A novel magnetic polyacrylonotrile-based palladium Core?Shell complex: A highly efficientcatalyst for Synthesis of Diaryl ethers

Article abstract of DOI:10.1016/j.jorganchem.2020.121266

The present article describes the synthesis of a new magnetic polyacrylonitrile-based Pd catalyst involving polyacrylonitrile modified via 2-aminopyridine as an efficient support to immobilize Pd nanoparticles. The simple reusability, easy separation and high stability of this Pd complex make it an excellent candidate to generate a C–O bond via Ph-X activation which is a really important subject in achieving biologically active compounds. It is worth to note access to good and high yields as well as broad substrate scope have resulted from superior reactivity of this catalyst complex. Furthermore, the structure of the magnetic polyacrylonitrile-based heterogeneous catalyst was characterized by fourier transmission infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD). Also, its thermal properties were studied by thermogravimetric analysis (TGA).

Full text of DOI:10.1016/j.jorganchem.2020.121266

Journal Pre-proof
A novel magnetic polyacrylonotrile-based palladium Core−Shell complex: A highly
efficient catalyst for Synthesis of Diaryl ethers
Firouz Matloubi Moghaddam, Atefeh Jarahiyan, Mohammad Eslami, Ali Pourjavadi
PII:
S0022-328X(20)30168-6
DOI:
https://doi.org/10.1016/j.jorganchem.2020.121266
JOM 121266
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 22 February 2020
Revised Date: 20 March 2020
Accepted Date: 28 March 2020
Please cite this article as: F.M. Moghaddam, A. Jarahiyan, M. Eslami, A. Pourjavadi, A novel
magnetic polyacrylonotrile-based palladium Core−Shell complex: A highly efficient catalyst for
Synthesis of Diaryl ethers, Journal of Organometallic Chemistry (2020), doi: https://doi.org/10.1016/
j.jorganchem.2020.121266.
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Revised
A Novel Magnetic Polyacrylonotrile-based Palladium Core−Shell
Complex: A Highly Efficient Catalyst for Synthesis of Diaryl Ethers
Firouz Matloubi Moghaddam a*, Atefeh Jarahiyan a, Mohammad Eslami a, Ali Pourjavadib
a
Laboratory of Organic Synthesis and Natural Products, Department of Chemistry, Sharif University of Technology,
Tehran, Iran, Email: matloubi@sharif.edu
Polymer Research Laboratory, Department of Chemistry, Sharif University of Technology Tehran, Iran
b
Abstract
The present article describes the synthesis of a new magnetic polyacrylonitrile-based Pd catalyst involving
polyacrylonitrile modified via 2-aminopyridine as an efficient support to immobilize Pd nanoparticles. The simple
reusability, easy separation and high stability of this Pd complex make it an excellent candidate to generate a C-O bond
via Ph-X activation which is a really important subject in achieving biologically active compounds. It is worth to note
access to good and high yields as well as broad substrate scope have resulted from superior reactivity of this catalyst
complex. Furthermore, the structure of the magnetic polyacrylonitrile-based heterogeneous catalyst was characterized
by fourier transmission infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and
transmission electron microscopy (TEM), X-ray diffraction (XRD). Also, its thermal properties were studied by
thermogravimetric analysis (TGA).
Keywords: Polyacrylonitrile; Magnetic Complex; Unsymmetrical diphenyl ether; Palladium nanoparticle; C−Cl bond
Activation;
stability, as well as high catalytic efficiency feature
large in applying it as a proper starting compound to
1. Introduction
prepare heterogeneous catalysts [13, 14]. Furthermore,
PAN has abundant modifiable nitrile functional
Nowadays, catalytic strategies for the synthesis of
groups that can be simply transformed into carboxyl,
organic compounds are in focus. Among different
amino-carbonyl and other functional groups which
types of catalysts, heterogeneous catalysts play a
subsequently can be modified to attain ligands [15-
crucial role in many organic reactions due to their
17]. In these regards, PAN has recently become a
recyclability, insolubility in solvents and long-term
source of interest; Tao et al. prepared various
stability [1, 2]. In this category, designing appropriate
copper(II)-Schiff
bases-functionalized
supports and development of their synthesis to
stabilize various metals have attracted chemists’
interest because solid supports’ properties can
directly influence the catalytic behavior [3, 4]. For
this aim, there have been many efforts to utilize
polymers as efficient supports like polystyrene,
polyaniline, polyacrylonitrile [5,6], cellulose [7],
chitosan [8], starch [9] and so on. Their uniform
structures, high reusability, chemical stability, high
porosity, and high surface area make them suitable
candidates for immobilization of various transition
metals, metal oxides, and different nanostructured
materials [3].
polyacrylonitrile fiber catalysts and their catalytic
activities have been explored in one-pot
multicomponent
copper-catalyzed
azide-alkyne
cycloaddition reaction and aldehyde, alkyne, amine
coupling reaction [18]. In addition to this result, in
2019, Ma et al. designed a series of new prolinamide
functionalized polyacrylonitrile fiber catalysts to
investigate Knoevenagel condensation and one-pot
Knoevenagel-Michael multi-component tandem
reactions in a green solvent and efficiency of these
catalysts have been proved [19]. In other words, this
group paid attention to produce novel sulfonic acid-
functionalized polyacrylonitrile fibers as a solid
support to synthesize quinoline derivatives,
quinazolinone, and 4-hydroxycoumarin with high
yields and broad substrate scope in ethanol or water
[20]. Besides their advantages, there are still some
limitations like low activity, complicated separation,
Considering
the
following
advantages,
polyacrylonitrile (PAN) is the most attractive
polymer in organic synthesis as a immobilization
support [10-12]. Having unique properties of low cost,
light density, simple production, high thermal
1

