alyzed the reduction of nitroaromatics Catal. Com-
mun. 37 64
References
17. Jamal S, Rezaei T, Khorramabadi H, Hesami A,
Ramazani A, Amani V and Ahmadi R 2017 Chemos-
elective reduction of nitro and nitrile compounds
with magnetic carbon nanotubes supported Pt(II) cat-
alyst under mild conditions Ind. Eng. Chem. Res. 56
12256
18. Zuoa P, Duana J, Fana H, Qua S and Shen W 2018 Facile
synthesis high nitrogen-doped porous carbon nanosheet
from pomelo peel and as catalyst support for nitroben-
zene hydrogenation Appl. Surf. Sci. 435 1020
1. Talmage S S, Opresko D M, Maxwell C J, Welsh C J,
Cretella F M, Reno P H and Daniel F B 1999 Nitroaro-
matic munition compounds: environmental effects
and screening values Rev. Environ. Contam. Toxicol.
1611
2. Kovacic P and Somanathan R 2014 Nitroaromatic com-
pounds: Environmental toxicity, carcinogenicity, muta-
genicity, therapy and mechanism J. Appl. Toxicol. 34
810
3. Yan F, He Y, Ding L and Su B 2015 Highly ordered
binary assembly of silica mesochannels and surfac-
tant micelles for extraction and electrochemical analysis
of trace nitroaromatic explosives and pesticides Anal.
Chem. 87 4436
19. Cao Y, He L and Ni J 2011 Method for the synthesis
of amine by reduction of nitro compound in presence of
a metal oxide-supported gold catalyst Faming Zhuanli
Shenqing CN 102086143 A 20110608
20. Mohammadi-Aghdam B, Bahari S and Molaei R 2013
The Pd (0) nanoparticles stabilized by collagen fibres as
a recyclable heterogeneous catalyst for the Stille reaction
under aerobic condition J. Chem. Sci. 125 813
4. Liu X, Ma X, Liu S, Liu Y and Xia C 2015 Metal fluo-
ride promoted catalytic hydrogenation of aromatic nitro
compounds over RANEY® Ni RSC Adv. 5 36423
5. Deiber G, Foussard J N and Debellefontaine H 1997
Removal of nitrogenous compounds by catalytic wet air
oxidation. Kinetic study Environ. Pollut. 96 311
6. Keiichi T, Wandee L and Teruaki H 1997 Photocatalytic
degradation of mono-, di- and trinitrophenol in aqueous
TiO2 suspension. J. Mol. Catal. A: Chem. 122 67
7. Clemenceau A, Wang Q and Zhu J 2018 Cooperative
Pd/Cu catalysis: multicomponent synthesis of tetrasub-
21. Hemantha
H
P
and Sureshbabu
V
V
2011
Poly(vinyl)chloride supported palladium nanoparti-
cles: a catalyst for rapid hydrogenation reactions Org.
Biomol. Chem. 9 2597
22. Lara P and Philippot K 2014 The hydrogenation of
nitroarenes mediated by platinum nanoparticles: an
overview Catal. Sci. Technol. 4 2445
23. Chaiseeda K, Nishimura S and Ebitani K 2017 Gold
nanoparticles supported on alumina as a catalyst for sur-
face plasmon-enhanced selective reductions of nitroben-
zene ACS Omega 2 7066
24. Feng W, Huang T, Gao L, Yang X, Deng W, Zhou R and
Liu H 2018 Textile-supported silver nanoparticles as a
highlyefficient and recyclable heterogeneous catalyst for
nitroaromatic reduction at room temperature RSC Adv. 8
6288
25. Viswanathan P and Ramaraj R 2018 Gold nanodots self-
assembled polyelectrolyte film as reusable catalyst for
reduction of nitroaromatics J. Chem. Sci. 130 10
26. Shang H, Pan K, Zhang L, Zhang B and Xiang X 2016
Enhanced activity of supported Ni catalysts promoted
by Pt for rapid reduction of aromatic nitro compounds
Nanometre 6 103
27. Ai Y, Liua L, Jing K, Qi L, Fana Z, Zhoua J, Suna H-Bin,
Shao Z and Liang Q 2017 Noncovalently functional-
ized carbon nanotubes immobilized Fe-Bi bimetallic
oxides as a heterogeneous nanocatalyst for reduction of
nitroaromatics NANOSO 10 116
α
stituted imidazolones from methyl Isocyanoacetates,
primary amines, and aryl(vinyl) iodides Org. Lett. 20
126
8. Mei N, Liu B and Bing V Int. 2016 Pd nanoparticles
supported on Fe3O4@C: An effective heterogeneous
catalyst for the transfer hydrogenation of nitro com-
pounds into amines J. Hydrog. Energy 41 17960
9. Morse J R, Callejas J F, Darling A J and Schaak R E 2017
Bulk iron pyrite as a catalyst for the selective hydrogena-
tion of nitroarenes Chem. Commun. 53 4807
10. Kalyanaraman V and George M V 1973 Alkali metal
reduction of aromatic nitro compounds J. Org. Chem. 38
507
11. Asghar A S and Kazemi F 2016 Photocatalytic reduction
of nitroaromatic compounds to amines using a nanosized
highly active CdS photocatalyst under sunlight and blue
LED irradiation Chem. Pap. 70 531
12. Qi Z, Dong H, Yu H, Zhao M and Yu H 2017 In-situ
electrochemical NOx removal process for the lean-burn
engine exhaust based on carbon black gas diffusion elec-
trode J. Clean. Prod. 151 465
28. Barot N, Shaikh T and Kaur H 2017 A PLA-TiO2 particle
brushasanovelsupportforCuNPs:acatalystforthefast-
sequential reduction and N-arylation of nitroarenes New
J. Chem. 41 5347
13. Li Y, Gong Y, Xu X, Zhang P, Li H and Wang Y 2012
A practical and benign synthesis of amines through
Pd@mpg-C3N4 catalyzed reduction of nitriles Catal.
