Synthesis, characterization, and application of palladium-dithizone immobilized on magnetic nanoparticles as an efficient and recoverable catalyst for Suzuki type coupling reactions

Article abstract of DOI:10.1016/j.tetlet.2015.11.096

A novel, magnetically separable catalyst was synthesized by the immobilization of Pd on magnetite nanoparticles (MNPs) coated with dithizone. The activity of this catalyst was examined for the synthesis of various biaryls via the C-C coupling reaction of aryl halides and sodium tetraphenylborate or phenylboronic acid under mild reaction conditions. Fe₃O₄/SiO₂-DTZ-Pd was characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, vibrating sample magnetometer, and scanning electron microscopy.

Full text of DOI:10.1016/j.tetlet.2015.11.096

Accepted Manuscript
Synthesis, characterization, and application of palladium-dithizone immobi-
lized on magnetic nanoparticles as an efficient and recoverable catalyst for
Suzuki type coupling reactions
Arash Ghorbani-Choghamarani, Hossein Rabiei
PII:
S0040-4039(15)30404-4
DOI:
http://dx.doi.org/10.1016/j.tetlet.2015.11.096
TETL 47036
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
12 May 2015
27 October 2015
29 November 2015
Please cite this article as: Ghorbani-Choghamarani, A., Rabiei, H., Synthesis, characterization, and application of
palladium-dithizone immobilized on magnetic nanoparticles as an efficient and recoverable catalyst for Suzuki type
coupling reactions, Tetrahedron Letters (2015), doi: http://dx.doi.org/10.1016/j.tetlet.2015.11.096
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Graphical Abstract
Synthesis, characterization, and application of
palladium-dithizone immobilized on magnetic
nanoparticles as an efficient and recoverable
catalyst for Suzuki type coupling reactions
Arash Ghorbani-Choghamarani,* Hossein Rabiei
DTZ
SiO2

Tetrahedron Letters
1
Tetrahedron Letters
journal homepage: www.elsevier.com
Synthesis, characterization, and application of palladium-dithizone immobilized on
magnetic nanoparticles as an efficient and recoverable catalyst for Suzuki type
coupling reactions
Arash Ghorbani-Choghamarani,* Hossein Rabiei
Department of Chemistry, Faculty of Science, Ilam University, P.O. Box, 69315516, Ilam, Iran.
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A novel, magnetically separable catalyst was synthesized by the immobilization of Pd on
magnetite nanoparticles (MNPs) coated with dithizone. The activity of this catalyst was
examined for the synthesis of various biaryls via the C-C coupling reaction of aryl halides and
sodium tetraphenylborate or phenylboronic acid under mild reaction conditions. Fe3O4/SiO2-
DTZ-Pd was characterized by transmission electron microscopy, X-ray diffraction, Fourier
transform infrared spectroscopy, energy dispersive X-ray spectroscopy, vibrating sample
magnetometer and scanning electron microscopy.
Available online
Keywords:
Suzuki reaction
C-C Coupling
Supported palladium
Dithizone
2009 Elsevier Ltd. All rights reserved.
Sodium tetraphenylborate
Phenylboronic acid
tetraphenylborate and phenylboronic acid are two stable and
commercially available reagents which have been utilized for the
Suzuki-Miyaura reaction. It has been reported that all four phenyl
1. Introduction
Catalysts and catalytic reactions have attracted significant
attention in industrial applications and fundamental research.1 In
recent years, effort in catalysis research have been allocated to the
application of useful and safe heterogeneous catalysts.2
Heterogeneous catalysts are more efficient than homogeneous
catalysts because of their recyclability.3,4 However, some
heterogeneous palladium catalysts have low reactivity because of
leaching from the support.5,6 Thus, the design of new
heterogeneous catalysts that retain the activities and selectivity of
homogeneous catalysts is important.7 In the past few years, among
various solid supports, Fe3O4 has shown high-performance due to
its unusual magnetic properties, high stability and recoverability
with an external magnet.8 Because of the widespread applications
in biotechnology, biomedical, material science, and environmental
fields, much attention has been paid to the synthesis of different
functionalized magnetic nanoparticles (MNPs).9-12
groups of sodium tetraphenylborate can be coupled with aryl
halides to efficiently generate the product.17
The work herein, details the synthesis and characterization of a
novel MNPs‐supported Pd-dithizone complex and its use in the
Suzuki-Miyaura coupling reaction of sodium tetraphenylborate or
phenylboronic acid with variety of aryl halides. This catalyst could
be readily recovered from the reaction mixture by application of an
external magnet.
The Suzuki-Miyaura cross-coupling between aryl halides and
organoboranes represents one of the most efficient methods for
synthesis of biaryls.13 Substituted biaryl compounds have
considerable application for the synthesis of biologically active
substances such as pharmaceuticals and herbicides.14,15 Boronic
acids, which are stable to air and moisture with low toxicity are
Scheme 1. Synthesis of Fe3O4/SiO2-DTZ-Pd
typically used in the Suzuki-Miyaura reaction.16 Sodium
———
*Address correspondence to A. Ghorbani-Choghamarani, Department of Chemistry, Faculty of Science, Ilam University, P.O. Box 69315516, Ilam, Iran;
Tel/Fax: +98 841 2227022; E-mail address: arashghch58@yahoo.com or a.ghorbani@mail.ilam.ac.ir