and reusability of the catalyst which should be
improved.
immobilization of Pd nanoparticles, first of all,
acrylonitrile was polymerized on the modified
magnetite nanoparticles' surface (PAN) and then
simply functionalized by 2-aminopyridine (AP)
because of its modifiable nitrile functional groups.
Finally, Pd nanoparticles were held onto the magnetic
PAN/AP by applying K2PdCl4 as a palladium source
(Scheme 2). The prepared catalyst was investigated
by fourier transmission infrared (FT-IR) spectroscopy,
transmission electron microscopy (TEM), field
emission scanning electron microscopy (FE-SEM)
and X-ray diffraction (XRD). Also, its thermal
properties were studied by thermogravimetric
analysis (TGA).
On the other hand, during the previous years, there
has been growing interest in C–C, C–O, and C–N
bond formation. Among them, diaryl ether structures
with C–O bond are one of the most important
intermediates for pharmaceuticals, biochemical,
agrochemicals and other biologically active scaffolds
such as Fenoprofe, Sorafenib, XK469, Tafenoquine,
AMG900 that make them interesting synthesis
molecules [21-24]. Although versatile copper
catalyst’s systems have been designed for their
synthesis under different conditions, they are often
complicated by the formation of byproducts and also
high reaction temperatures (125–220 ̊C), high boiling
polar solvents, and the stoichiometric amounts of
copper reagents are their drawbacks [25-27].
Scheme 2. Synthesis of Pd0@magnetic PAN/AP catalyst.
Figure 1. Some biological active compounds containing
The FT-IR spectra of samples are given in Fig. 1.
As shown in Figure 1, Fe-O and Si-O stretching
vibration illustrated peaks at 585 and 1093 cm-1. The
bands at 1408 and 1714 cm-1 are related to C=C and
diaryl ether scaffolds.
Encouraged by this, we have made a new
magnetic polyacrylonitrile-based catalyst to embed
Pd0 with high metal loading, reusability, and stability.
To deal with separation problems and metal residue
in products, a magnetic catalyst has been prepared.
After characterization, our research effort was
devoted to developing C‐O bond formation as one
of the Ullmann-type condensations from the reaction
of aryl halides and different phenols under mild
reaction conditions and satisfactory results were
obtained (Scheme 1).
C=O
stretching
bonds
of
3-
(trimethoxysilyl)propylmethacrylate
(MPS),
respectively [31]. For PAN, the absorption band at
2378 cm-1 is assigned to nitrile stretching vibrations
which disappeared after substitution with 2-
aminopyridine. The new bands at 1664, 1165, 630,
2886 and 2959 cm-1 are CN of amino stretching
vibration peak (N-sp2), N-sp3 C bond, bending
vibration of C‒H in pyridine heterocyclic ring and
CH2 of the 2-aminopyridine, respectively [32, 33].
Scheme 1. Pd0-catalyzed C-O coupling between
aryl halide (1a) and phenols (2a).
2. Results and Discussion
Synthesis and characterization of catalyst
A reusable Pd-based complex was designed for
Ullmann type reaction due to the fundamental
importance of C-O bond construction in organic
synthesis [28-30]. To make a proper support for
2

