Immobilized palladium on modified magnetic nanoparticles and study of its catalytic activity in suzuki-miyaura C-C coupling reaction

Article abstract of DOI:10.1002/aoc.3440

A new magnetically reusable nanosolid, Fe₃O₄@PPCA@Pd(0) (PPCA = piperidine-4-carboxylic acid), as a versatile and highly effective catalyst was fabricated and characterized using transmission and scanning electron microscopies, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared and energy-dispersive spectroscopies and vibrating sample magnetometry. This nanosolid shows great catalytic activity for the synthesis of biphenyl compounds in short reaction times and with high yields. The magnetic character of this catalyst allows retrieval and multiple uses without appreciable loss of its catalytic activity. Our system not only solves the basic problems of catalyst separation and recovery, but also the reactions can be performed in green media.

Full text of DOI:10.1002/aoc.3440

Full paper
Received: 19 October 2015
Revised: 9 December 2015
Accepted: 14 December 2015
Published online in Wiley Online Library: 6 March 2016
(wileyonlinelibrary.com) DOI 10.1002/aoc.3440
Immobilized palladium on modified magnetic
nanoparticles and study of its catalytic activity
in suzuki–miyaura C–C coupling reaction
Gouhar Azadi and Arash Ghorbani-Choghamarani*
A new magnetically reusable nanosolid, Fe3O4@PPCA@Pd(0) (PPCA = piperidine-4-carboxylic acid), as a versatile and highly
effective catalyst was fabricated and characterized using transmission and scanning electron microscopies, X-ray diffraction,
thermogravimetric analysis, Fourier transform infrared and energy-dispersive spectroscopies and vibrating sample magnetometry.
This nanosolid shows great catalytic activity for the synthesis of biphenyl compounds in short reaction times and with high yields.
The magnetic character of this catalyst allows retrieval and multiple uses without appreciable loss of its catalytic activity. Our system
not only solves the basic problems of catalyst separation and recovery, but also the reactions can be performed in green media.
Copyright © 2016 John Wiley & Sons, Ltd.
Keywords: Fe3O4@PPCA@Pd(0); nanosolid; recyclable; coupling reaction; biphenyl
palladium complexes have received much attention as promising
Introduction
green media and reusable homogeneous catalysts for coupling
reactions.[12–16] Sodium tetraphenylborate (NaBPh4) is a stable,
Heterogeneous catalysts have been extensively employed in various
non-toxic and commercially accessible phenylating agent. The
fields because they have fewer of the drawbacks of homogeneous
cross-coupling reactions of aryl halides with NaBPh4 in the presence
catalysts, such as the difficulties in recovery and regeneration.
of transition metal complexes have been reported.[17] Therefore,
Nanometre-sized catalyst supports have recently attracted a great
herein we report a convenient procedure for the synthesis of a
deal of interest because of their high surface area and outstanding
stability and activity in the liquid phase.[1] In particular, magnetic
new and recoverable nanocatalyst, Fe3O4@PPCA@Pd(0) (PPCA =
piperidine-4-carboxylic acid), with high efficiency for carbon–carbon
nanomaterials have had major impacts on catalysis and many other
areas, such as medicine, drug delivery and remediation. These inex-
bond formation in green media.
pensive materials are accessible via simple syntheses and they can
be easily enhanced/tuned by postsynthetic surface modifications.
Functionalized nanoparticles have emerged as feasible substitutes
Experimental
to conventional materials as robust, active, high-surface-area
catalyst supports.[2]
Materials
The palladium-catalysed Suzuki reaction has been recognized as
The reagents and solvents used in this work were all purchased
one of the most attractive and widely utilized methods for carbon–
from Aldrich and Merck chemical companies and used without
carbon bond formation[3–6] and many homogeneous palladium
further purification. Fourier transform infrared (FT-IR) spectra were
catalysts are used for this reaction.[7,8] One of the major industrial
recorded as KBr pellets with a Bruker VRTEX 70 model FT-IR
disadvantages of performing homogeneously catalysed reactions
spectrophotometer. Powder X-ray diffraction (XRD) patterns were
is the difficulty of separating the catalyst from the product to be
collected using
a Rigaku Dmax 2500 diffractometer with
able to reuse the high-priced catalyst. Heterogenation of existing
homogeneous palladium catalysts would be an attractive solution
to this problem because of their easy separation and simple
recycling. Therefore, many attempts have been performed for
heterogenation of palladium catalysts on a variety of polymeric,
organic and inorganic supports.[9]
nickel-filtered Cu Kα radiation (λ = 1.5418 Å, 40 kV). Transmission
electron microscopy (TEM) images were recorded using a
Zeiss-EM10C TEM. Superparamagnetic properties of the catalyst
were measured with a vibrating sample magnetometry (VSM) in-
strument (MDKFD) operating at room temperature.
