Synthesis and activity evaluation of a FeCl2-promoted palladium hollow nano-sphere heterogeneous catalyst in Mizoroki–Heck coupling reactions

Article abstract of DOI:10.1016/j.apcata.2014.09.001

A high-active, high-quality, and high-yield hollow Pd–PVP–Fe (palladium–poly(N-vinylpyrrolidone)–iron) nano-sphere catalyst with cubic structure was synthesized via a cheap method without using any support. This catalyst exhibited excellent catalytic activity in the Mizoroki–Heck reactions of less reactive chlorobenzene and some aryl bromides with n-butyl acrylate. The catalyst was fully characterized using SEM (scanning electron microscopy), EDX (energy dispersive X-ray spectroscopy), TEM (transmission electron microscopy), HRTEM (high resolution TEM), SAED (selected area electron diffraction) pattern, XRD (X-ray diffraction spectroscopy), FT-IR (Fourier transform infrared spectrophotometry), UV–Vis Spectrophotometry, Zeta sizer, and AAS (atomic absorption spectrometry). Effects of FeCl₂·4H₂O and PVP concentrations as well as their compatibility with palladium in the catalytic system were investigated. The catalytic property of the catalyst can be controlled by adjusting the proportion of Fe⁰, Pd⁰, and PVP concentration. The reused catalyst showed excellent activity as well as negligible leaching of the metal nanostructures into solution from the catalyst system.

Full text of DOI:10.1016/j.apcata.2014.09.001

Accepted Manuscript
Title: Synthesis and Activity Evaluation of a FeCl –Promoted
2
Palladium Hollow Nano–sphere Heterogeneous Catalyst in
Mizoroki–Heck Coupling Reactions
Author: Parvaneh Ghaderi-Shekhi Abadi Ezzat Rafiee Shirin
Nadri Gelareh Hajian Mohammad Joshaghani
PII:
S0926-860X(14)00550-X
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.apcata.2014.09.001
APCATA 14981
To appear in:
Applied Catalysis A: General
Received date:
Revised date:
Accepted date:
12-4-2014
28-8-2014
3-9-2014
Please cite this article as: P.G.-S. Abadi, E. Rafiee, S. Nadri, G. Hajian, M. Joshaghani,
Synthesis and Activity Evaluation of a FeCl ndashPromoted Palladium Hollow
2
Nanondashsphere Heterogeneous Catalyst in MizorokindashHeck Coupling Reactions,
Applied Catalysis A, General (2014), http://dx.doi.org/10.1016/j.apcata.2014.09.001
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Synthesis and Activity Evaluation of a FeCl –Promoted Palladium Hollow
2
Nano–sphere Heterogeneous Catalyst in Mizoroki–Heck Coupling
Reactions
b
a,b
a
a
Parvaneh Ghaderi-Shekhi Abadi , Ezzat Rafiee , Shirin Nadri , Gelareh Hajian ,
a,b*
Mohammad Joshaghani
a
Department of Inorganic Chemistry, Faculty of Chemistry, Razi University, Kermanshah, 67149, Iran
b
Institute of Nano Science and Nano Technology, Razi University, Kermanshah, 67149, Iran
Abstract: A high–active, high–quality, and high–yield hollow Pd–PVP–Fe (palladium–
poly(N–vinylpyrrolidone)–iron) nano–sphere catalyst with cubic structure was synthesized
via a cheap method without using any support. This catalyst exhibited excellent catalytic
activity in the Mizoroki–Heck reactions of less reactive chlorobenzene and some aryl
bromides with n–butyl acrylate. The catalyst was fully characterized using SEM (Scanning
Electron Microscopy), EDX (Energy Dispersive X–ray Spectroscopy), TEM (Transmission
Electron Microscopy), HRTEM (High Resolution TEM), SAED (Selected Area Electron
Diffraction) pattern, XRD (X–ray Diffraction Spectroscopy), FT–IR (Fourier Transform
Infrared Spectrophotometry), UV–Vis Spectrophotometry, Zeta sizer, and AAS (Atomic
Absorption Spectrometry). Effects of FeCl
2 2
.4H O and PVP concentrations as well as their
compatibility with palladium in the catalytic system were investigated. The catalytic
0
0
property of the catalyst can be controlled by adjusting the proportion of Fe , Pd , and PVP
*
Corresponding author: Tel./Fax: +98 831–4274559; E–mail: mjoshaghani@razi.ac.ir
1
Page 1 of 32

