Application of the polyacrylonitrile fiber as a novel support for polymer-supported copper catalysts in terminal alkyne homocoupling reactions

Article abstract of DOI:10.1016/j.jcat.2016.01.022

A commercially available synthetic polyacrylonitrile fiber, capable of acting as a novel support for polymer-supported copper catalyst in terminal alkyne homocoupling reactions, is presented. Detailed characterization by inductively coupled plasma (ICP) analysis, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) confirmed the changes and stability of the fiber catalyst during the modification and utilization processes. Moreover, the catalytic reactions proceeded at room temperature using air as a green oxidant to afford nearly quantitative yields (95-99%); the fiber catalyst has shown excellent activity and superior recyclability (over 16 cycles); and the procedure is operationally simple and amenable to the gram scale in continuous-flow processing. Furthermore, the prominent features (high strength, good flexibility, etc.) of the polyacrylonitrile fiber make the fiber-supported catalyst very attractive for fixed-bed reactors in the chemical industry.

Full text of DOI:10.1016/j.jcat.2016.01.022

Journal of Catalysis 337 (2016) 233–239
Contents lists available at ScienceDirect
Journal of Catalysis
journal homepage: www.elsevier.com/locate/jcat
Application of the polyacrylonitrile fiber as a novel support
for polymer-supported copper catalysts in terminal alkyne
homocoupling reactions
Xian-Lei Shi a, , Qianqian Hu , Fang Wang , Wenqin Zhang , Peigao Duan
⇑
b
a
c
a,
⇑
a
Department of Applied Chemistry, Opening Laboratory of Alternative Energy Technologies, Henan Polytechnic University, Jiaozuo, Henan 454003, People’s Republic of China
Department of Pharmacy, School of Medicine, Henan Polytechnic University, Jiaozuo, Henan 454003, People’s Republic of China
Department of Chemistry, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, People’s Republic of China
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
A commercially available synthetic polyacrylonitrile fiber, capable of acting as a novel support for
polymer-supported copper catalyst in terminal alkyne homocoupling reactions, is presented. Detailed
characterization by inductively coupled plasma (ICP) analysis, Fourier transform infrared spectroscopy
Received 1 December 2015
Revised 22 January 2016
Accepted 23 January 2016
(FTIR), and scanning electron microscopy (SEM) confirmed the changes and stability of the fiber catalyst
during the modification and utilization processes. Moreover, the catalytic reactions proceeded at room
temperature using air as a green oxidant to afford nearly quantitative yields (95–99%); the fiber catalyst
has shown excellent activity and superior recyclability (over 16 cycles); and the procedure is opera-
tionally simple and amenable to the gram scale in continuous-flow processing. Furthermore, the promi-
nent features (high strength, good flexibility, etc.) of the polyacrylonitrile fiber make the fiber-supported
catalyst very attractive for fixed-bed reactors in the chemical industry.
Keywords:
Supported catalyst
Fiber catalyst
Homocoupling reactions
Recyclability
Continuous-flow processing
Ó 2016 Elsevier Inc. All rights reserved.
1
. Introduction
The utilization of recyclable catalysts for organic synthesis to
also play important roles in the construction of a number of func-
tional polymeric materials [27–29]. Therefore, much attention has
been paid to the development of efficient methods for the synthe-
sis of 1,3-diyne derivatives [30–32]. Although significant progress
has been made in this area, the exploitation of a new, mild, and
effective procedure for the synthesis of 1,3-diynes is still desirable
and valuable [33–35]. Polyacrylonitrile fiber (PANF) has been
widely applied not only in civilian use but also in industry. Given
the many advantages of PANF, such as low cost and simple produc-
tion technology, high strength and light density, and corrosion and
mildew resistance, PANF provides an appealing alternative to
many other materials as a support for heterogeneous catalysts.
