Nickel nanoparticles supported on diphenylphosphinated poly(vinyl alcohol-co-ethylene) as a new heterogeneous and recyclable catalyst for Mizoroki–Heck reactions

Article abstract of DOI:10.3184/174751917X15040898434417

Nickel nanoparticles (NiNPs) supported on diphenylphosphinated poly(vinyl alcohol-co-ethylene) (DPP-PVA-co-PE) were synthesised by first reacting poly(vinyl alcohol-co-ethylene) with chlorodiphenylphosphine (ClPPh₂) under basic conditions and then treating the product with Ni(OAc)₂ followed by reduction with NaBH₄. (DPP-PVA-co-PE)-NiNPs, a new metallised polymer, was then shown to efficiently catalyse Mizoroki–Heck reactions of aryl iodides, bromides or activated chlorides with olefins such as styrene and n-butyl acrylate in dimethylformamide. In contrast with other polymer-supported catalysts, the main advantage of this method is the low cost of the catalyst due to the simple synthetic route using easily obtained materials and good recoverability. Transmission electron microscopy and X-ray diffraction measurements were used to show the high metal dispersion and small sizes of Ni nanoparticle on the surface of the modified polymer. DPP-PVA-co-PE-NiNPs could be recycled several times.

Full text of DOI:10.3184/174751917X15040898434417

JOURNAL OF CHEMICAL RESEARCH 2017
VOL. 41 SEPTEMBER, 541–546
RESEARCH PAPER 541
Nickel nanoparticles supported on diphenylphosphinated poly(vinyl alcohol-
co-ethylene) as a new heterogeneous and recyclable catalyst for Mizoroki–
Heck reactions
Farzaneh Ebrahimzadeh*
Department of Chemistry, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
Nickel nanoparticles (NiNPs) supported on diphenylphosphinated poly(vinyl alcohol-co-ethylene) (DPP-PVA-co-PE) were synthesised by first reacting
poly(vinyl alcohol-co-ethylene) with chlorodiphenylphosphine (ClPPh2) under basic conditions and then treating the product with Ni(OAc)2 followed
by reduction with NaBH . (DPP-PVA-co-PE)-NiNPs, a new metallised polymer, was then shown to efficiently catalyse Mizoroki–Heck reactions of aryl
iodides, bromides or activ4 ated chlorides with olefins such as styrene and n-butyl acrylate in dimethylformamide. In contrast with other polymer-supported
catalysts, the main advantage of this method is the low cost of the catalyst due to the simple synthetic route using easily obtained materials and good
recoverability. Transmission electron microscopy and X-ray diffraction measurements were used to show the high metal dispersion and small sizes of Ni
nanoparticle on the surface of the modified polymer. DPP-PVA-co-PE-NiNPs could be recycled several times.
Keywords: diphenylphosphinated polymer, Mizoroki–Heck reaction, functionalised polymer, nickel nanoparticle, modified diphenylphosphinated
poly(vinyl alcohol-co-ethylene)
Cross-coupling of aryl halides and olefins catalysed by
transition metals is one of the most effective methods for the
synthesis of molecules which are of importance as intermediates
in the pharmaceutical industry, as molecular devices, as
antioxidants or as UV absorbers.1 These reactions with high
activity and excellent yields are often catalysed by palladium
complexes in homogeneous solution.2 However, the high cost
and general inaccessibility of palladium led to a search for
cheaper transition metal alternatives. In recent years, it has been
shown that transition metals other than palladium such as Co,3,4
Rh, Ir,5 Mn,6 Cu,6,7 Fe,8 and Ni9 are capable of catalysing such
transformations, regardless of the actual catalyst working mode.
For carbon–carbon cross-coupling reactions, nickel seems the
most favourable candidate as a catalyst among inexpensive
transition metals for the replacement of palladium.10 In 2004,
Ni complexes were used in Heck reactions for the first time9
and the authors showed that mechanisms of the Ni- and Pd-
catalysed Heck reactions were similar to each other. Sincec
Ni is less electronegative than Pd, the low-cost Ni complexes
are able to achieve fast oxidative addition reactions and facile
olefin insertion. On the other hand, the reductive elimination,
was more difficult than Pd in the same oxidation state.10,11 From
this result it was clear that less reactive electrophiles such as
alkyl halides, aryl fluorides and chlorides, and also some
phenol derivatives could achieve better coupling reactions in
the presence of a Ni catalyst.