concentration. The reused catalyst showed excellent activity as well as negligible leaching
of the metal nanostructures into solution from the catalyst system.
Keywords: Hollow; Palladium; Iron; Heterogeneous Catalysis; Mizoroki–Heck Reactions.
1
. Introduction
One promising way of increasing activity in catalytic systems is the use of transition
metal (0) nanoclusters because a large percentage of atoms lie on the surface of
nanoclusters [1]. Among these metals, iron (0) nanoclusters, FeNC, have been the subject
of increasing interest, mostly due to economic considerations. However, the high reactivity
of FeNC towards agglomeration and oxidation restricts their applications to only oxygen
free and/or stabilizer containing systems [2, 3]. The problem of oxidation could be
suppressed in inert conditions but this makes the process more complicated. Therefore, it is
difficult to introduce a simple way to synthesize stable FeNC without having to use inert
atmosphere and reducing agents. As a result, synthesis of stable FeNC in air without
employing any reducing agent is still a challenge.
Procedures leading to monodisperse FeNC are well documented [4]. There are several
reasons that smaller particle sizes might result in a greater density of reactive surface sites
or surface sites of higher intrinsic reactivity [5]. The most common chemical methods
include thermal decomposition of [Fe(CO)
9], reductive decomposition of [Fe(NSi(CH
salts [8], and finally, preparation of Fe nanoparticles in SAE 10 mineral oil by FeCl
5
] [4, 6–8] or water–in–oil emulsions of FeCl
3
[
3
)
3
)
2
] [7], reduction of (Fe(acac)
3
) or other iron
3
[10].
Unfortunately, conducting the thermal decomposition reactions to achieve desired
nanostructures of specific size, shape, and monodispersity is very difficult at high
2
Page 2 of 32

temperatures and for a prolonged period of time. In addition, micelle and micro emulsion
templates require organic solvents or ligands as template.
Bimetallic catalysis has been around for a long time, although further improvements can
0
be made. Coating nano–Fe using another metal such as Ag, Pd, Pt, Ni, and Cu is an
efficient approach used in organic reactions [11–13]. Historically, nanostructure bimetallic
palladium catalysts such as hollow Pd–Fe nanospheric catalyst [14], Pd/Cu nanoparticles
[
15], and heterobimetallic iron–palladium amidoamine dendrimers [16] have been widely
used mainly in dechlorination reactions [17–19] and to some extent in the cross coupling
reactions [16, 20, 21]. The most important drawback to this approach is the decrease of
catalyst efficiency over time due to formation of an iron hydroxide layer, which delays
reactant contact with the catalyst [22]. Taking a suitable interface (PVP) is probably a
reasonable way to prevent the oxidation of Fe(0). Therefore, PVP has been the focus of
many studies as a polymeric protective agent for the growth of nanoparticles [23, 24] and
for preparation of specific morphologies, sizes, or new crystal structures of inorganic or
organic materials [25]. There are few reports on PVP–stabilizing Pd catalysts in cross–
coupling reactions [26, 27].
Because we are interested in developing highly active palladium catalysts for coupling
reactions [28–31], we synthesized a PVP coated bimetallic Pd–Fe catalyst via a cheap,
mild, simple, and practical reflux method in ambient atmosphere and employed it in the
Mizoroki–Heck reactions of aryl halides with n–butyl acrylate. We used iron as the second
metal of choice, not only to enhance the dispersion of Pd active sites, but also to provide
adequate promoted property for the as–obtained material to Mizoroki–Heck reactions.
3
Page 3 of 32