Figure 2. FT-IR spectra of (a) Fe3O4@SiO2, (b)
Fe3O4@SiO2@MPS, (c) The magnetic PAN, (d) The
magnetic PAN/AP support.
The XRD pattern was investigated with a copper
target (λ = 1.54 Å) for 2θ in the range of 0–80°
(Figure 3). This pattern exhibits the crystalline nature
of Fe3O4 didn't change after completion of catalyst’s
synthesis and this result is confirmed based on
comparing 2θ= 30, 36, 43, 54, 57, 63 with related
JCPDS Card (No.98-011-1284).
Figure 5. (a) Elemental mapping and (b) EDX of
Pd0@magnetic PAN/AP catalyst.
Figure 3. XRD patterns of the magnetic PAN/AP support.
FE-SEM and TEM analysis were performed to
investigate morphological properties. The related FE-
SEM image of the fresh catalyst showed a smooth
surface of the catalyst (Figure 4a) and it didn’t
significantly change after 8 runs (Figure 4b).
Elemental mapping and EDX of prepared catalysts
are shown in Figures 5a and b, EDX analysis
confirmed the presence of different components of
the catalyst and according to the elemental mapping
images, Pd nanoparticles were distributed
homogeneously onto the prepared support. The TEM
image depicts nanoparticles that have mean diameter
of 34 nm and core-shell structure can be seen after
modifying of magnetite’s surface with organic layers
in both the fresh and recovered catalyst as well as
there is no significant change in the particle size of
the recovered catalyst (Figure 6a and b).
Figure 6. TEM micrographs of Pd0@magnetic PAN/AP
catalyst (a) The fresh catalyst and (b) The recovered
catalyst after 8 runs.
TGA analysis was used to measure thermal weight
loss of the catalyst under an argon atmosphere to
measure the amount of organic phase which
immobilized on the Fe3O4. This weight loss around
100 °C is attributable to the elimination of adsorbed
water and others are related to the burning of polymer
chains and organic groups. As seen in Figure 7, the
catalyst shows good thermal stability and about 20 %
of ligand immobilized on the magnetic PAN/AP
support.
Figure 4. FE-SEM micrographs of Pd0@magnetic
PAN/AP catalyst (a) The fresh catalyst and (b) The
recovered catalyst after 8 runs.
3