Magnetic nanostructured materials are attractive candidates as
heterogeneous catalysts due to their multifunctional properties
such as small size, superparamagnetism, low toxicity, etc.,[10]
especially because they meet the goals of green chemistry.
Magnetic-supported catalysts can be efficiently isolated from the
product solution through a simple magnetic separation process
after completion of a reaction.[11] Recently, magnetic-supported
*
Correspondence to: Arash Ghorbani-Choghamarani, Department of Chemistry,
Faculty of Science, 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, 360–366
Copyright © 2016 John Wiley & Sons, Ltd.

Fe3O4@PPCA@Pd(0)-catalysed C–C coupling reaction
Synthesis of palladium complex immobilized on Fe3O4@PPCA
nanoparticles
(d, C1, J = 72 Hz), 116.17 (d, C6, J = 68 Hz). Anal. Calcd for C12H8F2
(%): C, 75.78; H, 4.24. Found (%): C, 76.38; H, 3.96.
Magnetic Fe3O4@PPCA nanoparticles were prepared through the
chemical co-precipitation method.[20] Then in the next step, the
prepared Fe3O4@PPCA (1000 mg) was added to a solution of Pd
(OAc)2 (500 mg) in ethanol (25 ml). This mixture was refluxed
for 15 h. Pd(II) ions were adsorbed onto the magnetic nanocarrier
and reduced by NaBH4 to produce Fe3O4@PPCA@Pd(0). Subse-
quently, the reaction mixture was cooled to room temperature,
and the solid was separated by magnetic decantation. The
nanomagnetic catalyst was washed with copious amounts of
absolute ethanol and dried under vacuum at room temperature
to yield the immobilized palladium catalyst on magnetic
nanoparticles.
M.p. 119–121°C. FT-IR (KBr, νmax, cmÀ1): 3449, 3074, 1601, 1520,
1439, 1396, 1346, 1269, 1180, 1109, 890, 851, 816, 760, 695, 612,
578. 1H NMR (400 MHz, DMSO, δ, ppm): 8.29–8.33 (m, 2Harom),
7.99–8.02 (m, 2Harom), 7.94–7.97 (m,1Harom), 7.68–7.71 (m,1Harom),
7.58–7.65 (m, 1Harom). 13C NMR (100 MHz, DMSO, δ, ppm): 151.63
(dd, C3, J1 = 78 Hz, J2 = 48 Hz), 149.18 (dd, C4, J1 = 68 Hz,
J1 = 48 Hz), 147.44 (s, C4’), 144.72 (s, C1’), 135.83 (dd, C2, J1 = 26 Hz,
J2 = 16 Hz), 128.52 (s, C2’ and C6’), 124.86 (dd, C5, J1 = 26 Hz,
J2 = 16 Hz), 124.55 (s, C3’ and C5’), 118.76 (d, C1, J = 68 Hz), 117.08
(d, C6, 72 Hz). Anal. Calcd for C12H7F2NO2 (%): C, 61.28; H, 3.00; N,
5.96. Found (%): C, 60.88; H, 2.65; N, 5.76.
General procedure for C–C coupling reaction of aryl halides
with NaBPh4
A 10 ml pressure-safe vial was charged with aryl halides (1 mmol),
NaBPh4 (0.5 mmol), Na2CO3 (3 mmol), Fe3O4@PPCA@Pd(0) (8 mg,
0.37 mol%) and 2 ml of poly(ethylene glycol) (PEG). The vial was
then sealed and heated at 100°C for the appropriate time. After
completion of the reaction (monitored using TLC), the reaction mix-
ture was diluted with water and the resultant mixture was extracted
with diethyl ether to isolate the products, dried over anhydrous
Na2SO4 (1.5 g), filtered off and evaporated under reduced pressure
to afford the corresponding pure products.