2
. Experimental
2
.1. Preparation of hollow Pd–PVP–Fe nano-sphere catalyst
In a typical synthesis, 0.00113 g (0.0063 mmol) PdCl and 0.058 g (0.0014 mmol) PVP
2
were dissolved in distilled water:DMF (N,N–dimethylformamide) (1:5 V/V) under stirring
for 5 min until the solution became homogeneous. In a separate beaker, 0.015 g (0.075
mmol) FeCl
2
.4H
2
O and 0.058 g (0.0014 mmol) PVP were dissolved in same solvent under
solution under ultrasonic bath. The mixture was
stirring and added drop wise to PdCl
2
sonicated for 1 min under mild power to form a homogeneous solution, and then the
resulting homogeneous solution was refluxed at 110 °C for 16 h. After thermal treatment,
the resulting precipitate was collected, filtered, and washed with distilled water and
absolute ethanol for several times to remove any possible impurities, and finally dried in
vacuo before characterization. The as–obtained crystalline Pd–PVP–Fe sample was denoted
as the C catalyst. The concentration of Pd was 7.8 Wt.% which was determined using
3
AAS [32]. Preparation conditions for all catalysts are summarized in Table 1.
Table 1.
2
.2. Catalyst characterization
Analytical grades of PdCl
2
2 2
, FeCl .4H O, PVP (M.W. = 40,000), and DMF were
purchased from Merck and were used without further purification. UV–vis spectra were
recorded on Perkin Elmer Lambda 25 UV–vis spectrophotometer. The FT–IR spectra of the
samples were recorded at room temperature using a Bruker, ALPHA spectrophotometer at
-1
-1
a spectral resolution of 4 cm using KBr pellets in the range of 400-4000 cm . X-ray
4
Page 4 of 32

diffraction (XRD) patterns were obtained on an Inel French, EQUINOX 3000 model X–ray
diffractometer using Cu-K radiation. Scanning electron microscopy (SEM) has been
performed using an AIS2300C microscope with scanning range from 0 to 20 keV. Energy-
dispersive X-ray (EDX) measurements were made with an IXRF model 550i attached to
SEM. SEM/EDX samples were prepared by coating of solid particles into a conductive
layer. The transmission electron microscopy (TEM), high–resolution transmission electron
microscopy (HRTEM) images and selected area electron diffraction (SAED) patterns were
recorded on a Jeol JEM–2100 transmission electron microscope, operating at 200 kV.
Sample specimens for TEM studies were prepared by dispersing some solid in ethanol,
ultrasonicating for approximately 30 s and placing few drops of the suspension on a copper
grid, which were then put into the desiccators for drying.
The size distribution of the samples was obtained using a laser particle size analyzer
(
HPPS5001, Malvern, UK). The Pd content in catalyst was determined by an AA–670
Shimadzu • ame atomic absorption spectrometer with a deuterium background corrector
and a palladium hollow cathode lamp. Thin layer chromatography on precoated silica gel
Fluorescent 254 nm (0.2 mm) on aluminum plates was used for monitoring the reactions.
2
.3. General procedure for Heck reaction between aryl halides and n–butyl acrylate
In a typical reaction, a suspension of aryl halide (1.0 mmol), K CO (1.0 mmol), n–butyl
2
3
acrylate (1.0 mmol), C (0.0042 g, 0.032 % Pd), and DMF (1 mL) were mixed in a reaction
3
•
ask. The reaction mixture was stirred at 130 °C for an appropriate amount of time. The
suspension was cooled down to room temperature and • ltered off. The catalyst was washed
5
Page 5 of 32

