Mizoroki-Heck reaction over palladium nanoparticles supported on WO3

Article abstract of DOI:10.1016/j.materresbull.2016.06.007

Palladium nanoparticles supported on metal oxide WO₃were synthesized and the physicochemical properties of compounds were characterized by X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES) at O and Pd K-edges, energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic activity of compounds in the carbon-carbon coupling reactions of aryl halides with olefins (Mizoroki-Heck reaction) was studied. The catalyst can be easily separated from the reaction mixture and reused after washing without reduction in activity.

Full text of DOI:10.1016/j.materresbull.2016.06.007

Accepted Manuscript
Title: Mizoroki–Heck reaction over palladium nanoparticles
supported on WO3
Author: Mojtaba Amini Dina Bahrami Heydarloo Mohammad
Rahimi Min Gyu Kim Sanjeev Gautam Keun Hwa Chae
PII:
S0025-5408(16)30251-3
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.materresbull.2016.06.007
MRB 8807
To appear in:
MRB
Received date:
Revised date:
Accepted date:
17-9-2015
23-5-2016
4-6-2016
Please cite this article as: Mojtaba Amini, Dina Bahrami Heydarloo, Mohammad
Rahimi, Min Gyu Kim, Sanjeev Gautam, Keun Hwa Chae, Mizoroki–Heck reaction
over palladium nanoparticles supported on WO3, Materials Research Bulletin
http://dx.doi.org/10.1016/j.materresbull.2016.06.007
This is a PDF file of an unedited manuscript that has been accepted for publication.
As a service to our customers we are providing this early version of the manuscript.
The manuscript will undergo copyediting, typesetting, and review of the resulting proof
before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that
apply to the journal pertain.

Mizoroki–Heck reaction over palladium nanoparticles supported on
WO
3
1
1
2
3
Mojtaba Amini,* Dina Bahrami Heydarloo, Mohammad Rahimi, Min Gyu Kim, Sanjeev
4
5
Gautam and Keun Hwa Chae,*
1
Department of Chemistry, Faculty of Science, University of Maragheh, Maragheh, Iran
2
Department of Material Science &Engineering, Faculty of Engineering, University of Maragheh,
Golshahr, Maragheh, Iran
3
Beamline Research Division, Pohang Accelerator Laboratory, Pohang University of Science and
Technology, Pohang 790-784, South Korea
4
Dr. S.S. Bhatnagar University Institute of Chemical Engineering & Technology, Panjab University,
Chandigarh, 160-014, India
5
Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea
*
Corresponding author(s); Tel.: +98 41 37278900; Fax: +98 41 37276066. Email address: mamini@maragheh.ac.ir
(M. Amini), khchae@kist.re.kr (K.H.Chae)
1

Graphical abstract
Highlights
1
2
3
) Palladium nanoparticles supported on WO
3
were synthesized.
) Excellent yield has been achieved.
) Recoverability and reusability of catalysts were studied.
2

Abstract
Palladium nanoparticles supported on metal oxide WO were synthesized and the
3
physicochemical properties of compounds were characterized by X-ray diffraction (XRD), X-ray
absorption near edge spectroscopy (XANES) at O and Pd K-edges, energy dispersive X-ray
analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy
(TEM). The catalytic activity of compounds in the carbon–carbon coupling reactions of aryl
halides with olefins (Mizoroki–Heck reaction) was studied. The catalyst can be easily separated
from the reaction mixture and reused after washing without reduction in activity.
Keywords: nanostructures; chemical synthesis; X-ray diffraction; transmission electron
microscopy (TEM); catalytic properties
1. Introduction
Mizoroki–Heck reactions as an efficient method for carbon–carbon bond formation are one of
the most useful transformations in organic synthesis that tolerates various functional groups,
such as ketones, esters, amides, ethers or heterocyclic rings [1-5]. Heck coupling reactions are
generally catalysed by soluble palladium (Pd) complexes containing various ligands in organic
solvents and, more recently, as well as in aqueous media [6-12]. Many of these homogeneous
catalytic processes, which are the first choice of chemists because of their high activity and
selectivity, however these are not easy to handle, difficult to separate, and have limited reuse
potential often due to contamination with final products or formation of metal-complexes [13-
1
6]. Catalyst separation and reusability are a critically important issue for the sustainable
development of any catalytic process [17, 18].Therefore, heterogeneous catalysis is gaining
increasing importance in the production of fine chemicals and pharmaceuticals and in chemical
technology due to its definite technical advantages, namely production processes,
competitiveness and economy. To enhance the reusability of catalysts, the nano-Pd catalysts are
commonly immobilized onto inorganic or organic supports [19-27]. This type of catalysis
provides high reaction rate and high turnover numbers (TON) and often affords high selectivities
3