2
Tetrahedron Letters
2. Results and Discussion
selected. Finally, the effect of Fe3O4/SiO2-DTZ-Pd loading was
examined. The reaction was performed in the presence of 0.33,
The MNPs/SiO2-DTZ-Pd complex was synthesized according 0.50, and 0.66 mol% of Fe3O4/SiO2-DTZ-Pd (Table 1). Increasing
to Scheme 1. Initially, Fe3O4 was formed via the chemical co- the amount of Fe3O4/SiO2-DTZ-Pd catalyst to 0.66 mol% did not
precipitation of Fe2+ and Fe3+ in basic solution. Following this, the significantly increase the yield of the biphenyl (Table 1, entry 17).
MNPs were coated with 3-(chloropropyl)triethoxysilane. Then, Additionally, the coupling reaction did not occur in the absence of
catalyst (Table 1, entry 18). Based on these results the optimum
catalyst loading was 0.50 mol%. Likewise, the reaction conditions
were optimized for the coupling reaction using phenylboronic
acid, (Table 1, entries 19-34). The best result was observed in PEG
at 60 °C using 0.33 mol% of catalyst and 3 mmol of Na2CO3 as
base (Table 1, entry 24).
dithizone‐functionalized Fe3O4 were synthesized by the reaction of
chloro-functionalized MNPs and diphenylthiocarbazone. Finally,
palladium was bonded to the MNPs/SiO2-DTZ surface.
The morphology and size of the MNPs/SiO2-DTZ-Pd complex
was investigated using scanning electron microscopy (SEM) (ESI,
Fig. S1a) and transmission electron microscopy (TEM) (ESI, Fig.
S2). TEM micrographs confirmed the spherical shape of Fe3O4.
The energy dispersive X-ray spectroscopy (EDS) spectrum of the
MNPs/SiO2-DTZ-Pd (ESI, Fig S1b) clearly showed the presence
of Pd in the magnetic nanoparticles. The distribution of the
elements (atomic percent) in the complex was determined as Si =
1.49%, Fe = 29.15%, O = 62.38% and Pd = 5.59%. Fourier
transform infrared (FT-IR) spectra of the Fe3O4 nanoparticles
(MNPs) (pink curve), chloro-functionalized MNPs (blue curve), Entry
Table 1. Optimization of the Fe3O4/SiO2-DTZ-Pd catalyzed
Suzuki-Miyaura cross-coupling reaction of iodobenzene with
sodium tetraphenylborate or phenylboronic acid.a
Phenylating
reagent
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
Temp.
(°C)
80
80
80
80
80
80
80
80
80
80
80
r.t.
60
100
80
80
80
60
60
60
60
60
60
60
60
60
r.t.
60
70
80
60
60
60
Cat.
(mg)
3
3
3
3
3
3
3
3
3
3
3
3
3
3
2
4
-
2
2
2
2
2
2
2
2
2
2
2
2
2
3
Time
(min)
30
30
30
30
30
30
30
30
30
30
5 h
5 h
5 h
35
150
35
24 h
130
130
130
130
130
130
130
130
130
5 h
130
130
130
135
130
130
Yield
(%)b
25
30
15
80
75
96
65
80
55
35
-
Solvent
Base
MNPs-DTZ (green curve) and MNPs/SiO2-DTZ-Pd (red curve) are
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
EtOH
H2O
1,4-dioxane
DMSO
DMF
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
EtOH
DMSO
DMF
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Et3N
Na2CO3
KOH
NaHCO3
-
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Et3N
Na2CO3
K2CO3
NaHCO3
-
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
shown in ESI, Fig S3. The pink curve showed characteristic peaks
at 3399 cm-1 due to stretching of the O-H bonds which were
attached to the surface of the MNPs and a sharp peak at 580 cm−1
due to vibrations of the Fe–O bond. Peaks at 997and 1044 cm−1 in
the IR spectrum of the chloro-functionalized MNPs were assigned
to the Si–O stretching vibrations. The NH group of MNPs-DTZ
was observed at 3397 cm−1, while the NH group of MNPs/SiO2-
DTZ Pd appeared at 3438 cm−1, indicating the attachment of Pd on
-
20
95
70
98
-
66
57
91
96
55
94
91
62
-
10
93
92
94
95
95
97
the surface of MNPs-DTZ. An XRD spectrum of the prepared
MNPs/SiO2-DTZ-Pd was collected and six characteristic peaks
(2θ=30.1°, 35.3°, 43.0°, 53.4°, 56.9°and 62.5°) were observed as
well as three characteristic peaks (2θ=39.3°, 45.9° and 67.1°),
related to formation of the structure of Pd NPs. The magnetic
properties of samples containing a magnetite component were
studied using a vibrating sample magnetometer (VSM) at room
temperature. The saturation magnetization of MNPs/SiO2-DTZ Pd
NaPh4B
NaPh4B
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
was determined as 51.6 emu/g (ESI, Fig. S5a). A comparison with
the VSM of Fe3O4 (Fig. S5b) indicated that the magnetization of
Fe3O4 was considerably decreased upon coating the organic layers
on the surface of the magnetic nanoparticles.19
The catalytic activity of MNPs/SiO2-DTZ-Pd was explored in
the Suzuki coupling reaction. To develop optimal reaction
conditions, the reaction of iodobenzene with sodium
tetraphenylborate or phenylboronic acid was explored as a model
reaction. The exact loading of Pd on the magnetic nanoparticles
was determined to be 1.65×10-3 mol·g−1 based on inductively
coupled plasma atomic emission spectroscopy (ICP-OES).
32
4
5
33
a
Reaction conditions: iodobenzene (1 mmol), NaPh4B (0.5 mmol) or PhB(OH)2 (1.2
mmol), base (3 mmol), solvent (2 mL).
b Isolated yield (based on the aryl halide).
To explore the generality and scope of the catalytic system, the
coupling of various aryl halides (chlorides, bromides and iodides)
with sodium tetraphenylborate or phenylboronic acid was examined
(Table 2). Aryl halides with both electron withdrawing and
donating groups efficiently reacted with sodium tetraphenylborate
or phenylboronic acid in the presence of catalytic Fe3O4/SiO2-
DTZ-Pd in good to high yields. Interestingly, the reactions were
clean and no by-products were detected.
Various parameters were investigated for the model reaction
including catalyst loading, solvent, base, and temperature (Table
1). Different solvents were initially examined. Low yields of the
biphenyl compound were observed using H2O (30%) and EtOH
(15%) (Table 1, entries 1 and 2) whereas DMF and DMSO led to
the corresponding biphenyl product in 75% and 80% yield
respectively (Table 1, entries 4 and 5). Polyethylene glycol (PEG)
was selected as the best reaction media in terms of reactivity and
activity. Next, the effects of different organic and inorganic bases
were examined (Table 1, entries 6-11). The highest yield was
achieved using K2CO3 (Entry 6). The effect of temperature on the
reaction was also examined which showed a gradual increase in
yield corresponding with an increase in temperature (Table 1).
Based on these results, an optimal temperature of 80 °C was
The recyclability of the Fe3O4/SiO2-DTZ-Pd was also studied.
After completion, the catalyst was removed from the reaction
mixture by magnetic decantation and subjected to the next
catalytic run under the same reaction conditions. The catalyst
could be reused at least five times without significant loss of
catalytic activity (Figure 1).

