Palladium-S-propyl-2-aminobenzothioate immobilized on Fe3O4 magnetic nanoparticles as catalyst for Suzuki and Heck reactions in water or poly(ethylene glycol)

Article abstract of DOI:10.1002/aoc.3449

A moisture- and air-stable heterogenized palladium catalyst was synthesized by coordination of palladium with S-propyl-2-aminothiobenzamide supported on Fe₃O₄ magnetic nanoparticles. The prepared nanocatalyst was characterized using Fourier transform infrared, energy-dispersive X-ray and inductively coupled plasma atomic emission spectroscopies, X-ray diffraction, vibrating sample magnetometry, transmission and scanning electron microscopies, dynamic laser scattering and thermogravimetric analysis. This catalyst could be dispersed homogeneously in water or poly(ethylene glycol) and further applied as an excellent nano-organometal catalyst for Suzuki and Heck reactions. The catalyst was easily separated with the assistance of an external magnet from the reaction mixture and reused for several consecutive runs without significant loss of its catalytic efficiency or palladium leaching. The leaching of catalyst was examined using hot filtration and inductively coupled plasma atomic emission spectroscopy. Also, the effects of various reaction parameters on the Suzuki and Heck reactions are discussed.

Full text of DOI:10.1002/aoc.3449

Full paper
Received: 26 November 2015
Revised: 5 January 2016
Accepted: 10 January 2016
Published online in Wiley Online Library: 10 March 2016
(wileyonlinelibrary.com) DOI 10.1002/aoc.3449
Palladium–S-propyl-2-aminobenzothioate
immobilized on Fe3O4 magnetic nanoparticles
as catalyst for Suzuki and Heck reactions in
water or poly(ethylene glycol)
Arash Ghorbani-Choghamarani*, Bahman Tahmasbi and Parisa Moradi
A moisture- and air-stable heterogenized palladium catalyst was synthesized by coordination of palladium with S-propyl-2-
aminothiobenzamide supported on Fe3O4 magnetic nanoparticles. The prepared nanocatalyst was characterized using Fourier
transform infrared, energy-dispersive X-ray and inductively coupled plasma atomic emission spectroscopies, X-ray diffraction,
vibrating sample magnetometry, transmission and scanning electron microscopies, dynamic laser scattering and thermogravi-
metric analysis. This catalyst could be dispersed homogeneously in water or poly(ethylene glycol) and further applied as an excel-
lent nano-organometal catalyst for Suzuki and Heck reactions. The catalyst was easily separated with the assistance of an external
magnet from the reaction mixture and reused for several consecutive runs without significant loss of its catalytic efficiency or
palladium leaching. The leaching of catalyst was examined using hot filtration and inductively coupled plasma atomic emission
spectroscopy. Also, the effects of various reaction parameters on the Suzuki and Heck reactions are discussed. Copyright ©
2016 John Wiley & Sons, Ltd.
Keywords: magnetic nanoparticle; palladium; C–C coupling; Heck reaction; Suzuki reaction
temperature for calcination or a lot of time and tedious conditions
for their preparation. The separation drawback can be overcome by
Introduction
Palladium is one of the most crucial metals in catalysis and it has
been commonly applied as one of the most powerful tools for the
formation of the carbon–carbon bond in organic synthesis.[1,2] In par-
ticular, palladium-catalysed cross-coupling reactions of aryl halides
such as Suzuki and Heck coupling reactions have become powerful
methods in modern synthetic organic chemistry for the preparation
of natural products, agrochemicals, pharmaceuticals, biologically
active compounds, herbicides, UV screens, hydrocarbons, polymers,
liquid crystal materials and advanced materials.[3–6] Homogeneous
palladium catalysts have been extensively studied in synthetic
organic chemistry because of their high catalytic activity and
selectivity.[7] However, there are several drawbacks of homogeneous
catalysts, such as the purification of the final products, recycling of
the catalyst and deactivation of the catalyst.[8,9] Additionally, removal
of palladium from organic products at the end of a reaction is highly
desirable because of its high cost and toxicity.[10] Hence, the
heterogenization of homogeneous catalysts can help in their use
for practical processes to overcome the problems mentioned
above.[11] Therefore, to combine the advantages of both heteroge-
neous and homogeneous catalysts, immobilization of homogeneous
catalysts on nanoparticles is the best choice, which efficiently bridges
the gap between heterogeneous and homogeneous catalysts.[12–14]
However, the supporting nanocatalysts such as MCM-41,[15,16] SBA-
15,[17] TiO2 nanoparticles,[18] heteropolyacids,[19] ionic liquids,[2] car-
bon nanotubes[20] or some polymers[21] have various disadvantages
such as difficult or time-consuming and expensive separation of fine
particles from a reaction mixture. Also some of them require high
the use of magnetic nanoparticles (MNPs), which can be rapidly
and easily isolated from a reaction mixture using an external
magnet.[22] More importantly, magnetic separation is more effective
and easier than filtration or centrifugation, is simple, economical
and clean separation, promising for industrial applications.[23] One
of the most promising MNP supports is superparamagnetic iron ox-
ide with high surface area that can be prepared in water using com-
mercially available materials such as FeCl3Á.4H2O and FeCl2Á4H2O.[24]
We report here the synthesis and characterization of a palladium
complex immobilized on Fe3O4 MNPs. This reusable catalyst was
applied for the Suzuki and Heck reactions with a minimal leaching
of palladium species.