Nickel complexes with several kinds of ligands such as
sterically hindered phosphines,12 N-heterocyclic carbenes13,14
and 1,3-dinitrone pincer complexes15 were developed as
effective catalysts for Heck coupling reactions. NiBr2(PPh3)/
Zn dust,16 NiCl2·H2O/PPh3,17 NiP(OPh)3 and NiP(OEt)3,6,18,19 and
Ni(acac)2/carbene-derived N-heterocyclics20 are some of the
homogenous Ni catalysts reported for highly effective carbon–
carbon coupling in Heck reaction. But sometimes, using
these homogenous catalysts problems were observed such as
difficulty in separation, inability to recycle, and deactivation via
their aggregation. To overcome these problems, heterogeneous
catalysts such as a silica-supported poly-γ-aminopropylsilica Ni
complex,21 a Ni/triphenyl phosphine trisulfonate (Ni-TPPTS)
supported on silica,22 and an O-carboxymethyl chitosan-
supported Ni catalyst23 were effective. Control of the activity
of the heterogeneous catalyst increased the selectivity of the
vinylation of aryl halides with olefins. The kind and amount of
dispersion of metal and the nature of the support influenced and
determined the catalytic activity of the heterogeneous catalyst.
Polymer supports of transition metals have some benefits over
traditional solution-phase chemistry such as simple recovery
by filtration of supported complexes from reaction mixtures,
the ability for recyclability, and the capability to show more
selectivity. Functionalisation of the polymer by a suitable ligand
increases the ability to bind more metal and increases stability.
Poly (vinyl alcohol) (PVA) as an example, could carry only low
concentrations of metal. This polymer loses the metal easily
due to weak interaction between the polymer and the metal,
but when a phosphine is inserted into the polymer structure, the
capacity of reserve metal on polymer during the reaction was
increased dramatically.24
Accordingly, industrial and laboratory applications of
polymer-supported transition metal complexes have been much
studied. The nature of the polymer backbone,25 the functionality
and compatibility of a ligand with the metal, the capacity
of ligands on the polymer26 and the nature and extent of the
cross-linking agent27 are some of the parameters that determine
the amount of complexation that occurs between polymer-
supported ligands and metal ions.
Here we report a novel, simple method for the synthesis
of diphenylphosphinated poly(vinyl alcohol-co-ethylene)
supported nickel nanoparticles (DPP-PVA-co-PE)-NiNPs
which we used to catalyse Mizoroki-Heck reactions of
aryl iodides, bromides or activated chlorides with alkenes,
exemplified by styrene and butyl acrylate. The recyclability of
the catalyst was also investigated.
Results and discussion
Synthesis and characterisation of diphenylphosphinated poly (vinyl
alcohol-co-ethylene) containing Ni nanoparticles (DPP-PVA-co-PE-
NiNPs)
This procedure was very similar to our method used for the
preparation of DPP-PVA-Pd.24 PVA-co-PE is more soluble in an
aqueoussolventandhasmorecompatibilityandstabilitythanPVA
in water and DMF. This new modified polymer was synthesised
by functionalisation of hydroxyl groups on poly(vinyl alcohol-
co-ethylene) (PVA-co-PE) with chlorodiphenylphosphine
under basic conditions (Scheme 1). The amount of phosphine
supported on the polymer was determined by a gravimetric
* Correspondent. E-mail: polychemfar@miau.ac.ir

542 JOURNAL OF CHEMICAL RESEARCH 2017
Et
PPh
3N/
2Cl
acetone
n
m
OPPh2
n
m
OPPh2
OH
co
DPP-PVA- -PE
co
PVA- -PE
Scheme 1
*
*
O
O
Ni(OAc)2
EtOH/H
OPPh2-Ni(OAc)2
OPPh2
PPh2
Ph2P
2O/acetone
80 °C
Ni
OAc
AcO
NaBH4, EtOH
68 °C, 30 min
OPPh2-Ni
OPPh2- Ni(OAc)2
Scheme 2
method which showed that there was increasing weight during
the functionalisation process. Calculations showed that 40.45%
of the hydroxyl groups on PVA-co-PE were functionalised by
diphenyl phosphine.
