MCM-41-immobilised nitrogen and sulfur mixed tridentate palladium(0) complex: A highly efficient and recyclable catalyst for the Suzuki reaction of aryl bromides in air

Article abstract of DOI:10.3184/174751917X14878812592698

The novel MCM-41-immobilised nitrogen and sulfur mixed tridentate palladium(0) complex [MCM-41-2N,S-Pd(0)] was prepared from 3-(2-aminoethylamino) propyltrimethoxysilane by immobilisation on MCM-41, followed by reaction with thiophene-2-carboxaldehyde and PdCl₂ and then reduction with hydrazine hydrate. This phosphine-free heterogeneous palladium(0) complex was a highly active catalyst for the Suzuki reaction of aryl bromides in air and could be recycled at least 8 times without significant loss of activity.

Full text of DOI:10.3184/174751917X14878812592698

186 RESEARCH PAPER
VOL. 41 MARCH, 186–191
JOURNAL OF CHEMICAL RESEARCH 2017
MCM-41-immobilised nitrogen and sulfur mixed tridentate palladium(0)
complex: a highly efficient and recyclable catalyst for the Suzuki reaction
of aryl bromides in air
Dayi Liua, Pingping Wangb, Jingting Aia, and Mingzhong Caia*
aCollege of Chemistry & Chemical Engineering, Jiangxi Normal University, Nanchang 330022, P.R. China
bCollege of Chemistry & Chemical Engineering, Jiujiang University, Jiujiang 332000, P.R. China
The novel MCM-41-immobilised nitrogen and sulfur mixed tridentate palladium(0) complex [MCM-41-2N,S-Pd(0)] was prepared from
3-(2-aminoethylamino)propyltrimethoxysilane by immobilisation on MCM-41, followed by reaction with thiophene-2-carboxaldehyde and
PdCl2 and then reduction with hydrazine hydrate. This phosphine-free heterogeneous palladium(0) complex was a highly active catalyst
for the Suzuki reaction of aryl bromides in air and could be recycled at least 8 times without significant loss of activity.
Keywords: palladium, Suzuki coupling, functionalised MCM-41, aryl bromide, heterogeneous catalysis
Suzuki–Miyaura coupling is a particularly important reaction
in organic synthesis, since it is one of the most powerful
tools for constructing a biaryl structure, which is present
in many biologically active compounds, liquid crystals and
electroluminescent materials.1–3 However, when homogeneous
palladium catalysts such as Pd(PPh3)4 or Pd(PPh3)2Cl2 are
used in the preparation of fine chemical products, we must
address the problem of residual toxic metal in the product.4
Furthermore palladium, which is increasingly expensive,
cannot be recovered and reused. In contrast, heterogeneous
catalysts can be easily separated from the reaction mixture
by simple filtration and reused in successive reactions
provided that the active sites have not become deactivated.
Heterogeneous catalysis also helps to minimise waste derived
from reaction workup, contributing to the development of
green chemical processes.5–8 From the standpoint of green and
sustainable chemistry, development of immobilised palladium
catalysts is challenging and important.9–11 Recently, palladium
complexes immobilised on cross-linked polymers12–14 or silica
gels15–19 have been used as catalysts for the Suzuki–Miyaura
reaction. However, these supported catalysts have generally
suffered from some drawbacks such as limited mass transfer,
low specificity and selectivity in addition to leaching of the
catalytic species from the surface of the support20 and some of
these studies have been related to polymer-supported phosphine
palladium catalysts.12,21–23 It is well-known that transition-metal
catalysts containing phosphine ligands are unstable24–26 at high
temperatures. Furthermore, the procedure for preparing the
polymer-supported phosphine palladium complexes is rather
complicated since the synthesis of the phosphine ligands
usually requires multi-step sequences.
The development of new phosphine-free heterogeneous
palladium complexes having a high activity and excellent
recyclability is a topic of enormous importance. Our strategy
was guided by three considerations: the heterogeneous ligand
should be easily accessible (1), starting from readily available
and inexpensive reagents (2). The heterogeneous palladium
catalyst should ideally be air-stable, which should allow its
storage in normal bottles with unlimited shelf life (3). The
discovery of the mesoporous material MCM-41 has given an
enormous stimulus to research in heterogeneous catalysis
and has provided a new possible candidate for a solid support
to immobilise homogeneous catalysts.27–29 MCM-41 has a
regular pore diameter of ca. 5 nm and a specific surface area
>700 m2 g–1.30 Considering the fact that the MCM-41 support
has an ultrahigh surface area and the catalytic palladium
species is anchored on the inner surface of the mesopore of
the MCM-41, we expect that an MCM-41-supported palladium
catalyst will exhibit high catalytic activity and excellent
reusability. So far, some functionalised MCM-41-supported
palladium,31–34 rhodium,35 gold36,37 and copper38–41 complexes
have been prepared and used successfully in organic reactions.
