Application of the polyacrylonitrile fiber as a support for the green heterogeneous base catalyst and supported phase-transfer catalyst

Article abstract of DOI:10.1039/c4ra12069h

A facile synthesized polyethylene polyamine functionalized polyacrylonitrile fiber (PANF-PA), capable of acting as the heterogeneous base catalyst and supported phase-transfer catalyst (SPTC), was presented in Knoevenagel condensation-cyclization and nucleophilic substitution for the synthesis of a number of substituted iminocoumarins and sulfones in aqueous systems, respectively. Excellent results are shown in terms of simple procedures, high chemical yields (up to 96%), extensive applicability and superior catalytic recyclability even for 10 cycles. The deeper active principle of the PANF-PA as SPTC was explained through detailed characterization by means of elemental analysis, FTIR spectroscopy and SEM. Moreover, the procedures can be effectively scaled up, and the solvent can be easily recovered. As well as, the prominent features (high strength, good flexibility etc.) of the polyacrylonitrile fiber are very attractive for fixed-bed reactors in the chemical industry. This journal is

Full text of DOI:10.1039/c4ra12069h

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Application of the polyacrylonitrile fiber as a
support for the green heterogeneous base catalyst
Cite this: RSC Adv., 2014, 4, 64347
and supported phase-transfer catalyst†
*
*
Xian-Lei Shi, Minli Tao, Huikun Lin and Wenqin Zhang
A facile synthesized polyethylene polyamine functionalized polyacrylonitrile fiber (PANF-PA), capable of
acting as the heterogeneous base catalyst and supported phase-transfer catalyst (SPTC), was presented
in Knoevenagel condensation–cyclization and nucleophilic substitution for the synthesis of a number of
substituted iminocoumarins and sulfones in aqueous systems, respectively. Excellent results are shown in
terms of simple procedures, high chemical yields (up to 96%), extensive applicability and superior
catalytic recyclability even for 10 cycles. The deeper active principle of the PANF-PA as SPTC was
explained through detailed characterization by means of elemental analysis, FTIR spectroscopy and SEM.
Moreover, the procedures can be effectively scaled up, and the solvent can be easily recovered. As well
as, the prominent features (high strength, good flexibility etc.) of the polyacrylonitrile fiber are very
attractive for fixed-bed reactors in the chemical industry.
Received 9th October 2014
Accepted 13th November 2014
DOI: 10.1039/c4ra12069h
www.rsc.org/advances
industry. Given many advantages of PANF, such as low cost and
simple production technology, corrosion and mildew resistant,
Introduction
high strength and light density, as well as its contains an
abundance of cyano groups which can be easily transformed
into carboxyl, amide or other functional groups,14–16 PANF
provides an appealing option to other synthons as a support for
heterogeneous catalysts. Moreover, the good exibility of ber
makes it convenient for knitting into the desired shapes, which
is very attractive for the xed-bed reactors in chemical industry.
Nevertheless, there are few heterogeneous catalysts based on
PANF, so it is highly desirable to develop novel and green
catalysts based on PANF. In our previous work, the poly-
propylene ber was used as the new support for heterogeneous
Brønsted acid catalyst17 and supported ionic liquids catalysis.18
Besides, the modied amine-functionalized PANF was also used
to catalyze Knoevenagel condensation and achieved excellent
results.19 Following the pioneering studies of our work on ber
catalyst,20 especially the excellent results obtained in aqueous
systems, which inspired us to further investigate the use of
PANF as support for designing novel heterogeneous catalysts. In
the present study, we report a convenient synthesized poly-
ethylene polyamine functionalized PANF (PANF-PA), function as
heterogeneous base catalyst and supported phase-transfer
catalyst (SPTC), which were veried for the synthesis of imino-
coumarins and sulfones in aqueous systems, respectively.
In contemporary synthetic chemistry, the development of
environmentally benign and cost-efficient catalytic systems to
minimize waste production and maximize catalyst efficiency
has become one of the main themes.1,2 And with this objective,
the application of novel and recyclable catalysts for organic
synthesis has attracted much attention.3 Among those, the
heterogenization of homogeneous catalysts onto solid supports
has been well investigated and proved to be more crucial to
chemical processes, and it will continue to inuence and
motivate the development of catalysts for environmental
remediation.4,5 Currently, the commonly used materials for
heterogeneous catalysts are polymers,6,7 mesoporous mate-
rials,8,9 and nanoparticles,10,11 exploiting new supports for the
more facile heterogeneous type catalytic synthesis, which may
quickly move on from the laboratory to the green industrial
plant, has received increasing interest.12,13 However, nding a
new support with prominent stability for heterogeneous catal-
ysis that provides the desired product in good catalytic activity is
very oen at the beginning of a long journey.