Iodometry was used for determining the amount of diphenyl
phosphine group functionalised on the polymer. The capacity
of the polymer was shown to be 6.24 mmol diphenyl phosphine
g–1 of the polymer. This polymer was air and water stable and
it could swell in aqueous conditions. The solubility of PVA-
co-PE and DPP-PVA-co-PE in water and 5% NaOH solution
were investigated. The results revealed that they showed a great
difference, with PVA-co-PE easily soluble in water and 5%
NaOH solution, but DPP-PVA-co-PE was insoluble. It indicated
that DPP-PVA-co-PE was more stable in the aqueous solvent.
Complexations of NiNPs with new functionalised polymers
were carried out in a solution of the metal salt. The DPP-PVA-
co-PE-NiNPs catalyst was prepared by stirring PVA-co-PE-
PPh2 with a solution of Ni(OAc)2·4H2O. Then NaBH4 was added
slowly to this mixture to reduce Ni(OAc)2 to NiNPs (Scheme
2). Filtration and purification of the polymer was achieved by
washing with various solvents which yielded the blue polymer-
immobilised Ni nanoparticles (DPP-PVA-co-PE-NiNPs).
We used inductively coupled plasma (ICP) to determine the
Ni content of the catalyst. For this purpose, the DPP-PVA-co-
PE-NiNPs were treated successively with a mixture of conc.
H2SO4, HNO3, and HCl, and filtered. The filtrate was diluted
with distilled water and subjected to ICP determination using
the calibration curve method. The amounts of nickel in the
complex were found to be 5.4 mmol·g–1.
Fig. 1 X-ray diffraction of DPP-PVA-co-PE-NiNPs powder.
(a)
(b)
Dispersions of nano-sized nickel particles with very high
stability were characterised by X-ray powder diffraction (XRD)
and transmission electron microscopy (TEM). Figure 1 shows
a typical XRD pattern of the DPP-PVA-co-PE-NiNPs sample
after drying. Three characteristic peaks for nickel 2휃 = 47.5,
53.61, 77.31°, corresponding to Miller indices (111), (200),
(220), respectively, were observed, indicating that the resulting
powders are face-centred cubic nickel (PDF #04-0850).28
The morphology and particle size of the catalyst were
characterised by transmission electron microscopy (TEM). The
TEM image of DPP-PVA-co-PE-NiNPs samples (Fig. 2) shows
good-defined particles dispersed in the DPP-PVA-co-PE matrix
with a certain degree of homogeneity. The mean diameter of the
nanoparticles determined by TEM is about 30 5 nm. An XRD
Fig. 2 (a)TEM image of DPP-PVA-co-PE-NiNPs; (b) X-ray diffraction
patterns of DPP-PVA-co-PE-NiNPs.
pattern also proved the existence of the nickel nanometal core
in the particles.
XRD patterns of this reaction showed crystallinity of Ni(0)
NPs on the surface of the polymers. The diffraction rings
can be recognised to be the (111), (200), (220) and (311)
crystallographic planes of the Ni(0)NPs.

JOURNAL OF CHEMICAL RESEARCH 2017 543
X
O
nBu
O
OPPh2- Ni / DMF/Et3N
nBu
O
+
O
R
R
2
1
3
X= Cl, Br, I
X
OPPh2- Ni / DMF/Et3N
+
R
R
X= Cl, Br, I
5
4
Scheme 3
Table 1 Optimisation of the reaction conditions (base, solvent, duration of
reaction) for the reaction between iodobenzene (1, R = H, X = I) and n-butyl
acrylate (2) in the presence of DPP-PVA-co-PE-NiNPs (Scheme 3)a
Table 2 Yields of a series of butyl cinnamate derivatives 3 (R = various)
or a series of stilbene derivatives 5 (R = various) prepared from a
halobenzene 1 (X = Cl, Br or I; R = various) and n-butyl acrylate 2 (2.0
mmol) or styrene 4 (2.0 mmol) in the presence of DPP-PVA-co-PE-NiNPs
(0.08 g) (Scheme 3)a
Entry Base
Solvent
DMF
DMF
DMF
DMF
Time (h)
Conversion (%)
1
2
3
4
5
6
7
8
9
None
NaOAc
Cs2CO3
K2CO3
Et3N
Et3N
Et3N
Et3N
Et3N
24
24
24
2
10
40
60
90
100
80
70
30
100
Entry
1
2
R
H
H
X
I
I
Substrate Product
Time (h) Yieldb (%)
2
4
3a
5a
2
5
93
85
3
4-NO2
I
2
3b
1
95
DMF
2
EtOH
CH3CN
CHCl3
DMSO
12
12
12
2
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
4-NO2
4-MeO
4-MeO
H
I
I
I
4
2
4
2
4
2
4
2
4
2
4
2
4
2
4
2
4
5b
3c
5c
3a
5a
3d
5d
3e
5e
3a
5a
3b
5b
3f
3
4
7
5
8
2
3.5
3
4.5
6
8
2.5
6
1.5
2
6.5
90
87
84
92
75
90
85
70
60
90
75
84
80
90
76
60
45
Br
Br
Br
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
aReaction conditions: a stirred mixture of polymer (0.08 g) and a base (2.5 mmol) was
heated at 80 °C in solvent (3 ml) for 15 min and then iodobenzene (1.0 mmol) and n-butyl
acrylate (2.0 mmol) were added and heated for various times.