In continuing our efforts to develop greener synthetic pathways
for organic transformations, our new approach, described
in this paper, was to design and synthesise a new MCM-41-
immobilised nitrogen and sulfur mixed tridentate palladium(0)
complex [MCM-41-2N,S-Pd(0)], which was used as an effective
palladium catalyst for the Suzuki reaction of aryl bromides in
air.
Results and discussion
Although the phosphine ligands can stabilise palladium and
influence its reactivity, the simplest and cheapest palladium
catalysts are of course phosphine-free systems, specifically
when used in low loading. A new MCM-41-immobilised
nitrogen and sulfur mixed tridentate palladium(0) complex
[MCM-41-2N,S-Pd(0)] was synthesised from commercially
readily available and inexpensive 3-(2-aminoethylamino)
propyltrimethoxysilane by immobilisation on MCM-41,
followed by reaction with thiophene-2-carboxaldehyde and
PdCl2 and then reduction with hydrazine hydrate (Scheme 1)
(see SAFETY WARNING 1 in Experimental section). Small
angle XRD analysis of the MCM-41-2N,S-Pd(0) indicated that,
in addition to an intense diffraction peak (100), two higher
order peaks (110) and (200) with lower intensities were detected
and therefore the chemical bonding procedure did not diminish
the structural ordering of the MCM-41.
Elemental analyses and X-ray photoelectron spectroscopy
(XPS) were used to characterise the MCM-41-immobilised
nitrogen and sulfur mixed tridentate palladium (0) catalyst. The
S:Pd mole ratio of the MCM-41-2N,S-Pd(0) was determined to
be 1.77, which is due to the fact that an excess of MCM-41-2N,S
was used to react with PdCl2 in the preparation of the MCM-41-
2N,S-Pd(0) complex to achieve good stability and recyclability
of the supported Pd(0) catalyst. The catalyst prepared in this way
is referred to as MCM-41-2N,S-Pd(0) or the MCM-41-2N,S-
Pd(0) complex and was used throughout this study. The XPS
data for MCM-41-2N,S-Pd(0), MCM-41-2N,S-Pd(II), MCM-
41-2N,S and PdCl2 are listed in Table 1. It can be seen that the
binding energies of Si2p, N1s and O1s of MCM-41-2N,S-Pd(II)
* Correspondent. E-mail:caimzhong@163.com

JOURNAL OF CHEMICAL RESEARCH 2017 187
H
O
O
H
O
H
O
1. (MeO)3Si(CH2)3NH(CH2)2NH2
Toluene, 100 oC, 24 h
N
i
S
N
H
O
H
O
S
, EtOH, 30 oC, 48 h
2.
OMe
H
C O
S
MCM-41-2N,S
MCM-41
H
O
O
N
H2NNH2.H2O
PdCl2, CH3COCH3
reflux, 72 h
Si
N
P
d
H
S
O
C
EtOH, 30 oC, 5 h
l
OMe
2
MCM-41-2N,S-PdCl2
H
O
O
N
S
i
S
N
H
O
Pd(0)
OMe
MCM-41-2N,S-Pd(0)
Scheme 1
Table 1 Binding energies (eV) from XPS data for MCM-41-2N,S, MCM-
are similar to those of MCM-41-2N,S and the binding energy
of Cl2p of MCM-41-2N,S-Pd(II) is similar to that of PdCl2.
However, the difference of Pd3d5/2 binding energies between
MCM-41-2N,S-Pd(II) and PdCl2 is 0.7 eV. The difference of S2p
binding energies between MCM-41-2N,S-Pd(II) and MCM-41-
2N,S is 0.5 eV. These results suggest that a coordination bond
between S and Pd is formed in the MCM-41-2N,S-Pd(II). The
binding energy (336.8 eV) of Pd3d5/2 of MCM-41-2N,S-Pd(0) is
lower than the binding energy (337.6 eV) of Pd3d5/2 of MCM-
41-2N,S-Pd(II). The Pd3d5/2 binding energy depends strongly
on the nature of the ligands. Consequently, it is impossible to
identify the reduced complex as a zerovalent one on the basis
of its Pd3d5/2 binding energy only. However, the binding energy
of Cl2p in the MCM-41-2N,S-Pd(0) cannot be detected, the shift
(lower) of Pd3d5/2 binding energy together with the dark grey
colour suggests that the reduction of the starting palladium(II)
complex to the lower valent state has taken place. In addition,
the difference of N1s binding energies between MCM-41-2N,S-
Pd(0) and MCM-41-2N,S is 0.7 eV. This result shows that
a coordination bond between N and Pd is also formed in the
MCM-41-2N,S-Pd(0), further confirming the reduction of the
MCM-41-2N,S-Pd(II) to the MCM-41-2N,S-Pd(0). The MCM-
41-2N,S-Pd(0) complex formed is stable in air for one month
but for prolonged storage is better stored under an atmosphere
of argon in which case no decomposition and deactivation are
noted over the period of six months at room temperature. This
result indicates that our consideration (3) has not been fully
achieved by immobilisation of palladium(0) on MCM-41.