Previously, we have investigated the merits and details of function-
alized PANF as a sensor or material for the detection and adsorp-
tion of metal ions [36,37], and the results suggested that
functionalized PANF possessed good adsorption ability for metallic
salts. Based on the above-mentioned studies, we envisaged that
the fiber could be used as a support for metal active sites. Inspired
by this idea, and in continuation of our interest in the development
of novel fiber catalysts and green chemistry [38–41], in the present
work, we further apply PANF as a support to develop a new kind of
polymer-supported copper catalyst and evaluate it in the terminal
alkyne homocoupling reaction for the synthesis of conjugate
minimize waste production and maximize catalyst efficiency is
one of the key issues in green synthetic strategy [1,2], and with this
objective, great efforts in catalysis research have been devoted to
the development and application of effective, reusable, and safe
supported catalysts [3,4]. Among those, due to their good activity,
enhanced stability, and easier handling, the immobilization of
metal active sites onto solid supports for more efficient catalytic
systems in economical and environmentally benign chemical pro-
cesses has attracted much attention [5,6]. A variety of supports
such as polymers [7–9], silicas [10–12], zeolites [13,14], and some
metal particles [15–17] have been tried for the above purpose, par-
ticularly for supported copper catalysts [18–20]. In the mainstream
of contemporary themes, exploiting new and effective supports for
more facile catalytic synthesis, which may quickly move on from
the laboratory to the green industrial plant, has received increasing
interest [21–23].
Conjugate 1,3-diynes are widely present in natural products
and pharmaceuticals with a variety of bioactivities [24–26]. They
⇑
Corresponding authors. Fax: +86 0391 3987811.
E-mail addresses: shix1@tju.edu.cn (X.-L. Shi), pgduan@hpu.edu.cn (P. Duan).
1
,3-diynes. As expected, the PANF showed good performance as a
http://dx.doi.org/10.1016/j.jcat.2016.01.022
021-9517/Ó 2016 Elsevier Inc. All rights reserved.
0

2
34
X.-L. Shi et al. / Journal of Catalysis 337 (2016) 233–239
support for metal active sites, and the fiber-supported copper cat-
alyst could mediate homocoupling reactions efficiently at room
temperature in air and could easily be recovered and reused over
umn chromatography over silica gel to afford the corresponding
1,3-diynes. For the recycling process, the washed PANFTAꢀCuI
was conducted to the next cycle without any further treatment.
1
6 cycles without significant loss of activity. Moreover, the cat-
alytic process of the homocoupling reaction is operationally simple
and amenable to the gram scale in continuous-flow processing.
2
.5. Enlargement experiments procedures in continuous-flow
processing
2
. Experimental
A mixture of phenylacetylene (50 mmol, 5.11 g), n-butylamine
25 mmol, 1.83 g), and AcOEt (150 mL) in a flask open to the air
was stirred at room temperature. The fiber catalyst PANFTAꢀCuI
0.50 g, 2 mol%) was packed into a silicone column between the
(
2.1. Materials
(
Commercially available polyacrylonitrile fiber (PANF, 93.0%
flask and peristaltic pump. The catalytic column was kept at room
temperature while the reaction solution from the flask was
pumped into the system at a flow rate of about 0.22 mL/min. After
completion of the reaction, pure AcOEt (20 mL) was added to the
flask, which was pumped into the system to wash the fiber cata-
lyst. Finally, the solvent, ethyl acetate, was recovered by simple
distillation and about 161 mL of ethyl acetate was obtained (orig-
inal 150 mL + 20 mL, recovery 94.7%, ignoring the trace n-
butylamine). The residue was purified by column chromatography
over silica gel to afford the product (4.86 g), with an isolated yield
of 96%.
acrylonitrile, 6.5% methyl acrylate, and 0.4–0.5% sodium styrene
sulfonate) with a length of 10 cm and a diameter of 30 ± 0.5
from the Fushun Petrochemical Corporation of China) was used.
l
m
(
All other chemicals used were analytical grade and employed with-
out further purification. Water was deionized.
2
.2. Apparatus and instruments
The copper content of the fibers was measured by inductively
coupled plasma (ICP) analysis on a PE5300DV analyzer. Fourier
transform infrared (FTIR) spectra were obtained with an AVATAR
3
60 FTIR spectrometer (Thermo Nicolet), KBr disc. A scanning elec-
3. Results and discussion
tron microscope (Hitachi, Model S-4800) was used to characterize
1
the surface morphology of the fibers. H NMR spectra were
3.1. The preparation of the fiber-supported copper catalyst
recorded on an AVANCE III (Bruker, 600 MHz) instrument using
TMS as the internal standard. 13C NMR spectra were recorded on
an AVANCE III (Bruker, 151 MHz) instrument with complete proton
decoupling. Melting points were measured with a Yanagimoto MP-
We started this study to synthesize the designed fiber catalyst.
