A new palladium heterogeneous complex (Pd-Gu@BOEH): chemoselective, phosphine-free and practical nanocatalyst in carbon–carbon cross-coupling reaction

Article abstract of DOI:10.1007/s11164-020-04315-4

Herein, boehmite nanoparticles were synthesized via combination of Al(NO₃)₃·9H₂O and NaOH in aqueous solution. This nanomaterial converted to Pd-Gu@BOEH in several sequences. Pd-Gu@BOEH was used as efficient and recoverable nanocatalyst for the chemoselective C–C band formation such as Mizoroki–Heck and Suzuki–Miyaura reactions without any phosphine ligands or inert atmosphere. This catalyst has been characterized by several analyses such as EDS, WDX, SEM, XRD, FT-IR, TEM, TGA, AAS and BET. Also, obtained products from C–C coupling reactions were identified by NMR spectroscopy and their melting points. This catalyst was recycled in described reactions without palladium leaching. The reused catalyst was characterized by EDS, WDX, XRD, FT-IR and AAS analysis, which showed good stability during reaction process.

Full text of DOI:10.1007/s11164-020-04315-4

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-020-04315-4
A new palladium heterogeneous complex (Pd‑Gu@BOEH):
chemoselective, phosphine‑free and practical nanocatalyst
in carbon–carbon cross‑coupling reaction
Fariba Jafari1,2 · Arash Ghorbani‑Choghamarani2,3 · Neda Hasanzadeh2
Received: 16 August 2020 / Accepted: 23 October 2020
© Springer Nature B.V. 2020
Abstract
Herein, boehmite nanoparticles were synthesized via combination of Al(NO3)3·9H2O
and NaOH in aqueous solution. This nanomaterial converted to Pd-Gu@BOEH
in several sequences. Pd-Gu@BOEH was used as efcient and recoverable nano-
catalyst for the chemoselective C–C band formation such as Mizoroki–Heck and
Suzuki–Miyaura reactions without any phosphine ligands or inert atmosphere. This
catalyst has been characterized by several analyses such as EDS, WDX, SEM, XRD,
FT-IR, TEM, TGA, AAS and BET. Also, obtained products from C–C coupling
reactions were identifed by NMR spectroscopy and their melting points. This cat-
alyst was recycled in described reactions without palladium leaching. The reused
catalyst was characterized by EDS, WDX, XRD, FT-IR and AAS analysis, which
showed good stability during reaction process.
Keywords Boehmite nanoparticles · Palladium · C–C coupling · Heck reaction ·
Suzuki reaction
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1116
4-020-04315-4) contains supplementary material, which is available to authorized users.
* Arash Ghorbani-Choghamarani
arashghch58@yahoo.com; a.ghorbani@basu.ac.ir
1
Department of Chemistry, Khozestan Science and Research Branch, Islamic Azad University,
Ahvaz, Iran
2
Department of Chemistry, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
3
Department of Organic Chemistry, Faculty of Chemistry, Bu-Ali Sina University,
6517838683 Hamedan, Iran
Vol.:(0123456789)
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F. Jafari et al.