Polyacrylonitrile ber (PANF) is known as “articial wool”
and has been widely applied not only in civilian use but also in
Department of Chemistry, Tianjin University, Collaborative Innovation Center of
Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied
Catalysis Science and Technology, Tianjin 300072, P. R. China. E-mail: shixl@tju.
edu.cn; zhangwenqin@tju.edu.cn; Fax: +86-22-27403475; Tel: +86-22-27890922
Results and discussion
The preparation of PANF-PA
† Electronic supplementary information (ESI) available: The acid exchange
capacity of PANF-PA, scale-up experimental procedures and NMR spectra of all
compounds. See DOI: 10.1039/c4ra12069h
The PANF-PA was prepared according to the amination proce-
dure as shown in Scheme 1. As discussed in our previous work,19
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tolerance, whether activated nitriles (Table 1, entries 1–6)
including ordinary malononitrile, 4-nitrophenylacetonitrile,
complicated nitriles such as 4-tosylacetonitrile and N-benzyl-2-
cyanoacetamide, or different substituted salicylaldehydes
(Table 1, entries 7–10) reacted efficiently to afford the corre-
sponding products in good to excellent yields. Moreover, it is
worth mentioning that there was no evident electronic inu-
ence of the substituents on the aryl ring of salicylaldehydes on
the yields of iminocoumarins. However, the steric effect and
electronic effect on the activated nitriles had observable inu-
ence on the yield of the synthesized products. For instance, the
substrate of 4-nitrophenylacetonitrile (Table 1, entry 1)
obtained a high yield due to its bigger steric effect which was
favorable for formation of trans Knoevenagel condensation
product, and further in favor of the next cyclization, neverthe-
less, benzoylacetonitrile and 4-tosylacetonitrile (Table 1, entries
3 and 4) with high-activity for Knoevenagel condensation and
against for trans products, and nally afforded slightly lower
yields of the corresponding iminocoumarins.
PANF-PA as supported phase-transfer catalyst for the
synthesis of sulfones. The nucleophilic substitution is a crucial
and frequently used transformation for the formation of C–C
and C–heteroatom bonds in organic synthesis. However, it
seldom carried out in neat water owing to the limited water
solubility of organic substrates,28 and the most common way to
solve this problem is the employ of phase-transfer catalyst (PTC)
due to it facilitate reactions between water-soluble reagents and
organic soluble substrates.29 The application of sulfones in
organic synthesis has especially proven valuable in many of the
most demanding and sophisticated total syntheses con-
ducted,30,31 moreover, the polyethylene polyamine functional-
ized resin have been demonstrated with good phase-transfer
catalytic activity.32 Therefore, we next extended the PANF-PA as
the SPTC in nucleophilic substitution for the synthesis of
sulfones (Table 2). A 5% mol catalyst loading of PANF-PA was
used twice to mediate all the substituted halides and sodium 4-
toluenesulnate in neat water to obtain the corresponding
sulfones. As list in Table 2, it can be seen that the reactions
proceed smoothly with PANF-PA to give the products in excel-
lent yields whether benzyl bromides or benzyl chlorides, and all
the latter yields were higher than the former ones. It is worth
noting that there was no signicant inuence of the position of
the substituents on the yield of the synthesized products (Table
2 entries 3–5). However, the electronic nature of the substitu-
ents on the aryl ring of halides had an evident effect on the yield
of sulfones (Table 2 entries 6–8). Besides, trace product
formation was observed under the given reaction conditions
with the inert haloalkane (Table 2, entry 10).
Scheme 1 Preparation of the fiber catalyst PANF-PA.
the amination was found to be strongly inuenced by the
reaction time and temperature, and the extent of immobiliza-
tion was measured by weight gain (weight gain ¼ [(W2 ꢀ W1)/W1]
ꢁ 100%, where W1 and W2 are the weight of the ber sample
before and aer amination, respectively) and acid exchange
capacity. Under the screened condition of amination with
polyethylene polyamine in water, a weight gain of 35% PANF-PA
was obtained successfully and found to be with opportune
loading and strength, and the corresponding acid
exchange capacity in aqueous 0.1 M HCl was determined to be
4.02 mmol gꢀ1 (see ESI†).