the reaction rate and subsequently products’ yield
(entry 7-11). Moreover, applying 2 mmol of K3PO4
instead of 1 mmol increased the product yield. The
reaction efficiency was increased when 80 ̊C was
applied rather than room temperature. To access the
optimal amount of catalyst, different amounts of
Pd0@magnetic PAN/AP were performed (entry 1, 12-
16). As mentioned in Table 1, using 5 mol% of
catalyst was sufficient to provide excellent yield and
increasing the amount of catalyst has no remarkable
effect on the product's yield, finally, only a trace
amount of the favorite product was created by use of
catalyst without a transition metal (entry 17-19).
Our optimal approach is to use phenol (1 mmol),
aryl halide (1mmmol), Pd0@magnetic PAN/AP
catalyst (5 mol%) and K3PO4 (2 mmol) in DMF at
Figure 7. TGA thermogram of the magnetic
PAN/AP support.
80 ̊C for 2h. These conditions were applied to obtain
different diaryl ether derivatives and the results have
been summarized in Table 2. The substitution
variation on starting substrates was investigated like
several electron-donating and -withdrawing groups
on aryl halide (1a-h), phenol (2a-e), 1-naphthol (2f)
and 2-naphthol (2g) to study electronic effects. First,
the scope of phenols was investigated, with electron-
donating groups on phenol substrates such as
methoxy and methyl, diaryl ethers are formed in fair
to good yield (entry 4 and 5) and on the contrary,
electron-withdrawing groups on it like a nitro group
show lower yield (entry 24) because such groups can
reduce the nucleophilicity of phenols. The reaction
between 1-naphthol and electron-withdrawing aryl
halides required a longer reaction time to attain high
yields (entry 33). In aryl halides scope, different
groups were examined (1a-h) and the best results
were obtained when aryl iodides and bromides
substrates were used rather than unactivated aryl
chlorides. It is worth to note aryl chlorides are less
active halides which in this case they have generated
the expected products. Also, the electron-rich and
weak electron-poor groups on aryl halides have
provided a similar yield of the desired product and
strong electron-withdrawing groups indicate high
yield despite using aryl chloride (entry 6) but a steric
hindrance in 1-chloro-2-nitro benzene can reduce
product yield (entry 7 and 20).
Based on the literature review, a catalytic cycle is
demonstrated in Scheme 3. It is suggested that the
reaction begins with an oxidative‐addition step of
obtained Pd (0) catalyst to generate aryl-Pd (II)
intermediate I. Subsequently, insertion of phenol or
1-naphthol, 2-naphthol produces intermediate II.
After reductive elimination of intermediate II, the
expected product is made and active Pd (0) catalyst is
returned to the next reaction cycle.
To study the recyclability of the catalyst, a series
of the model reaction was performed and the
prepared Pd catalyst was isolated after each reaction,
washed with methanol (3×10 mL), dried at 60 °C for
12 h, and prepared for the next reaction to prove the
reusability of the catalyst (Figure 8). Interestingly,
based on ICP result, no remarkable metal leaching
was observed in the eighth run. Besides, the
recovered catalyst reused several times without
significantly change in the products’ yield.
According to the CHN analysis of the magnetic
PAN/AP support, the contents of various components
in the support were examined and the results were
summarized as follows: %C= 22.15, %H=
3.09 ,and %N= 5.95 in comparison with its previous
step: %C= 11.43, %H= 2.60 ,and %N= 4.10. This
result is momentous evidence to confirm that PAN
and 2-aminopyridine were loaded onto the magnetic
core as confirmed by TGA analysis. Besides, the Pd0
content was investigated by ICP ‐ OES and the
loading of palladium revealed that the high loading of
metal on the surface of the support (0.69 mmol. g−1).
3. Catalytic activity
In the past few years, the continuous efforts
toward the construction of the C-O bond have
produced different procedures for the synthesis of
various copper and palladium catalysts [34-37]. So,
the new Pd0@magnetic PAN/AP was studied as an
efficient catalyst to improve the reaction condition of
the O-arylation of phenols with aryl halides. The
model reaction involves the reaction of the phenol,
bromobenzene, and K3PO4 by varying the catalyst
precursor, temperature, solvent and reaction time as
seen in Table1. According to this table, no reaction
took place without a transition metal catalyst even
under harsh conditions and in the presence of strong
inorganic bases (entry 17-19). The combination of Pd
catalyst (5 mol%), K3PO4 (2 mmol) in DMF at 80 ̊C
for 2h was optimal, affording product 3a in 90%
isolated yield (entry 12). Both DMF and NMP have
been optimal solvents as aprotic polar ones but since
DMF is a more common solvent for organic reactions,
it has been chosen as a solvent (entry 1, 2). Among
various bases, K3PO4 and Cs2CO3 with strong basic
properties were found to be optimal but Cs2CO3 is a
moisture-sensitive and more expensive base; on the
other hand, K3PO4 is a cost-effective base which a
variety of polar solvent such as NMP can be used
with it [38]. In addition, other bases such as KOH,
NaOH, K2CO3, and NaHCO3 decreased the product
yield. For instance, K2CO3 can be applied to
deprotonated phenols but it acts moderately. And also,
NaHCO3 with weak basic properties can be decreased
4