Experimental
+B: Preparation of Palladium–S-propyl-2-aminobenzothioate
Immobilized on Fe3O4 MNPs
Free Fe3O4 MNPs were synthesized according to our recently
reported procedure via a chemical co-precipitation technique using
FeCl3Á6H2O and FeCl2Á6H2O in basic solution at 80°C.[23] The
*
Correspondence to: Arash Ghorbani-Choghamarani, Department of Chemistry,
Ilam University, PO Box 69315516, Ilam, Iran. E-mail: arashghch58@yahoo.com
Department of Chemistry, Faculty of Science, Ilam University, PO Box, 69315516,
Ilam, Iran
Appl. Organometal. Chem. 2016, 30, 422–430
Copyright © 2016 John Wiley & Sons, Ltd.

Pd-ATBA-MNPs applied as nanocatalyst in C–C bond forming
obtained Fe3O4 nanoparticles (1.5 g) were dispersed in 50 ml of
ethanol–water (1:1 v/v) solution by sonication for 30 min, and then
2.5 ml of (3-mercaptopropyl)trimethoxysilane (MPTMS) was added
to this mixture. The reaction mixture was stirred under nitrogen at-
mosphere at 40°C for 8 h. Then, the nanoparticles were washed
with ethanol five times and separated through magnetic decanta-
tion. The prepared nanoparticles (SH-MNPs) were dried at room
temperature. The obtained SH-MNPs (1 g) were dispersed in 50
ml of ethanol by sonication for 20 min, and then isatoic anhydride
(2.5 mmol) was added to the reaction mixture. The reaction mixture
was stirred under nitrogen atmosphere at 80°C for 8 h. Then, the
resulting nanoparticles (ATBA-MNPs) were washed with ethanol
several times and separated using magnetic decantation and dried
at room temperature. The obtained ATBA-MNPs (0.5 g) were dis-
persed in 25 ml of ethanol by sonication for 20 min, and then palla-
dium acetate (0.25 mmol) was added to the reaction mixture. The
reaction mixture was stirred under nitrogen atmosphere at 80°C
for 20 h. Then, NaBH4 (0.3 mmol) was added to the reaction mixture
and reaction was continued for 2 h. The final product was separated
using magnetic decantation and washed with ethanol to remove
the unattached substrates. The nanoparticle product (Pd-ATBA-
MNPs) was dried at room temperature.
(1.5 g). Then the solvent was evaporated and pure products were
obtained in yields of 81–98%.
Results and Discussion
Catalyst Preparation
The catalyst was prepared using a concise route, which is outlined
in Scheme 1. Initially, SH-MNPs were prepared according to new re-
ported procedure.[23] Subsequently, ATBA-MNPs were synthesized
by reaction of SH-MNPs with isatoic anhydride. Ultimately, Pd-
ATBA-MNPs were obtained via coordination of palladium with 2-
aminothiobenzamide immobilized on Fe3O4 (Scheme 1). This cata-
lyst was characterized using X-ray diffraction (XRD), transmission
electron microscopy (TEM), scanning electron microscopy (SEM),
energy-dispersive X-ray spectroscopy (EDS), dynamic laser scatter-
ing (DLS), Fourier transform infrared (FT-IR) spectroscopy, vibrating
sample magnetometry (VSM), thermogravimetric analysis (TGA)
and inductively coupled plasma atomic emission spectroscopy
(ICP-OES).
Catalyst Characterization
The prepared catalyst was characterized using several techniques.
In order to investigate the crystal phase of Pd-ATBA-MNPs, XRD
analysis was performed and the pattern of this sample is shown
in Fig. 1. As can be seen, the iron oxide phase is identified by the
peak positions at 30.2° (2 2 0), 35.6° (3 1 1), 43.3° (4 0 0), 54.1° (4 2
2), 57.4° (5 1 1) and 63.1° (4 4 0), which is consistent with the stan-
dard Fe3O4 XRD spectrum.[12] These results reveal that the surface
modification of the Fe3O4 nanoparticles does not lead to their
phase change. Also the XRD pattern of Pd-ATBA-MNPs contains a
General Procedure for C–C Coupling Reaction using Sodium
Tetraphenylborate (Suzuki Reaction)
A mixture of aryl halide (1 mmol), sodium tetraphenylborate (0.5
mmol), Na2CO3 (3 mmol) and Pd-ATBA-MNPs (0.004 g, 0.66 mol%)
was stirred in water at 80°C. The progress of the reaction was mon-
itored using TLC. After completion of the reaction, the mixture was
cooled to room temperature and the catalyst was separated using
an external magnet and washed with diethyl ether. The reaction
mixture was extracted with water and diethyl ether. The organic
layer was dried over Na2SO4 (1.5 g). Then the solvent was evapo-
rated and pure biphenyl derivatives were obtained in good to ex-
cellent yields.
General Procedure for Coupling of Aryl Halides with
Phenylboronic Acid (Suzuki Reaction)
A mixture of aryl halide (1 mmol), phenylboronic acid (1 mmol),
Na2CO3 (3 mmol) and Pd-ATBA-MNPs (0.005 g, 0.82 mol%) was
added to a reaction vessel. The mixture was stirred in water at
80°C and the progress of the reaction was monitored using TLC. Af-
ter completion of the reaction, the catalyst was separated using an
external magnet and washed with ethyl acetate. The reaction mix-
ture was extracted with water and ethyl acetate and the organic
layer dried over anhydrous Na2SO4 (1.5 g). Then the solvent was
evaporated and pure biphenyl derivatives were obtained in good
to excellent yields.