with distilled water and absolute ethanol. It was dried in vacuo and used for the next
reaction cycle without any pretreatment.
3
. Results and Discussion
3
.1. Phase, structure, and morphology of the catalyst
The phase and crystalline changes, purity, and the elemental composition of the as–
obtained catalyst were characterized by XRD and EDX analysis. Fig. 1a shows the powder
0
XRD pattern of the C
3
catalyst. In general, the patterns of the Pd crystal have crystalline
structure with peaks appearing at 40.12˚, 46.36˚, 68.12˚, 82.10˚, and 86.62˚, corresponding
to the (111), (200), (220), (311), and (222) planes of the cubic structure of Pd (JCPDS 00–
0
87–0643, a = 3.91 Å) while the diffraction peaks observed at 45.90˚, 53.30˚, and 77.75˚
correspond to the (111), (200), and (220) planes of the cubic structure of Fe (JCPDS 00–
0
3
88–2324, a = 3.43 Å). This observation is in a good agreement with reported results [33,
4]. There is no additional peak indicating the high purity of product. The intensity of XRD
lines decrease slightly due to low loading of PVP [35]. The average crystallite size of the
2
2
Pd and Fe calculated using the Scherrer equation (D = [kλ ⁄ (√ߚ exp – ߚ inst) cosθ]) from
c
the peaks width of Pd (111) and Fe (111) are estimated to be 23.62 and 28.51 nm,
respectively. The XRD pattern shows Pd peaks width similar to that the Fe peaks indicating
6
Page 6 of 32

a smaller average crystallite size compared to Fe, and is consistent with a monocrystalline
shell layer.
Fig. 1b shows elemental maps images obtained by EDX for the C catalyst. The EDX
3
analysis reveals that Pd metal particles are well dispersed in the catalyst, which agrees well
with the XRD analysis.
Fig. 1.
The UV–Vis spectra of C , C , C , and C catalysts are shown in Fig. 2a. The
3
1
6
5
disappearance of a broad band at 300–400 nm in C and C catalysts is interpreted to
3
5
II
0
indicate the complete conversion of Pd to Pd (Fig. 2a(A), (D)) [21, 36] while its
II
appearance in C catalyst (Fig. 2a(B)) reveals the presence of Pd .
1
The FT–IR spectra of the pure PVP [37] as the mother solution, as well as C , C , C ,
3
1
5
and C catalysts are shown in Fig. 2b(A), (B), (C), (D), and (E), respectively. For pure PVP
6
-1
(
Fig. 2b(A)), the band at 750 cm corresponds to the C–C stretching vibration, and 1100
-1
-1
cm is related to the C–N stretching vibration (pyridine ring). The peak at 1300 cm is C–
-1
H stretching vibrations. The peak at 1550 cm is stretching vibration of C꞊O. As for the
pure PVP FT–IR spectrum, the C , C , and C spectra prove the presence of PVP on the
3
5
6
metal nanostructures. The FT–IR spectra of these catalysts have no absorption peaks in the
-1
range of 400–1000 cm , indicating the catalysts are free of metal oxide impurities. This
resistance to oxidation may be due to the presence of PVP surfactant which protects the
-1
surface of metal nanostructures. In contrast, the peaks at 449 and 571 cm for the PVP–free
7
Page 7 of 32

C (Fig. 2b(C)), corresponds to the metal–oxygen (Fe–O) vibrational modes of the iron
1
oxide compounds.
Fig. 2c–f show typical low and high–magnification SEM images of the hollow C3
catalyst. Broken spheres are also observed, providing sufficient proof of the hollow nature
of the catalyst (Fig. 2d). The hydrodynamic size of the hollow C catalyst is about 51.5 nm
3
with PDI (Polydispersity Index) of 0.435, meaning that there existed aggregation in
colloidal suspensions less.
Fig. 2.
3
Typical low and high magnification TEM images of the C catalyst are shown in Fig. 3a,
b. Fig. 3a indicates that the catalyst consist of relatively uniform spheres. Moreover, the
strong contrast between the dark edge and pale center con• rms their hollow structures. The
high magni• cation TEM image (Fig. 3b) further reveals that the spherical shape is
composed of hollow structure with an average shell size of 9 ± 1 nm. The size distribution
by means of Microstructure Measurement Software was obtained with the relative
precision by measuring about of one hundred hollow nano–spheres from TEM image. The
hollow nano–spheres are relatively monodisperse, with an average size of 49 ± 7 nm (Fig.
3
c).
The SAED pattern (Fig. 3d) from the edge of a hollow nano–sphere structure shows
monocrystalline diffraction of the cubic system, this observation is in a good agreement
with the XRD pattern results. The high–resolution TEM image of the C
3
catalyst in Fig. 3e
8
Page 8 of 32