Introduction
Homogeneous catalysts have various advantages and applications [1–3]. Mean-
while, in the last decade, their applications were decreased due to non-reusability
[4]. Therefore, reusable, stable and economic environmentally heterogeneous cat-
alysts were great emerged in chemical processes [5–7]. Nanoparticles are known
materials in the range of 1–100 nm, which can put out as a bridge between het-
erogeneous and homogeneous catalysis [8–10]. For example, silica nanomateri-
als [11], carbon nanotubes [12], Metal–organic framework (MOF) [13], polymers
[14], heteropoly acid [15], graphene oxide [16], ionic liquids [17], iron oxide
[18, 19], biomaterials [20], chitosan [21–23], etc. have been applied as catalyst
or solid catalytic supports. Boehmite nanoparticles (aluminum hydroxide) is one
of the aluminum hydroxide phases, which recently employed for the production
of heterogeneous nanocatalysts [24, 25]. Boehmite nanoparticles consist of dou-
ble sheet layers of aluminum oxide hydroxide, which is linked by hydrogen bond
between hydroxyl groups [26, 27]. High congeries of hydroxyl groups is located
on the surface of boehmite nanoparticles, which could be grafted by other func-
tional groups for production of heterogeneous catalysts [28]. Several methods are
presented for preparation of boehmite nanoparticles and its physical and chemical
properties are dependent on experimental synthesis procedure. Therefore, prop-
erties of boehmite nanoparticles such as morphology, crystalline structure and
surface structure could be controlled [29, 30]. Therefore, boehmite nanoparticles
are excellent support for fabrication of heterogeneous catalysts due to its unique
advantages such as the commercial availability, stability, high surface area, non-
toxicity and ease of surface modifcation [31]. Therefore, we report a complex of
palladium on boehmite nanoparticles (Pd-Gu@BOEH) as versatile and recyclable
nanocatalyst for the chemoselective C–C band formation such as Mizoroki–Heck
and Suzuki–Miyaura reactions. C–C Coupling reactions have been employed as
a powerful tools in the production of natural products, UV screens, pharmaceu-
ticals, hydrocarbons, polymers, agrochemicals, biologically active compounds,
liquid crystal materials, herbicides, cosmetics and advanced materials [32–38].
Commonly, the carbon–carbon coupling reactions were reported by various pal-
ladium complexes including phosphine ligand derivatives. Phosphine-free cata-
lysts are of great importance in catalyst science, because phosphine ligands have
several drawbacks such as air- and moisture-sensitive properties, high production
cost, non-reusability, non-stability and moreover [39, 40].
Experimental
Preparation of Pd‑Gu@BOEH nanocatalyst
The modifed boehmite NPs by 3-choloropropyltrimtoxysilane (Cl@boehmite)
were prepared based on the recent reported method [8]. Then, N-PrCl@BOEH
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A new palladium heterogeneous complex (Pd‑Gu@BOEH):…
(1 g) was difused in 50 mL of toluene by bath sonication, then guanidine nitrate
(2.5 mmol) and three ethyl amine (4 mL) were added to the mixture. The obtained
suspension was mixed by stirring under nitrogen atmosphere for 72 h at 100 °C.
Then, the modifed nanomaterials (Gu@BOEH) were washed with EtOH several
times. Finally, the 0.5 g of Gu@BOEH was dissolved in EtOH (25 mL) under
bath sonication, then Pd(OAc)2 (0.25 g) was added to the resulting suspension.
The reaction mixture was refuxed and stirred under N2 atmosphere for 20 h. In
fnal step, NaBH4 (0.4 mmol) was added to the reaction mixture and stirring con-
tinued for more 2 h. The fnal products (Pd-Gu@BOEH) were isolated by fltra-
tion and washed with EtOH and H2O, several times.
Experimental procedure for Suzuki cross‑coupling reaction in the presence
of Pd‑Gu@BOEH
In a round bottom fask, aryl halide (1 mmol), phenylboronic acid (PhB(OH)2),
Pd-Gu@BOEH (0.95 mol%, 0.010 g) and Na2CO3 (0.318 g, 3 mmol) were mixed
and stirred in PEG (1 mL) at 80 °C. After reaction completion, as monitored by
TLC, the remained catalyst was removed using simple fltration and washed by
ethyl acetate. The products were extracted from water by ethyl acetate and, then, the
organic layer was dried over anhydrous sodium sulfate (about 1.5 g). Finally, ethyl
acetate was evaporated and biphenyls achieved between 88 and 98% of yields.