and yields. In these reactions, activity mainly depends on the nature of the support used for the
reaction [28]. From earlier works the support is known to affect the electronic density at the
surface of palladium and their catalytic properties for Heck reactions [28]. Augustine and
O’Leary took into consideration a number of oxide-based catalysts and found that support effects
are observed only in the coupling of 4-nitrobenzoylchloride that was relatively slow over
Pd/MgO in comparison with both Pd/SiO
The present work focuses on the model reaction of bromobenzene with styrene catalysed by
palladium nanoparticles supported on WO as a support. The palladium nanoparticles supported
on WO was prepared and various analytical methods such as. XRD, XANES, SEM, EDX and
TEM were utilized to characterize the nanoparticles.
2
and Pd/Al
2
O
3
[29, 30].
3
3
2
. Experimental details
2
.1. Materials
Chemicals and solvents were purchased from Merck and Fluka and used without further
purification. WO nanoparticles were synthesized according to our previous published procedure
3
[31].
2
.2. Synthesis of supported palladium nanoparticles
Supported palladium nanoparticles were prepared by an impregnation method using Pd(OAc)
a source for Pd. The required amount of Pd(OAc) , to give 5wt% Pd loading, was mixed and was
pulverized with support. Methanol (20 mL) was added to the mixture of Pd(OAc) and support.
This mixture was mechanically stirred to ensure the homogeneous distribution of Pd(OAc) over
the supports. After stirring, CH OH was evaporated under vacuum using a rotary evaporator.
2
as
2
2
2
3
After impregnation, Pd(0) nanoparticles were obtained by reduction of the Pd(II)/WO
3
with
hydrazine hydrate.
2
.3. General Procedures for the Heck Reaction
A flask was charged with 0.003g of catalyst along with an appropriate amount of aryl halide (1.0
mmol), olefin (1.1 mmol), Na
2
CO
3
(2.0mmol), and DMSO (2 mL) and a magnetic stir bar. The
4

mixture was heated to 120°C with stirring for a specified period of time. After the reaction
mixture was cooled to room temperature, H O (5 mL) was added and the product was extracted
with diethyl ether (210 mL). The aqueous solution was separated from the organic layer. The
diethyl ether solution was dried over CaCl , and evaporated to dryness under reduced pressure to
2
2
afford the desired product, which was then washed with hexane (35 mL). The purity of the
compounds was checked by GC and NMR and yields are based on the aryl halide.
3. Results and Discussion
3
.1. Catalyst characterization
XRD patterns were recorded for WO
structure and phase formation of Pd nanoparticles supported on WO
of the Pd/WO showed only peaks of WO3 support (monoclinic) [31]. No peaks attributed to Pd
were observed in the pattern of catalyst. Also no characteristic peaks of impurities for both WO
and Pd/WO are detected in the patterns demonstrating that the samples have high phase purity.
3
and supported palladium nanoparticles to determine
(Fig. 1). The XRD patterns
3
3
3
3
XANES spectra are just a finger print for a specific molecule and hence a powerful tool to
investigate the electronic structure of a material. According to the dipole selection rule, the O K-
edge spectra are due to transitions from atomic-like 1s state to unoccupied bound and free states
with p-character, which experience some relaxation in the presence of the 1s core-hole positive
charge. The O K-edge spectra reflect also the shape of the density of metal d-states, due to a
hybridisation between the metal d and oxygen 2p orbitals. The normalised oxygen K-edge
XANES of compounds are shown in Fig. 2. The O K-edge XANES patterns of the WO
3
and
sample containing palladium nanoparticles supported on WO showed clear peaks of WO
3
3
support (monoclinic). The results of XANES data analysis are in agreement with those reported
previously [32, 33]. Despite some changes in intensity of peaks, no shift in the position of the
absorption edge was observed for WO
3
and supported palladium nanoparticles. These results
and matrix of it remains same.
show that Pd-nanoparticles are only supported on WO
3
5