The catalytic properties of PANF-PA
PANF-PA as heterogeneous base catalyst for the synthesis of
iminocoumarins. Natural and synthetic coumarins have
demonstrated a broad spectrum of applications in biology and
medicine.21,22 Moreover, their 2-imino analogues, iminocou-
marins, are less known but can be excited at longer wavelengths
than coumarins, and comprising a very important class of
protein tyrosine kinase (PTK) inhibitors with low molecular
weight.23,24 Nevertheless, most of the currently used methods for
the synthesis of iminocoumarins suffer from several short-
comings, including the use of non-recoverable catalysts, high-
power microwaves, long periods of reaction time, troublesome
procedures as well as limited substituents.25–27 Exploiting effi-
cient approaches to iminocoumarins would be of great interest
and value. Thus the efficacy of the PANF-PA function as
heterogeneous base catalyst was evaluated via Knoevenagel
condensation–cyclization between salicylaldehydes and acti-
vated nitriles to afford a wide variety of iminocoumarins
(Scheme 2).
Based on our previous work,19 and to gauge the scope of this
ber catalyst, a variety of substituted activated nitriles were
selected to react with salicylaldehydes in the presence of 5%
mol of PANF-PA loading in a mixed-aqueous system (ethanol–
water) to produce the corresponding iminocoumarins (Table 1).
It is gratifying that the catalytic system is of excellent group
The recyclability of the PANF-PA. As features of the hetero-
geneous catalysis system, the easy separation from the reaction
mixture and the reusability of PANF-PA were also investigated in
the reactions described above, which further proved the supe-
rior recyclability of the ber catalyst during vigorous operating
conditions. Under the same reaction conditions described in
Tables 1 and 2, salicylaldehyde and 4-nitrophenylacetonitrile,
benzyl bromide and sodium 4-toluenesulnate were selected as
the model substrates to examine the reusability of PANF-PA,
Scheme 2 Synthesis of iminocoumarins catalyzed by PANF-PA in a
mixed-aqueous system.
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Table 1 PANF-PA-mediated synthesis of iminocoumarinsa
Entry
1
Salicylaldehyde
Activated nitrile
Product
Time (h)
1.0
Yieldb (%)
95
1a
2
3
1b
1c
0.5
2.5
91
86
4
5
1d
1e
2.5
1.5
82
93
6
1f
1g
1h
1i
2.0
1.0
2.0
1.0
2.0
92
96
94
94
93
7
8
9
10
1j
11
1a
1a
1.0
1.0
tracec
95d
12
a
Reaction conditions: salicylaldehydes (2 mmol), activated nitriles (2 mmol) and PANF-PA (0.025 g, 5 mol% catalyst loading based on acid exchange
capacity) in water–EtOH mixtures (10 mL, 2 : 8 v/v), under reuxing. b Isolated yields. c Blank control (without any catalyst). d 5 mol% piperidine as
the catalyst.
respectively. Aer completion of each cycle, the PANF-PA was consistent with our previous work.19 However, in the nucleo-
ltered out and washed with the corresponding solvents, then philic substitution for synthesis of sulfone, the weight of PANF-
the recycled PANF-PA was used directly for the next cycle PA increased obviously from 0.025 to 0.033 g, which motivated
without any additional treatment. The results show that the us to further perform detailed characterization of the ber
reactions proceeded smoothly without extension of reaction catalyst in this process.
time or marked loss in the yield (Fig. 1). Furthermore, the
weight of PANF-PA before and aer ten cycles was also detected.
In the reaction for the synthesis iminocoumarin, there was
almost no weight change of PANF-PA aer ten cycles, which is
The characterization of PANF-PA
In the nucleophilic substitution for the synthesis of sulfones, all
the former yields were lower than the latter ones (Table 2) and
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Table 2 PANF-PA-mediated synthesis of sulfonesa
Entry
1
Halide
Product
Yield 1b (%)
89
Yield 2c (%)
95
2a
2
2b
92
96
3
4
5
6
7
8
2c
2d
2e
2a
2f
91
89
90
85
82
88
95
94
93
91
87
94
Fig. 1 Recyclability of PANF-PA for the synthesis of iminocoumarin
and sulfone.
catalyst in nucleophilic substitution, we performed detailed
characterization of the ber samples in different stages. The
original PANF, PANF-PA, the rst recovered catalyst in the
model nucleophilic substitution (PANF-PA-1) and the 10th
recovered catalyst (PANF-PA-10) were all characterized by means
of elemental analysis (EA), Fourier transform infrared spec-
troscopy (FTIR) and scanning electron microscopy (SEM).
Elemental analyses (EA). EA data of the PANF, PANF-PA,
PANF-PA-1 and PANF-PA-10 are listed in Table 3. Compared to
the original PANF, the carbon and nitrogen contents of PANF-
PA decreased and the hydrogen content increased as expected
(Table 3, entries 1 and 2). Aer PANF-PA being used as the
catalyst in the nucleophilic substitution of benzyl bromide and
sodium 4-toluenesulnate, the amounts of carbon, hydrogen
and nitrogen of PANF-PA-1 (Table 3, entry 3) all decreased, that
perhaps due to the benzyl bromides reacted with the amine
groups of the ber, and it has no nitrogen, less carbon and
hydrogen than PANF-PA. These results can be act as an evidence
to prove the formation of ammonium salt on the ber and verify
our above inference. What is more, the EA data of the 10th
recovered PANF-PA-10 (Table 3, entry 4) almost stayed the same
with that of PANF-PA-1, which indicated that the ber catalyst
can be reused more times.