Scheme 1. Synthesis of Pd-ATBA-MNPs.
3 1 1
900.0
800.0
700.0
600.0
500.0
400.0
300.0
200.0
100.0
0.0
2 2 0
General Procedure for Coupling of Aryl Halides with Butyl Ac-
rylate or Acrylonitrile (Heck Reaction)
4 4 0
Pd
4 0 0
Pd
5 1 1
4 2 2
Pd
A mixture of aryl halide (1 mmol), alkene (1.2 mmol), Na2CO3 (3
mmol) and Pd-ATBA-MNPs (0.010 g, 1.64 mol%) was stirred in
poly(ethylene glycol) (PEG) at 100–120°C and the progress of
the reaction was monitored using TLC. After completion of the
reaction, the mixture was cooled to room temperature and the
catalyst was separated using an external magnet and washed
with diethyl ether. The reaction mixture was extracted with wa-
ter and diethyl ether. The organic layer was dried over Na2SO4
0.0
10.0
20.0
30.0
40.0
/ degree
50.0
60.0
70.0
80.0
2
Figure 1. XRD pattern of Pd-ATBA-MNPs.
Appl. Organometal. Chem. 2016, 30, 422–430
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

A. Ghorbani-Choghamarani, B. Tahmasbi and P. Moradi
In order to extend the characterization of the catalyst, DLS anal-
ysis of Fe3O4 nanoparticles and Pd-ATBA-MNPs was performed.
The DLS results for Fe3O4 nanoparticles and Pd-ATBA-MNPs are
shown in Fig. 3. In this analysis we find that as-prepared Fe3O4
nanoparticles are 78.1 nm in diameter, while after immobilization
of the palladium complex on Fe3O4, the size is increased to 93.8
nm in diameter. This increase in particle diameter is due to the pres-
ence of organic layers and palladium complex on the surface of
Fe3O4 nanoparticles. The observed particle size from DLS analysis
is slightly larger than that found using TEM or XRD due to the effect
of agglomeration of nanoparticles and solvation. On the basis of
100
80
a
60
b
40
20
0
-10000 -8000 -6000 -4000 -2000
0
2000 4000 6000 8000 10000
-20
-40
-60
-80
-100
Figure 2. (a, b) TEM and (c) SEM images of Pd-ATBA-MNPs. (d) EDS
spectrum of Pd-ATBA-MNPs.
series of peaks (39.9°, 46.6° and 67.6°) which are indexed to Pd on
the surface of Fe3O4.[25] The average size of nanocatalyst particle di-
ameter is calculated to be 12.14 nm from the XRD results using
Scherrer’s equation (D = kλ/β cos θ), which is confirmed from TEM
(Figs 2(a) and (b)) and SEM (Fig. 2(c)) images. TEM and SEM images
provide more accurate information as to the particle size and mor-
phology of the catalyst particles. Figure 2 shows the SEM and TEM
images of Pd-ATBA-MNPs. It can be seen that most of the particles
are quasi-spherical with an average diameter of about 10–15 nm,
which is in accord with the XRD results. Also, the size and morphol-
ogy of Pd-ABA-MNPs are quite homogeneous.
H (Oe)
Figure 4. Magnetization curves for (a) Fe3O4 and (b) Pd-ATBA-MNPs at
room temperature.
To characterize the catalyst in terms of the supporting palladium
metal on Fe3O4 surface, the metal content of Pd-ATBA-MNPs was
investigated using EDS. As shown in Fig. 2(d), the EDS spectrum
of Pd-ATBA-MNPs shows the presence of Fe, O, Si, C, S and N, as well
as Pd species in the surface of the catalyst. In order to determine
the exact amount of Pd in Pd-ATBA-MNPs, ICP-OES was used. From
this analysis, the amount of Pd in the catalyst is found to be 1.64 ×
10À3 mol gÀ1
.
Figure 3. DLS measurements of (A1, A2) Fe3O4 nanoparticles and (B1, B2)
Figure 5. FT-IR spectra of (a) Fe3O4 MNPs, (b) SH-MNPs, (c) ATBA-MNPs and
Pd-ATBA-MNPs.
(d) Pd-ATBA-MNPs.
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2016, 30, 422–430

Pd-ATBA-MNPs applied as nanocatalyst in C–C bond forming
110
105
100
95
The magnetic properties of Fe3O4 nanoparticles and Pd-ATBA-
MNPs were measured using VSM at room temperature. The room
temperature magnetization curves of Fe3O4 nanoparticles and Pd-
ATBA-MNPs are shown in Fig. 4. VSM measurements for Fe3O4
nanoparticles show that the saturation magnetization (Ms) is 74.09
emu gÀ1 (Fig. 4(a)), while Ms of Pd-ATBA-MNPs is decreased to
42.16 emu gÀ1 (Fig. 4(b)).[26] On the basis of these results, the
successful grafting of organic layers including palladium complex
on Fe3O4 is verified.