The information about the surface of WO
3
and sample containing palladium nanoparticles
supported on WO was obtained by the scanning electron microscopy (SEM) image as presented
3
in Fig.3. The SEM image shows particles with diameters in the range of nanometers.
Transmission electron microscopy (TEM) images of the catalysts show that Pd nanoparticles are
formed and dispersed on the WO with a size about 50-100 nm (Fig. 4).
3
3
.2. Catalytic effects
Initially, the reaction of bromobenzene with styrene was chosen as a model reaction in the
presence of Pd/WO catalyst. All reactions were performed under air without any additive.
3
Results are summarized in Table 1. In order to understand the effect of catalyst amount on the
catalytic reactivity, the first, catalyst screening of the reaction was carried out. When the amount
of Pd/WO catalyst was increased from 0.001 to 0.005g, the yield of product increased
3
drastically from 49 to 68% (entries 1–5). With a further increase of catalyst to 0.006 g, the yield
of trans-stilbene remains almost constant (entry 6). Because of lower amount of Pd loading, we
chose 0.005 g of Pd/WO
3
catalyst for further experiments. Then effects of various bases and
CO and K CO gave better results
solvents were investigated (entries7–17). It appeared that Na
2
3
2
3
than any other bases with 68% and 65% of yields, respectively. In case of solvents, using DMSO
as a solvent provided excellent results. As shown in table 1 (entry 18), the catalytic activity of
the system decreased dramatically when Pd/WO
3
was replaced by WO support.
3
Although the temperature-dependent curves in Fig. 5a confirm very low trans-stilbene yield in
low temperatures (r.t.-60 °C), a significant growth in the product yield is observed at higher
temperatures. Moreover performing the reaction at 100°C caused lower conversions than120 °C.
Also, with an increase in the reaction time from 1 to 5h, the yield of trans-stilbene shows a
significant increase from 54 to 70%. Further increase of the reaction time to 6h shows no effect
on the yield of trans-stilbene (Fig. 5b).
On the basis of the optimized reaction conditions, the coupling reactions between a range of aryl
halides and olefins were carried out in the presence of palladium nanoparticles supported on
6

WO3, Na
2
CO as a base, and DMSO as a solvent at 120°C. As shown in Table 2, aryl iodides
3
with a variety of electron-rich and electron-poor substituent proceeded smoothly, giving the
coupling products in good to excellent yields. The reactivity of aryliodides with electron-
withdrawing substituent was higher than those with electron donating substituent. Furthermore,
steric hindrance due to the ortho substituents on the aryliodides affected the reaction progress
and therefore aryliodides substituted with methoxy group at ortho position were less reactive to
the coupling reaction than the para derivative.
It is worth noting that the most electron-poor aryl bromide, 4-acetylbromobenzene, showed a
good reactivity and was successfully coupled with olefins in good to excellent yields (entries 9-
1
2). However, the Heck coupling of bromobenzene due to the strong C-Br bond compared to C-I
bond was rather difficult to proceed under the same reaction conditions (entries 13-16).
In final, a further set of experiments were carried out to check the reusability of the Pd/WO
3
for
the Heck reaction at 120 °C for 5 h. For each recycle, the catalyst was recovered from reaction
mixture by filtration, washed 2-3 times with distilled water and ethyl ether repeatedly, dried at 50
°
C for half an hour, and reused for the next run. As shown in Fig. 7, yield slightly decreased due
to the loss of catalyst activity after the catalyst was reused four times, which might be caused by
catalyst agglomeration in the catalytic process.
By comparing of the SEM images of the fresh and recycled Pd/WO
the recycled catalyst show signs of support agglomeration after repeated of the Heck reaction
Fig. 8a). Also the comparison of the XANES patterns of the fresh and reused catalyst signifies
that some structural changes have occurred in the reused catalyst. The first intense peak at 531
3
catalyst, it was found that
(
eV in the O K-edge spectrum of fresh Pd/WO
conduction band due to 5d(t2g)(TM)–2p(O) interaction. XANES spectra for used Pd/WO
modified and shifted for main-peak/edge, which indicating a change in the WO
To further confirm the electronic structure of Pd-supported WO , XANES measurement at Pd K-
3
is related to oxygen 2p(O) states in the 5d(t2g
)
3
are
3
matrix (Fig. 8b).
3
edge is performed as shown in Figure 8(c) for fresh and used Pd/WO3.The line shapes of the
normalized NEXAFS indicate that Pd in the fresh catalyst is totally metallic while the used
catalyst is mixed state of Pd metallic and Pd-O with very low concentration of Pd in compared to
the fresh catalyst [34, 35]. Also the EXAFS Fourier transform results in Fig. 8c shows that Pd
metallic particle size in reused Pd/WO
support agglomeration, structural changes, oxidation of Pd metallic to Pd and leaching of Pd are
3
is relatively very small than that in fresh Pd/WO
3
. Thus,
II
primarily responsible for the reduction in Pd/WO catalytic activity upon its repeated use.
3
7