2g
9
2h
2i
81
84
10
Trace
Trace
11
2a
2a
<70d
92e
—
—
12
a
Reaction conditions: halide (2 mmol), sodium p-toluenesulnate (2.5
mmol), and PANF-PA (0.025 g, 5 mol% based on acid exchange capacity)
b
in water (10 mL), 90 ꢂC for 0.5 h. First cycle catalyzed with PANF-PA,
c
isolated yields. Second cycle catalyzed with the front PANF-PA,
isolated yields. Blank control (without any catalyst).
tetraethylammonium bromide as the catalyst.
d
e
5 mol%
Fourier transform infrared spectroscopy (FTIR). Samples of
PANF, PANF-PA, PANF-PA-1 and PANF-PA-10 were pulverized by
cutting and then prepared into KBr pellets. Their FTIR spectra
are shown in Fig. 2. On comparing the FTIR spectra of the PANF-
the yield of rst run (88%) in repeated reactions was lower than
all of the subsequent ones (>92%). These results above sug-
gested that there must be some changes on the ber catalyst
during catalytic process. Aer amination, the PANF-PA contains
a lots amine group which can be easily reacted with benzyl
bromides and the formation of ammonium salts. Perhaps it is
due to the additional phase-transfer ability of ammonium salts,
which further improved the catalytic activity of the ber catalyst.
Moreover, the modied amine-functionalized PANF has been
characterized thoroughly in our previous work.19 So in order to
verify our deduction and investigate the rangeability of ber
Table 3 EA data of PANF, PANF-PA, PANF-PA-1, and PANF-PA-10
Entry
Fiber sample
C (%)
H (%)
N (%)
1
2
3
4
PANF
65.55
54.92
54.23
54.18
5.669
7.057
6.079
6.072
23.54
20.37
15.71
15.56
PANF-PA
PANF-PA-1
PANF-PA-10
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PA (Fig. 2b) with that of the PANF (Fig. 2a), the most striking PANF-EA body extended obviously, and the surface of the
change is the broad absorption bands around 3250 cmꢀ1, which PANF-PA was thickly dotted with scarring (Fig. 3b). With the
is characterized as the N–H stretching vibration. Aer used in sequential utilization, the surface of the ber samples
nucleophilic substitution, the PANF-PA-1 (Fig. 2c) exhibited new became increasingly coarser (Fig. 3c and d). However, the
absorption bands at 768 and 695 cmꢀ1 that belongs to the overall integrity of the ber was untouched. This observation
vibrational modes of benzene ring, which can be act as another above may be ascribed to “some changes on the PANF” and as
evidence to prove the formation of ammonium salt on the ber
a consequence of the modication and the catalytic
(agree well with the EA data). Moreover, the specic absorption processes.
peak of the PANF-PA-10 (Fig. 2d) are quite similar to PANF-PA-1
but with a slight enhancement, which further veries the above
Scaleup procedures for the synthesis of iminocoumarin and
sulfone catalyzed by PANF-PA
deduction and indicates that the active groups are still catalyt-
ically active aer being recycled many times.
Scanning electron microscope (SEM). Fig. 3 presents the
SEM images of PANF, PANF-PA, PANF-PA-1, and PANF-PA-10.
Compared to the original PANF (Fig. 3a), the diameter of
Finally, to illustrate the synthetic utility of the ber catalyst, the
large-scale reactions of the two processes were also conducted
on the model reactions (see ESI†). The approaches were scaled
up to gram scales, and both reactions proceeded smoothly
without any extension of reaction time to afford high product
yields of 96% (iminocoumarin) and, 89% and 97% (two runs for
sulfone). From the combination of the above experimental
results and the potential performance for being used in a xed-
bed reactor, it is obvious that the PANF-PA will be very attractive
to the chemical industry.
Conclusions
In summary, a facile synthesized and reusable PANF-PA has
been developed, and successfully employed as highly efficient
heterogeneous base catalyst and supported phase-transfer
catalyst for the synthesis of a range of iminocoumarins and
sulfones in aqueous systems, respectively. The detailed char-
acterization by EA, FTIR and SEM conrmed the deeper active
principle of the PANF-PA functioned as SPTC and was recycled
with excellent stability, moreover, which is very helpful for us to
further design novel SPTC based on PANF. To the best of our
knowledge, such a functionalized ber has been used here for
the rst time in organic synthesis not only used as heteroge-
neous base catalyst but also as SPTC, respectively, and displays
high activity and recyclability. The simple procedures can be
efficiently scaled up, as well as the prominent features of PANF
are very attractive to the xed-bed reactor in the chemical
industry.