90
85
80
Successful functionalization of the MNPs can be deduced from
FT-IR spectra. The FT-IR spectra for bare Fe3O4 nanoparticles, SH-
MNPs, ATBA-MNPs and Pd-ATBA-MNPs are shown in Fig. 5. The
strong band at 580 cmÀ1 comes from the vibrations of Fe O bonds
of Fe3O4.[23] The spectrum of Fe3O4 shows a stretching vibration at
3440 cmÀ1 which incorporates the contributions from both sym-
metric and asymmetric modes of O H bonds which are attached
to the surface of Fe3O4 nanoparticles. Also, a peak appears at
1631 cmÀ1 corresponding to the stretching vibrational mode of
an adsorbed water layer.[12,23] Immobilization of MPTMS on the sur-
face of MNPs was indicated by the appearance of two peaks at 2922
and 2852 cmÀ1, assigned to the C H stretching vibrations, and also
S H stretching vibration modes as a weak band that appears near
2450 cmÀ1 (Fig. 5(b)) which is absent in the spectrum of ATBA-
MNPs (Fig. 5(c)). Reaction of isatoic anhydride with MPTMS
produces ATBA-MNPs for which the presence of carbonyl group is
indicated by the band at 1630–1640 cmÀ1 (Fig. 5(c)). In addition,
in the spectrum of Pd-ATBA-MNPs (Fig. 5(d)) the broad band in
the range 1400–1650 cmÀ1 is attributed to the formation of
palladium complex. All of these bands reveal that the surface of
Fe3O4 nanoparticles is successfully modified with organic layers.
Bond formation between the nanoparticles and the complex can
be inferred from TGA. The TGA curve of the Pd-ATBA-MNPs shows
75
70
65
60
25
125
225
325
425
525
625
725
Temperature( C)
Figure 6. TGA curves of Fe3O4 MNPs (black), SH-MNPs (blue), ATBA-MNPs
(red) and Pd-ATBA-MNPs (green).
Scheme 2. Carbon–carbon coupling reaction using sodium
tetraphenylborate in the presence of Pd-ATBA-MNPs.
this analysis, the successful immobilization of organic layers includ-
ing palladium complex on the Fe3O4 surface is verified.
Table 1. Optimization of reaction conditions for C–C coupling reaction of iodobenzene with sodium tetraphenylborate in the presence of Pd-ATBA-
MNPs
Entry
Catalyst (mg)
Solvent
Base
Temperature (°C)
Time (min)
Yield (%)a
b
1
—
10
8
PEG
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
NaHCO3
Et3N
80
80
80
80
80
80
80
80
80
80
80
80
60
40
r.t.
60
r.t.
300
10
20
25
30
60
30
70
25
30
30
30
30
30
30
420
420
—
2
PEG
98
96
96
97
74
93
45
98
88
61
60
62
47
21
88
55
3
PEG
4
6
PEG
5
4
PEG
6
2
PEG
7
4
EtOH
CH3COOEt
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
8
4
9
4
10
11
12
13
14
15
16
17
4
4
4
NaOH
4
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
4
4
4
4
a
Isolated yield.
b
No reaction.
Appl. Organometal. Chem. 2016, 30, 422–430
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

A. Ghorbani-Choghamarani, B. Tahmasbi and P. Moradi
Table 2. Catalytic C–C coupling reaction of aryl halides using NaBPh4 in the presence of catalytic amount of Pd-ATBA-MNPs (4 mg, 0.66 mol%) in H2O at
80°C
Entry
Aryl halide
Iodobenzene
Time (min)
Yield (%)a
TOF (hÀ1
)
Melting point (°C)
1
2
3
4
5
6
7
8
9
25
55
98
97
79
96
95
95
94
96
81b
356.36
160.33
32.64
67–69[16]
42–43[27]
Oil[28]
41–43[27]
159–161[29]
68–69[16]
70–72[27]
80–83[29]
64–66[27]
4-Iodotoluene
2-Iodotoluene
220
25
4-Bromotoluene
4-Bromophenol
Bromobenzene
4-Bromochlorobenzene
4-Bromobenzonitrile
Chlorobenzene
349.09
575.75
287.87
854.54
872.72
8.41
15
30
10
10
350
a
Isolated yield.
b
Reaction conditions: aryl halide (1 mmol), Pd-ATBA-MNPs (10 mg, 1.65 mol%), sodium tetraphenylborate (0.5 mmol) and Na2CO3 (3 mmol) in PEG at
100°C.
Catalytic Study
After characterization of the catalyst structure, its catalytic activity
was studied in C–C coupling reactions, namely Suzuki and Heck re-
actions. Initially, we were interested in finding a simple and efficient
method for carbon–carbon coupling bond formation in the pres-
ence of Pd-ATBA-MNPs as an efficient nanocatalyst (Scheme 2).
In order to optimize reaction conditions, initially we examined
the reaction of iodobenzene (1 mmol) with sodium tetraphenyl-
borate (0.5 mmol) as a model reaction and the effects of various pa-
rameters such as solvent, temperature, base and amount of catalyst
were studied for this model reaction (Table 1). At first, we find that
the reaction does not proceed in the absence of Pd-ATBA-MNPs
(Table 1, entry1). Then, we examined the effect of various solvents,
PEG, EtOH, CH3COOEt and water, at 80°C (Table 1, entries 6–9). The
best results are obtained for water. Also, the effect of temperature
was studied (Table 1, entries 9, 13–17) and excellent yield of the
product is obtained at 80°C (Table 1, entry 9). Also, the coupling
of iodobenzene and sodium tetraphenylborate was performed in
the presence of Pd-ATBA-MNPs in water at 80°C using 3 equiv. of
Scheme 3. Pd-ATBA-MNP-catalysed Suzuki reaction.
the mass loss of the organic functional groups as the catalyst de-
composes upon heating. Figure 6 shows the TGA curves for bare
Fe3O4 nanoparticles, SH-MNPs, ATBA-MNPs and Pd-ATBA-MNPs.