4
. Conclusions
The palladium nanoparticles supported on WO
3
were successfully synthesized and characterized
by XRD, XANES, NEXAFS, SEM, EDX and TEM. This new material was found to be an
effective catalyst for the carbon–carbon coupling reactions of aryl halides with olefins
(Mizoroki–Heck reaction). This coupling reaction is an efficient way to prepare styrene
derivatives, which are important chemicals for many applications. Effects of catalyst amount,
solvent, base and temperature effects, reaction time and nature of supports on the yield of Heck
reaction were also studied. The high efficiency and use of only catalyst without any additives
make the method useful and attractive for the Heck reaction. Finally, a further set of experiment
was carried out to check the reusability of the Pd/WO catalyst for the Heck reaction under air.
3
Acknowledgments
M. Amini thanks the Research Council of the University of Maragheh for financial support of
this work. S.G. is thankful to Prof. J.M. Chen (BL20A1, NSRRC) for experimental support and
also acknowledges the travel subsidy given by Panjab University for Synchrotron experiment at
NSRRC, Hsinchu, Taiwan.
Appendix A. Supplementary data
Experimental characterization data for Heck coupling products are available in the
Supplementary Data.
8

References
[
[
[
[
[
[
1] R. F. Heck, J. P. Nolley, Palladium-catalyzedvinylic hydrogen substitution reactions with
aryl, benzyl, and styryl halides, J. Org. Chem., 37 (1972) 2320-2322.
2] T. Mizoroki, K. Mori, A. Ozaki, Arylation of Olefin with Aryl Iodide Catalyzed by
Palladium, Bull. Chem. Soc. Jpn., 44 (1971) 581.
3] J-Z. Jiang, C.Cai, Heterogeneous Heck Reaction in Microemulsion with Palladium
Supported Na-Y Zeolites as Catalyst, J. Dispersion Sci. Technol. 27 (2006) 1137–1140.
4] A. de Meijere, F. E. Meyer, Fine Feathers Make Fine Birds: The Heck Reaction in
Modern Garb, Angew. Chem., Int. Ed. Engl., 33 (1995) 2379-2411.
5] I. P. Beletskaya, A. V. Cheprakov, The Heck Reaction as a Sharpening Stone of
Palladium Catalysis , Chem. Rev., 100 (2000) 3009-3066.
6] S.M. S. Hussain, M. B. Ibrahim, A. Fazal, R. Suleiman, M. Fettouhi, B. E. Ali,
Palladium–bis(oxazoline) complexes with inherent chirality: Synthesis, crystal structures
and applications in Suzuki, Heck and Sonogashira coupling reactions, Polyhedron, 70
(
2014) 39-46.
7] M. Amini, M. Bagherzadeh, Z. Moradi-Shoeili, D. M. Boghaei, Pd(OAc)
ligand as an active catalyst for Mizoroki–Heck reaction in aqueous media, RSC Adv. 2
2012) 12091-12095.
[
2
without added
(
[
8] Y. Wang, Q. Yang, L. Yang, J. Shi, M. Zhang, A novel N–O ligand for palladium
catalyzed Mizoroki–Heck reaction in neat water, Tetrahedron Lett., 54 (2013) 5314-5317.
9] M. Trivedi, G. Singh, R. Nagarajan, N. P. Rath, Imidazole containing palladium(II)
complexes as efficient pre-catalyst systems for Heck and Suzuki coupling reaction:
Synthesis, structural characterization and catalytic properties, Inorg. Chim. Acta, 394
[
(2013) 107-116.
[
10] M. Amini, M. Bagherzadeh, S. Rostamnia, Efficient imidazolium salts for palladium-
catalyzed Mizoroki–Heck and Suzuki–Miyaura cross-coupling reactions, Chin. Chem.
Lett. 24 (2013) 433–436.
[
11] M. Oberholzer, C. M. Frech, Mizoroki†“Heck reactions catalyzed by palladium
dichloro-bis(aminophosphine) complexes under mild reaction conditions. The importance
of ligand composition on the catalytic activity, GreenChem., 15 (2013) 1678-1686.
9