Commun. 28 9

J. Chem. Sci.
(2018) 130:160
Page 9 of 9 160
29. Sorribes I, Liu L and Corma A 2017 Nanolayered Co- 38. Dey R, Mukherjee N, Ahammed S and Ranu B C
Mo-S catalysts for the chemoselective hydrogenation of
nitroarenes ACS Catal. 7 2698
2012 Highly selective reduction of nitroarenes by iron(0)
nanoparticles in water Chem. Commun. 48 7982
30. Ayoub H, Lair V, Griveau S, Brunswick P, Bedioui F 39. Shah D and Kaur H 2014 Resin-trapped gold nanopar-
and Cassir M 2011 SUDOSCAN device for the early
detectionofdiabetes:invitromeasurementversusresults
of clinical tests Sensor Lett. 9 2147
ticles: An efficient catalyst for reduction of nitro com-
pounds and Suzuki-Miyaura coupling J. Mol. Catal. A:
Chem. 381 70
31. Yu J and Xu G 2018 A kind of cobalt nickel super 40. Bordbar M 2017 Biosynthesis of Ag/almond shell
capacitor electrode and its preparation process [Machine
Translation] Faming Zhuanli Shenqing CN 107658150
A 20180202
nanocomposite as a cost-effiective and efficient catalyst
for degradation of 4-nitrophenol and organic dyes RSC
Adv. 7 180
32. Jamal S, Rezaei T, Malekzadeh A M, Poulaei S, 41. Zhao Y, Luo Y, Yang X, Yang Y and Song Q 2017
Ramazani A and Khorramabadi H 2018 Chemo-
selective reduction of nitro and nitrile compounds
using Ni nanoparticles immobilized on hyperbranched
Tunable preparation of ruthenium nanoparticles with
superior size-dependent catalytic hydrogenation proper-
ties J. Hazard. Mater. 332 124
polymer-functionalized magnetic nanoparticles Appl. 42. Kang H, Kim M and Park K H 2015 Effective immo-
Organometal. Chem. 32 3975
bilization of gold nanoparticles on core-shell thiol-
functionalized GO coated TiO2 and their catalytic appli-
cation in the reduction of 4-nitrophenol Appl. Catal. A:
Gen. 502 239
33. Meng X, Cheng H, Akiyama Y, Hao Y, Qiao W, Yu Y,
Zhao F, Fujita S and Arai M 2009 Selective hydrogena-
tion of nitrobenzene to aniline in dense phase carbon
dioxide over Ni/C-Al2O3: significance of molecular 43. Wang A, Yin H, Lu H, Xue J, Ren M and Jiang T 2009
interactions J. Catal. 264 1
Effect of organic modifiers on the structure of nickel
nanoparticles and catalytic activity in the hydrogena-
tion of p-nitrophenol to p-aminophenol Langmuir 25
12736
34. Romanazzi G, Fiore A M, Malia M, Rizzuti A, Leonelli
C, Nacci A, Mastrorilli P and Dell’Annaa M M 2018.
Polymer supported Nickel nanoparticles as recyclable
catalyst for the reduction of nitroarenes to anilines in 44. Sahiner N, Yildiz S and Al-Lohedan H 2015 The
aqueous medium Mol. Catal. 446 31
resourcefulness of p(4-VP) cryogels as template for in
situ nanoparticle preparation of various metals and their
use in H2 production, nitro compound reduction and dye
degradation Appl. Catal. B: Environ. 166 145
35. Yadagiri J, Koppadi K S, Enumula S S, Vakati V, Kama-
raju S R R, Burri D R and Somaiah P V 2018 Ni/KIT-6
catalysts for hydrogenolysis of lignin-derived diphenyl
ether J. Chem. Sci. 130 106
36. Kalbasi R J, Nourbakhsh A A and Babaknezhad F
2011 Synthesis and characterization of Ni nanoparticles-
polyvinylamine/SBA-15 catalyst for simple reduction of
aromatic nitro compounds Catal. Commun. 12 955
45. Liu K, Wang Y, Cheng P, Liu Y, Kong C, Yi Z, Li M,
Liu Q, Zhong W, Takagi H and Wang D 2018 Nanosized
nickel decorated sisal fibers with tailored aggregation
structures for catalysis reduction of toxic aromatic com-
pounds Ind. Crops Prod. 119 226
37. Mahata N, Cunha A F, Orfao J J M and Figueiredo 46. Kang J, Han R, Wang J, Yang L, Fan G and Li F 2015 In
J L 2008 Hydrogenation of nitrobenzene over nickel
nanoparticles stabilized by filamentous carbon Appl.
Catal. A: Gen. 351 204
situ synthesis of nickel carbide-promoted nickel/carbon
nanofibers nanocomposite catalysts for catalytic appli-
cations Chem. Eng. J. 275 36