exhibits a 0.33 nm spacing between two adjacent lattice planes corresponding to the
separation of the Pd (111) lattice planes of cubic palladium [20].
Fig. 3.
It is reported that polar groups such as the C=O groups of PVP chains, can interact with
metal ions and form coordinating complexes [38]. On the other hand, DMF could act as a
powerful reducing agent to generate nanostructures in the presence of PVP [39–42].
Therefore, it seems that as the PdCl or FeCl .4H O were added to the PVP, the crosslink
2
2
2
2
+
2+
PVP led to the formation of PVP layers containing Pd or Fe on water drops in DMF
which is a suitable place for nucleation. This medium favors reduction/nucleation path
relative to growth and results in small particles with a narrow size distribution [43]. After
thermal treatment and evaporation of precipitant, hollow spheres could be obtained on
removing water drops (Scheme 1).
Scheme 1.
3
.2. Catalytic behavior
All studied catalysts were subjected to Mizoroki–Heck coupling reactions between aryl
halides and n–butyl acrylate in DMF under air atmosphere. In comparison with previous
reports on the Heck coupling reactions using Pd/Fe NPs [44, 45], the coupling of
bromobenzene with n–butyl acrylate took place very quickly (45 min) in the presence of
the hollow C
3
catalyst to give the corresponding arylated product with complete conversion
9
Page 9 of 32

and selectivity (Table 2, entry 4), corresponding to the TON 326 and TOF 435 (Tables 2
and 3).
We tested the catalytic efficacy of other Pd–based catalysts in the Mizoroki–Heck
coupling reaction (Table 2). In the absence of catalyst, no product was formed after 10 h
(
(
6
Table 2, entry 1). Similarly, Pd–free C exhibiteds very low activity within the same time
Table 2, entry 7). C
1
and C exhibited suitable activity but at longer times (Table 2, entries
5
0
2
and 6) which may be attributed to the absence of PVP (conductive pathways) and Fe
(
promoted). However, the C catalyst demonstrated ef• cient conversion of reactants to
3
product at shorter time (Table 2, entry 4).
Table 2.
We investigated the efficacy of C catalyst in the Mizoroki–Heck reaction of various
3
aryl bromides and chlorobenzene with n–butyl acrylate. Aryl bromides containing different
electronic and steric effects showed obvious differences in reactivity (Table 3, entries 1–3),
indicating this reaction is sensitive to electronic and steric properties of the substituent.
Additionally, C catalyst could also catalyze the Mizoroki–Heck reaction between
3
chlorobenzene and n–butyl acrylate to give the corresponding coupling product with high
yield and low reaction times (Table 3, entry 4) and TON 261 and TOF 149.
Table 3.
1
0
Page 10 of 32

In comparison with other heterogeneous Pd–catalysts used in the Mizoroki–Heck
coupling reaction of chlorobenzene, the C catalyst shows remarked higher activity and
3
shorter reaction times (Table 4).
Table 4.
The C catalyst could be easily separated from the reaction solution. The reusability of
3
this catalyst was examined at repeatedly five times during the coupling reaction between
bromobenzene and n–butyl acrylate (Table 5), showing its superiority over the
homogeneous catalysts. No significant decrease in the yield was observed during the
catalyst recycling study. This means the nature of the hollow Pd–PVP–Fe nano–sphere
catalyst did not change after being used repetitively for repeatedly five times.
Table 5.
3
.3. Mechanism of electron behaviors the hollow Pd–PVP–Fe nano–sphere catalyst at
Mizoroki–Heck reactions
An electrically conducting polymer, PVP, has excellent wetting properties that make it a
good encapsulating agent. PVP as a polymer can form a conducting matrix and act as a
backbone in state coating on material [50]. Our results show that catalyst efficiency is a key
function of PVP concentration. The maximum efficiency in the Mizoroki–Heck coupling
was obtained at 0.0029 mmol of the PVP (Table 2, entry 4). Less efficiency of the catalyst
in containing lower amounts of PVP may be due to ease of iron oxidation. In higher
1
1
Page 11 of 32