H
4-CN
4-CN
4-CH3
4-CH3
H
The resulting DPP-PVA-co-PE-NiNPs can be easily swelled
and handled in organic solvents such as dimethyl formamide
(DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF),
acetone and water.
H
4-NO2
4-NO2
4-CF3
4-CF3
4-CH3
4-CH3
Mizoroki–Heck reaction of aryl halides and olefins by the new
polymeric catalyst
5f
3e
5e
We planned to use this new functional polymer, DPP-PVA-
co-PE-NiNPs for C–C bond formation through Heck coupling
reactions of aryl iodides, bromides and chlorides with styrene
and n-butyl acrylate. We first optimised the reaction conditions
using the reaction between iodobenzene and n-butyl acrylate
and the results are shown in Table 1. Some bases such as
Na2CO3, K2CO3, Et3N and Cs2CO3 and solvents like EtOH,
DMF, MeCN and DMSO were studied but, as can be seen, using
DMF or DMSO as solvent and Et3N as a base was optimal. We
chose Et3N/DMF at 80 °C as our preferred method for coupling
various alkenes with aryl halides. Under these conditions, the
optimum ratio of the catalyst to iodobenzene was found to be
24
aReaction conditions: a stirred mixture of polymer (0.08 g) and Et3N (2.5 mmol) was
heated at 80 °C in DMF (3 mL) for 15 min and then an aryl halide (1; X = Cl, Br, or I; R =
various) (1.0 mmol) and n-butyl acrylate 2 (2.0 mmol) or styrene 4 (2.0 mmol) were added
and heated for various times; bIsolated yield
As shown in Table 2 both electron-rich (methoxy) and
electron-deficient (nitro) aryl iodides reacted with n-butyl
acrylate to give the corresponding products (entries 3 and
5). A complete conversion was obtained for the reaction of
bromobenzene, p-methylbenzene and 4-cyanobromobenzene
with n-butyl acrylate after 5, 3 and 2 h respectively (entries
7, 9 and 11). Electron donating and electron-deficient groups
on the aryl iodide or bromide reacted good to well, but only
an electron-deficient group on a chloride reacted well.
p-Nitrochlorobenzene and p-trifluoromethylchlorobenzene in
reaction with n-butyl acrylate were completely converted to
the products after 2.5 and 1.5 h respectively (entries 15 and
17). It was observed that the time of reaction increased for
p-chlorotoluene and the yield of the product was significantly
decreased (entry 19).
0.05 mol%(Table 1).
The coupling of n-butyl acrylate or styrene with aryl
iodides, bromides, and activated chlorides were carried out at
a temperature of 80 °C (Scheme 3). A mixture of aryl halide,
alkene, Et3N, DMF, and catalyst was stirred in an oil bath for
1–24 h. Under these reaction conditions, all the desired products
were isolated in 55–95% yields. The reactions were monitored
by TLC or GC.
The results of the Heck reaction between an aryl iodide,
bromide or chloride with n-butyl acrylate or styrene are shown
in Table 2.

544 JOURNAL OF CHEMICAL RESEARCH 2017
In other experiments, the coupling reaction of aryl halides
with styrene was studied. A similar protocol was also employed.
The results of the Heck coupling reactions of aryl halides and
styrene are also shown in Table 2. By comparing the yields and
times of styrene reactions, it was found that all aryl halides
with n-butylacrylate reacted faster than a similar reaction with
styrene under the same conditions.
Styrene was found to couple smoothly with iodobenzene
in a good time (5 h) and yield (85%). High activities for aryl
bromides and activated aryl chlorides were also found when
the reactions were carried out to afford the coupled products
in moderate to good yields. Bromobenzene was a less reactive
substrate but coupled with styrene in a longer time (8 h) and
lower yield of product (75%) (entry 8).
acetone, ethanol, THF and drying in air. ICP analysis gave a
low Ni leaching (0.3%).
A
recycling test using the model reaction between
iodobenzene and butyl acrylate showed the catalyst could be
recycled three times without appreciable loss of activity. The
catalyst could be recovered easily by filtration and the second
and third recycles gave yields of 84 and 75%. This indicated the
high stability and good reusability of DPP-PVA-co-PE-NiNPs.
Transmission electron microscopy (TEM) of DPP-PVA-co-
PE-NiNPs after the first recycling step (Fig. 3) showed that
the particle size and shape of particle is preserved during this
recycling step. The Ni nanoparticles (30 5 nm) are stable on
the surface of polymers after recovery.
The mechanism of the Ni-catalysed Heck reaction is quite
similar to that of the Pd-catalysed Heck reaction. There are four
major steps in a catalytic cycle: (a) a σ-aryl-Ni(II) complex is
made via oxidative addition; (b) an olefin substrate coordinates
to the metal, followed by the insertion of the olefin at the C–
Ni bond; (c) an intramolecular β-hydride elimination happens,
providing the coupling product; (d) after the removal of HX
from the complex, Ni(0) catalyst is regenerated (Scheme 4).
Compared to the Pd system, the oxidative addition of an aryl
chloride is not much more difficult than oxidative addition of
an aryl iodide in the Ni system. Therefore, the Ni-catalysed
Heck reaction may be applied to aryl chlorides relatively easily.
Diphenylphosphine appears to be favourable ligands for the Ni-
catalysed Heck reactions.
The application of this system for coupling of chlorobenzene
and styrene was also successful at 80°C. Electron donating
groups such as methyl and electron withdrawing groups such as
4-nitro and 4-trifluoromethyl reacted well with styrene (entries
14, 16, 18, 20).
After the reaction, the catalyst was separated from the
mixture by filtration, and could be reused after washing with
Table 3 shows a comparison of DPP-PVA-co-PE-NiNPs
with some reported homogenous and heterogeneous catalysts
for Heck reaction of alkyl halide with alkenes. Short reaction
times with good to excellent yields show the effectiveness of
this catalyst in accelerating the reaction.
Conclusion
In conclusion, the heterogeneous DPP-PVA-co-PE-NiNPs
catalyst exhibited excellent activity and selectivity for the
Fig. 3 TEM image of DPP-PVA-co-PE-NiNPs after first recycle step.
Ar
Ar-X
R
OPPh2- Ni
a
reductive
elimination
d
oxidative
addition
L
L
L
II
Ni Ar
Ni
II
X
Ar
CH
=
L
OPPh2
L
HC
R
Et3NH+ X-
b
c
L
L
R
II
Ar
Ni
X
Et3N
R
trans-metallation
Scheme 4

JOURNAL OF CHEMICAL RESEARCH 2017 545
Table 3 Reaction of bromobenzene with n-butyl acrylate under different heterogeneous catalyst reported in the literature
Entry
1
Catalysts/condition
Ni(OAc)2/ TPPTS22
Substrate
2
R
H
X
I
Product
3a
Time (h)
22
Yield (%)
88
2
3
4
5
DPP-PVA-co-PE-NiNPs
NiCl2.6H2O/Zn29
Nickel(II) thiosemicarbazone complex30
NiCl2-6H2O/Ph3P complex/ NMP31
2
2
2
2
H
I
3a
3a
3a
3a
1
72
24
19
95
5
H
H
H
Br
Br
Br
85
81
O-Carboxymethyl chitosan supported
6
2
H
Br
3a
12
67
heterogeneous Ni catalyst23
7
Ni(acac)2/ IMes-HCl/ Bu4NI20
DPP-PVA-co-PE-NiNPs/DMF
Silica supported poly-γ-aminopropylsilica Ni21
Ni/PANI32
2
2
4
4
4
4
4
4
4
2
2
2
2
2
H
Br
3a
3a
5a
5a
5a
5c
5c
5b
5b
3a
3a
3a
3a
3a
20
5
86
92
90
69
85
85
87
60
90
55
95
5
8
H
Br
9
H
I
15
36
5
10
11
12
13
14
15
16
17
18
19
20
H
I
DPP-PVA-co-PE-NiNPs
Ni (0)/K2CO3/Ar/ NMP19
H
I
4-OMe
I
24
7
DPP-PVA-co-PE-NiNPs
4-OMe
I
6
Ni/Al2O3
4-NO2
I
24
3
DPP-PVA-co-PE-NiNPs
Ni(OAc)2/ TPPTS/ethylene glycol22
4-NO2
I
H
H
I
22
1
DPP-PVA-co-PE-NiNPs
NiCl2.6H2O/Zn18
Nickel(II) thiosemicarbazone complex33
NiCl2-6H2O/Ph3P complex/ NMP19
I
H
H
H
Br
Br
Br
72
24
19
85
81
O-Carboxymethyl chitosan supported
heterogeneous Ni catalyst23
21
2
H
Br
3a
12
67
14
Ni(acac)2/ IMes-HCl/ Bu4NI 20
2
2
H
Br
3a
3a
20
86
15
DPP-PVA-co-PE-NiNPs/DMF
H
Br
5
92
in a vacuum oven for 24 h to afford DPP-PVA-co-PE (6.24 mmol
vinylation and coupling reaction of aryl iodides, bromides
and chlorides with olefins. Nickel nanoparticles supported on
polymer have good activity in Heck reactions and it is more
attractive in that it is very cheap compared with palladium. The
Heck reaction with this polymeric nickel catalyst could also be
important from an industrial point of view.
diphenylphosphine g–1 polymer) as a white powder (2.3 g).
Determination of phosphine value on DPP-PVA-co-PE by iodometry
For iodometric determination of phosphine functionalised on DPP-
PVA-co-PE, excess I2 (0.3 g, 1.2 mmol) was added to the DPP-PVA-co-
PE (0.10 g) in CH3CN (10 mL) and the mixture was stirred for 5 h. The
mixture was filtered and washed with CH3CN (3 × 5 mL). The filtrate
was titrated with Na2S2O3 solution (0.05 M) in the presence of fresh
starch as an indicator to calculate the unreacted I2 and consequently the
reacted I2 with phosphine. The capacity of phosphine function on DPP-
PVA-co-PE was calculated to be 6.24 mmol g−1 phosphine.
Experimental
All reagents and solvents were commercial reagent grade and obtained
from Fluka, Merck or Sigma-Aldrich and used without further
purification. Poly(vinyl alcohol-co-ethylene) (PVA, MW: 125,000, DP
= 1700, CAS Number 25067-34-9) was purchased from Sigma-Aldrich.
The progress of reactions was followed by thin layer chromatography
(TLC) on silica-gel Polygram SILG/UV 254 plates or by gas–liquid
chromatography (GLC) on a Shimadzu model GC 10-A instrument
fitted with a hydrogen flame ionisation detector. All yields refer to the
isolated products. IR spectra (KBr pellets) were run on a Shimadzu
FTIR-8300 spectrophotometer. NMR spectra were recorded in CDCl3
on a BrukerAvance DPX instrument (250 MHz). All products were
characterised by comparison of their FTIR and NMR spectra and
physical data with those reported in the literature. The Ni analysis and
leaching tests were carried out using an ICP-OES analyser (Varian,
Vista-Pro). TEM analyses were performed on a Philips model CM 10
instrument. The XRD data were obtained with an XRD D8, Advance
Bruker Diffractometer.
Synthesis of the DPP-PVA-co-PE-NiNPs
The DPP-PVA-co-PE (1 g, containing 6.24 mmol diphenyl-
phosphinated ligands) and ethanol (15 mL) were placed in a flask.