The TGA curves of all samples show a small amount of weight loss
below 200°C, attributed to desorption of physically adsorbed sol-
vents and surface hydroxyl groups.[12] In the TGA curve of the cata-
lyst, a weight loss of about of 22% from 200 to 600°C results from
the decomposition of immobilized organic moieties on the Fe3O4
surface. Meanwhile, weight losses of about 2, 5 and 9% from 200
to 600°C occur for Fe3O4 MNPs, SH-MNPs and ATBA-MNPs, respec-
tively. These results indicate that the palladium complex has been
supported on the surface of Fe3O4 nanoparticles.
Table 3. Optimization of Suzuki reaction conditions for coupling of 4-nitrobromobenzene (1 mmol) with PhB(OH)2 (1 mmol) in the presence of Pd-ATBA-
MNPs
Entry
Catalyst (mg)
Solvent
H2O
Base
Amounts of base (mmol)
Temperature (°C)
Time (min)
Yield (%)a
b
—
1
—
3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
NaHCO3
Et3N
3
80
80
80
80
80
80
80
80
80
60
r.t.
80
120
120
30
20
30
30
30
30
30
30
30
30
2
H2O
3
98
98
3
5
H2O
3
4
10
5
H2O
3
99
5
EtOH
CH3COOEt
PEG
3
52
6
5
3
75
7
5
3
20
8
5
H2O
3
91
9
5
H2O
3
38
10
11
12
5
H2O
Na2CO3
Na2CO3
Na2CO3
3
51
5
H2O
3
Trace
42
5
H2O
1.5
a
Isolated yield.
b
No reaction after 10 h.
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2016, 30, 422–430

Pd-ATBA-MNPs applied as nanocatalyst in C–C bond forming
Table 4. Coupling of aryl halides with PhB(OH)2 in the presence of catalytic amount of Pd-ATBA-MNPs (5 mg, 0.82 mol%) in water at 80°C
Entry
Aryl halide
Time (min)
Yield (%)a
TOF (hÀ1
)
Melting point (°C)
1
2
3
4
5
6
7
8
9
10
Iodobenzene
40
50
97
92
99
85
93
90
98
93
75
68b
177.44
134.63
482.93
103.66
21.95
68[16]
44–45[27]
157–160[29]
45[27]
53–54[30]
68[16]
111–113[27]
83[29]
68–70[27]
83[29]
4-Iodotoluene
4-Bromophenol
15
4-Bromotoluene
60
4-Bromoaniline
310
70
Bromobenzene
94.08
4-Bromonitrobenzene
4-Bromobenzonitrile
4-Bromochlorobenzene
4-Chlorobenzonitrile
30
239.02
272.19
156.79
36.86
25
35
135
a
Isolated yield.
b
Reaction conditions: aryl halide (1 mmol), Pd-ATBA-MNPs (5 mg, 0.82 mol%), PhB(OH)2 (1 mmol) and Na2CO3 (3 mmol) in PEG at 100°C.
donating (Table 2, entries 2–5) and electron-withdrawing (Table 2,
entries 7 and 8) groups on the aromatic ring, with sodium
tetraphenylborate were then investigated to confirm the generality
of the present method. However, the reaction with aryl chloride
shows less reactivity towards coupling and requires much more
Scheme 4. Pd-ATBA-MNP-catalysed Heck reaction.
Pd-ATBA-MNPs (10 mg, 1.65 mol%) than that for aryl iodides and
bromides (Table 2, entry 9). It is worth mentioning that all products
are obtained in good to excellent yields. Therefore, the results
reveal that this methodology is effective for a wide range of aryl
halides including chlorides, bromides and iodides.
In order to extend the general application of Pd-ATBA-MNPs as a
catalyst, reactions of various aryl halides with phenylboronic acid
were studied (Scheme 3). In order to optimize the reaction condi-
tions and obtain the best catalytic system, the reaction of 4-
nitrobromobenzene (1 mmol) with phenylboronic acid (1 mmol)
was used as a model reaction, and was examined under various re-
action parameters such as base, solvent, temperature and amount
various bases (Table 1, entries 10–12). The most effective base is
Na2CO3. Therefore, the best result is obtained by carrying out the
reaction with Pd-ATBA-MNPs (0.004 g, 0.66 mol%), iodobenzene
(1 mmol), sodium tetraphenylborate (0.5 mmol) and Na2CO3
(3 mmol) in water at 80°C (Table 1, entry 9).
In order to show the efficiency of this catalytic system, a variety of
aryl iodides, chlorides and bromides were coupled with sodium
tetraphenylborate in the presence of Pd-ATBA-MNPs (4 mg, 0.66
mol%) to produce corresponding biphenyls (Table 2). The reactions
of the various aryl halide derivatives, including those with electron-
Table 5. Optimization of reaction conditions for C–C coupling reaction of iodobenzene with butyl acrylate
Entry
Catalyst (mg)
Solvent
Base
Amounts of base (mmol)
Temperature (°C)
Time (min)
Yield (%)a
1
3
5
PEG
PEG
PEG
PEG
PEG
DMSO
PEG
H2O
PEG
PEG
PEG
PEG
PEG
PEG
PEG
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Et3N
3
3
3
3
3
3
3
3
3
3
3
3
3
3
1.5
100
100
100
100
100
100
100
100
80
90
90
50
40
30
70
70
70
180
70
70
70
70
70
85
42
51
2
3
7
60
4
10
15
10
10
10
10
10
10
10
10
10
10
90
5
90
6
40
7
55
8
Trace
63
9
10
11
12
13
14
15
100
100
100
100
100
100
51
NaOEt
10
NaHSO4
NaHCO3
NaOH
20
40
15
Na2CO3
51
a
Isolated yield.