Fig. 2 FTIR spectra of (a) PANF, (b) PANF-PA, (c) PANF-PA-1 and (d)
PANF-PA-10.
Experimental
Reagents
Commercially available polyacrylonitrile ber (PANF, the
number average molecular weight of the spinning solution is
53 000 to 106 000, 93.0% acrylonitrile, 6.5% methyl acrylate and
0.4–0.5% sodium styrene sulfonate) with a length of 10 cm and
a diameter of 30 ꢃ 0.5 mm (from the Fushun Petrochemical
Corporation of China) was used. All the salicylaldehydes, acti-
vated nitriles, halides, sodium p-toluenesulnate and poly-
ethylene polyamine, and the other reagents used were analytical
grade and employed without further purication. Water was
deionized.
Fig. 3 SEM images of (a) PANF, (b) PANF-PA, (c) PANF-PA-1 and (d)
PANF-PA-10.
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CDCl3) d 153.82, 147.96, 143.28, 135.56, 131.71, 130.10, 129.79,
129.08, 128.29, 124.13, 123.91, 119.84, 115.82.
Apparatus and instruments
The Elemental analyses (EA) were performed on a vario micro
cube analyzer (Elementar). Fourier transform infrared (FTIR)
spectra were obtained with an AVATAR 360 FTIR spectrometer
(Thermo Nicolet), KBr disc. A scanning electron microscope
(SEM) (Hitachi, model S-4800) was used to characterize the
surface of the bers. 1H NMR spectra were recorded on an
AVANCE III (Bruker, 400 MHz) instrument using TMS as the
internal standard. 13C NMR spectra were recorded on an
AVANCE III (Bruker, 101 MHz) instrument with complete
proton decoupling. Melting points were measured with a
Yanagimoto MP-500 apparatus and were uncorrected.
3-Cyaniminocoumarin (1b). Yellow solid; mp ¼ 164–166 ꢂC;
1H NMR (400 MHz, DMSO) d 8.41 (s, 1H), 7.69–7.64 (m, 1H),
7.42–7.36 (m, 2H), 7.17 (s, 1H), 5.90 (s, 1H). 13C NMR (101 MHz,
DMSO) d 162.75, 154.64, 149.76, 147.85, 147.20, 135.06, 130.43,
125.19, 118.44, 116.48.
3-Benzoyliminocoumarin (1c). Yellow solid; mp ¼ 214–
215 ꢂC; 1H NMR (400 MHz, DMSO) d 8.47 (s, 1H), 8.01–7.45 (m,
10H). 13C NMR (101 MHz, DMSO) d 192.61, 158.91, 155.06,
146.22, 136.98, 134.80, 134.49, 130.70, 130.44, 129.64, 127.28,
125.80, 119.16, 117.25.
3-(4-Tolylsulfonyl)iminocoumarin (1d). Yellow solid; mp ¼
191 ꢂC; 1H NMR (400 MHz, DMSO) d 9.16 (s, 1H), 8.14–7.39 (m,
9H), 2.43 (s, 3H). 13C NMR (101 MHz, DMSO) d 155.83, 155.54,
149.65, 145.86, 136.53, 136.39, 132.22, 130.59, 129.56, 127.83,
126.19, 118.35, 117.31, 22.03.
Preparation of polyethylene polyamine functionalized
polyacrylonitrile ber (PANF-PA)
Dried PANF (3.00 g), polyethylene polyamine (30 g) and deion-
ized water (30 mL) were introduced into a three-necked ask
connected with a condenser. The mixture was reuxed (105 ꢂC)
with stirring for 24 h. The ber was ltered out and washed
repeatedly with water (60–70 ꢂC) until the pH of the washed
water was 7, and then the ber sample was dried overnight at
60 ꢂC under vacuum to give the PANF-PA (4.0560 g, with a
weight gain of 35% and the acid exchange capacity was
4.02 mmol gꢀ1, see ESI†).
3-(N-Phenylcarboxamide)iminocoumarin (1e). Yellow solid;
1
ꢂ
mp ¼ 189–190 C; H NMR (400 MHz, DMSO) d 12.82 (s, 1H),
9.27 (s, 1H), 8.59 (s, 1H), 7.84 (d, J ¼ 7.4 Hz, 1H), 7.71 (d, J ¼ 7.7
Hz, 2H), 7.61 (s, 1H), 7.41 (t, J ¼ 7.4 Hz, 2H), 7.34–7.25 (m, 2H),
7.16 (s, 1H). 13C NMR (101 MHz, DMSO) d 160.57, 156.70,
154.42, 142.49, 139.15, 134.13, 131.01, 129.96, 129.59, 125.11,
124.93, 121.62, 121.08, 120.51, 119.41, 115.86.