After stirring for 10 min, Ni(OAc)2·4H2O (0.62 g, 2.5 mmol) in EtOH
(10 mL) was added to the mixture, under reflux. After 2 h, NaBH4
solution (1.1 mL, 10% w/v) was added during 20 min and the mixture
was stirred at 65 °C for 72 h. The mixture was filtered and washed with
acetone, followed by ether, then dried at 60 °C in the vacuum oven for
24 h. The loading of Ni was measured as 5.4 mmol g–1 (ICP).
Heck reaction of aryl halides and n-butyl acrylate or styrene in the
presence of DPP-PVA-co-PE; general procedure
To a flask containing DPP-PVA-co-PE (0.8 g, 0.004 mol) and Et3N
(0.33 g, 3.0 mmol) was added in DMF (3 mL) 80 °C and stirred for
15 min. Then an aryl halide (1.0 mmol) and n-butyl acrylate (0.24 g,
2.0 mmol) (or styrene) were added to the mixture. GC and TLC of
the reaction mixture showed the completion of the reaction after
1–8 h. The mixture was cooled to room temperature and the coupled
product was extracted with diethyl ether (3 × 5 mL). Evaporation of
the solvent followed by chromatography on a short column of silica
gel using n-hexane/ethyl acetate (5/1) as eluent gave the coupled
Synthesis of DPP-PVA-co-PE
PVA-co-PE (32% in ethylene) [1 g, 15.45 mmol (monomer unit PVA)]
and 10% Et3N solution (10 mL) were placed in a 100 mL three neck
flask for 24 h, then ClPPh2 (3.40 g, 15.5 mmol) was added dropwise to
the mixture at –10 °C under Ar. After addition of ClPPh2, the mixture
was stirred at 25°C for 24 h. The product was isolated by filtration,
washed with cold THF, ethanol, and diethyl ether and dried at 30 °C

546 JOURNAL OF CHEMICAL RESEARCH 2017
product in 80–90% yield (Table 2). The remaining mixture which
contains DPP-PVA-co-PE was washed with acetone (3 × 5 mL),
THF, and acetonitrile and reused for another run. All products were
characterised by comparison of their melting point and 1H NMR with
authentic samples.24,34,35
1-Nitro-4-styrylbenzene (3b): Yield 90%; [Lit.24 m.p. 113–114 °C];
FTIR (νmax, cm–1) KBr: 3077 (C–H), 1596 (N=O), 1542, 1348 (C–N),
1106 (C=C), 855, 741, 700; 1H NMR δ 7.50–7.46 (m, 3H), 7.60 (t, J =
7.5 Hz, 2H), 7.71 (d, J = 8.7 Hz, 2H), 8.27 (d, J = 8.72 Hz, 2H).
Butyl (E)-3-(4-methoxyphenyl) acrylate 3c: Yield 87%; [Lit.24,34,35
m.p. 92–93 °C];1H NMR δ 0.9 (t, 3H), 1.46 (m, 2H), 1.64 (m, 2H), 3.97
(t, 2H), 3.83 (s, 3H), 6.32 (d, 1H, J = 16 Hz), 7.48 (d, 1H, J = 16 Hz),
6.94 (d, 2H, J = 8.5 Hz), 7.62 (d, 2H, J = 8.52 Hz).
1-Methoxy-4-styrylbenzene (5c): Yield 84%; [Lit.35 m.p. 86–87 °C];
1H NMR δ 3.86 (s, 3H), 6.99 (d, J = 10.7 Hz, 2H), 7.28 (t, J = 3.8 Hz,
1H), 7.43 (dd, J = 9.8, 4.3 Hz, 2H), 7.55 (m, J = 7.3 Hz, 4H).
(E)-1-Methyl-4-styrylbenzene (5e): Yield 60%; [Lit.24,35 m.p.
110–111 °C]; 1H NMR δ 2.37–2.45 (m, 3H), 7.10–7.16 (m, 2H), 7.26
(m, 2H), 7.31 (dd, J = 8.2, 5.2 Hz, 1H), 7.38 (m, 2H), 7.48 (m, 2H),
7.54–7.59 (m, 2H); 13C NMR δ 137.1, 134.2, 129.3, 128.7, 127.3, 126.4,
20.8.
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Received 1 July 2017; accepted 15 August 2017
Paper 1704858
https://doi.org/10.3184/174751917X15040898434417
Published online: 1 September 2017
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