amounts of PVP, it seems that the crowding of Pd active sites is responsible for the decline
in efficiency (Table 2, entries 2, 3, and 5).
A plausible mechanism is shown in (Scheme 2). A core/shell model has been proposed
for metal structures, wherein the shell is a PVP and the cores are Pd(0) and Fe(0) that
situate together. The Pd(0) nanostructures present at the surface facilitate the oxidative-
addition of aryl halide to generate Pd(II) complex (1). Migratory–Insertion of n–butyl
acrylate into the Pd in a syn–addition fashion to give complex (2) followed by –hydride
elimination step produces Pd(II) complex (3). The Pd(II) species could be reduced in the
presence of Fe(0) and regenerate active Pd(0) species. This electron transfer generates
Fe(II) species which receive lone pair electrons from PVP shell and reduce into Fe(0) [51].
This mechanism explains why the hollow Pd–PVP–Fe nanospheres (C catalyst) show
3
higher catalyst efficiency than Fe–free C catalyst (Table 2, entries 4 and 6). This reaction
5
cycle may be carried out repeatedly and only a small amount of the Pd(0) catalyst solid is
needed to carrying the coupling reaction. The reactants momentarily stick on the catalyst
surface sites and the products leave the surface.
Scheme 2.
3
.4. Characterization of the hollow Pd–PVP–Fe nano-sphere catalyst after Mizoroki–
Heck reaction
We decided to analyze the C catalyst after the Mizoroki–Heck reaction by the SEM,
3
UV–Vis, and FT–IR spectroscopy. SEM images of the reused C catalyst (Fig. 4a–g) show
3
1
2
Page 12 of 32

that the hollow morphology of the catalyst is not considerably changed after the coupling
reaction. This would be expected for a core (active metal phase)–shell (PVP) structure.
Possible decomposition of PVP during the reaction was investigated using FT–IR and
-1
UV–Vis spectroscopies. Absence of absorption bands at 3342 cm (NH stretching
-1
-1
vibration), C–H (3089 cm stretching vibration), 2246 cm (C≡N stretching vibration), and
-
1
1
595 cm (C꞊C–C꞊C stretching vibration) at the FT–IR spectrum [52] of reused catalyst C
indicated that decomposition of PVP has not occurred (Fig. 4i).
No signi• cant decrease in the reactivity was observed during the catalyst recycling
3
0
0
study. This means that the nature of Pd and Fe active sites did not change after being used
repetitively for five times. This suggests that the iron oxide layer is very thin and electron
transport across the shell take place easily.
Fig. 4.
4
. Conclusion
In this paper, we developed a cheap and simple reflux method for preparation of a Pd–
PVP–Fe catalyst with hollow nano–spherical morphology with thin shell contain of metals
and polymer, uniform size distribution, and monocrystalline structure. The Heck reactions
of aryl bromides and chlorobenzene with n–butyl acrylate were carried out efficiently at
short reaction times, high yield, and complete selectivity. It seems that suitable
arrangement of metal cores together with PVP shell facilitates electron transfer through
catalytic cycle. In addition, the catalyst can be easily separated from the reaction system
and continuously reused several times.
1
3
Page 13 of 32

Acknowledgments
The authors thank the Razi University Research Council for support of this work.
1
4
Page 14 of 32

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[
7
[
[
1
[
4
1
8
Page 18 of 32