The synthesis procedure includes several steps: (1)
immobilization
of
(3-
on
Mercaptopropyl)trimethoxysilane
(MPS)
Fe3O4@SiO2; (2) polymerization of acrylonitrile on
Fe3O4@SiO2@MPS
microspheres;
(3)
immobilization of 2-aminopyridine (AP) on it; and
(4) preparation of Pd0@Magnetic PAN/AP. In the
following, the synthesis details will be described:
5.1.1. Immobilization of MPS on Fe3O4@SiO2
The magnetic nanoparticles were synthesized by the
co-precipitation method. First, FeCl2.4H2O (10 mmol,
2 g) and FeCl3.6H2O (20 mmol, 5.4 g) were dissolved
in 50 ml of deionized water in a three-necked flask.
Subsequently, ammonium hydroxide (28% v/v) was
added slowly into the mixture, with the solution pH
held in 10. The reaction was performed under an
argon atmosphere and mechanical stirrer at room
temperature for 30 min. The resulting magnetite
nanoparticles were collected by a magnet and washed
with deionized water (30 ml) and methanol (3 × 30
ml), and then dried in a vacuum oven at 60 °C for 12h.
In the following step, 1.0 g of obtained Fe3O4 was
dispersed in dry ethanol (20 ml) and 2 ml of
ammonium hydroxide (28% v/v) by ultrasonication
for 30 min. Then, 10 mmol of tetraethylorthosilicate
(TEOS) was added dropwise to the flask and the
mixture was stirred at 60 °C for 24 h. In the end, the
Fe3O4@SiO2 nanoparticles were separated using an
external magnet, washed with deionized water and
methanol three times, and finally dried in a vacuum
oven at 60 °C for 24 h. After dispersing 1.0 g of
Fe3O4@SiO2 by ultrasonic waves in 20 mL dry
ethanol, 2 mL of NH3 was added to the flask. Then,
3-(trimethoxysilyl)propylmethacrylate (MPS) (10
mmol, 3 mL) was added dropwise during 10 min to
the previous mixture and it was stirred at 60 °C for 48
h. The Fe3O4@SiO2@MPS nanoparticle was isolated
from the supernatant by use of a magnet, washed
them thoroughly with methanol and dried in a
vacuum oven at 60 °C for 12 h.
Scheme 3. Proposed Mechanism.
Figure 8. The recyclability of catalyst.
To compare the efficiency and activity of the
synthesized catalyst, several methods have been
collected in Table 3. The use of complex and bulky
ligands and expensive bases like Cs2CO3, long
reaction time, low yield and low scope of reaction are
some of the limitations of previous works. As can be
understood from these results, we have tried to find a
new catalytic system that can develop reaction time,
product yield, as well as catalyst loading and
reusability.
5.1.2. Polymerization of acrylonitrile on
Fe3O4@SiO2@MPS Microspheres
Polyacrylonitrile-coated Fe3O4@SiO2@MPS was
synthesized as follows. 0.50 g of Fe3O4@SiO2@MPS
in 30 mL deionized water, 3 mL of acrylonitrile and
10 mg of AIBN were mixed in a single-necked flask,
completely degassed under N2 atmosphere and
refluxed for 24h. The resulting magnetite
nanoparticles were separated by an external magnet
and washed with deionized water and methanol (3 ×
30 ml), and then dried in a vacuum oven at 60 °C for
12h to give the Magnetic PAN.
4. Conclusion
To sum up, an effective procedure for the
construction of a magnetic polyacrylonitrile-based Pd
catalyst has been described to synthesis C-O bond
formation. The importance of the diaryl ether
derivative scaffolds in pharmacologically active
compounds encouraged us to design a new catalyst
analog for the synthesis of such substrates to improve
reaction conditions. In the following, the scope of
various aryl halide and phenol was studied which
have demonstrated high yield even in less reactive
starting materials.
5.1.3. Immobilization of 2-aminopyridine (AP) on
functionalized magnetite nanoparticles
The magnetic PANs (0.50 g) in deionized water (25
mL) and 2-aminopyridine (10 mmol) were heated to
reflux for 5h. Then, the nanoparticles were separated,
washed with deionized water and methanol (3 × 30
ml), and dried in a vacuum oven at 60 °C for 12h to
give the Magnetic PAN/AP.
5. Experimental Section
5.1. Synthesis of Pd0@magnetic PAN/AP catalyst
5

5.1.4. Preparation of Pd@Magnetic PAN/AP
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Acknowledgments
This work was supported by the Research Affairs
Division Sharif University of Technology (SUT),
Islamic Republic of Iran and we acknowledge its
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Appendix A. Supplementary material
Supplementary data to this article can be found
online at https://doi.org/.............
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7