Tetrahedron Letters
3
12. Zhang, X.; Lin, M.; . Lin, X.; Zhang, Ch.; Wei, H.; Zhang,
H.; Yang, B. ACS Appl. Mater. Interfaces. 2014, 6, 458.
13. Dumbre, D.K.; Yadav, P.N.; Bhargava,S.K.; Choudhary, V.
R. J. Catal. 2013, 301, 140.
14. Durgun,G.; Aksın, O.; Artok, L. J. Mol. Catal. A: Chem.
2007, 278, 199.
15. Paul, S.; Clark, J. H. Green Chem. 2003, 5 , 638
16. Zhao, N.; Li, T.; Zhai, Z.; Qiu, J.; Xu, W.; Liu, H.; Wu,Y.
Chem. Cat. Chem. 2013, 5, 10.
17. Nikolai, A.B.; Victor, V.B. Tetrahedron 1997, 53,14450
18. Ghorbani-Choghamarani, A.; Ghasemi, B.; Safari, Z.;
Azadi, G. Catal. Commun. 2015, 60, 75.
19. Atashkar, B.; Rostami, A.; Tahmasbi, B. Catal. Sci.
Figure 1. Catalyst recyclability for the reaction of iodobenzene with
sodium tetraphenylborate
Technol. 2013,3, 2146
20. Peng,Y. Y.; Liu, J.; Lei, X.; Yin, Z. Green. Chem. 2010, 12,
1072.
21. Yang, J.; Liu, S.; Zheng, J. F.; Zhou, J. Eur. J. Org. Chem.
Conclusion
In conclusion we have developed a simple, clean and efficient
synthesis of a MNPs supported-Pd complex and examined its
catalytic activity for the synthesis of various biphenyls via the
reaction of sodium tetraphenylborate or phenylboronic acid with
various aryl halides. Mild reaction conditions, low catalyst
loading, good to high yields, ease of catalyst separation using an
external magnet and simple work-up procedure are some of the
attractive features of this protocol. Further studies on the effects of
Fe3O4/SiO2-DTZ- Pd catalyst for other systems are in progress in
our laboratory.
2012, 31, 6248.
22. Samarasimhars eddy, M.; Prabhu, G.; Vishwanatha, T. M.;
Sureshbabu,V. V. Synthesis 2013, 45, 1206.
23. Baia,L.; Wanga, J. X. Adv. Syn. Cat. 2007, 350, 320.
24. Orgiu, E.; Crivillers, N.; Rotzler, Mayor, M.; Samorì, P. J.
Mater. Chem. 2010, 20, 10800.
Acknowledgements
The authors thank the research facilities of Ilam University, Ilam,
Iran, for financial support of this research project.
Supplementary data
Supplementary data associated with this article can be found, in
the
online
version,
at
http://www.sciencedirect.com/science/journal/00404039.
References and notes
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Appl. Organometal. Chem. 2015, 29, 175 .
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A: Chem. 2013, 370, 181.
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Khalaj,M. J. Mol. Catal. A: Chem. 2015, 396, 297.
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2012, 7, 144.
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Chem. 2014, 395, 179.