3-(N-Benzylcarboxamide)iminocoumarin (1f). White solid;
1
ꢂ
mp ¼ 133–135 C; H NMR (400 MHz, DMSO) d 10.72 (br 1H),
9.02 (s, 1H), 8.50 (s, 1H), 7.95–6.80 (m, 9H), 4.52 (d, J ¼ 5.4 Hz,
2H). 13C NMR (101 MHz, DMSO) d 162.44, 158.71, 156.38,
154.38, 141.85, 139.73, 133.82, 130.82, 129.37, 128.24, 124.94,
121.14, 119.38, 115.77, 43.67.
General procedure for the synthesis of iminocoumarins
A mixture of salicylaldehyde (2 mmol), activated nitrile (2
mmol), and PANF-PA (0.025 g, 5% mol based on acid exchange
capacity) in water–EtOH (10 mL, 2 : 8 v/v) was stirred under
reuxing for the corresponding time in Table 1. Aer comple-
tion of the reaction, the ber catalyst and the crude product
were ltered out, then the former was just taken out with
common tweezers and washed with ethanol or toluene (10 mL),
and the later was recrystallized with the above solvent to obtain
the pure product. For recycle process, the washed ber catalyst
was conducted to the next cycle without any further treatment.
6-Methoxy-3-(4-nitrophenyl)iminocoumarin (1g). Yellow
solid; mp ¼ 202–203 ꢂC; 1H NMR (400 MHz, CDCl3) d 8.26 (d, J ¼
8.3 Hz, 2H), 7.84 (d, J ¼ 8.2 Hz, 2H), 7.38–6.85 (m, 5H), 3.82 (s,
3H). 13C NMR (101 MHz, CDCl3) d 155.95, 148.19, 147.96,
143.35, 135.48, 130.12, 129.79, 129.50, 123.89, 120.12, 118.47,
116.68, 111.34, 77.36, 56.16.
3-(N-Benzylcarboxamide)-6-methoxyiminocoumarin
(1h).
1
Yellow solid; mp ¼ 148–149 ꢂC; H NMR (400 MHz, CDCl3) d
10.76 (s, 1H), 8.46 (s, 1H), 7.62–7.28 (m, 5H), 7.04 (dd, J ¼ 6.8,
General procedure for the synthesis sulfones
5.8 Hz, 2H), 6.94 (s, 1H), 4.65 (d, J ¼ 5.6 Hz, 2H), 3.83 (s, 3H). 13
C
NMR (101 MHz, CDCl3) d 162.71, 158.19, 156.15, 148.66, 142.01,
138.76, 128.94, 127.92, 127.52, 121.10, 120.36, 119.53, 116.54,
111.99, 56.19, 44.13.
A mixture of halide (2 mmol), sodium p-toluenesulnate (2.5
mmol), and PANF-PA (0.025 g, 5% mol based on acid exchange
capacity) in water (10 mL) was stirred under 90 ꢂC for 0.5 h. Aer
completion of the reaction, the mixture was cooled to room
temperature, and then the ber catalyst and the crude product
were ltered out, the ber catalyst was just taken out with
common tweezers and washed with water (20 mL), and was used
again in the same substrates. The lter cake (crude product) was
rinsed with the above water and then dried to obtain the pure
sulfone. For recycle process, the washed ber catalyst was
conducted to the next cycle without any further treatment.
6-Bromo-3-(4-nitrophenyl)iminocoumarin (1i). Yellow solid;
mp ¼ 214–215 ꢂC; 1H NMR (600 MHz, CDCl3) d 8.29 (d, J ¼ 8.4
Hz, 2H), 7.83 (d, J ¼ 8.2 Hz, 2H), 7.54–6.99 (m, 5H). 13C NMR
(101 MHz, DMSO) d 157.31, 148.29, 140.98, 136.14, 130.99,
127.88, 125.29, 123.43, 119.17, 117.96, 111.07, 110.25.
3-(N-Benzylcarboxamide)-6-bromoiminocoumarin (1j). White
1
ꢂ
solid; mp ¼ 197–198 C; H NMR (400 MHz, CDCl3) d 10.60 (s,
1H), 8.41 (s, 1H), 7.75–7.49 (m, 3H), 7.35–7.28 (m, 5H), 7.00 (d, J ¼
8.7 Hz, 1H), 4.64 (d, J ¼ 5.7 Hz, 2H). 13C NMR (101 MHz, CDCl3) d
162.13, 157.18, 152.99, 140.67, 138.55, 135.52, 131.90, 128.97,
127.92, 127.60, 121.90, 120.90, 117.31, 116.83, 44.20.