Experimental procedure for Heck cross‑coupling reaction in the presence
of Pd‑Gu@BOEH
In a round bottom fask, aryl halide (1 mmol), sodium carbonate (0.318 g, 3 mmol),
1.2 mmol of alkenes (methyl acrylate, acrylonitrile or butyl acrylate) and Pd-Gu@
BOEH (0.95 mol%, 0.010 g) were mixed and stirred at 120 °C in PEG-400 as sol-
vent (1 mL). Finally, (as monitored by TLC), Pd-Gu@BOEH was removed by fltra-
tion and washed by diethyl ether. Then, the products were extracted from H2O by
diethyl ether. The organic solvents were dried over using anhydrous Na2SO4 (1 g)
and the organic solvents were evaporated. The products were isolated in 85–88% of
yields.
Selected spectral data
1
[1,1’‑Biphenyl]‑4‑carbonitrile H NMR (400 MHz, CDCl3): δH=7.78–7.76 (d, J=8
Hz, 2H), 7.73–7.71 (d, J=8 Hz, 2H), 7.64–7.62 (d, J=8 Hz, 2H), 7.54–7.50 (t, J=8
Hz, 2H), 7.48–7.46 (t, J=8 Hz, 1H) ppm. 13C NMR (100 MHz, CDCl3): δ=145.7,
139.2, 132.6, 129.1, 128.7, 127.7, 127.2, 118.9, 110.9 ppm.
1
4‑Methoxy‑1,1′‑biphenyl H NMR (400 MHz, CDCl3): δH=7.60–7.56 (t, J=8 Hz,
4H), 7.47–7.43 (t, J=8 Hz, 2H), 7.36–7.32 (t, J=8 Hz, 1H), 7.03–7.01 (d, J=8 Hz,
2H), 3.89 (s, 3H) ppm.13C NMR (100 MHz, CDCl3): δ=159.1, 140.8, 133.8, 128.7,
128.2, 126.7, 126.6, 114.2, 55.4 ppm.
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F. Jafari et al.
1
Butyl 3‑(p‑tolyl)acrylate H NMR (400 MHz, CDCl3): δH=7.71–7.67 (d, J=16 Hz,
1H), 7.47–7.45 (d, J=8 Hz, 2H), 7.23–7.21 (d, J8 Hz, 2H), 6.45–6.41 (d, J=16
Hz, 1H), 4.26–4.22 (t, J8 Hz, 2H), 2.41 (s, 3H), 1.76–1.69 (quint, J=8 Hz, 2H),
1.52–1.43 (s, J=8 Hz, 2H), 1.02–0.98 (t, J =8 Hz, 3H) ppm. 13C NMR (100 MHz,
CDCl3): δ=167.3, 144.6, 140.6, 131.8, 129.6, 128.0, 117.2, 64.4, 30.8, 21.5, 19.2,
13.8 ppm.
1
3‑(p‑Tolyl)acrylonitrile H NMR (400 MHz, CDCl3): δH=7.42–7.37 (m, 3H), 7.26–
7.24 (d, J=8 Hz, 2H), 5.88–5.84 (d, J16 Hz, 1H), 2.42 (s, 3H) ppm.13C NMR (100
MHz, CDCl3): δ=150.5, 141.8, 130.9, 129.8, 127.3, 118.5, 95.0, 21.5 ppm.
Result and discussion
Initially, Pd-Gu@BOEH was synthesized based on reported procedure, which is
outlined in Scheme 1. In the next step, the structure of Pd-Gu@BOEH was charac-
terized by EDS, WDX, SEM, XRD, FT-IR, TEM, TGA, AAS and BET techniques.
Catalyst characterizations
Scanning electron microscopy (SEM) technique was employed to obtain the exact
morphology of Pd-Gu@BOEH. The scanned images of this catalyst are presented
in Fig. 1.
Also, the morphology and size of Pd-Gu@BOEH were studied by TEM image
(Fig. 2). The unit cells of Pd-Gu@BOEH were displayed in cubic orthorhombic
structures with less than 50 nm in dimensions. Also, TEM image of this cata-
lyst was confrmed that palladium particles were successful immobilized on the
Scheme 1 Synthesis of Pd-Gu@BOEH
1 3

A new palladium heterogeneous complex (Pd‑Gu@BOEH):…
Fig. 1 SEM images of Pd-Gu@BOEH
Fig. 2 TEM images of Pd-Gu@BOEH
surface of boehmite. Based on TEM image, the diameter of palladium particles is
less than 10 nm.