Figure Captions
a
Table 1. Experimental parameters for the preparation of Pd–based catalysts.
Table 2. Products and yields for the Mizoroki–Heck reactions of n–butyl acrylate with
a
bromobenzene by various catalyst compositions.
Table 3. Products and yields for the Mizoroki–Heck reactions of n–butyl acrylate with
a
3
various aryl halides catalyzed by the C catalyst.
Table 4. Comparison of the activity of C
3
catalyst with other heterogeneous Pd–catalysts
used in the Mizoroki–Heck coupling reaction of chlorobenzene.
Table 5. Recycling test of the C catalyst (Reaction condition is listed in Table 2).
3
3
Fig. 1. (a) XRD pattern and (b) EDX spectrum of the C catalyst.
Fig. 2. (a) UV–Vis spectra of (A) C , (B) C , (C) C , and (D) C catalyst, (b) FT–IR spectra
3
1
6
5
of (A) pure PVP, (B) C
3
, (C) C
1
, (D) C
5
, and (E) C
6
catalyst, SEM images of the C
3
catalyst (c) at low magnification, and (d–f) at high magnification.
Fig. 3. TEM images of the C catalyst, (a) at low magnification and (b) at high
3
magnification, (c) the frequency and size distribution of hollow nano–spheres, (d) SAED
pattern, and (e) HRTEM image.
3
Fig. 4. The C catalyst after the Mizoroki–Heck reaction, (a, b) SEM images at low
magnification, (c–g) SEM images at high magnification, (h) UV–Vis, and (i) FT–IR
spectra.
Scheme 1. Proposal mechanism for synthesis of the C catalyst.
3
Scheme 2. Mechanism of electron behaviors the C catalyst at the Mizoroki–Heck
3
reactions.
1
9
Page 19 of 32

Table 1.
3
3
No. Symbol [Fe] (mmol) × 10
PVP (mmol) × 10
1
2
3
4
5
C1
C2
C3
C4
C5
C6
75.00
75.00
75.00
75.00
0.00
0
2.30
2.91
3.50
2.91
2.91
6
75.00
a
Reaction conditions: PdCl 0.0063 mmol (except for C
2
6
which is Pd–free), distilled water:DMF (1:5 V/V), T = 110
C, Time = 16 h.
°
2
0
Page 20 of 32

Table 2.
Br
n
CO Bu
2
Catalyst
n
+
CO Bu
2
K CO , DMF
2
3
o
1
30 C
b
-1
c
Entry Catalyst Time (min) Yield (%) TON
TOF (h )
1
2
3
4
5
6
7
a
None
C1
10 h
240
190
45
0
0
0
95
85
100
70
90
25
310
277
326
228
293
82
78
87
435
152
235
8
C2
C3
C4
90
C5
75
C6
10 h
Reaction condition: the Pd–based catalyst (0.0042 g),
bromobenzene (1.0 mmol), n–butyl acrylate (1.0 mmol), K
2 3
CO (1.0
mmol), 1 mL DMF, T = 130 °C.
b
TON = mmol of product/mmol of Pd catalyst.
c
TOF = TON/time.
2
1
Page 21 of 32

Table 3.
R
R
X
n
CO Bu
2
C Catalyst
3
n
+
CO Bu
2
K CO ,DMF
2
3
o
1
30 C
Time (min) Yield
%)
-1
Entry ArX
Selectivity (%) TON TOF(h )
(
OCH3
1
225
30
85
90
75
80
100
100
100
100
277
293
245
261
74
Br
CHO
2
587
122
149
Br
Br
3
120
105
Cl
4
a
Reaction condition: the Pd–based catalyst (0.0042 g), bromobenzene (1.0 mmol), n–butyl
CO (1.0 mmol), 1 mL DMF, T = 130 °C.
acrylate (1.0 mmol), K
2
3
2
2
Page 22 of 32

Table 4.
No. Catalyst
Time (h) Solvent
Temperature (°C) Yield (%) Ref.
1
2
Pd/Cu
24
15
DMF
DMF
100
120
66
60
20
32
Si-PVP-Pd
Complex/TBAB
3
PCP pincer palladium 24
nanoparticles/TBAB
DMF
100
67
51
4
5
6
Pd/TBAB
Pd(II) complex
Pd/Ti
24
24
10
DMF
DMF
MeOH
160
140
65
38
60
68
52
53
54
2
3
Page 23 of 32

Table 5.
-1
Run Yield
TON TOF (h )
(
%)
1
2
3
4
5
100
90
85
85
85
326
293
277
277
277
435
391
370
370
370
2
4
Page 24 of 32

Fig. 1.
2
5
Page 25 of 32

Fig. 2.
2
6
Page 26 of 32

Fig.3.
2
7
Page 27 of 32

Fig.4.
2
8
Page 28 of 32

Scheme 1.
2
9
Page 29 of 32