Results and discussion
In continuation of our previous works on the surface modification
of nanoparticles for various organic transformations,[18–20] in the
study reported here we decided to immobilize palladium nanopar-
ticles on the surface of Fe3O4@PPCA to achieve Fe3O4@PPCA@Pd(0)
nanocatalyst (Scheme 1).
General procedure for C–C coupling reaction of aryl halides
with phenylboronic acid
To a stirred solution of aryl halides (1 mmol), Na2CO3 (3 mmol) and
phenylboronic acid (1 mmol) in PEG (2 ml), Fe3O4@PPCA@Pd(0)
nanoparticles (8 mg, 0.37 mol%) were added and the reaction
mixture was stirred at 100°C. After completion of the reaction
(monitored using TLC), the catalyst was separated using an external
magnet. The mixture was diluted with diethyl ether and water and
the extracted organic layer was dried over Na2SO4 (1.5 g), filtered
off and evaporated under reduced pressure to afford the corre-
sponding pure products.
Catalyst characterization was performed using FT-IR spectros-
copy, TEM, XRD, thermogravimetric analysis (TGA), scanning elec-
tron microscopy (SEM), energy-dispersive spectroscopy (EDS) and
NH
HN
NH
O
O
HN
O
O
O
O
O
Fe3O4 NP
piperidine-4-carboxylic acid
NH4OH, N2, 80 °C, 6h
O
+
O
Representative NMR data
O
FeCl2. 4H2O
O
FeCl3. 6H2O
O
O
HN
O
Fe3O4@PPCA
NH
N
H
M.p. 38–39°C. FT-IR (KBr, νmax, cmÀ1): 3440, 3072, 1608, 1528,
1486, 1405, 1306, 1269, 1234, 1177, 1115, 1079, 1032, 883, 820,
764, 688, 577. 1H NMR (400 MHz, DMSO, δ, ppm): 7.74–7.80
(m, 1Harom), 7.68–7.70 (m, 2Harom), 7.52–7.56 (m, 2Harom), 7.45–7.50
(m, 2Harom), 7.38–7.42 (m, 1Harom). 13C NMR (100 MHz, DMSO,
δ, ppm): 151.11 (dd, C3, J1 = 272 Hz, J2 = 48 Hz), 148.67 (dd, C4,
J1 = 276 Hz, J2 = 52 Hz), 138.43 (s, C1’), 138.26 (dd, C2,
J1 = 24 Hz, J2 = 16 Hz), 129.47 (s, C3’ and C5’), 128.45 (s, C2’ and
C6’), 127.23 (s, C4’), 123.86 (dd, C5, J1 = 24 Hz, J2 = 12 Hz), 118.34
O
O
O
N
Pd
Fe3O4
N
O
Scheme 1. Synthesis of Fe3O4@PPCA@Pd(0).
Appl. Organometal. Chem. 2016, 30, 360–366
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

G. Azadi and A. Ghorbani-Choghamarani
VSM. Successful immobilization of PPCA on the surface of
Fe3O4@PPCA nanoparticles can be inferred from FT-IR spectra
(Fig. 1). The presence of magnetite nanoparticles is observable by
the strong adsorption band at 585 cmÀ1, corresponding to Fe–O
vibrations. The presence of a peak at around 2870–2900 cmÀ1 cor-
responds to the aliphatic C–H stretching of the methylene groups,
which is observable in the samples. The peak at 3437 cmÀ1 is due
to stretching vibration of N–H, which is overlapped by the O–H
stretching vibrations. Furthermore, it has been reported that the
wavenumber separation between the COOÀ (as) and COOÀ (s)
FT-IR bands can be used to distinguish the type of interaction. Since
the wavenumber separation between the COOÀ (as) and COOÀ (s)
bands is 172 cmÀ1 (1595–1423 = 172 cmÀ1), it can be concluded
that the interaction between the COOÀ group and the Fe atom is
covalent and bridging bidentate.[21] These results provide evidence
that the PPCA groups are successfully attached to the surface of
Fe3O4 nanoparticles. Reaction of Fe3O4@PPCA with Pd(OAc)2 and
then NaBH4 produces Fe3O4@PPCA@Pd(0). Figure 1(c) indicates
that the bending vibration absorption band of N–H at 1418 сmÀ1
is shifted to lower wavenumbers (1418 to 1398 сmÀ1), which is
perhaps due to the robust interaction between the N groups of
PPCA and metal particles.[22]
groups have been reported to desorb at temperatures above 260°C.