In our initial screening experiments, we carried out the
Suzuki coupling of phenylboronic acid (1.5 equiv.) with
4-bromoanisole using MCM-41-2N,S-Pd(0) as the catalyst
under various conditions to optimise the reaction conditions
and the results are summarised in Table 2. Firstly, the base
effect was examined by using 1 mol% of MCM-41-2N,S-Pd(0)
as catalyst in DMF as solvent at 80 ºC. For the bases evaluated
(K3PO4, Na2CO3, K2CO3, and Cs2CO3), K2CO3 was found to be
the most effective (Table 2, entry 3). Among the solvents used
(DMF, toluene, dioxane, xylene, and MeCN), xylene was found
to be the best choice (Table 2, entry 7). Raising the reaction
temperature shortened the reaction time, but did not increase
the yield of 4-methoxybiphenyl (Table 2, entry 9). The reaction
also proceeded smoothly at 60 ºC to afford the desired product
41-2N,S-Pd(II), MCM-41-2N,S-Pd(0) and PdCl2a
Sample
MCM-41-2N,S-Pd(0) 336.8 164.4 400.5 103.2 532.9
MCM-41-2N,S-Pd(II) 337.6 164.3 399.9 103.3 533.1 199.3
Pd3d5/2 S2p
N1s
Si2p O1s
Cl2p
MCM-41-2N,S
PdCl2
163.8 399.8 103.2 533.0
338.3
199.2
aThe binding energies are referenced to C1s (284.6 eV) and the energy differences were
determined with an accuracy of 0.2 eV.
in excellent yield (Table 2, entry 10). Even if the amount of the
catalyst was reduced to 0.5 mol%, the desired product could
be obtained in 95% yield (Table 2, entry 11). We were pleased
to find that the coupling reaction in air gave the same result
as under Ar (Table 2, entry 12). The control experiments
showed that no desired product was detected in the absence
of a palladium catalyst (Table 2, entry 13). Taken together, an
excellent result was obtained when the reaction was carried out
with 0.5 mol% of the catalyst using K2CO3 as base in xylene at
60 °C in air (Table 2, entry 12).
To examine the scope for this heterogeneous palladium-
catalysed Suzuki reaction, we have investigated the reaction
using a variety of arylboronic acids and various aryl bromides
as the substrates under the optimised reaction conditions
(Scheme 2) and the results are listed in Table 3. To our delight,
the Suzuki coupling reactions of aryl bromides having either
electron-donating or electron-withdrawing groups with
phenylboronic acid proceeded very smoothly at 60 °C to
afford the corresponding coupled products 3a–c in excellent
yields (Table 3, entries 1–3). The reactions of sterically
congested 2-bromotoluene and bulky 1-bromonaphthalene with
phenylboronic acid also gave high yields of the desired products
3d and 3e respectively (Table 3, entries 4 and 5). Heteroaryl
bromides such as 2-bromothiophene and 2-bromopyridine
proved to be suitable substrates and gave the corresponding
coupled products 3f and 3g in 87 and 89% yields respectively
(Table 3, entries 6 and 7).
The optimised reaction conditions could be applied to the
coupling reactions of some substituted phenylboronic acids
with a variety of aryl bromides and the results are also listed in

188 JOURNAL OF CHEMICAL RESEARCH 2017
Table 2 Optimisation of the coupling reaction of 4-bromoanisole with phenylboronic acid under various conditionsa
1 mol% MCM-41-2N,S-Pd(0)
( )
HO B
2
Br
+
MeO
MeO
Base, solvent, temp.
Entry
1
2
3
4
5
6
7
8
Base
Solvent
DMF
DMF
DMF
Temp./ºC
80
80
80
80
80
80
80
80
100
60
60
60
60
Time/h
3
3
3
3
3
3
3
3
2
4
8
8
Yield/%b
61
86
89
82
90
74
95
65
94
96
95
95
K3PO4
Na2CO3
K2CO3
Cs2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
DMF
Toluene
Dioxane
Xylene
MeCN
Xylene
Xylene
Xylene
Xylene
Xylene
9
10
11c
12c,d
13e
24
0
aAll reactions were performed using 4-bromoanisole (1.0 mmol), phenylboronic acid (1.5 mmol), MCM-41-2N,S-Pd(0) (1 mol%), base (2.0 mmol) in solvent (3.0 mL) under Ar.
bIsolated yield based on the 4-bromoanisole used.
cMCM-41-2N,S-Pd(0) (0.5 mol%) was used.
dIn air.
eNo palladium catalyst was used under Ar or in air.