1
The physical data, H and 13C NMR data of all compounds
3-(4-Nitrophenyl)iminocoumarin (1a). Yellow solid; mp ¼
1-(Benzylsulfonyl)-4-methylbenzene (2a). White solid; mp ¼
1
1
ꢂ
181–182 ꢂC; H NMR (400 MHz, CDCl3) d 8.28 (d, J ¼ 8.0 Hz, 2H), 141–142 C; H NMR (400 MHz, DMSO) d 7.62 (d, J ¼ 8.0 Hz,
7.85 (d, J ¼ 7.8 Hz, 2H), 7.70–7.14 (m, 6H). 13C NMR (101 MHz, 2H), 7.42–7.32 (m, 5H), 7.18 (d, J ¼ 6.4 Hz, 5H), 4.66 (s, 5H), 2.42
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(s, 3H). 13C NMR (101 MHz, DMSO) d 145.13, 136.51, 131.84,
130.43, 129.70, 129.17, 129.09, 128.94, 61.72, 21.95.
1-Nitro-4-(4-tolylsulfonylmethyl)benzene (2b). White solid;
mp ¼ 188–189 ꢂC; 1H NMR (400 MHz, DMSO) d 8.21 (d, J ¼ 8.5
Hz, 2H), 7.65 (d, J ¼ 8.0 Hz, 2H), 7.49–7.44 (m, 4H), 4.92 (s, 2H),
2.43 (s, 3H). 13C NMR (101 MHz, DMSO) d 148.33, 145.55,
137.45, 136.22, 133.17, 130.61, 128.96, 124.17, 60.90, 40.45,
21.98.
3 M. Benaglia, Recoverable and Recyclable Catalysts, Wiley, New
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6 J. Lu and P. H. Toy, Chem. Rev., 2009, 109, 815.
7 H.-J. Cho, S. Jung, S. Kong, S.-J. Park, S.-M. Lee and Y.-S. Lee,
Adv. Synth. Catal., 2014, 356, 1056.
8 C. Perego and R. Millini, Chem. Soc. Rev., 2013, 42, 3956.
9 C. M. A. Parlett, D. W. Bruce, N. S. Hondow, M. A. Newton,
A. F. Lee and K. Wilson, ChemCatChem, 2013, 5, 939.
1-Bromo-4-(4-tolylsulfonylmethyl)benzene (2c). White solid;
mp ¼ 170–171 ꢂC; 1H NMR (400 MHz, DMSO) d 7.63 (d, J ¼ 8.0
Hz, 2H), 7.54 (d, J ¼ 8.2 Hz, 2H), 7.44 (d, J ¼ 8.0 Hz, 2H), 7.14 (d, 10 D. Wang and D. Astruc, Chem. Rev., 2014, 114, 6949.
J ¼ 8.2 Hz, 2H), 4.69 (s, 2H), 2.43 (s, 3H). 13C NMR (101 MHz, 11 R. Mrowczynski, A. Nan and J. Liebscher, RSC Adv., 2014, 4,
´
´
DMSO) d 145.30, 136.30, 133.90, 132.10, 130.52, 129.25, 128.95,
5927.
122.78, 60.84, 21.97.
12 M. Rose, ChemCatChem, 2014, 6, 1166.
1-Bromo-3-(4-tolylsulfonylmethyl)benzene (2d). White solid; 13 L. M. Rossi, N. J. S. Costa, F. P. Silva and R. Wojcieszak, Green
1
ꢂ
mp ¼ 117–119 C; H NMR (400 MHz, DMSO) d 7.65–7.18 (m,
Chem., 2014, 16, 2906.
8H), 4.71 (s, 2H), 2.44 (s, 3H). 13C NMR (101 MHz, DMSO) d 14 O. M. Vatutsina, V. S. Soldatov, V. I. Sokolova, J. Johann,
145.37, 136.24, 134.49, 132.39, 132.03, 131.20, 130.85, 130.51,
128.98, 122.09, 60.84, 21.96.
M. Bissen and A. Weissenbacher, React. Funct. Polym.,
2007, 67, 184.
1-Bromo-2-(4-tolylsulfonylmethyl)benzene (2e). White solid; 15 R. X. Liu, B. W. Zhang and H. X. Tang, React. Funct. Polym.,
1
ꢂ
mp ¼ 147–148 C; H NMR (400 MHz, DMSO) d 7.63–7.32 (m,
1999, 39, 71.