[
[
[
[
[
12] M. Bagherzadeh, M. Amini, A. Ellern, L. K. Woo, Palladium and copper complexes with
oxygen–nitrogen mixed donors as efficient catalysts for the Heck reaction, Inorg. Chim.
Acta, 383 (2012) 46–51.
13] Q-L. Luo, J-P. Tan, Z-F. Li, Y. Qin, L. Ma, D-R. Xiao, Novel bis(azole) pincer palladium
complexes: synthesis, structures and applications in Mizoroki–Heck reactions, Dalton
Trans., 40 (2011) 3601-3609.
14] L. S. Søbjerg, D. Gauthier, A. T. Lindhardt, M. Bunge, K. Finster, R. L. Meyer, T.
Skrydstrup, Bio-supported palladium nanoparticles as a catalyst for Suzuki–Miyaura and
Mizoroki–Heck reactions, Green Chem., 11 (2009) 2041-2046.
15] S. Martínez, M. Moreno-Mañas, A. Vallribera, U. Schubert, A. Roig, E. Molins,
Nanosized metallic particles embedded in silica and carbon aerogels as catalysts in the
Mizoroki–Heck coupling reaction, New J. Chem., 30 (2006) 1093-1097.
16] C-S. Lee, Y-B. Lai, W-J. Lin, R. R. Zhuang, W-S. Hwang, Pd(II) complexes with mono-
and bis-chelate carbene ligands tagged with pyridinium cation: Synthesis, structures, and
their catalytic activities toward Heck reaction , J. Organomet. Chem., 724 (2013) 235-
2
43.
[
[
[
17] A. V. Martínez, J. A. Mayoral, J. I. García, Pd nanoparticles immobilized in [bmim][PF6]
supported on laponite clay as highly recyclable catalysts for the Mizoroki–Heck reaction ,
Appl. Catal. A: Gen., 472 (2014) 21-28.
18] ] Y. Kayaki, Y. Noguchi, T. Ikariya, Enhanced product selectivity in the Mizoroki–Heck
reaction using a supercritical carbon dioxide–liquid biphasic system , Chem. Commun.,
2
000 (2000) 2245-2246.
19] M. Bagherzadeh, F. Ashouri, L. Hashemi, A. Morsali, Supported Pd nanoparticles on
Mn-based metal–organic coordination polymer: Efficient and recyclable heterogeneous
catalyst for Mizoroki–Heck cross coupling reaction of terminal alkenes, Inorg. Chem.
Commun., 44 (2014) 10-14.
[
20] C. Diebold, S. Schweizer, J-M. Becht, C. Le Drian, Reusable polystyrene-supported Pd
catalyst for Mizoroki–Heck reactions with extremely low amounts of supported Pd, Org.
Biomol. Chem., 8 (2010) 4834-4836.
1
0