The strategy for preparing PANFTAꢀCuI was planned by following
our previous work and referring to the literature [42], and accord-
ing to a simple two-step process as shown in Scheme 1. First, the
tertiary amine groups were successfully immobilized on PANF by
amination with N,N-dimethyl-1,3-propanediamine in water, and
the extent of immobilization was measured by weight gain (weight
5
00 apparatus.
2
2
.3. Preparation of the fiber-supported copper catalyst
.3.1. Step 1
gain = [(W
2
À W
1
)/W
1
] Â 100%, where W
1 2
and W are the weight of
Dried PANF (2.50 g), N,N-dimethyl-1,3-propanediamine (35 g),
the fiber sample before and after amination, respectively); a
weight gain of 40% was obtained. Then the PANFTAꢀCuI was
afforded by chelation with excess CuI in acetonitrile, and the con-
and deionized water (15 g) were introduced into a three-necked
flask connected with a condenser. The mixture was refluxed with
stirring for 6 h. Next, the fiber sample was filtered off and washed
repeatedly with water (60–70 °C) until the pH of the filtrate was 7.
Finally, the fiber sample was dried overnight at 60 °C under vac-
À1
tent of the copper loading was 2.04 mmol g as determined by
inductively coupled plasma (ICP) analysis, which is consistent with
À1
the result calculated by weight (2.0 mmol g ).
uum to give tertiary amine functionalized PANF (PANFTA
,
3
.5020 g, with a weight gain of 40%).
3.2. The characterization of fiber-supported copper catalysts
2
.3.2. Step 2
To avoid any errors during the preparation process and investi-
gate the rangeability and stability of the fiber-supported copper
catalyst before and after the catalytic reaction, we performed a
detailed characterization of fiber samples at different stages. The
original polyacrylonitrile fiber (PANF), the tertiary amine function-
alized PANF (PANFTA), the fresh PANF-supported copper catalyst
(PANFTAꢀCuI), the catalyst recovered after the first run in the
homocoupling reaction (PANFTAꢀCuI-1), and the catalyst recovered
after the 16th cycle (PANFTAꢀCuI-16) were all characterized by
means of inductively coupled plasma (ICP) analysis, Fourier trans-
form infrared spectroscopy (FTIR), and scanning electron micro-
scopy (SEM).
CuI (3.43 g, 18 mmol) was dissolved in acetonitrile (135 mL),
and then the dried PANFTA (3 g, about 9 mmol tertiary amine
groups determined by acid exchange capacity) was introduced into
the solution. The mixture was stirred at room temperature for 24 h.
Next, the sample was filtered out and washed with acetonitrile
(
6
3 Â 50 mL) and AcOEt (2 Â 50 mL) and then dried overnight at
0 °C under vacuum to give the fiber-supported cooper catalyst
À1
(
PANFTAꢀCuI, 2.0 mmol g CuI loading by weight, which is consis-
tent with the ICP analysis).
2.4. General procedure for the terminal alkyne homocoupling reactions
The terminal alkyne (1.0 mmol), n-butylamine (0.5 mmol),
3.2.1. ICP analysis
PANFTAꢀCuI (0.01 g, 2 mol%), and AcOEt (3 mL) were added to a
The ICP analysis data of PANF, PANFTA, PANFTAꢀCuI, PANFTAꢀCuI-
1, and PANFTAꢀCuI-16 are listed in Table 1. It is obvious that the
original PANF and PANFTA did not contain copper. After the chela-
tion with CuI, the amount of copper of PANFTAꢀCuI was
short test-tube open to the air. The mixture was stirred at room
temperature for 12 h. After completion of the reaction, the PANFTA
-
ꢀ
CuI was taken out with common tweezers and washed with
À1
AcOEt (2 Â 10 mL), and the AcOEt solution was combined with
the reaction mixture. Then the solvent of the mixture was evapo-
rated under reduced pressure and the residue was purified by col-
2.04 mmol g . Moreover, after PANFTAꢀCuI was used as the cata-
lyst in the terminal alkyne homocoupling reaction once and 16
times, as can be seen from the table, there was no significant loss

X.-L. Shi et al. / Journal of Catalysis 337 (2016) 233–239
235
Scheme 1. Preparation of the fiber-supported copper catalyst PANFTAꢀCuI.
Table 1
The CuI content of PANF, PANFTA, PANFTAꢀCuI, PANFTAꢀCuI-1, and PANFTAꢀCuI-16 detected by ICP analysis.
Fiber sample
PANF
–
PANFTA
–
PANFTAꢀCuI
PANFTAꢀCuI-1
PANFTAꢀCuI-16
1.91
CuI content (mmol/g)
2.04
2.02
of copper during the course of the reaction even after 16 cycles.
These results revealed that the supported copper catalyst was suf-
ficiently stable to endure the vigorous stirring conditions, and also
indicated the PANF possesses prominent features to support metal
active sites.
the overlap with the amide II band, i.e., CAN stretching vibrations
and NAH bending vibrations. Moreover, after the formation of the
fiber-supported copper catalyst, almost all of the vibration of
PANFTAꢀCuI became a little weak (Fig. 1c), perhaps due to the
chelation of CuI and tertiary amine groups on the fiber, which
can act as evidence to prove that the fiber catalyst has been suc-
cessfully prepared (agrees well with the ICP analysis data). More-
over, the specific absorption peaks of the PANFTAꢀCuI-1 (Fig. 1d)
and PANFTAꢀCuI-16 (Fig. 1e) are almost the same as those of the
fresh PANFTAꢀCuI, which indicates that the polymer-supported
copper catalyst of PANFTAꢀCuI is very stable and can be reused sev-
eral times.
3.2.2. FTIR spectroscopy
Samples of PANF, PANFTA, PANFTAꢀCuI, PANFTAꢀCuI-1, and
PANFTAꢀCuI-16 were pulverized by cutting and then prepared into
KBr pellets, and their FTIR spectra are shown in Fig. 1. For the FTIR
À1
spectrum of PANF (Fig. 1a), the 2242 cm
absorption band is
À1
attributed to C„N vibrations and the 1731 cm C@O vibration
peak indicates the existence of methyl acrylate units in the copoly-
mer. When the FTIR spectrum of the PANFTA (Fig. 1b) is compared
with that of the PANF (Fig. 1a), the most striking change is the
broad absorption band around 3300 cm , which is characterized
as the NAH stretching vibration. The 2242 cm C„N vibration
3.2.3. SEM images
Fig. 2 presents the SEM images of PANF, PANFTA, PANFTAꢀCuI,
À1
PANFTAꢀCuI-1, and PANF ꢀCuI-16. The original PANF presented a
TA
À1
smooth surface (Fig. 2a). After amination, the diameter of the
PANFTA body was obviously extended, and the surface of the
PANFTA was thickly dotted with scarring (Fig. 2b), so after chela-
tion, CuI was immobilized on the fiber and the surface was thickly
dotted with spots (Fig. 2c). Indeed, the surface of the fiber samples
became increasingly coarse with each sequential modification and
utilization. However, except for the coarse surface, no other major
flaws were observed and the overall integrity of the fiber was
peak still exists in PANFTA, which suggests that not all the C„N
groups participate in the amination. Also, for PANFTA, the strong
À1
absorption band in the region of 1650 cm is assigned to the
À1
amide I band. The new broad peak at 1560 cm is attributed to
untouched. Moreover, it is worth noting that the images of PANFTA
-
ꢀ
CuI-1 and PANFTAꢀCuI-16 (Fig. 2d and e) are quite similar to that
of fresh PANFTAꢀCuI. This means that the PANF possesses good
properties for polymer-supported metal active sites, and it also
indicates that the fiber-supported copper catalyst is still catalyti-
cally active enough to be reused more times in the homocoupling
reactions.
3.3. Application of the fiber-supported copper catalyst in terminal
alkyne homocoupling reactions
3.3.1. Screening the fiber-supported copper catalyst for the
homocoupling reactions
Once the fiber-supported copper catalyst had been prepared,
the catalytic efficacy of PANFTAꢀCuI in the terminal alkyne homo-
coupling reaction was tested. Preliminary studies of this process
focused on the optimization of reaction conditions, and the homo-
coupling of phenylacetylene was taken as a model reaction. In the
initial experiment, with a copper content of 5 mol% on PANFTAꢀCuI
and THF as the solvent in air at room temperature, the influence of
Fig. 1. FTIR spectra of (a) PANF, (b) PANFTA, (c) PANFTAꢀCuI, (d) PANFTAꢀCuI-1, and
(
e) PANFTAꢀCuI-16.