Table 3 Heterogeneous Suzuki reaction of aryl bromides with arylboronic
Table 3. 4-Methylphenylboronic acid, 4-methoxyphenylboronic
acid, 4-cyanophenylboronic acid and 4-chlorophenylboronic
acid underwent coupling reactions with various aryl bromides
effectively to furnish the desired coupling products 3h–q
in excellent yields (Table 3, entries 8–17). A wide range of
electron-donating and electron-withdrawing groups such as
methyl, methoxy, chloro, cyano, nitro, ketone and ester present
in aryl bromides and arylboronic acids were well tolerated. Aryl
chlorides were inert under the same conditions, giving only traces
of cross-coupling products. To further illustrate that chloroarenes
were inert in the reaction system, 4-chloro-4’-methylbiphenyl (3i)
was selectively formed in 92% yield in the coupling reaction of
4-methylphenylboronic acid with 1-bromo-4-chlorobenzene
(Table 3, entry 9). Bulky 1-naphthylboronic acid was also a
suitable coupling partner and could undergo coupling reactions
with aryl bromides to afford the desired coupled products 3e,
3r and 3s in high yields (Table 3, entries 18–20). The Suzuki
coupling reactions of sterically hindered arylboronic acids such as
2-methylphenylboronic acid and 2-trifluoromethylphenylboronic
acid with aryl bromides also proceeded smoothly, affording the
desired coupled products 3t–v in good yields after 12 h (Table
3, entries 21–23). The present method provides a quite general
route for the synthesis of unsymmetrical biaryls having various
functionalities.
To determine whether the observed catalysis was due to the
heterogeneous catalyst MCM-41-2N,S-Pd(0) or to a leached
palladium species in solution, we performed a hot filtration test42
on the coupling reaction of 4-bromoanisole with phenylboronic
acid. The MCM-41-2N,S-Pd(0) complex was filtered off after 4
h of reaction time and the filtrate was allowed to react further
by addition of K2CO3 (1 mmol). The catalyst filtration was
performed at the reaction temperature (60 °C) in order to avoid
possible recoordination or precipitation of soluble palladium
upon cooling. We found that, after this hot filtration, no further
reaction was observed, indicating that leached palladium species
from the catalyst (if any) are not responsible for the observed
activity. It was determined by inductively coupled plasma atom
emission spectrometry (ICP-AES) analysis that no palladium
could be detected in the hot filtered solution. This result
suggests that the palladium catalyst remains on the support at
acids catalysed by MCM-41-2N,S-Pd(0)a
Entry Ar
Ar1
Ph
P h
Ph
Ph
Ph
Ph
Time/h Product
Yield/%b
95
93
96
85
90
87
1
4-MeOC6H4
8
5
3a
3b
3cc
3d
3e
3f
2
3
4
5
4-MeCOC6H4
4-O2NC6H4
2-MeC6H4
1-Naphthyl
2-Thienyl
3
7
6
5
6
7
8
9
2-Pyridyl
4-PhC6H4
4-ClC6H4
Ph
5
8
6
5
4
6
6
7
8
5
5
7
6
8
12
12
12
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
3q
3e
3r
3s
3t
89
94
92
90
92
93
89
90
92
96
91
88
85
83
87
81
86
4-MeC6H4
4-MeC6H4
4-MeC6H4
4-MeOC6H4
4-MeOC6H4
4-NCC6H4
4-NCC6H4
4-ClC6H4
4-ClC6H4
10
11
12
13
14
15
16
17
18
19
20
21
22
23
2-Pyridyl
4-O2NC6H4
4-MeC6H4
4-ClC6H4
4-MeC6H4
4-MeOC6H4
4-MeCOC6H4
4-MeOCOC6H4 4-ClC6H4
Ph
4-ClC6H4
4-MeC6H4
3-MeC6H4
Ph
1-Naphthyl
1-Naphthyl
1-Naphthyl
2-MeC6H4
2-CF3C6H4
2-MeC6H4
3u
3v
4-ClC6H4
aReactions were carried out with aryl bromide (1 mmol), arylboronic acid (1.5 mmol),
palladium catalyst (0.005 mmol), K2CO3 (2 mmol) in xylene (3.0 mL) at 60 ºC in air.
bYield of isolated product 3 based on the aryl bromide.
cIMPORTANT: see SAFETY WARNING 2 in Experimental section.
elevated temperature during the reaction and points to a process
heterogeneous in nature.
For a heterogeneous precious catalyst system, it is important
to examine its ease of separation, recoverability and reusability.
This heterogeneous palladium catalyst can be easily recovered
by simple filtration. We next investigated the possibility of
reusing the catalyst on the coupling reaction of 4-bromoanisole

JOURNAL OF CHEMICAL RESEARCH 2017 189
100 °C. Then the solid was filtered off, washed with CHCl3 (2 × 20 mL)
and dried under reduced pressure at 160 °C for 5 h. The dried white
solid (1.73 g) was then reacted with thiophene-2-carboxaldehyde
(0.263 g, 2.32 mmol) in dry ethanol (10 mL) at 30 °C for 48 h. The
solid product was filtered off, washed with ethanol (3 × 20 mL) and
diethyl ether (20 mL) and dried under reduced pressure at 120 °C for
5 h to obtain the hybrid material MCM-41-2N,S (1.834 g). The nitrogen
and sulfur contents were found to be 1.62 mmol g–1 and 0.79 mmol g–1
respectively by elemental analysis.
ꢀꢈꢈ
ꢇꢈ
ꢅꢈ
ꢃꢈ
ꢁꢈ
ꢈ
Preparation of MCM-41-2N,S-Pd(0) complex
SAFETY WARNING 1: Appropriate precautions must be taken
when using hydrazine hydrate as it is highly toxic and harmful to
health.
In a small Schlenk tube, the above-functionalised MCM-41 (MCM-41-
2N,S) (1.81 g, 1.43 mmol of S) was mixed with PdCl2 (0.143 g, 0.81
mmol) in dry acetone (40 mL). The mixture was refluxed for 72 h
under an argon atmosphere. The product was allowed to cool and was
then filtered off. The yellow solid was washed with distilled water (3 ×
20 mL) and acetone (2 × 20 mL) and then stirred with hydrazine
hydrate (1.5 g) and EtOH (25 mL) at 30 °C under Ar for 5 h. The
resulting product was filtered off, washed with EtOH (3 × 20 mL) and
Et2O (2 × 20 mL) and dried under reduced pressure at 60 °C for 5 h to
give a grey catalyst material [MCM-41-2N,S-Pd(0)] (1.854 g). The
palladium content was found to be 0.41 mmol g–1.
ꢀ
ꢁ
ꢂ
ꢃ
ꢄ
ꢅ
ꢆ
ꢇ
Recycling times
Fig. 1 Recycling of the MCM-41-2N,S-Pd(0) complex. Where 1 indicates
the original catalyst before the first recycling.
with phenylboronic acid in air. After carrying out the reaction,
the catalyst was separated by simple filtration and washed
with distilled water, ethanol and diethyl ether. After being air-
dried, it was reused directly without further purification. The
recovered catalyst was used in the next run and almost consistent
activity was observed for eight consecutive cycles (Fig. 1). The
high stability and excellent reusability of the catalyst should
result from the chelating action of nitrogen and sulfur mixed
tridentate ligand on palladium and the mesoporous structure of
the MCM-41 support. The result is important from industrial
and environmental points of view.
In conclusion, we have developed a novel, phosphine-free,
practical and economic catalyst system for the Suzuki reaction
of aryl bromides with arylboronic acids by using an MCM-41-
immobilised nitrogen and sulfur mixed tridentate palladium(0)
complex [MCM-41-2N,S-Pd(0)] as catalyst. The advantages
of our heterogeneous catalytic system over others are: (1) the
preparation of the MCM-41-2N,S-Pd(0) catalyst is simple and
convenient from reagents that are readily available commercially,
(2) the reaction conditions are very mild, i.e. only 0.5 mol%
palladium catalyst, air atmosphere and 60 °C and (3) excellent
performance and reusability of the phosphine-free catalyst.
Suzuki reaction of aryl bromides with arylboronic acids; general
procedure
A mixture of aryl bromide (1.0 mmol), arylboronic acid (1.5 mmol),
potassium carbonate (2.0 mmol), xylene (3 mL) and the MCM-41-
2N,S-Pd(0) complex (13 mg, 0.005 mmol of Pd) was stirred at 60 °C
under air for 3–12 h. The mixture was cooled and the MCM-41-2N,S-
Pd(0) complex was filtered off. It was then washed with distilled water
(2 × 10 mL), EtOH (2 × 10 mL) and Et2O (2 × 10 mL). The filtrate was
poured into a saturated aqueous NaCl solution (50 mL) and extracted
with CH2Cl2 (2 × 50 mL). The extracts were washed with water
(3 × 20 mL) and dried over MgSO4. After removal of the solvent, the
residue was purified by column chromatography on silica gel using
hexane or hexane/ethyl acetate (15:1 to 20:1) as eluent.
4-Methoxybiphenyl (3a): White solid; m.p. 88–90 °C (lit.44 81–83 °C);
1
IR (KBr): 1607, 1489, 1252, 1039, 759, 690 cm–1; H NMR (400 MHz,
CDCl3): δ 7.55–7.50 (m, 4H), 7.43 (t, J = 7.6 Hz, 2H), 7.33–7.29 (m, 1H),
6.97 (d, J = 8.4 Hz, 2H), 3.86 (s, 3H); 13C NMR (100 MHz, CDCl3): δ
159.1, 140.8, 133.8, 128.7, 128.2, 126.8, 126.7, 114.2, 55.4.
4-Acetylbiphenyl (3b): White solid; m.p. 117–118 °C (lit.44
116–118 °C); IR (KBr): 2999, 1682, 1602, 1265, 962, 767 cm–1;
1H NMR (400 MHz, CDCl3): δ 8.02 (d, J = 8.4 Hz, 2H), 7.71–7.63 (m,
4H), 7.49–7.37 (m, 3H), 2.63 (s, 3H); 13C NMR (100 MHz, CDCl3): δ
197.7, 145.8, 139.9, 135.9, 129.0, 128.9, 128.2, 127.3, 127.2, 26.7.
Experimental
All reagents were used as received without further purification.
Xylene was a commercial mixture of isomers (CAS No. 1330-20-7).
Toluene, chloroform and acetone were dried and distilled before use.
The mesoporous material MCM-41 was prepared according to the
literature procedure.43 All reactions were carried out in air in oven-
dried glassware with magnetic stirring. FTIR spectra were obtained
on a Nicolet MAGNA-IR 750 spectrometer. 1H NMR spectra were
recorded on a Bruker Avance 400 (400 MHz) spectrometer with TMS
as an internal standard using CDCl3 as the solvent. 13C NMR spectra
were recorded on a Bruker Avance 400 (100 MHz) spectrometer
using CDCl3 as the solvent. Palladium content was determined by
ICP-AES on an Atomscan16 instrument (TJA Corporation). X-ray
powder diffraction patterns were obtained on a Damx-rA instrument
(Rigaku). X-ray photoelectron spectra were recorded on an XSAM
800 instrument (Kratos). Microanalyses were obtained using a
PerkinElmer 240 elemental analyser.
4-Nitrobiphenyl (3c):
SAFETY WARNING 2: The manufacture and use for all purposes of
the compound 3c is prohibited in the UK by the Control of Substances
Hazardous to Health (COSHH) regulations. 4-Nitrobiphenyl (3c) is
a potent human carcinogen and the Journal of Chemical Research
strongly advises against its preparation.
Yellow solid; m.p. 113 °C (lit.44 109–111.5 °C); IR (KBr): 1597, 1576,
1
1515, 1345, 854, 739 cm–1; H NMR (400 MHz, CDCl3): δ 8.31 (d,
J = 8.4 Hz, 2H), 7.74 (d, J = 8.8 Hz, 2H), 7.63–7.42 (m, 5H); 13C NMR
(100 MHz, CDCl3): δ 147.7, 147.1, 138.8, 129.2, 128.9, 127.8, 127.4,
124.1.
2-Methylbiphenyl (3d): Colourless oil;44 IR (neat): 3061, 3022,
2956, 1479, 1382, 865, 749, 704 cm–1; 1H NMR (400 MHz, CDCl3): δ
7.43–7.21 (m, 9H), 2.27 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 142.0,
135.4, 130.3, 129.8, 129.2, 128.1, 127.3, 127.2, 126.8, 125.8, 20.5.
1-Phenylnaphthalene (3e): Colourless oil;45 IR (neat): 3056, 1592,
Synthesis of MCM-41-2N,S
A solution of 3-(2-aminoethylamino)propyltrimethoxysilane (1.54 g)
in dry chloroform (18 mL) was added to a suspension of MCM-41
(2.2 g) in dry toluene (180 mL). The mixture was stirred for 24 h at
1
1507, 1494, 1395, 762, 703 cm–1; H NMR (400 MHz, CDCl3): δ

190 JOURNAL OF CHEMICAL RESEARCH 2017
7.89–7.82 (m, 3H), 7.53–7.40 (m, 9H); 13C NMR (100 MHz, CDCl3): δ
140.8, 140.3, 133.8, 131.7, 130.1, 128.3, 127.7, 127.3, 127.2, 127.0, 126.1,
126.0, 125.8, 125.4.
4-Chloro-4’-methoxycarbonylbiphenyl (3q): White solid; m.p.
94 °C (lit.48 94 °C); IR (KBr): 2959, 1726, 1609, 1481, 1106, 826, 769
cm–1; 1H NMR (400 MHz, CDCl3): δ 8.12 (d, J = 8.4 Hz, 2H), 7.62 (d,
J = 8.4 Hz, 2H), 7.56 (d, J = 8.4 Hz, 2H), 7.45 (d, J = 8.4 Hz, 2H), 3.95
(s, 3H); 13C NMR (100 MHz, CDCl3): δ 166.9, 144.3, 138.4, 134.3,
130.9, 130.2, 129.1, 128.5, 126.9, 52.2.
1-(4-Chlorophenyl)naphthalene (3r): Colourless oil;45 IR (neat):
3059, 1597, 1506, 1489, 1394, 1089, 1016, 839, 799, 775 cm–1; 1H NMR
(400 MHz, CDCl3): δ 7.89–7.81 (m, 3H), 7.47–7.32 (m, 8H); 13C NMR
(100 MHz, CDCl3): δ 139.2, 139.0, 133.9, 133.4, 131.5, 128.6, 128.5,
128.1, 127.0, 126.4, 126.0, 125.8, 125.5.
2-Phenylthiophene (3f): White solid; m.p. 36–37 °C (lit.46 37–38 °C);
IR (KBr): 3073, 1601, 1532, 1489, 1446, 1256, 851, 755 cm–1; 1H NMR
(400 MHz, CDCl3): δ 7.59–7.56 (m, 2H), 7.35–7.18 (m, 5H), 7.04–7.01
(m, 1H); 13C NMR (100 MHz, CDCl3): δ 144.6, 134.5, 129.0, 128.2,
127.6, 126.1, 124.9, 123.2.
2-Phenylpyridine (3g): Colourless oil;46 IR (neat): 3061, 1587, 1564,
1
1469, 1449, 745, 692 cm–1; H NMR (400 MHz, CDCl3): δ 8.66 (d,
J = 4.8 Hz, 1H), 7.98–7.96 (m, 2H), 7.69–7.67 (m, 2H), 7.47–7.36 (m,
3H), 7.18–7.15 (m, 1H); 13C NMR (100 MHz, CDCl3): δ 157.5, 149.5,
139.4, 136.8, 129.0, 128.8, 127.0, 122.2, 120.6.
1-(4-Methylphenyl)naphthalene (3s): White solid; m.p. 48–50 °C
(lit.45 52–53 °C); IR (KBr): 3046, 2921, 1592, 1505, 1396, 1022, 823,
799, 775 cm–1; 1H NMR (400 MHz, CDCl3): δ 7.91 (d, J = 8.4 Hz, 1H),
7.87 (d, J = 8.0 Hz, 1H), 7.83 (d, J = 8.4 Hz, 1H), 7.53–7.38 (m, 6H),
7.29 (d, J = 8.0 Hz, 2H), 2.45 (s, 3H); 13C NMR (100 MHz, CDCl3):
δ 140.3, 137.9, 137.0, 133.9, 131.8, 130.0, 129.0, 128.3, 127.5, 127.0,
126.2, 126.0, 125.8, 125.5, 21.3.
4-(4-Methylphenyl)biphenyl (3h): White solid; m.p. 207–208 °C
(lit.47 208–209 °C); IR (KBr): 3029, 1642, 1567, 1481, 1145, 816,
1
765 cm–1; H NMR (400 MHz, CDCl3): δ 7.64–7.60 (m, 6H), 7.54
(d, J = 8.0 Hz, 2H), 7.43 (t, J = 7.6 Hz, 2H), 7.35 (t, J = 7.4 Hz, 1H),
7.26–7.21 (m, 2H), 2.39 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 140.8,
140.1, 139.8, 137.8, 137.2, 135.7, 129.6, 128.8, 127.5, 127.3, 127.1, 126.9,
21.2.
4-Chloro-4’-methylbiphenyl (3i): White solid; m.p. 121–123 °C
(lit.48 122–123 °C); IR (KBr): 3027, 1641, 1480, 1069, 954, 809 cm–1;
1H NMR (400 MHz, CDCl3): δ 7.48 (d, J = 8.4 Hz, 2H), 7.44 (d,
J = 8.0 Hz, 2H), 7.37 (d, J = 8.0 Hz, 2H), 7.25 (d, J = 7.6 Hz, 2H), 2.39
(s, 3H); 13C NMR (100 MHz, CDCl3): δ 139.6, 137.4, 137.1, 133.0,
129.6, 128.8, 128.2, 126.8, 21.1.
2-(4-Methylphenyl)pyridine (3j): Colourless oil;46 IR (neat): 3010,
2921, 1615, 1588, 1466, 1432, 1185, 829, 774 cm–1; 1H NMR (400 MHz,
CDCl3): δ 8.67–8.64 (m, 1H), 7.89 (d, J = 7.2 Hz, 2H), 7.66–7.63 (m,
2H), 7.26–7.21 (m, 2H), 7.16–7.12 (m, 1H), 2.38 (s, 3H); 13C NMR (100
MHz, CDCl3): δ 157.5, 149.7, 149.6, 138.9, 136.7, 129.5, 126.8, 121.8,
120.2, 21.3.
2-Methyl-3’-methylbiphenyl (3t): Colourless oil;44 IR (neat): 3023,
1
2922, 1515, 1382, 825, 759, 729 cm–1; H NMR (400 MHz, CDCl3):
δ 7.39–7.11 (m, 8H), 2.37 (s, 3H), 2.26 (s, 3H); 13C NMR (100 MHz,
CDCl3): δ 141.9, 141.8, 137.5, 135.2, 130.2, 129.9, 129.7, 127.9, 127.4,
127.1, 126.2, 125.6, 21.4, 20.4.
2-(Trifluoromethyl)biphenyl (3u): Colourless oil;44 IR (neat): 3067,
3032, 1682, 1602, 1316, 1129, 1036, 767, 749, 703 cm–1; 1H NMR (400
MHz, CDCl3): δ 7.88–7.83 (m, 1H), 7.66–7.41 (m, 8H); 13C NMR (100
MHz, CDCl3): δ 141.8, 140.2, 132.4, 131.6, 129.3, 129.2, 128.1, 127.9,
127.6, 126.3, 122.7.
4-Chloro-2’-methylbiphenyl (3v): Colourless oil;51 IR (neat): 3022,
1
1657, 1596, 1479, 1093, 1008, 835, 760 cm–1; H NMR (400 MHz,
CDCl3): δ 7.39–7.35 (m, 2H), 7.26–7.16 (m, 6H), 2.26 (s, 3H); 13C NMR
(100 MHz, CDCl3): δ 140.7, 140.4, 135.3, 132.8, 130.5, 130.4, 129.7,
128.3, 127.6, 125.9, 20.4.
4-Methoxy-4’-nitrobiphenyl (3k): Yellow solid; m.p. 99–100 °C
(lit.48 100–102 °C); IR (KBr): 2957, 1602, 1595, 1512, 1345, 1187, 1109
1
cm–1; H NMR (400 MHz, CDCl3): δ 8.28 (d, J = 8.8 Hz, 2H), 7.71
Acknowledgement
(d, J = 8.8 Hz, 2H), 7.59 (d, J = 8.8 Hz, 2H), 7.03 (d, J = 8.8 Hz, 2H),
3.89 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 160.5, 147.2, 146.6, 131.1,
128.6, 127.1, 124.2, 114.6, 55.4.
We thank the National Natural Science Foundation of China
(21462021) for financial support.
4-Methoxy-4’-methylbiphenyl (3l): White solid; m.p. 110–112 °C
(lit.48 110–111 °C); IR (KBr): 2916, 1609, 1503, 1289, 1251, 1039, 809
cm–1; 1H NMR (400 MHz, CDCl3): δ 7.52 (d, J = 8.4 Hz, 2H), 7.44 (d,
J = 8.0 Hz, 2H), 7.27–7.21 (m, 2H), 6.97 (d, J = 8.4 Hz, 2H), 3.85 (s,
3H), 2.37 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 158.9, 138.0, 136.4,
133.8, 129.5, 128.0, 126.6, 114.2, 55.4, 21.1.
4-Chloro-4’-cyanobiphenyl (3m): White solid; m.p. 125–127 °C
(lit.49 125–127 °C); IR (KBr): 2227, 1641, 1563, 1486, 1146, 1091, 952,
857 cm–1; 1H NMR (400 MHz, CDCl3): δ 7.74 (d, J = 8.4 Hz, 2H), 7.66
(d, J = 8.4 Hz, 2H), 7.51 (d, J = 8.8 Hz, 2H), 7.46 (d, J = 8.8 Hz, 2H);
13C NMR (100 MHz, CDCl3): δ 144.4, 137.6, 135.0, 132.7, 129.3, 128.5,
127.6, 118.7, 111.3.
4-Cyano-4’-methylbiphenyl (3n): White solid; m.p. 106–108 °C
(lit.48 107–109 °C); IR (KBr): 2226, 1642, 1605, 1564, 1494, 1146, 852,
815 cm–1; 1H NMR (400 MHz, CDCl3): δ 7.67 (d, J = 8.4 Hz, 2H), 7.63
(d, J = 8.4 Hz, 2H), 7.49 (d, J = 8.0 Hz, 2H), 7.28 (d, J = 8.0 Hz, 2H),
2.42 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 145.6, 138.8, 136.3, 132.6,
129.8, 127.5, 127.1, 119.1, 110.5, 21.2.
4-Chloro-4’-methoxybiphenyl (3o): White solid; m.p. 122–123
°C (lit.48 123–124 °C); IR (KBr): 2962, 1607, 1484, 1291, 1264, 1199,
823, 814 cm–1; 1H NMR (400 MHz, CDCl3): δ 7.51–7.46 (m, 4H), 7.38
(d, J = 8.4 Hz, 2H), 6.96 (d, J = 8.8 Hz, 2H), 3.86 (s, 3H); 13C NMR
(100 MHz, CDCl3): δ 159.3, 139.3, 132.7, 132.5, 128.9, 128.1, 128.0,
114.3, 55.4.
Received 22 January 2017; accepted 10 February 2017
Paper 1604447 DOI: 10.3184/174751917X14878812592698
Published online: 28 February 2017
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