4
Tetrahedron Letters
Table 2. Suzuki cross-coupling reaction of various aryl halides with sodium tetraphenylborate or phenylboronic acida.
Phenylating
reagent
Time
(min)
Entry
Aryl halide
Yieldb (%) m.p. (°C)
TON
TOF (h-1)
1
NaPh4B
30
98
95
67-6820
Oil21
198.0
396.0
2
NaPh4B
35
191.9
329.0
3
4
NaPh4B
NaPh4B
40
25
95
97
44-4720
84-8520
191.9
196.0
287.9
470.4
5
NaPh4B
60
97
Oil20
196.0
196.0
6
7
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
NaPh4B
20
60
25
30
80
50
25
30
60
96
93
92
97
96
95
93
98
95
44-4721
70-7120
193.9
187.9
185.9
196.0
193.9
191.9
187.9
198.0
191.9
581.7
187.9
446.2
392.0
145.4
230.3
451.1
396.0
191.9
8
67-6823
9
82-8323
10
11
12
13
14
56-5822
162-16323
105-10624
113-11520
52-5422
15
NaPh4B
10h
68
Oil23
137.3
13.7
16
17
NaPh4B
4h
92
94
66-6820
67-6820
185.9
284.8
46.5
PhB(OH)2
130
131.4
18
19
20
21
22
23
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
PhB(OH)2
40
120
60
91
89
93
90
90
92
44-4720
44-4720
70-7120
67-6820
82-8323
162-16323
275.8
269.7
281.8
272.7
272.7
278.8
413.7
134.9
281.8
86.1
190
150
60
109.1
278.8
a
Reaction conditions: aryl halide (1 mmol), NaPh4B (0.5 mmol) or PhB(OH)2 (1.2 mmol), base (3 mmol), 3 mg (0.5 mol%) of
Fe3O4/SiO2-DTZ-Pd for NaPh4B and 2 mg (0.33 mol%) of Fe3O4/SiO2-DTZ-Pd for PhB(OH)2, PEG (2 mL) .
b Isolated yield (based on the aryl halide).

Tetrahedron Letters
5
Highlights
Fe3O4/SiO2-DTZ-Pd was prepared
Fe3O4/SiO2-DTZ-Pd was characterized
by, FT-IR, XRD, TGA, SEM, VSM and
TEM techniques
Fe3O4/SiO2-DTZ-Pd applied for the C-C
coupling reaction