2
36
X.-L. Shi et al. / Journal of Catalysis 337 (2016) 233–239
Fig. 2. SEM images of (a) PANF, (b) PANFTA, (c) PANFTAꢀCuI, (d) PANFTAꢀCuI-1, and (e) PANFTAꢀCuI-16.
Table 2
a
Optimization of terminal alkyne homocoupling catalyzed by PANFTAꢀCuI :
Entry
Cat. loading (mol%)
Base
–
Solvent
Yield (%)b
1
2
3
4
5
6
7
8
9
5
5
5
5
5
5
5
5
5
5
0
THF
THF
THF
THF
THF
THF
EtOH
AcOEt
Toluene
DMSO
AcOEt
AcOEt
AcOEt
AcOEt
AcOEt
–
Et
Pyridine
Et NH
3
N
Trace
14
32
87
95
Trace
98
97
98
–
2
n-Propylamine
n-Butylamine
n-Butylamine
n-Butylamine
n-Butylamine
n-Butylamine
n-Butylamine
n-Butylamine
n-Butylamine
n-Butylamine
n-Butylamine
10
11
12
13
14
15
0.5
1
2
2
19
52
98
c
97
a
b
c
Reaction conditions: phenylacetylene (1.0 mmol), base (0.5 mmol), and solvent (3 mL), open to the air at room temperature for 12 h.
Isolated yield.
0
.2 eq. n-butylamine was used for 24 h.
bases on the terminal alkyne homocoupling reaction was investi-
gated (Table 2, entries 1–6). The reaction could not proceed with-
out a base (Table 2, entry 1). However, primary amines such as
n-propylamine and n-butylamine were found to be superior in
terms of conversion (Table 2, entries 5 and 6), especially
n-butylamine, which afforded a high yield of 95%. In contrast,
different solvents such as EtOH, AcOEt, toluene, and DMSO was
also investigated (Table 2, entries 7–10). Among those, except for
the polar solvent EtOH (Table 2, entry 7), all the solvents were
found to be reactive for this homocoupling reaction, and AcOEt
was selected for further optimization. Based on the blank control
experiment (Table 2, entry 11), the effect on the copper amount
of PANFTAꢀCuI was also examined (Table 2, entries 12–14).
It turned out that even with a catalyst loading of 2 mol%, the
pyridine and Et
2
NH gave very low yields and trace product was
N. Subsequently, the function of
observed in the presence of Et
3

X.-L. Shi et al. / Journal of Catalysis 337 (2016) 233–239
237
Table 3
a
Scope of the present PANFTAꢀCuI-catalyzed terminal alkyne homocoupling :
Entry
1
Substrate
Product
2a
Yield (%)b
98
99
98
99
96
99
2
3
4
5
6
2b
2c
2d
2e
2f
7
8
9
2g
2h
2i
97
98
95
94
1
0
2j
1
1
1
2
2k
2k
82
95c
a
b
c
Reaction conditions: terminal alkynes (1.0 mmol), n-butylamine (0.5 mmol), PANFTAꢀCuI (0.01 g, 2 mol%), AcOEt (3 mL), in air at room temperature for 12 h.
Isolated yield.
1
eq. n-butylamine was used for 24 h.
homocoupling reaction could also achieve a high yield of 98%
Table 2, entry 14). Moreover, cutting the base dosage but with a
longer reaction time could also achieve a high yield of product
Table 2, entry 15).
(
(
3
.3.2. Fiber-supported copper-catalyst-mediated synthesis of 1,3-
diynes
Under the optimized experimental conditions, we then exam-
ined the substrate scope to generalize the versatility of this
methodology, and the results are summarized in Table 3. It was
interesting to observe that the catalytic system has an excellent
group tolerance; different substituted aromatic (Table 3, entries
1
–8) and aliphatic (Table 3, entries 9–11) acetylenes reacted effi-
ciently to afford the corresponding 1,3-diynes in good to excellent
yields. Moreover, there was almost no influence of the electronic
nature of the substituents in the aryl ring of acetylenes on the yield
of products, as aromatic acetylenes with electron-donating
Fig. 3. Recyclability of PANFTAꢀCuI-mediated terminal alkyne homocoupling of
phenylacetylene.