Also the differential thermogravimetry (DTG) curve of the
nanocatalyst is shown in Fig. 2. The peak in the DTG curve shows
that the fastest weight loss occurs approximately between 260
and 320°C.
TEM micrographs supply exact information of particle size and
morphology of the catalyst (Fig. 3). The TEM image of
Fe3O4@PPCA@Pd(0) confirms that the catalyst is composed of
uniform nanometre-sized particles and the palladium is found to be
highly dispersed on the surface of the Fe3O4@PPCA with a diameter
size of approximately 4–22 nm. The diameter of the palladium parti-
cles calculated from XRD using the Sherrer equation is 5.63 1 nm.
TGA was used to determine the percentage of chemisorbed or-
ganic functional groups on the magnetic nanoparticles (Fig. 2).
The initial weight loss up to 100°C is due to the removal of physi-
cally adsorbed solvent, water and surface hydroxyl groups. Organic
Figure 3. TEM micrographs of Fe3O4@PPCA@Pd(0) with different
magnifications.
Figure 1. Comparison of FT-IR spectra: (a) pure PPCA; (b) Fe3O4@PPCA; (c)
Fe3O4@PPCA@Pd(0).
Figure 4. SEM images and EDS spectrum of Fe3O4@PPCA@Pd(0)
Figure 2. TGA and DTG thermograms of Fe3O4@PPCA@Pd(0).
nanocatalyst.
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Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2016, 30, 360–366

Fe3O4@PPCA@Pd(0)-catalysed C–C coupling reaction
Figure 4 shows SEM images and EDS spectrum of the synthesized
Fe3O4@PPCA@Pd(0). The EDS spectrum of the magnetic nanoparti-
cles indicates that the mass percent of C, N, O, Fe and Pd is 6.63,
1.56, 16.12, 70.71 and 4.98%, respectively.
The XRD pattern indicates that the product consists of magnetite,
Fe3O4, and the line profile, shown in Fig. 5, was fitted for observed
six peaks with the following: (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1) and
(4 4 0). Also the XRD pattern of Fe3O4@PPCA@Pd(0) contains a se-
quence of particular diffraction peaks (40.1°, 46.6° and 68°), which
are indexed to Pd(0) indicating the presence of Pd(0) in the pre-
pared nanocatalyst.[6]
Table 2. Synthesis of 4-nitrobiphenyl in the presence of various
amounts of catalyst at 100°Ca
Entry
Catalyst (mg)
Time (min)
Yield (%)
Figure 5. XRD pattern of Fe3O4@PPCA@Pd(0).
1
2
3
4
5
0.00 (0.00 mol%)
3 (0.14 mol%)
5 (0.23 mol%)
8 (0.37 mol%)
10 (0.46 mol%)
20
20
20
20
20
No reaction
64
86
98
98
a
Reaction conditions: 1-bromo-4-nitrobenzene (1 mmol), NaBPh4
(0.5 mmol), base (3 mmol), PEG (1 ml).
Fe
O -PPCA-Pd, PEG
4
3
x
+
NaPh
B
4
Na CO , 100 °C
2
3
R
R
X= I or Br
Scheme 3. Biphenyl synthesis catalysed by Fe3O4@PPCA@Pd(0).
Figure 6. VSM curve of Fe3O4@PPCA@Pd(0).
Table 3. C–C coupling reaction of aryl halides with NaBPh4 catalysed
by Fe3O4@PPCA@Pd(0) at 100°C
Entry
X
R
Time (min) Yield (%)
M.p. (°C)
Fe3O4@PPCA@Pd(0), PEG
Br
+
NO2
NaBPh4
NO2
109–111[23]
60–64[23]
84–86[24]
40–42[23]
55–57[25]
79–81[23]
55[25]
60–64[23]
Oil[26]
Oil[24]
Na2CO3, 100 °C
1
Br
I
4-NO2
H
20
40
40
40
25
25
40
20
40
15
30
35
35
98
95
83
98
96
95
90
97
90
95
97
97
92
2
Scheme 2. Synthesis of 4-nitrobiphenyl catalysed by Fe3O4@PPCA@Pd(0).