Captions for Schemes:
Scheme 1. Pd0-catalyzed C-O coupling between aryl halide (1a) and phenols (2a).
Scheme 2. Synthesis of Pd0@magnetic PAN/AP catalyst.
Scheme 3. Proposed Mechanism.
Captions for Figures:
Figure 1. Some biological active compounds containing diaryl ether scaffolds.
Figure 2. FT-IR spectra of (a) Fe3O4@SiO2, (b) Fe3O4@SiO2@MPS, (c) The magnetic PAN,
(d) The magnetic PAN/AP support.
Figure 3. XRD patterns of the magnetic PAN/AP support.
Figure 4. FE-SEM micrographs of Pd0@magnetic PAN/AP catalyst (a) The fresh catalyst and (b) The
recovered catalyst after 8 runs.
Figure 5. (a) Elemental mapping and (b) EDX of Pd0@magnetic PAN/AP catalyst.
Figure 6. TEM micrographs of Pd0@magnetic PAN/AP catalyst (a) The fresh catalyst and (b) The
recovered catalyst after 8 runs.
Figure 7. TGA thermogram of the magnetic PAN/AP support.
Figure 8. The recyclability of the catalyst.
8

Table 1. Optimization condition for Pd0@magnetic PAN/AP catalyst on diaryl ether formationa
Yield (%)b
Entry
Solvent
Base
Catalyst (mg) Temperature
(°C)
Time (h)
DMF
K3PO4
K3PO4
K3PO4
K3PO4
10
10
10
10
10
10
10
10
10
10
10
5
80
80
80
80
80
80
80
80
80
80
80
80
80
80
80
80
120
120
2
91
1
NMP
2
91
2
CH3CN
DMSO
2
52
3
2
73
4
1,4-Dioxane K3PO4
2
65
5
Toluene
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
K3PO4
KOH
8
46
6
2
67
7
NaOH
K2CO3
NaHCO3
Cs2CO3
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
Cs2CO3
2
71
8
8
48
9
8
Trace
89
10
11
12c
13
15
16
17
18
19
2
2
90
2.5
1
2
70
2
51
7.5
-
2
91
24
24
24
Trace
Trace
Trace
-
-
aphenol (1 mmol), bromobenzene (1 mmol), base (1 mmol), catalyst, solvent (2 ml) and temperature.
bIsolated yield.
Cphenol (1 mmol), bromobenzene (1 mmol), base (2 mmol), catalyst, solvent (2 ml).
9

Table 2. Reaction Scope of C-O bond formation via Pd0@Magnetic PAN/AP catalyst.
10

Table 3. Comparison of catalysts activity in C-O coupling reactions of aryl halides with phenols.
Entry Catalyst(Loading)
Reaction conditions
Time
Yield
Reference
X=I/ Br /Cl X=I/ Br /Cl
[(Cinnamyl)PdCl]2 (0.025 Bulky biarylphosphine ligand,
-/16h/-
-/91/-
[39]
[40]
1
2
mol%)
Toluene/DME, K3PO4, r.t.
CuFe2O4 (5 mol %)
2,2,6,6-tetramethylheptane- 3,5- 24/24/24
dione, NMP, Cs2CO3, 135 ,
Argon atmosphere
91/34/trace
CuI (5mol%)
Picolonic acid, DMSO, K3PO4,
80
21/-/-
85/-/-
[41]
3
4
5
6
7
8
UiO 66 NH2
Mlm/CuO NPs (5mol%)) atmosphere
CuBr
DMSO,KOH, 110 , N2
18/18/24
-/1.5/-
5/15/20
4/4/3.5
2/2/4
95/93/30
-/55/-
[42]
ACHN initiator, DMF, Cs2CO3,
100 , Microwave
K2CO3, 120
[43]
Pd/ZnO nanoparticles
(0.05 mol%)
98/80/70
84/88/90
92/90/81
[44]
Pd–ZnFe2O4 (10 mol%)
DMSO, K3PO4, 110
DMF, K3PO4, 80
[45]
Pd0@Magnetic PAN/AP
This work
11

Highlights
∑ Synthesis of Diaryl ethers via a Palladium-Magnetic Polyacrylonotrile Catalyst.
∑ Unexpected C−Cl Bond Activation.
∑ The simple reusability, easy separation and high stability of catalyst.
∑ The good and high yields as well as broad substrate scope have been resulted.

Declaration of interests
☒ The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
☐The authors declare the following financial interests/personal relationships which may be considered
as potential competing interests: