A highly active nickel-fibre complex as a catalyst for the Heck reaction

Article abstract of DOI:10.3184/174751916X14547740527373

A new amidoxime fibre-nickel catalyst (AOFs-Ni(0)) was synthesised by a coordination and reduction reaction. The X-ray diffraction patterns indicated that the Ni(II) ions were reduced to Ni(0). The scanning electron microscope image showed that the Ni(0) particles which were reduced in situ had a diameter of about 300 nm. This catalyst demonstrated high activity in the Heck coupling reaction of aryl iodine and conjugated alkenes without the protection of an inert atmosphere.

Full text of DOI:10.3184/174751916X14547740527373

164 RESEARCH PAPER
VOL. 40 MARCH, 164–166
JOURNAL OF CHEMICAL RESEARCH 2016
A highly active nickel–fibre complex as a catalyst for the Heck reaction
Zhi-Chuan Wu, Quan Yang, Meng Chen, Li Liu and Ting-Xian Tao*
Department of Biological and Chemical Engineering, Anhui Polytechnic University, Wuhu 241000, P.R. China
A new amidoxime fibre–nickel catalyst (AOFs–Ni(0)) was synthesised by a coordination and reduction reaction. The X-ray diffraction
patterns indicated that the Ni(II) ions were reduced to Ni(0). The scanning electron microscope image showed that the Ni(0) particles
which were reduced in situ had a diameter of about 300 nm. This catalyst demonstrated high activity in the Heck coupling reaction of aryl
iodine and conjugated alkenes without the protection of an inert atmosphere.
Keywords: amidoxime fibres, fibre–nickel complex, heterogeneous catalyst, Heck reaction
Results and discussion
The Mizoroki–Heck reaction has become one of the most useful
carbon–carbon bond-forming reactions in organic synthesis
and it has been intensively developed from both synthetic and
mechanistic points of view.1–4 The reaction has been applied in
many areas, including the synthesis of bioactive compounds,
natural products, drug intermediates, fine chemicals, UV
absorbers, antioxidants and industrial applications.5–10
Although palladium is the most active catalyst in these
carbon–carbon bond forming reactions, nickel was considered
the most promising replacement of palladium among the
inexpensive transition for metals. The study of nickel catalysed
Heck reactions is important in an industrial context. In early
studies, NiCl2(PPh3) was used to catalyse the reaction of aryl
halides with the olefins.11–12 Kelkar13 reported the vinylation
of bromobiphenyls using NiCl2 (PPh3) in the presence of an
inorganic base. However, the homogeneous catalysts suffer from
the drawbacks of difficult separation and limited lifetime.14–16
In addition, phosphine or amine ligands are often necessary
and the reactions are often sensitive to oxygen.17 To overcome
these problems, heterogeneous catalysts were tentatively
employed.18–19 For example, Yu20 reported that polyaniline/
Pd(0) nanocomposites could be a good catalyst for the Heck
reaction.
In this paper, we report a new amidoxime fibre–nickel
complex (AOFs–Ni(0)) catalyst for the Heck reaction. Scheme 1
shows the synthetic route of AOFs–Ni(0). The AOFs can easily
be obtained by the reaction of polyacrylonitrile (PAN) and
NH2OH. The –NH2 and –OH in AOFs have a high coordinating
ability with metal cations.21–22 A new amidoxime fibre–nickel
catalyst was then synthesised by the ‘coordination–reduction’
reaction between the amidoxime groups in the fibres and the
Ni(II) ions.
The catalytic activity of the AOFs–Ni(0) was tested by using
them in the Heck reaction. The results of the AOFs–Ni(0)
catalysed Heck reaction showed that the reaction could be carried
out under mild conditions without the protection of an inert
atmosphere. In addition, the catalyst is environmentally-friendly
since phosphine or amine ligands are not used. This method is an
efficient alternative for the nickel-catalysed Heck reactions.
Characterisation of the catalyst
The SEM pattern (Fig. S1 in the ESI) of AOFs–Ni(0) showed
that Ni particles had a uniform distribution on the surface of
the AOFs and the average size of the Ni particles was about 300
nm. The characteristic peaks of Ni(0) at the 2θ angles of 46.2°
was observed in the XRD pattern (Fig. S2 in the ESI) of AOFs–
Ni(0), indicating that Ni(II) was reduced to nickel particles on
the surface of the AOFs.
Heck reaction of iodobenzene with phenylethylene
Table 1 (entries 1–4) showed the Heck reaction of iodobenzene
with phenylethylene at different temperatures. It can be seen that
the reaction temperature has some influences on the catalytic
performance. Using DMF as a solvent and K2CO3 as a base,
the Heck reaction could be carried out at 100 °C with a yield
of 78%. When the temperature was increased from 100 °C to
130 °C, the yield increased although when the temperature was
above 110 °C, the yield decreased. Hence 110 °C was selected
as the optimum reaction temperature.
Different solvents and bases can affect this reaction. We
examined DMF, DMSO, i-PrOH and EtOH (Table 1, entries 5–8)
in the reaction. The corresponding yield was 95%, 95%, 12%,
13%. Hence DMF is the best solvent for this reaction. We also
examined different bases in this reaction, including Bu3N, Et3N
and K2CO3. The corresponding yield was 40%, 39% and 80%
(Table 1, entries 9–11). Hence we choose K2CO3 for this reaction.
In Table 1 entries 12–15 we can see the best reaction time is 9
h. We explored the reaction of iodobenzene with phenylethylene
catalysed by different amounts of Ni/AOFs ranging from 0.98
mol%, 1.47 mol% and 1.96 mol% at 110 °C. The results are
listed in Table 1 (entries 16–18). It can be seen that the best
amount of catalyst is 1.47 mol%.
Heck reaction of iodobenzene with acrylic acid
Table 2 (entries 1–4) shows the Heck reaction of iodobenzene
with acrylic acid at different temperatures. Using DMF as the
solvent and tributylamine as the base, 120 °C was selected as the
optimum reaction temperature. We investigated the influence of
different alkaline reagents on the Heck reaction. The results are
C
N
NH2OH
NH2
NH2
N
NH2
N
ꢀꢂꢕꢖ.ꢕꢂꢒ
ꢀꢁꢂꢃ
ꢀꢁꢄꢅꢆ
OH
Ni(II)
C
C
C
N
OH
OH
AOFs
ꢄꢇꢈꢁꢉꢊꢋꢁꢈꢌ ꢍꢁꢎꢌꢏꢐꢆ
ꢑꢒꢓꢐꢔꢀꢁꢄꢅꢆ
AOFs-Ni(II)
Scheme 1 Synthesis route of the AOFs supported nickel complex.
* Correspondent. E-mail: tingxiantao@126.com

JOURNAL OF CHEMICAL RESEARCH 2016 165
Table 1 Effects of the reaction temperature, catalyst amount, solvent
and base on catalytic performance of the Heck reaction of iodobenzene
with phenylethylene
Table 2 Effects of the reaction temperature, catalyst amount and base
on catalytic performance of the Heck reaction of iodobenzene and
acrylic acid
COOH
ꢁꢂꢃꢄꢅꢆꢇꢈꢉꢊ
ꢁꢂꢃꢄꢅꢆꢇꢈꢉꢊ
COOH
ꢀ
ꢀ
ꢋꢌꢄꢍ，ꢎꢍꢏꢐꢍꢑꢌꢒꢓꢑꢍ
+
ꢘ
ꢄꢔꢕꢖꢍꢗꢒ
ꢋꢌꢄꢍ，ꢎꢍꢏꢐꢍꢑꢌꢒꢓꢑꢍ
ꢄꢔꢕꢖꢍꢗꢒ
AOFs–Ni(0)/
Entry Temperature/°C Solvent Base
Time/h Yield/%a
Entry Temperature/°C Base
solvent
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMSO
EtOH
Acetone
DMF
Time/h
Yield/%a
15
20
83
80
83
80
21
83
55
20
17
20
40
83
57
mol%
1
2
3
4
5
6
7
8
100
110
120
130
120
120
120
120
120
120
120
120
120
120
120
Bu3N
Bu3N
Bu3N
Bu3N
Bu3N
Et3N
K2CO3
Bu3N
Bu3N
Bu3N
Bu3N
Bu3N
Bu3N
Bu3N
Bu3N
8
8
8
8
8
8
8
8
8
8
8
6
7
8
9
1
2
3
4
5
6
7
8
100
110
120
130
110
110
110
110
110
110
110
110
110
110
110
110
110
110
DMF
DMF
DMF
DMF
DMF
K2CO3 1.47
K2CO3 1.47
K2CO3 1.47
K2CO3 1.47
K2CO3 1.47
9
9
9
9
9
9
9
9
9
9
9
7
8
9
10
9
9
9
78
94
90
80
94
94
12
14
40
39
95
54
60
94
73
78
94
94
DMSO K2CO3 1.47
i-PrOH K2CO3 1.47
EtOH
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
K2CO3 1.47
Bu3N 1.47
9
9
10
11
12
13
14
15
10
11
12
13
14
15
16
17
18
Et3N
1.47
K2CO3 1.47
K2CO3 1.47
K2CO3 1.47
K2CO3 1.47
K2CO3 1.47
K2CO3 0.98
K2CO3 1.47
K2CO3 1.96
DMF
DMF
DMF
aYield based on the iodobenzene used.
Table 4 Successive trials using recycled AOFs–Ni(0) catalysts in the
reaction of iodobenzene and phenylethylenea
aYield based on the iodobenzene used.
Recycling times
1st recycle
2nd recycle
3rd recycle
4th recycle
Time/h
Yield/%
88
75
65
40
9
9
9
9
Table 3 The Heck reaction of substituted aryl halides with conjugated
alkenes catalysed by AOFs–Ni(0)
ꢁꢄ
ꢅꢆꢇꢈꢉꢊꢋꢌꢍꢎ
ꢀ
ꢃ
ꢁꢄ
aAll reactions were carried out with iodobenzene (9 mmol), phenylethylene (15 mmol),
K2CO3 (30 mmol), AOFs–Ni(0) (1.47 mol %) and DMF (6 mL) at 110 °C in the air.
ꢏꢐꢇ ꢑꢄꢒꢆꢓꢔꢕꢖꢓꢊ
ꢁꢂ
ꢁꢂ
Entry
R1
R2
Products
Yield/%
Table 5 Successive trials using recycled AOFs–Ni(0) catalysts in the
reaction of iodobenzene and acrylic acida
1
2
3
4
5
6
7
8
H
Ph
Ph
Ph
Ph
-COOH
-COOH
-COOH
-COOH
A
B
C
D
E
G
F
99
94
85
68
85
86
93
73
4-COOH
4-NO2
4-H3CO
H
4-NO2
4-H3CO
4-COOH
Recycling times
1st recycle
2nd recycle
3rd recycle
4th recycle
Time/h
Yield/%
88
80
75
50
8
8
8
8
aAll reactions were carried out with iodobenzene (9 mmol), acrylic acid (15 mmol), Bu3N
H
(30 mmol), AOFs–Ni(0) (1.47 mol%) and DMF (6 mL) at 120 °C in the air.
listed in Table 2 entries 5–7. It can be seen that tributylamine is
preferred and from entries 8–11 the best solvent is DMF. Entries
12–15 show that 8 h is the best reaction time.
It could be seen that the catalytic activity of AOFs–Ni(0)
decreased a little after the second recycling. But at the fourth
recycling the yield decreased considerably. This was ascribed
to Ni leaching.
Heck reaction of aryl halides derivatives with conjugated alkenes
In order to examine the catalytic activity of the AOFs–Ni(0)
catalyst with other substrates, some related experiments are
shown in Table 3. This shows that the Heck reaction of acrylic
acid or styrene with aryl iodides can be carried out efficiently
with a relatively high yield. It was found that the yields were
generally high for both electron-donating and electron-
withdrawing aryl iodides although the latter gave a higher yield
than electron-donating aryl iodides.
Experimental
Materials
Reagents were purchased from Beijing Chemical Reagents Co.
(Beijing, P.R. China) and Sinopharm Chemical Reagent Co., Ltd
(Shanghai, P.R. China). The PAN fibres were provided by the Jilin
Carbon Co., Ltd. (Jilin, P.R. China).
The morphologies of sample fibres was observed by SEM (Hitachi
S-4800 field-emission). The phase structures of sample fibres were
examined using a Philips X’ Pert PRO SUPER (XRD) with CuKα
radiation in step-scan mode. Reaction products were characterised
Recycling of the catalyst
1
The catalyst can be easily separated from the reaction mixture
by filtration during the work-up procedure. The results were
summarised in Table 4 and Table 5.
by their HNMR spectra (Bruker ARX-300 spectrometer), GC-MS
spectra (GCMS-QP2010 Hra 5MS/NP) and HRMS spectra (solariX 70
FT-MS Bruker, Germany).

166 JOURNAL OF CHEMICAL RESEARCH 2016
Preparation of the catalysts
J = 15.6 Hz, 1H), 6.90–7.51(m, 4H); HRMS (CH3OH): C10H10O3
([M – H]–: calcd: 177.05462; found: 177.05103).
4-carboxycinnamic acid (i): m.p. 254–258 °C (lit.27 253–259 °C).
HRMS (CH3OH): C10H10O3 ([M – H]–: calcd: 191.03388; found:
191.03094).
The PAN fibres (1.0 g) were first immersed in 100 mL 1 mol
L–1 NH2OH aqueous solution at 70 °C for 1.5 h to introduce
–NH2 and –OH groups onto the fibre surface. The resultant
fibres were termed amidoxime fibres (AOFs). Subsequently, the
AOFs were rinsed with distilled water and then immersed in
100.0 mL 0.129 mol L–1 NiSO4 aqueous solution at about 45 °C
for 1 h to allow the AOFs to coordinate with Ni2+ ions. Then
the fibres were further immersed into 50.0 mL 25% N2H4•H2O
aqueous solution at room temperature for 30 min to reduce the
Ni(II). The products were rinsed with distilled water and dried,
to give the black AOFs–Ni(0) catalysts.
We are thankful to financial support from the National Nature
Science Foundation of China (21171003, 21571003).
Electronic Supplementary Information
The SEM pattern and the XRD pattern of AOFs–Ni(0), are
available through:
stl.publisher.ingentaconnect.com/content/stl/jcr/supp-data
Analysis of nickel content in AOFs–Ni(0) catalysts
AOFs–Ni(0) complex was immersed in nitric acid solution (50 mL,
50% HNO3) and the nickel was dissolved. The content of Ni in AOFs–
Ni(0) surface was then analysed by a coordination titration method
with EDTA as the indicator, and the result was 1.47 mol%
Received 25 November 2015; accepted 17 January 2016
Paper 1503734 doi: 10.3184/174751916X14547740527373
Published online: 25 February 2016
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Typical procedure for the Heck reaction
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(or acrylic acid), tributylamine (30 mmol) and DMF (10 mL) were
placed in a round-bottomed flask with 1.47 mol% AOFs–Ni(0) as
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1
were characterised by melting point, H NMR, HRMS and GC-MS
spectroscopy.
1
Diphenylethene (a): m.p. 124–126 °C (lit.23 123–125 °C). H NMR
(300 M Hz, CDCl3): δ 7.12 (s, 2H), 7.26–7.53(m, 10H). GC-MS (5MS/
NP, CH3OH): C14H12 (M = 180).
1-methoxy-4-(styryl)benzene (b): m.p. 154–157 °C (lit.24
1
155–157 °C). H NMR (300 M Hz, CDCl3): δ 3.829(s, 3H), 6.90(d,
J = 8.4 Hz, 2H), 7.00–7.47(m, 10H). GC-MS (5MS/NP, CH3OH):
C15H14O (M = 210).
1-nitro-4-(styryl)benzene (c): m.p. 132–134 °C (lit.25 132–133 °C).
1H NMR (300 M Hz, CDCl3): δ 8.22 (d, J = 8.1 Hz, 2H), 7.63(d, J = 8.1
Hz, 2H), 7.11–7.54(m, 7H); HRMS (CH3OH): C14H11O2 N ([M + H]+:
calcd: 226.08625; found: 226.08827).
1-carboxyl-4-(styryl)benzene (d): m.p. 249–251 °C (lit.26
1
250–253 °C). H NMR (300 M Hz, CDCl3): δ 8.08 (s, 2H), 7.60(d,
J = 7.5 Hz, 2H), 7.16–7.53(m, 7H); HRMS (CH3OH): C15H12O2 ([M –
H]–: calcd: 223.07535; found: 223.07354).
23 F. Rok, S. Matej, G. Stanislav, S. Gaj and A. Zdenko, J. Org. Chem., 2015,
80, 7803.
1
Cinnamic acid (f): m.p. 133–134 °C (lit.27 133–134 °C). HNMR
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(300 M Hz, CDCl3): δ 6.46 (d, J = 15.9 Hz, 1H), 7.79 (d, J = 15.9 Hz,
1H), 7.16–7.55(m, 5H); HRMS (CH3OH): C9H8O2 ([M – H]–: calcd:
147.04405; found: 147.03919).
4-nitrocinnamic acid (g): HRMS (CH3OH): C9H7O4N ([M – H]–:
calcd: 192.02913; found: 192.02621).
4-methoxycinnamic acid (h): m.p. 174–175 °C (lit.28 175 °C). 1HNMR
(300 M Hz, CDCl3): δ 3.84(s, 3H), 6.31(d, J = 15.9 Hz, 1H), 7.73 (d,