Appl. Organometal. Chem. 2016, 30, 422–430
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

A. Ghorbani-Choghamarani, B. Tahmasbi and P. Moradi
Table 6. Coupling of aryl halides with butyl acrylate or acrylonitrile (Heck reaction) in the presence of catalytic amount of Pd-ATBA-MNPs (10 mg, 1.64
mol%)
Entry
Aryl halide
Iodobenzene
Alkene
Time (min)
Yield (%)a
TOF (hÀ1
)
Melting point (°C)
1
Butyl acrylate
Butyl acrylate
Butyl acrylate
Butyl acrylate
Butyl acrylate
Butyl acrylate
Butyl acrylate
Butyl acrylate
Butyl acrylate
Butyl acrylate
Acrylonitrile
Acrylonitrile
Acrylonitrile
Acrylonitrile
40
80
90
94
82.32
42.99
28.68
15
Oil[31]
Oil[32]
Oil[31]
Oil[32]
Oil[32]
Oil[31]
Oil[31]
Oil[32]
59–60[32]
60[32]
Oil[33]
Oil[33]
Oil[34]
Oil[34]
2
4-Iodotoluene
3
4-Iodoanisole
125
200
1560
215
500
60
98b
82b
81b
94b
86
4
2-Iodotoluene
5
4-Bromotoluene
4-Bromoanisole
Bromobenzene
3-Bromopyridine
4-Bromonitrobenzene
4-Chloronitrobenzene
Iodobenzene
1.90
15.99
6.29
50
6
7
8
82
9
105
2880
240
1080
295
480
91
31.71
1.1
10
11
12
13
14
87b
97b
93b
96b
95b
14.79
3.15
11.90
7.24
Bromobenzene
4-Iodotoluene
4-Bromotoluene
a
Isolated yield.
b
Reaction temperature: 120°C.
Our prepared catalyst not only shows high efficiency in the
Suzuki reaction, but also exhibits good performance in the Heck
reaction. Therefore, we investigated the Heck reaction in the
presence of Pd-ATBA-MNPs via coupling of various aryl halides with
butyl acrylate or acrylonitrile (Scheme 4).
In order to establish the optimum conditions, a model reaction
using iodobenzene and butyl acrylate was selected to optimize
the reaction under various conditions. The activity of the catalyst
in various amounts was studied, and comparable yields are ob-
tained (Table 5). The best result is observed with 10 mg (1.64 mol%)
of Pd-ATBA-MNPs (Table 5, entry 4). Several solvents were also
tested; among them PEG gives the best result. Next we examined
the effect of the base on the outcome of the coupling reaction
(Table 5, entries 9–15). It is found that Na2CO3 gives a better result
than Et3N, NaOEt, NaHSO4, NaHCO3 and NaOH.
The scope of this methodology was evaluated in the Heck
reaction for other substrates and the results are summarized in
Table 6. This methodology is applicable for a wide range of aryl
halides with both electron-donating groups (Table 6, entries 2–
6, 13, 14) and electron-withdrawing groups (Table 6, entries 9
and 10) in the reaction with butyl acrylate. In this study, acryloni-
trile was applied as another alkene (Table 6, entries 11–14) under
the optimized conditions with various aryl halides (bromides and
iodides) and all products are obtained in good to excellent
yields. This procedure is very simple and has the ability to toler-
ate a variety of aryl halides.
100
95
90
85
80
75
70
65
60
55
50
a
b
1
2
3
4
5
6
7
8
9
Run number
Figure 7. Recyclability of Pd-ATBA-MNPs in the coupling of iodobenzene (1
mmol) with (a) NaBPh4 (0.5 mmol) and (b) PhB(OH)2 (1 mmol) under reaction
conditions.
of Pd-ATBA-MNPs (Table 3). As expected, no product is observed in
the absence of the catalyst (Table 3, entry 1). Initially, the model re-
action was carried out in several solvents, EtOH, water, CH3COOEt
and PEG, and it is found that water gives the best yield; in other sol-
vents lower yields are observed (Table 3, entries 4–7). The reaction
is significantly affected by the nature of base and the additive used.
Therefore, a variety of bases were tested (Table 3, entries 7–9). The
best result is observed using 3 mmol of Na2CO3. Therefore, the best
results are obtained in water at 80°C in the presence of 5 mg (0.82
mol%) of Pd-ATBA-MNPs using 3 mmol of Na2CO3 (Table 3, entry 3).
After the optimization of the reaction conditions, various aryl
halides including several functional groups were reacted under
optimum conditions and the corresponding biphenyl are ob-
tained in short reaction times with good to excellent yields
(Table 4). The experimental procedure is very simple and also a
wide range of aryl halides (chloride, bromide and iodide)
possessing electron-donor and electron-withdrawing substitu-
ents can be successfully employed to prepare the corresponding
biphenyls in excellent yields at room temperature. Aryl bromides
and aryl iodides react in shorter times compared to aryl chlorides
(Table 4, entry 10).