The elements content of Pd-Gu@BOEH was studied by energy-dispersive
X-ray spectroscopy (EDS). As shown in Fig. 3, the catalyst structure contains Al,
O, Si, C, N and Pd species.
Also, the exact amount of palladium in Pd-Gu@BOEH was calculated by
AAS, which was found to be 1.08 × 10–3 mol g−1 (11.51%W).
In order to see distributions of elements in the structure of describe nanoparti-
cles, wavelength-dispersive X-ray spectroscopy (WDX) was used (Fig. 4). It can
be seen, the elements homogeneously dispersed on the surface of catalyst.
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F. Jafari et al.
Fig. 3 EDX spectrum of
Pd-Gu@BOEH
Fig. 4 Elemental mapping of a Al, b O, c Si, d C, e N, f Pd for Pd-Gu@BOEH
Presence of organic coating layers on boehmite nanoparticles was calculated by
TGA analysis (Fig. 5). TGA/DTA diagrams of Pd-Gu@BOEH show three weight
loss. The removal of adsorbed solvents (about 5%) is observed before 150 °C as
frst weight loss [24]. The second weight loss is shown a big peak of weight loss
(about 12%), which was observed between 200 and 500 °C. This large weight loss
is due to the calcination of organic coating layers on boehmite nanoparticles. The
1 3

A new palladium heterogeneous complex (Pd‑Gu@BOEH):…
Fig. 5 TGA–DTG–DTA diagrams of Pd-Gu@BOEH
fnal weight loss (about 2%) was indicated above 600 °C. This weight loss may be
corresponded to transformation of thermal phase of boehmite nanoparticles [31].
BET isotherms from nitrogen adsorption–desorption for Pd-Gu@BOEH
are shown in Fig. 6. The obtained surface area of Pd-Gu@BOEH is 61.5 m2/g
that lower than boehmite nanoparticles (122.8 m2/g [24]. Also, mean pore
diameter (nm) of catalyst (5 nm) is lower than boehmite nanoparticles (36 nm
[37]. The reduced in surface area and pore diameter of catalyst confrmed the
Fig. 6 N2 adsorption–desorption
Adsorption / desorption isotherm
300
isotherm of Pd-Gu@BOEH
200
100
0
0
0.5
1
p/p0
ADS
DES
1 3

F. Jafari et al.
Scheme 2 Carbon–carbon band forming in the presence of Pd-Gu@BOEH
Table 1 Optimization of Suzuki reaction conditions for coupling of 4-bromonitrobenzen with PhB(OH)2
in the presence of Pd-Gu@BOEH
Entry
Catalyst (mg)
Solvent
Base
Temperature (°C)
Time (min)
Yield (%)a
1
2
3
4
5
6
7
8
–
8
PEG
PEG
PEG
PEG
EtOH
DMSO
H2O
PEG
PEG
PEG
PEG
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Et3N
80
80
80
80
Refux
80
80
80
80
400
375
315
295
315
315
315
315
315
315
315
–
90
95
96
30
80
75
44
83
41
Trace
10
12
10
10
10
10
10
10
10
9
10
11
K2CO3
Na2CO3
Na2CO3
60
r.t
aIsolated yield
immobilization of organic layers and palladium complex on the Boehmite nano-
particles [37].
Catalytic application of Pd‑Gu@BOEH in C–C band forming
The catalytic activity of Pd-Gu@BOEH was applied in the chemoselective C–C
band formation such as Suzuki and Heck cross-coupling reactions (Scheme 2).
Initially, the synthesis of biphenyl via cross-coupling of PhB(OH)2 with
4-bromonitrobenzen was investigated in the presence of Pd-Gu@BOEH under
various conditions (Table 1). As shown in entry 3 of Table 1, 10 mg (containing
0.95 mol% of palladium) of Pd-Gu@BOEH indicated the best amount of catalyst
1 3

A new palladium heterogeneous complex (Pd‑Gu@BOEH):…
for selected coupling reaction. Also, in among of diferent solvents (Table 1, entries
4–7) and bases (Table 1, entries 7–9), PEG as solvent and Na2CO3 as base were
selected as the best parts of coupling reactions. Finally, the efect of temperature was
examined, which 80 °C exhibited the best reaction out-put.
After optimization of the reaction conditions, the obtained optimal conditions
applied for the cross-coupling of a variety of aryl halides including aryl iodide
(Ar–I), aryl bromide (Ar–Br) and aryl chloride (Ar–Cl) and the obtained results
are presented in Table 2. TOF and TON numbers were calculated for all reactions,
in which the good number of TOF and TON was obtained for all aryl halides
Table 2 Catalytic C–C band forming of aryl halides with PhB(OH)2 in the presence of Pd-Gu@BOEH
Time Yield
TOF
Entry
Aryl halide
TON
(min) (%)a
(h-1)
1
40
60
98
88
103.1
154.7
92.6
2
3
92.6
35
55
94
96
95
98.9
169.6
110.2
50.0
4
5
101.1
100.0
120
6
175
91
95.8
32.8
7
8
160
100
92
94
96.8
98.9
36.3
59.4
9
315
95
100
19.0
a Isolated yield.
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F. Jafari et al.
Scheme 3 Chemoselectivity in C–C coupling reactions in the presence of Pd-Gu@BOEH
Scheme 4 The mechanism for the Suzuki coupling reaction using Pd-Gu@BOEH as catalyst
bearing electron-rich and electron-poor groups in the presence of Pd-Gu@BOEH.
The calculated TOF values and reaction times in Table 2 indicate that the reactiv-
ity of aryl halides is as: Ar–I > Ar–Br > Ar–Cl. As shown in entries 4 and 5 of
Table 2, the chemoselectivity of Pd-Gu@BOEH was confrmed in the coupling of
PhB(OH)2 with 4-bromophenol and 1-chloro-4-bromobenzene (Scheme 3).
Based on authentic reports, the mechanism for the Suzuki coupling reaction
using Pd-Gu@BOEH as catalyst is presented in Scheme 4 [2, 38].
As shown in Scheme 2, the catalytic application of Pd-Gu@BOEH was also
investigated in the coupling of aryl halides with several alkenes (Heck reaction).
To defne the ideal conditions, the reaction coupling of iodobenzene (Ph-I)
with butyl acrylate using diferent amounts of Pd-Gu@BOEH as catalyst exam-
ined as model reaction (Table 3), which 10 mg (containing 0.95 mol% of pal-
ladium) of this catalyst was obtained as optimal amount of catalyst. As shown
in entries 4–9 of Table 3, several bases and solvents were tested, which PEG
(Table 3, entry 3) and Na2CO3 (Table 3, entry 3) were selected after diferent
reaction conditions. Finally, the temperature role was studied (Table 3, entries 3
and 10), in which the best result achieved at 120 °C.
1 3

A new palladium heterogeneous complex (Pd‑Gu@BOEH):…
Table 3 Optimization conditions for the coupling reaction of butyl acrylate with Ph-I using Pd-Gu@
BOEH as catalyst
Entry
Catalyst (mg)
Solvent
Base
Temperature Time (min)
(ºC)
Yield (%)a
1
2
3
4
5
6
7
8
9
–
10
8
PEG
PEG
PEG
PEG
DMSO
DMF
Toluene
PEG
PEG
PEG
NaCO3
NaCO3
NaCO3
NaCO3
NaCO3
NaCO
NaCO3
KOH
120
120
120
120
120
120
120
120
120
100
100
30
30
30
40
40
40
30
25
40
–
85
80
78
–
–
–
65
55
–
5
10
10
10
10
10
10
Et3N
NaCO3
10
aIsolated yield
With optimal conditions in hand, a variety of aryl halide derivatives were coupled
whit methyl acrylate, acrylonitrile and butyl acrylate in the presence of Pd-Gu@
BOEH as catalyst (Table 4). As results shown, aryl halides including electron-
rich and electron-poor functional groups were coupled with methyl acrylate, butyl
acrylate and acrylonitrile that corresponding products were isolated with good
yields, TON and TOF factors.