(Table 3, entries 2–7) and electron-withdrawing groups (Table 3,
entry 8) resulted in the formation of products in nearly quantita-
tive yields. In addition, it is worth mentioning that the reactivity
of the common aliphatic acetylenes is inferior to that of aromatic
acetylenes; however, increasing the base dosage could also afford
a high yield of 95% (Table 3, entries 8 and 9). These results indi-
cated that the PANFTAꢀCuI has wider applicability for homocou-
pling reactions to a wide variety of terminal alkynes.
of PANFTAꢀCuI were also investigated for the model reaction. After
the completion of each cycle, the PANFTAꢀCuI was simply taken out
with common tweezers and washed with AcOEt, and then the
recovered catalyst was conducted directly to the next cycle
without any additional treatment. The results show that the
reaction proceeded smoothly without marked loss in the yield
and the activity of PANFTAꢀCuI for almost 16 cycles (Fig. 3). How-
ever, It should be noted that after several cycles (more than 10),
the catalytic activity decreased slightly (15 runs with a yield of
86%), but when the reaction time was prolonged to 24 h the
3.3.3. The recyclability of the fiber-supported copper catalyst in the
terminal alkyne homocoupling reactions
As features of the supported catalysis system, the easy separa-
tion from the reaction mixture, the recyclability, and the stability

2
38
X.-L. Shi et al. / Journal of Catalysis 337 (2016) 233–239
Scheme 2. A diagrammatic sketch of continuous-flow processing.
Table 4
Comparison of the homocoupling of phenylacetylene in various supported-catalyst systems.
Entry
1
Cat. base/T (°C)
Cat. dosage (mol%)
1
Oxidant
Air
Solvent
CH Cl
Yield (%)a
94
Run final yield (%)b
Ref.
MCM-41-2N-CuI
Piperidine/rt
CuI-TEDETA/SBA-15
2
2
10
93%
5
53%
6
61%
8
92%
5
84%
2
82%
16
97%
[43]
2
3
4
5
6
7
3
O
2
DMSO
99
99
99
97
90
98
[44]
-/50
(1 Atm)
Air
SBA-15@amine-Cu
Piperidine/rt
Cu(II)-TD@nSiO
DBU/rt
5
Piperidine
[45]
2
0.6
5
Air
Air
CH
–
3
CN
[46]
A-21ꢀCuI
[47]
n-Butylamine/rt
Cu(OH)x/TiO
/90
PANFTAꢀCuI
n-butylamine/rt
2
5
O
2
Toluene
CH CO Et
[48]
-
(1 Atm)
Air
2
3
2
Our work
a
Yields under optimized experimental conditions.
Yields of the final run.
b
homocoupling yield was as high as that of the first cycle (yield
7%). Moreover, a certain stability of this catalyst was also
observed, because during the course of our study, PANFTAꢀCuI
stored on shelves remained equally active after at least up to three
months.
alyst reusability, which compare favorably with a number of differ-
ent reaction systems reported in the past. Moreover, the easily
available support, the simple procedure for catalyst preparation,
and the extremely simple separation operation (with common
tweezers), as well as the prominent catalyst reusability and recy-
clability, make this polymer-supported copper catalyst a highly
attractive alternative to a lot of current methodologies.
9
3.3.4. Scale-up of the fiber-supported copper-catalyst-mediated
terminal alkyne homocoupling reactions in continuous-flow
processing
Finally, to illustrate the utility of PANFTAꢀCuI, a large-scale
experiment on the homocoupling reactions in continuous-flow
processing was also conducted on the model reaction. The very
simple flow reactor is shown in Scheme 2, and the catalytic column
was kept at 25 °C while a solution of phenylacetylene, n-
butylamine, and ethyl acetate was pumped into the system at a
flow rate of 0.22 mL/min. Interestingly, the effluent liquid by post-
processing yielded the product at more than 96%. From the combi-
nation of the above experimental results and the prominent
features of the fiber support (good flexibility, high mechanical
strength, and convenience for knitting into the desired shapes for
the various industrial fix-bed reactors), it is obvious that the fiber
catalytic system is very attractive for the application in chemical
industry.