Reusability of Catalyst
The reusability of catalysts is an important advantage for commercial
applications. Therefore, the recovery and recyclability of Pd-ATBA-
MNPs were studied in the coupling reaction of iodobenzene with
phenylboronic acid and sodium tetraphenylborate. After completion
of the reaction, the catalyst was easily and rapidly recovered from the
reaction mixture using an external magnet. The remaining magnetic
nanocatalyst was further washed with diethyl ether to remove resid-
ual product and decantation of the reaction mixture. Then, the reac-
tion vessel was charged with fresh substrate and subjected to the
next run. As shown in Fig. 7, the catalyst can be recycled over nine
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2016, 30, 422–430

Pd-ATBA-MNPs applied as nanocatalyst in C–C bond forming
Table 7. Comparison of results for Pd-ATBA-MNPs with those for other catalysts in the coupling of iodobenzene with phenylboronic acid
Entry
1
Catalyst (mol% of Pd)
Conditions
Time (h)
5
Yield (%)a
Ref.
[3]
Polymer-anchored Pd(II) Schiff base
complex (0.5 mol%)
K2CO3, DMF–H2O (1:1), 80°C
99
[31]
[35]
[36]
[37]
[38]
[39]
[40]
[41]
[42]
2
NHC–Pd(II) complex (1.0 mol%)
Fe3O4@SiO2@mSiO2–Pd(II) (0.5 mol%)
PVP–Pd NPs (0.8 × 10À3 mol%)
Pd NPs (1.0 mol%)
THF, Cs2CO3, 80°C
EtOH, K2CO3, 80°C
K2PO4, EtOH/H2O, 90°C
H2O, KOH, 100°C
12
3
88
98
94
95
94
95
88
99
97
3
4
2
5
12
2
6
CA/Pd(0) (0.5–2.0 mol%)
H2O, K2CO3, 100°C
DMF, Cs2CO3, 130°C
EtOH/H2O, K2CO3, 80°C
DMF, Cs2CO3, 100°C
H2O, K2CO3, 100°C
7
PdCl2 (0.05 mol%)
2
8
Pd/Au NPs (4.0 mol%)
24
24
3
9
Pd(II)–NHC complex (0.01 mmol)
N,N′-bis(2-pyridinecarboxamide)-1,2-benzene
palladium complex (1 mol%)
Pd-MPTAT-1 (0.02 g)
10
[43]
[44]
[45]
11
12
13
14
NaOH, DMF–H2O (1:5), 85°C
K2CO3, 1,4-dioxane–H2O (5:1), 80°C
K2CO3, 1,4-dioxane–H2O (1:1), 95°C
H2O, Na2CO3, 80°C
8
10
4
95
96
91
97
LDH–Pd(0) (0.3 g)
PANI–Pd (2.2 mol%)
Pd-ATBA-MNPs (0.82 mol%)
0.67
This work
a
Isolated yield.
runs without any significant loss of its catalytic activity. The average
isolated yield for nine successive runs is 92.5 and 94.8%, which clearly
demonstrates the practical recyclability of this catalyst.
OES. The Pd-ATBA-MNPs exhibit excellent catalytic activity, high re-
usability and air and moisture stability for the Heck and Suzuki reac-
tions. This methodology is effective for a wide range of aryl halides
including chlorides, bromides and iodides. A high conversion of
substrates was obtained in C–C coupling reactions using sodium
tetraphenylborate, phenylboronic acid, acrylonitrile and butyl acry-
late in the presence of this catalyst. Also, the catalyst can be reused
up to nine times without any significant loss of its activity or palla-
dium leaching.
In order to determine any leaching of palladium in the reaction
mixture and to show that Pd-ATBA-MNPs are a heterogeneous
catalyst, a hot filtration test was performed in the Suzuki reaction
of iodobenzene with phenylboronic acid. In this study we find that
the yield of product in half the reaction time is 52%. Then the
reaction was repeated and in half of the reaction time the catalyst
was separated and the filtrate allowed to react further. The yield
of reaction in this stage is 54%, confirming that the leaching of
palladium does not occur.
Also, to measure the exact leaching of palladium in the cata-
lyst, the amount of palladium in Pd-ATBA-MNPs was determined
using ICP-OES after five recycles. The amount of palladium in the
catalyst is found to be 1.62 × 10À3 mol gÀ1 based on ICP-OES for
the catalyst after five re-use runs, meaning that the catalyst
leaching is only 0.11%. The results from hot filtration test and
ICP-OES technique show that leaching of palladium during the
reaction is negligible.
Acknowledgments
This work was supported by the research facilities of Ilam University,
Ilam, Iran.
References
[1] G. P. McGlacken, L. M. Bateman, Chem. Soc. Rev. 2009, 38, 2447.
[2] Y. Wang, J. Luo, Z. Liu, Appl. Organometal. Chem. 2013, 27, 601.
[3] S. M. Islam, A. S. Roy, P. Mondal, N. Salam, Appl. Organometal. Chem.
2012, 26, 625.
[4] S. Pasa, Y. S. Ocak, H. Temel, T. Kilicoglu, Inorg. Chim. Acta 2013, 405, 493.
[5] S. Nadri, M. Joshaghani, E. Rafiee, Appl. Catal. A 2009, 362, 163.
[6] A. R. Hajipour, F. Raiee, J. Iran. Chem. Soc. 2015, 12, 1177.
[7] G. Herve, G. Sartori, G. Enderlin, G. Mackenzie, C. Len, RSC Adv. 2014,
4, 18558.
[8] C. W. Lim, I. S. Lee, Nano Today 2010, 5, 412.
[9] V. Polshettiwar, R. Luque, A. Fihri, H. Zhu, M. Bouhrara, J. M. Basset,
Chem. Rev. 2011, 111, 3036.
[10] F. Havasi, A. Ghorbani-Choghamarani, F. Nikpour, New J. Chem. 2015,
39, 6504.