Reusability of the catalyst
The recyclability of Pd-Gu@BOEH was considered in the coupling of PhB(OH)2
and Ph-I (Fig. 7). To reusing of the catalyst, in the end of each reaction, the catalyst
was isolated by centrifugation and employed for next run. The mediocre yields for
8 continuous runs were about 93.8%, which indicates the excellent recyclability of
Pd-Gu@BOEH.
Characterization of the recycled catalyst
To show the stability of Pd-Gu@BOEH after reusing, the recycled Pd-Gu@BOEH
was characterized by XRD, FT-IR, EDS, WDX and AAS techniques.
The XRD pattern of recovered Pd-Gu@BOEH (Fig. 8) includes several peaks of
2ꢀ at 14.15, 28.85, 38.50, 45.10, 49.25, 51.90, 55.70, 64.40, 68.50 and 72.35, which
are related to the standard XRD pattern of boehmite [6, 45]. Therefore, boehmite
nanoparticles are stable after modifcation and also it is stable under organic reac-
tion conditions. Also, XRD pattern of recovered Pd-Gu@BOEH (Fig. 8) has shown
several peaks of 2ꢀ at 40.1° (200), 46.7° (220) and 67.8° (331) that are related to the
presence of Pd(0) in the catalyst [9, 37].
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F. Jafari et al.
Table 4 Coupling of aryl halide derivatives with alkenes in the presence of a catalytic amount of Pd-
Gu@BOEH
Time Yield
Entry Aryl halide
Alkene
Product
TONTOF (h-1)
(min) (%)a
Butyl
acrylate
1
30
85 89.5 178.9
Butyl
acrylate
2
3
140
88 92.6
75 78.9
39.7
63.2
Butyl
acrylate
160
Butyl
acrylate
4
5
220
78 82.1
22.4
Acrylonitrile
80
80 84.2
63.2
6
7
Acrylonitrile
Acrylonitrile
120
84 88.4
44.2
330
80 84.2
15.3
Methyl
acrylate
8
50
80 84.2 101.0
Methyl
acrylate
9
165
75 78.9
28.7
a Isolated yield.
The elements content of Pd-Gu@BOEH after recovering was studied by EDS
(Fig. 9) and WDX (Fig. 10) analysis. As shown in Fig. 9, recovered Pd-Gu@
BOEH includes Al, O, Si, C, N and Pd elements. Also, WDX analysis indicated
a good homogeneous dispensation of these elements in the reused catalyst. EDS
and WDX analysis of recovered Pd-Gu@BOEH showed a good agreement with
EDS and WDX analysis of fresh catalyst. Also, the amount of Pd element in recy-
cled Pd-Gu@BOEH was calculated by AAS analysis. Based on AAS analysis, the
1 3

A new palladium heterogeneous complex (Pd‑Gu@BOEH):…
Fig. 7 Recyclability of Pd-Gu@
BOEH in the coupling of Ph-I
and PhB(OH)2
100
80
60
40
20
0
1
2
3
4
5
6
7
8
Run number
2500
2000
1500
1000
500
Pd
Pd
Pd
0
10
20
30
40
50
60
70
80
2θ / degree
Fig. 8 XRD pattern of Pd-Gu@BOEH after reusing
Fig. 9 EDX spectrum of
Pd-Gu@BOEH after reusing
amount of Pd in the fresh and recycled Pd-Gu@BOEH was 1.08×10−3 mol g−1 and
1.02×10−3 mol g−1, respectively, which shows that Pd leaching of this catalyst is
negligible.