3
I
4-OCH3
4-CH3
4-CHO
4-CN
4
I
5
Br
Br
Br
Br
Br
Br
Br
Br
Br
6
7
4-NH2
H
Table 1. Effects of solvent and base on the synthesis of 4-nitrobiphenyl
catalysed by Fe3O4@PPCA@Pd (0)a
8
9
2-COCH3
3-CF3
3-CHO
4-CO2H
4-CH3
Entry
Solvent
Base
Time (min)
Yield (%)
75
10
11
12
13
47–48[27]
230[27]
40–42[23]
1
2
3
4
5
6
7
8
9
DMF
DMSO
EtOH
H2O
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
NaHCO3
KOH
20
20
20
20
20
20
20
20
20
Trace
62
No reaction
No reaction
98
a
Reaction condition: aryl halide (1 mmol), NaBPh4 (0.5 mmol), Na2CO3
(3 mmol), catalyst (8 mg, 0.37 mol%), PEG (1 ml).
Dioxane
PEG
PEG
98
PEG
No reaction
35
OH
B
OH
PEG
Et3N
Fe3O4-PPCA-Pd, PEG
x
+
R
Na2CO3, 100 °C
a
R
Reaction conditions: 1-bromo-4-nitrobenzene (1 mmol), NaBPh4
(0.5 mmol), base (3 mmol), Fe3O4@PPCA@Pd(0) (8 mg, 0.37 mol%),
solvent (1 ml), 100°C.
R1
X= I or Br
Scheme 4. Biphenyl synthesis catalysed by Fe3O4@PPCA@Pd(0).
Appl. Organometal. Chem. 2016, 30, 360–366
Copyright © 2016 John Wiley & Sons, Ltd.
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G. Azadi and A. Ghorbani-Choghamarani
Table 4. Fe3O4@PPCA@Pd(0)-catalysed C–C bond formationa
VSM analysis shows that the immobilized palladium catalyst is
superparamagnetic (Fig. 6). It is reported[9] that Ms. (magnetization
saturation) of bare Fe3O4 nanoparticles is 73.7 emu gÀ1 and Ms. of
Entry
X
R
R1
Time (min)
Yield (%)b
the nanocomposite prepared in the present study is 48 emu gÀ1
.
1
Br
I
4-NO2
H
H
55
35
75
35
20
45
75
20
25
60
45
45
60
30
45
40
45
30
150
98
95
91
95
88
98
91
90
90
94
97
94
95
94
95
97
91
95
91
These results indicate that the magnetization of Fe3O4 decreases
when coated with PPCA and then palladium.
2
H
3
I
4-OCH3
4-CH3
4-CH3
4-CN
H
H
The catalytic activity of the prepared Fe3O4@PPCA@Pd(0) was eval-
uated in C–C coupling reactions. The model reaction of 1-bromo-4-
nitrobenzene with NaBPh4 was examined in various solvents and in
the presence of diverse bases at 100°C (Scheme 2; Table 1).
In order to explore the role of this nanocatalyst in the C–C
coupling reaction, several experiments were carried out using
various amounts of catalyst. The results are summarized in Table 2.
The results indicate that no product is observed in the absence of
catalyst, while the reaction proceeds efficiently in the presence of
4
I
H
5
Br
Br
Br
Br
Br
Br
Br
I
H
6
H
7
H
8
4-Cl
H
9
3-CF3
3-CHO
4-NO2
H
H
10
11
12
13
14
15
16
17
18
19
H
OCH3
OCH3
OCH3
OCH3
3,4-diF
3,4-diF
3,4-diF
3,4-diF
3,4-diF
I
4-OCH3
H
Br
Br
I
4-NO2
H
I
4-OCH3
H
Br
Br
4-OCH3
a
Reaction conditions: aryl halide (1 mmol), PhB(OH)2 (1 mmol),
Na2CO3 (3 mmol), catalyst (8 mg, 0.37 mol%), PEG (1 ml). All
products were identified and characterized by comparison of their
physical and spectral data with those of authentic samples.
b
Isolated yield.
Table 5. Recycling of Fe3O4@PPCA@Pd(0) in the reaction of 1-bromo-
4-nitrobenzene with NaPh4B at 100°C
Figure 8. XRD pattern of reused Fe3O4@PPCA@Pd(0) catalyst.
Cycle
1st
98
2nd
95
3rd
90
4th
90
Yield (%)
Figure 7. Comparison of FT-IR spectra: (a) Fe3O4@PPCA@Pd(0) and (b)
reused Fe3O4@PPCA@Pd(0).