4
. Conclusions
In summary, we presented in this work the first application of
PANF as a novel support for a new polymer-supported copper cat-
alyst and verified in terminal alkyne homocoupling reactions. The
fiber-supported catalyst had a higher CuI loading of 2.04 mmol g
À1
than many previous reports and was shelf-stable without any par-
ticular protection. The mediated reaction proceeded smoothly at
room temperature using air as a green oxidant and generated the
corresponding 1,3-diynes at nearly quantitative yields. Moreover,
the catalyst did not show significant leaching of copper and can
be reused over 16 cycles without decreased reaction yields. Fur-
thermore, this methodology offered simple separation procedures
and an efficient scale-up process in continuous-flow processing,
as well as good flexibility and high strength of PANF for convenient
knitting into desired shapes, thus making the fiber-supported cat-
alyst more attractive for fixed-bed reactors in the chemical indus-
try. Complementary studies on fiber-supported-copper-catalyzed
reactions in fixed-bed reactors and further applications of fiber to
support other metal active sites are now in progress.
3.4. Comparison of the homocoupling of phenylacetylene in different
supported-catalyst systems
According to the results above and compared with different
supported-catalyst systems under their optimized experimental
conditions (Table 4), the fiber-supported copper process still has
advantages in terms of reaction conditions, product yield, and cat-
The supporting material contains the acid exchange capacity of
tertiary amine-functionalized fibers, the detection method of ICP

X.-L. Shi et al. / Journal of Catalysis 337 (2016) 233–239
239
1
analysis, the characterization data of compounds, and copies of H
[19] B. Kaboudin, R. Mostafalu, T. Yokomatsu, Green Chem. 15 (2013) 2266–2274.
[20] X. Guo, C. Hao, G. Jin, H.-Y. Zhu, X.-Y. Guo, Angew. Chem., Int. Ed. 53 (2014)
1
3
NMR and C NMR spectra.
1
973–1977.
21] Q.M. Kainz, O. Reiser, Acc. Chem. Res. 47 (2014) 667–677.
[22] M. Rose, ChemCatChem 6 (2014) 1166–1182.
[
Acknowledgments
[
23] L.M. Rossi, N.J.S. Costa, F.P. Silva, R. Wojcieszak, Green Chem. 16 (2014) 2906–
933.
24] A.L.K. Shi Shun, R.R. Tykwinski, Angew. Chem., Int. Ed. 45 (2006) 1034–1057.
2
This work was financially supported by the Henan Polytechnic
University (B2016-45), the National Natural Science Foundation
of China (21306133), and the Program for New Century Excellent
Talents in University (NCET-13-775).
[
[25] N. Panthama, S. Kanokmedhakul, K. Kanokmedhakul, J. Nat. Prod. 73 (2010)
366–1369.
1
[
26] B. Zhang, Y. Wang, S.-P. Yang, Y. Zhou, W.-B. Wu, W. Tang, J.-P. Zuo, Y. Li, J.-M.
Yue, J. Am. Chem. Soc. 134 (2012) 20605–20608.
[
[
27] M. Gholami, R.R. Tykwinski, Chem. Rev. 106 (2006) 4997–5027.
28] S. Eisler, A.D. Slepkov, E. Elliott, T. Luu, R. McDonald, F.A. Hegmann, R.R.
Tykwinski, J. Am. Chem. Soc. 127 (2005) 2666–2676.
Appendix A. Supplementary material
[
[
[
29] T. Luu, E. Elliott, A.D. Slepkov, S. Eisler, R. McDonald, F.A. Hegmann, R.R.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.jcat.2016.01.022.
Tykwinski, Org. Lett. 7 (2005) 51–54.
30] J.D. Crowley, S.M. Goldup, N.D. Gowans, D.A. Leigh, V.E. Ronaldson, A.M.Z.
Slawin, J. Am. Chem. Soc. 132 (2010) 6243–6248.
31] S. Zhang, X. Liu, T. Wang, Adv. Synth. Catal. 353 (2011) 1463–1466.
References
[32] H.-Y. Gao, H. Wagner, D. Zhong, J.-H. Franke, A. Studer, H. Fuchs, Angew.
Chem., Int. Ed. 52 (2013) 4024–4028.
[
33] K. Kamata, S. Yamaguchi, M. Kotani, K. Yamaguchi, N. Mizuno, Angew. Chem.,
Int. Ed. 47 (2008) 2407–2424.
[
[
[
[
1] M. Benaglia, Recoverable and Recyclable Catalysts, Wiley, New York, 2009.
2] R.A. Sheldon, Chem. Soc. Rev. 41 (2012) 1437–1451.
3] P. Barbaro, F. Liguori, Chem. Rev. 109 (2009) 515–529.