8H), 4.79 (s, 2H), 2.44 (s, 3H). 13C NMR (101 MHz, DMSO) d 16 G. Moroi, D. Bilba and N. Bilba, Polym. Degrad. Stab., 2004,
145.57, 136.50, 134.12, 133.66, 131.49, 130.63, 129.40, 129.11,
128.55, 126.34, 61.50, 22.00.
84, 207.
17 X.-L. Shi, H. Yang, M. Tao and W. Zhang, RSC Adv., 2013, 3,
1-Methyl-4-(4-tolylsulfonylmethyl)benzene (2f). White solid;
3939.
mp ¼ 152–153 ꢂC; 1H NMR (400 MHz, DMSO) d 7.62 (d, J ¼ 8.0 18 X.-L. Shi, M. Zhang, Y. Li and W. Zhang, Green Chem., 2013,
Hz, 2H), 7.42 (d, J ¼ 7.9 Hz, 2H), 7.12 (d, J ¼ 7.8 Hz, 2H), 7.06 (d,
15, 3438.
J ¼ 7.8 Hz, 2H), 4.60 (s, 2H), 2.42 (s, 3H), 2.30 (s, 3H). 13C NMR 19 G. Li, J. Xiao and W. Zhang, Green Chem., 2011, 13, 1828.
(101 MHz, DMSO) d 145.08, 138.52, 136.58, 131.72, 130.44, 20 X.-L. Shi, X. Xing, H. Lin and W. Zhang, Adv. Synth. Catal.,
129.70, 128.95, 126.61, 61.41, 21.96, 21.64.
2014, 356, 2349.
1-Fluoro-4-(4-tolylsulfonylmethyl)benzene (2g). White solid; 21 O. A. Abd-Allah, Farmaco, 2000, 55, 641.
mp ¼ 170–171 ꢂC; 1H NMR (400 MHz, DMSO) d 7.62 (d, J ¼ 8.0 22 H. S. P. Rao, M. Babua and A. Desaia, RSC Adv., 2014, 4,
Hz, 2H), 7.43 (d, J ¼ 8.0 Hz, 2H), 7.24–7.14 (m, 4H), 4.68 (s, 2H),
11064.
2.43 (s, 3H). 13C NMR (101 MHz, DMSO) d 164.26, 161.83, 23 T. R. Burke, B. Lim, V. E. Marquez, Z. H. Li, J. B. Bolen,
145.24, 136.31, 133.94, 133.85, 130.49, 128.98, 126.10, 126.07,
116.17, 115.95, 60.73, 21.97.
I. Stefanova and I. D. Horak, J. Med. Chem., 1993, 36, 425.
24 T.-I. Kim, M. S. Jeong, S. J. Chung and Y. Kim, Chem.–Eur. J.,
2010, 16, 5297.
1
ꢂ
4-Tosylacetonitrile (2h). White solid; mp ¼ 145–146 C; H
NMR (400 MHz, DMSO) d 7.91 (d, J ¼ 8.1 Hz, 2H), 7.58 (d, J ¼ 8.0 25 D. Guo, T. Chen, D. Ye, J. Xu, H. Jiang, K. Chen, H. Wang and
Hz, 2H), 5.24 (s, 2H), 2.48 (s, 3H). 13C NMR (101 MHz, DMSO) d
H. Liu, Org. Lett., 2011, 13, 2884.
146.96, 135.33, 131.10, 129.23, 113.29, 45.69, 22.09.
26 J. Volmajer, R. Toplak, S. Bittner, I. Leban and A. M. Le
Marechal, Tetrahedron Lett., 2003, 44, 2363.
27 Y. Shen, S. Cui, J. Wang, X. Chen, P. Lu and Y. Wang, Adv.
Synth. Catal., 2010, 352, 1139.
Acknowledgements
This work was nancially supported by the National Natural
Science Foundation of China (no.: 20834002 and 21306133) and
Tianjin Research Program of Application Foundation and
Advanced Technology (no.: 14JCYBJC22600).
28 C. Arani and V. F. Valery, Chem. Rev., 2009, 109, 725.
29 J. Li, J. Cao, J. Wei, X. Shi, L. Zhang, J. Feng and Z. Chen, Eur.
J. Org. Chem., 2011, 19, 229.
30 N. S. Simpkins, Sulfones in Organic Synthesis, Tetrahedron
Organic Chemistry Series, Pergamon Press, New York, 1993.
31 B. T. V. Srinivas, V. S. Rawat, K. Konda and B. Sreedhar, Adv.
Synth. Catal., 2014, 356, 805.
Notes and references
1 M. Lancaster, Green Chemistry: An Introductory Text, RSC,
Cambridge, 2002.
32 A. Akalah and D. C. Sherring, Chem. Rev., 1981, 81, 557.
2 R. A. Sheldon, Chem. Soc. Rev., 2012, 41, 1437.
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 64347–64353 | 64353