Figure 9. SEM image of reused Fe3O4@PPCA@Pd(0) catalyst.
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Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2016, 30, 360–366

Fe3O4@PPCA@Pd(0)-catalysed C–C coupling reaction
Table 6. Comparison with reported results for C–C coupling reaction
Entry
1
Catalyst
Solvent
EtOH
Temperature (°C)
80
Time (h)
6
Yield (%)
97[28]
Memantine-modified
palladium catalyst
ERGO-Pd
2
3
4
5
EtOH
H2O
Reflux
80
2
26
0.5
0.9
91[29]
48[30]
98.2[31]
Pd/SiO2
Pd/g-C3N4
H2O–EtOH (1:1)
PEG
25
Fe3O4@PPCA@Pd(0)
100C
98 (this work)
Fe3O4@PPCA@Pd(0) nanoparticles. The resulting optimum amount
is 8 mg (0.37 mol%) of Fe3O4@PPCA@Pd(0), and increasing the
catalyst amount does not show any significant change in yield.
Therefore, we used the optimized reaction conditions for subse-
quent investigation as follows: 8 mg (0.37 mol%) of catalyst, PEG
as solvent, Na2CO3 as base, at 100°C. With the optimized condi-
tions in hand, we selected a variety of structurally diverse aryl
iodides and bromides to investigate the scope and efficiency of
Fe3O4@PPCA@Pd(0) in promoting the synthesis of biphenyls
(Scheme 3; Table 3). As is evident from Table 3, both electron-rich
and electron-deficient aryl iodides and bromides are superior and
deliver products with good to excellent yields. In general, the reac-
tions are clean and no side products are detected.
After successful synthesis of various biphenyl compounds
through reaction of aryl halides with NaPh4B, the same methodol-
ogy was extended for the synthesis of these compounds via the
reaction of aryl halides with phenylboronic acid (Scheme 4). In
this procedure, a series of aryl halides with electron-donating
and electron-withdrawing substituent were reacted with
phenylboronic acid to yield the corresponding biphenyls. As evi-
dent from Table 4, in all cases the reaction gives the products
in high yields. Also the effects of substituent upon the reactivity
of phenylboronic acid were probed. As evident from Table 4
(entries 11–19), in all cases the reaction gives the products in
short reaction time with high yields.
In order to determine whether the palladium leaches out from
the solid catalyst during reaction, the hot filtration test was done
for the synthesis of 4-nitrobiphenyl with phenylboronic acid. The
catalyst was separated by applying an external magnet when the
reaction had proceeded to nearly 50% completion, and the filtrate
was allowed to react further. No further progress of the reaction is
observed, which confirms that the palladium does not leach from
the nanocatalyst in hot conditions.
An important aspect for a heterogeneous catalyst is facile
recovery and simple reusability. For this reason, the reusability of
the catalyst was tested for the model reaction. The recyclability of
Fe3O4@PPCA@Pd(0) was examined in the synthesis of 4-
nitrobiphenyl. The catalyst was recovered after each run, washed
three times with diethyl ether, dried, and applied in subsequent
runs. It is found that the catalyst can be recovered many times
without significant loss of its activity (Table 5).
In order to investigate the efficiency of this new catalyst in
comparison with known reported literature data, the results for
the preparation of 4-nitrobiphenyl with phenylboronic acid, as a
representative example, are compared with the best of the well-
known data from the literature in Table 6. These results suggest that
Fe3O4@PPCA@Pd(0) is a very effective heterogeneous catalyst for
the C–C coupling reaction.
Conclusions
A novel nanocatalyst was prepared by supporting PPCA and then
Pd(0) on magnetic nanoparticles. The catalyst is easily synthesized,
and catalyses the C–C coupling reaction. The present synthesis
methodology shows attractive characteristics such as: the use of
magnetically recoverable and reusable catalyst, convenient one-
pot operation, short reaction time, good to excellent yields and
the use of PEG as a green reaction medium that is considered
to be relatively environmentally benign. Thus this work can intro-
duce the unique application of a catalytic coupling reaction in
chemistry.
Acknowledgments
We gratefully acknowledge financial support of this work by Ilam
University, Ilam, Iran.
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Appl. Organometal. Chem. 2016, 30, 360–366