[11] D. Astruc, F. Lu, J. R. Aranzaes, Angew. Chem. Int. Ed. 2005, 44, 7852.
[12] M. Hajjami, B. Tahmasbi, RSC Adv. 2015, 5, 59194.
[13] S. Shylesh, V. Schunemann, W. R. Thiel, Angew. Chem. Int. Ed. 2010,
49, 3428.
Comparison of Catalyst
In order to examine the efficiency of the procedures presented, we
compared the results of the coupling of iodobenzene with
phenylboronic acid (Table 7) with previously reported results. This
catalyst shows shorter reaction time and higher reaction yield than
the other catalysts. Also this nanomagnetic catalyst is superior in
terms of price, non-toxicity, stability and ease of separation than
the previously reported ones. In addition, the recoverability and
recyclability of this catalyst are more rapid and easier than those
of the other catalysts.
[14] A. Ghorbani-Choghamarani, B. Tahmasbi, F. Arghand, S. Faryadi, RSC
Adv. 2015, 5, 92174.
[15] M. Nikoorazm, A. Ghorbani-Choghamarani, N. Noori, Appl. Organometal.
Conclusions
Chem. 2015, 29, 328.
[16] A. Ghorbani-Choghamarani, F. Nikpour, F. Ghorbani, F. Havasi, RSC Adv.
2015, 5, 33212.
[17] P. Sharma, A. P. Singh, Catal. Sci. Technol. 2014, 4, 2978.
[18] S. S. Soni, D. A. Kotadia, Catal. Sci. Technol. 2014, 4, 510.
An efficient heterogeneous catalyst (Pd-ATBA-MNPs) was synthe-
sized. This catalyst was characterized using several techniques,
namely FT-IR spectroscopy, XRD, VSM, TEM, SEM, EDS and ICP-
Appl. Organometal. Chem. 2016, 30, 422–430
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

A. Ghorbani-Choghamarani, B. Tahmasbi and P. Moradi
[19] M. M. Heravi, S. Sadjadi, J. Iran. Chem. Soc. 2009, 6, 1.
[20] M. Melchionna, S. Marchesan, M. Prato, P. Fornasiero, Catal. Sci. Technol.
2015, 5, 3859.
[21] Y. He, C. Cai, Appl. Organometal. Chem. 2011, 25, 799.
[22] A. Rostami, B. Tahmasbi, A. Yari, Bull. Korean Chem. Soc. 2013, 34,
1521.
[23] A. Ghorbani-Choghamarani, Z. Darvishnejad, B. Tahmasbi, Inorg. Chim.
Acta 2015, 435, 223.
[24] A. Ghorbani-Choghamarani, M. Norouzi, J. Mol. Catal. A 2014, 395, 172.
[25] W. Zhang, X. Chen, T. Tang, E. Mijowska, Nanoscale 2014, 6,
12884.
[26] B. Atashkar, A. Rostami, B. Tahmasbi, Catal. Sci. Technol. 2013, 3,
2140.
[27] Y. Y. Peng, J. Liu, X. Lei, Z. Yin, Green Chem. 2010, 12, 1072.
[28] X. Zheng, Q. Yang, Z. Li, Z. Zhu, X. Cui, H. Fu, H. Chen, R. Li, Catal.
Commun. 2014, 57, 143.
[33] Y. Leng, F. Yang, K. Wei, Y. Wu, Tetrahedron 2010, 66, 1244.
[34] L. Wang, H. Li, P. Li, Tetrahedron 2009, 65, 364.
[35] X. Le, Z. Dong, Z. Jin, Q. Wang, J. Ma, Catal. Commun. 2014, 53, 47.
[36] P. M. Uberman, L. A. Pérez, S. E. Martín, G. I. Lacconi, RSC Adv. 2014, 4,
12330.
[37] M. Nasrollahzadeh, S. M. Sajadi, M. Maham, J. Mol. Catal. A 2015,
396, 297.
[38] V. W. Faria, D. G. M. Oliveira, M. H. S. Kurz, F. F. Goncalves,
C. W. Scheeren, G. R. Rosa, RSC Adv. 2014, 4, 13446.
[39] S. J. Sabounchei, A. Hashemi, Inorg. Chem. Commun. 2014, 47, 123.
[40] M. Nasrollahzadeh, A. Azarian, M. Maham, A. Ehsani, J. Ind. Eng. Chem.
2015, 21, 746.
[41] Q. Xu, W. L. Duan, Z. Y. Lei, Z. B. Zhu, M. Shi, Tetrahedron 2005, 61,
11225.
[42] Q. Du, W. Zhang, H. Ma, J. Zheng, B. Zhou, Y. Li, Tetrahedron 2012,
68, 3577.
[29] L. Baia, J. X. Wanga, Adv. Synth. Catal. 2007, 350, 315.
[30] Z. Du, W. Zhou, F. Wang, J. X. Wang, Tetrahedron 2011, 67, 4914.
[31] T. Chen, J. Gao, M. Shi, Tetrahedron 2006, 62, 6289.
[32] N. Iranpoor, H. Firouzabadi, A. Tarassoli, M. Fereidoonnezhad,
Tetrahedron 2010, 66, 2415.
[43] A. Modak, J. Mondal, M. Sasidharan, A. Bhaumik, Green Chem. 2011, 13,
1317.
[44] S. Singha, M. Sahoo, K. M. Parida, Dalton Trans. 2011, 40, 7130.
[45] H. A. Patel, A. L. Patel, A. V. Bedekar, Appl. Organometal. Chem. 2015,
29, 1.
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2016, 30, 422–430