[
[
[
21] H. Hagiwara, Y. Sugawara, T. Hoshi, T. Suzuki, Sustainable Mizoroki†“Heck reaction
in water: remarkably high activity of Pd(OAc)2 immobilized on reversed phase silica gel
with the aid of an ionic liquid , Chem. Commun., 2005 (2005) 2942-2944.
22] Y. Lee,M. C. Hong, H. Ahn,J. Yu,H. Rhee, Pd nanoparticles immobilized on
poly(NIPAM-co-4-VP) hydrogel: Highly active and reusable catalyst for carbon–carbon
coupling reactions in water , J. Organomet. Chem.769 (2014) 80–93.
23] N. Moitra, A. Matsushima, T. Kamei, K. Kanamori, Y. H. Ikuhara, X. Gao, K. Takeda,
Y. Zhu, K. Nakanishi, T. Shimada, A new hierarchically porous Pd@HSQ monolithic
catalyst for Mizoroki–Heck cross-coupling reactions , New J. Chem., 38 (2014) 1144-
1
149 .
[24] T. Mino, Y. Shirae, Y. Sasai, M. Sakamoto, T. Fujita, Phosphine-Free Palladium
CatalyzedMizoroki−Heck Reaction Using Hydrazone as a Ligand, J. Org. Chem., 71
(2006) 6834–6839.
[
[
[
[
25] M. Opanasenko, P. Štěpnička, J. Čejka, Heterogeneous Pd catalysts supported on silica
matrices, RSC Adv., 4 (2014) 65137-65162
26] A. Biffis, M. Zecca, M. Basato, Metallic Palladium in the Heck Reaction: Active Catalyst
or Convenient Precursor?, Eur. J. Inorg. Chem. (2001)1131–1133.
27] H.-U. Blaser, A. Spencer, The palladium-catalysed arylation of activated alkenes with
aroyl chlorides J. Organomet. Chem. 233 (1982) 267-274.
28] A. Biffis, M. Zecca, M. Basato, Reactivity of chelating dicarbene metal complex
catalysts, I: An investigation on the Heck reaction, J. Mol. Catal. A: Chem. 173 (2001)
2
49–274
[
[
[
29] R.L. Augustine, S.T. O’Leary, Heterogeneous catalysis in organic chemistry Part 8.: The
use of supported palladium catalysts for the Heck arylation, J. Mol. Catal. 72 (1992) 229–
2
42.
30] R.L. Augustine, S.T. O’Leary, Heterogeneous catalysis in organic chemistry. Part 101.
Effect of the catalyst support on the regiochemistry of the heck arylation reaction, J. Mol.
Catal. A: Chem. 95 (1995) 277–285.
31] M.Amini, B.Pourbadiei, T. P. A. Ruberu, L. K. Woo, Catalytic activity of MnOx/WO3
nanoparticles: synthesis, structure characterization and oxidative degradation of
methylene blue , New J. Chem. 38 (2014) 1250-1255.
1
1

[
32] J. Purans, A. Kuzmin, P. Parent, C. Laffon, Study of the electronic structure of rhenium
and tungsten oxides on the O K-edge , Physica B 259–261 (1999) 1157–1158.
[
33] J. Purans, A. Kuzmin, P. Parent, C. Laffon, X-ray absorption study of the electronic
structure of tungsten and molybdenum oxides on the O K-edge, ElectrochimicaActa 46
(2001) 1973–1976.
[
34] B-R. Chen, C. George, Y. Lin, L. Hu, L. Crosby, X. Hu, P.C. Stair, L. D. Marks, K. R.
Poeppelmeier, R. P. Van Duyne, M. J. Bedzyk, Morphology and oxidation state of ALD-
grown Pd nanoparticles on TiO2- and SrO-terminated SrTiO3 nanocuboids, Surf. Sci.
6
48 (2016) 291–298.
[
35] Y. Yao, C. Patzig, Y. Hu, R. W. J. Scott, In Situ X‑ray Absorption Spectroscopic Study
of Fe@FexOy/Pd and Fe@FexOy/Cu Nanoparticle Catalysts Prepared by Galvanic
Exchange Reactions, J. Phys. Chem. C, 119 (2015) 21209−21218.
1
2