4] B.M.L. Dioos, I.F.J. Vankelecom, P.A. Jacobs, Adv. Synth. Catal. 348 (2006) 1413–
[
34] A. Kusuda, X.-H. Xu, X. Wang, E. Tokunaga, N. Shibata, Green Chem. 13 (2011)
843–846.
[
[
[
[
[
[
[
35] T. Oishi, K. Yamaguchi, N. Mizuno, ACS Catal. 1 (2011) 1351–1354.
36] G. Li, L. Zhang, Z. Li, W. Zhang, J. Hazard. Mater. 177 (2010) 983–989.
37] X. Liu, X. Liu, M. Tao, W. Zhang, J. Mater. Chem. A 3 (2015) 13254–13262.
38] X.-L. Shi, M. Zhang, Y. Li, W. Zhang, Green Chem. 15 (2013) 3438–3445.
39] X.-L. Shi, H. Lin, P. Li, W. Zhang, ChemCatChem 6 (2014) 2947–2953.
40] X.-L. Shi, X. Xing, H. Lin, W. Zhang, Adv. Synth. Catal. 356 (2014) 2349–2354.
41] X.-L. Shi, M. Zhang, H. Lin, M. Tao, Y. Li, W. Zhang, Chem. Asian J. 10 (2015)
1
446.
[
[
[
[
[
5] W. Yu, M.D. Porosoff, J.G. Chen, Chem. Rev. 112 (2012) 5780–5817.
6] D. Cantillo, C.O. Kipper, ChemCatChem 6 (2014) 3286–3305.
7] Y. Zhang, S.N. Riduan, Chem. Soc. Rev. 41 (2012) 2083–2094.
8] Z. Donga, Z. Ye, Adv. Synth. Catal. 356 (2014) 3401–3414.
9] Y. Monguchi, K. Nozaki, T. Maejima, Y. Shimoda, Y. Sawama, Y. Kitamura, Y.
Kitadeb, H. Sajiki, Green Chem. 15 (2013) 490–495.
7
52–758.
42] C. Girard, E. Önen, M. Aufort, S. Beauvière, E. Samson, J. Herscovici, Org. Lett. 8
2006) 1689–1692.
[
[
10] S. Minakata, M. Komatsu, Chem. Rev. 109 (2009) 711–724.
11] H. Noda, K. Motokura, A. Miyaji, T. Baba, Angew. Chem., Int. Ed. 51 (2012)
[
(
8
017–8020.
[
[
43] R. Xiao, R. Yao, M. Cai, Eur. J. Org. Chem. 22 (2012) 4178–4184.
44] Z. Ma, X. Wang, S. Wei, H. Yang, F. Zhang, P. Wang, M. Xie, J. Ma, Catal.
Commun. 39 (2013) 24–29.
[
[
[
12] S. Das, T. Asefa, ACS Catal. 1 (2011) 502–510.
13] A. Primo, H. Garcia, Chem. Soc. Rev. 43 (2014) 7548–7561.
14] P.A. Jacobs, M. Dusselier, B.F. Sels, Angew. Chem., Int. Ed. 53 (2014) 8621–
[
[
45] H. Li, M. Yang, X. Zhang, L. Yan, J.LiY. Qi, New J. Chem. 37 (2013) 1343–1349.
46] M. Nasr-Esfahani, I.A. Mohammadpoor-Baltork, R. Khosropour, M. Moghadam,
V. Mirkhani, S. Tangestaninejad, V. Agabekov, H.A. Rudbari, RSC Adv. 4 (2014)
8
626.
[
15] A. Aijaz, A. Karkamkar, Y.J. Choi, N. Tsumori, E. Rönnebro, T. Autrey, H.
Shioyama, Q. Xu, J. Am. Chem. Soc. 134 (2012) 13926–13929.
16] M.B. Gawande, P.S. Brancoa, R.S. Varma, Chem. Soc. Rev. 42 (2013) 3371–3393.
17] D. Wang, D. Astruc, Chem. Rev. 114 (2014) 6949–6985.
18] S.E. Allen, R.R. Walvoord, R. Padilla-Salinas, M.C. Kozlowski, Chem. Rev. 113
14291–14296.
[
[
[
[
47] Y. He, C. Cai, Catal. Sci. Technol. 2 (2012) 1126–1129.
[
48] T. Oishi, T. Katayama, K. Yamaguchi, N. Mizuno, Chem. Eur. J. 15 (2009) 7539–
7542.
(
2013) 6234–6438.