A comparison of FT-IR spectra of the catalyst before and after recycling is shown
in Fig. 11. As shown, there are no changes in the FT-IR of Pd-Gu@BOEH after
recovery, which is confrmed the stability of this catalyst under organic reaction
conditions.
1 3

F. Jafari et al.
Fig. 10 Elemental mapping of a Al, b O, c Si, d C, e N, f Pf for Pd-Gu@BOEH after reusing
Hot fltration test
In order to show the heterogeneous nature and stability of Pd-Gu@BOEH under
organic reaction conditions, hot fltration test was performed for the coupling of 4
Ph-I with PhB(OH)2. In this investigation, the reaction was stopped after half‐time
of the reaction, which 49% of biphenyl was obtained as product. In another experi-
ment, the mentioned reaction was repeated and Pd-Gu@BOEH was removed after
half‐time of reaction, then the remained mixture was permitted to continue for a
further 40 min. Afterward, only 54% of product was obtained. These experiments
confrm that the leaching of palladium did not occur.
Comparison of the Catalyst
The practicality and activity of Pd-Gu@BOEH were compared to authentic reported
literatures in the obtained results from coupling of 4-Iodotoluene or Ph-I with
PhB(OH)2 (Table 5). As results shown, the isolated yield and TOF numbers in the
presence of Pd-Gu@BOEH are comparable with previous catalysts. Additionally,
several reported procedures are required special device to perform the Suzuki cou-
pling reaction such as microwave irradiation or ultrasonic sonication.
1 3

A new palladium heterogeneous complex (Pd‑Gu@BOEH):…
Fig. 11 FT-IR spectra of Pd-Gu@BOEH a before and b after reusing
Table 5 Comparison of Pd-Gu@BOEH in the Suzuki coupling reaction with authentic reported
researches
Entry
Catalyst
Aryl halide
Time (min)
Yield (%) [References]
1
2
3
4
5
6
7
8
Pd-SMU-MNPs
4-Iodotoluene
4-Iodotoluene
4-Iodotoluene
4-Iodotoluene
4-Iodotoluene
4-Iodotoluene
4-Iodotoluene
Ph-I
60
90
30
5
94 [9]
Pd-imi-CC@MCM-41/Fe3O4
Pd NPs@CMC/AG
Pd NPs@APC
CL-Gly-Pt
Pd(0)–Schif-base@MCM-41
Pd-adenine@boehmite
95 [41]
75 [42]
67 [43]
60 [44]
97 [45]
89 [46]
95 [37]
7
200
50
35
Fe3O4@Boehmite-NH2-CoII
NPs
9
SBA-16–2 N-Pd(II)
Pd(II)–NHC complex
NHC-Pd(II) complex
Pd(0)–SMTU–boehmite
Pd(0)–SMTU–boehmite
Pd-Gu@BOEH
Ph-I
Ph-I
Ph-I
Ph-I
4-Iodotoluene
4-Iodotoluene
Ph-I
120
24 h
12 h
45
90
35
97 [47]
99 [48]
88 [49]
94 [50]
87 [50]
94 [This work]
98 [This work]
10
11
12
13
14
15
Pd-Gu@BOEH
40
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F. Jafari et al.
Conclusion
In conclusion, we have successfully fabricated a guanidine complex of palladium on
the surface of modifed boehmite (Pd-Gu@BOEH) and further was characterized by
several techniques such as EDS, WDX, SEM, XRD, FT-IR, TEM, TGA, AAS and
BET. After characterization of Pd-Gu@BOEH, its catalytic application was con-
sidered for the chemoselective C–C band formation such as Heck and Suzuki reac-
tions. The catalyst shows high catalytic activity and the all products were obtained
in remarkable yields, high purity, good TON and TOF values. This catalyst shows a
good recyclability in the described reactions without generating of any by-product.
Acknowledgements Authors thank Bu-Ali Sina University and Islamic Azad University, Ahvaz branch
for fnancial support of this research project.
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