Fig. 1. XRD pattern of WO
3
and sample containing palladium nanoparticles supported on WO
3
1
3

Fig. 2. O K-edge XANES patterns of WO
supported on WO
3
and sample containing palladium nanoparticles
3
1
4

Fig. 3. SEM images of: a) WO
3
; b) Pd/WO
3
1
5

Fig. 4.TEM images of sample containing palladium nanoparticles supported on WO
3
1
6

Fig. 5. Effects of (a) the temperature of reactionand; (b) the time of reactionon the Heck reaction
in presence of Pd/WO as a catalyst
3
1
7

Fig. 7. Recycling studies of the catalyst Pd/WO for the Heck reaction
3
1
8

Fig. 8. a) SEM images; b) XANES patterns; c) Pd K-edge NEXAFSand EXAFS fitting of fresh
and reused catalyst, Pd/WO
3
.
1
9

Table 1.The Effect of various conditions on the Heck reaction.a
Entry Amount catalyst
Base
Solvent
Temperature Time Yield
b
of
(°C)
(h)
(%)
catalyst
1
2
3
4
5
6
7
8
9
0.001 Pd/WO
0.002 Pd/WO
0.003 Pd/WO
0.004 Pd/WO
0.005 Pd/WO
0.006 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
0.005 Pd/WO
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Na
Na
Na
Na
Na
Na
2
2
2
2
2
2
CO
CO
CO
CO
CO
CO
3
3
3
3
3
3
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
49
53
59
61
68
65
65
63
7
15
8
5
25
25
53
47
40
K
2
CO
PO
3
Na
NH
NaOAc
KOH
3
4
3
1
0
1
2
3
4
5
6
7
1
1
1
1
1
1
1
Na
Na
Na
Na
Na
Na
2
2
2
2
2
2
CO
CO
CO
CO
CO
CO
3
3
3
3
3
3
H
2
O
CH
CH
DMF
O/DMSO
O/DMF
DMSO
3
OH
3
CN
H
2
H
2
1
8
0.005
WO
3
Na
2
CO
3
100
5
b
0
a
Reaction conditions: 1.0 mmol of aryl halide, 1.2 mmol of olfins, 2 mmol of base. Isolated yield
2
0

a
Table 2. Heck reaction between aryl halides and olefins in presence of Pd/WO
3
as a catalyst.
Yield (%)b
96
Entry
1
Ar-X
Olefins
Ph
Products
I
O
O
2
3
96
95
I
(
CH ) CH
(CH ) CH
2 3 3
2
3
3
O
Ph
Ph
O
O
O
I
I
CH CH
CH CH3
2
3
2
O
O
CN
CN
4
5
93
94
Ph
Ph
MeO
MeO
I
I
O
6
7
8
95
89
91
CH O
(CH ) CH
3
2
3
3
O
Ph
I
OMe
OMe
O
O
I
(
CH ) CH
(CH ) CH
2 3 3
2
3
3
O
O
OMe
OMe
9
Ph
83
85
CH CO
Br
Br
CH CO
3
3
O
O
1
1
0
1
CH CO
3
(CH ) CH
(
CH ) CH
2
3
3
2
3
3
O
O
CH CO
3
O
O
85
CH CO
Br
Br
3
CH CH3
CH CH
2
2
3
O
O
CH CO
3
CN
CN
1
1
2
3
88
70
CH CO
3
CH CO
3
Ph
Br
O
O
O
1
1
1
4
5
6
43
Br
Br
(CH ) CH
(CH ) CH
2
3
3
2
3
3
O
Ph
O
O
41
48
CH CH
CH CH3
2
3
2
O
Ph
O
CN
CN
Ph
Br
a
Reaction conditions: 1.0 mmol of aryl halide, 1.2 mmol of olfins, 2 mmol of Na
Isolated yield
2
CO
3
, 120 °C, 5h.
b
2
1