Nanosized MCM-41 supported protic ionic liquid as an efficient novel catalytic system for Friedlander synthesis of quinolines

Article abstract of DOI:10.1016/j.catcom.2012.02.004

Nanosized MCM-41 has been synthesized by sol-gel method. n-Butanesulfonic acid pyridinium hydrogensulfate as protic ionic liquid has been dispersed on the MCM-41 nanoparticles. The morphology of the MCM-41 and MCM-41 supported ionic liquid has been studie

Full text of DOI:10.1016/j.catcom.2012.02.004

Catalysis Communications 22 (2012) 13–18
Contents lists available at SciVerse ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Nanosized MCM-41 supported protic ionic liquid as an efficient novel catalytic
system for Friedlander synthesis of quinolines
⁎
Mohammad Abdollahi-Alibeik , Marjan Pouriayevali
Department of Chemistry, Yazd University, Yazd 89195-741, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Nanosized MCM-41 has been synthesized by sol–gel method. n-Butanesulfonic acid pyridinium hydrogensulfate
as protic ionic liquid has been dispersed on the MCM-41 nanoparticles. The morphology of the MCM-41 and
MCM-41 supported ionic liquid has been studied by SEM, XRD, BET and FT-IR techniques. The catalytic perfor-
mance of the nanosized MCM-41 supported ionic liquid was investigated in the Friedlander synthesis of
quinolines.
Received 19 October 2011
Received in revised form 1 February 2012
Accepted 2 February 2012
Available online 18 February 2012
© 2012 Elsevier B.V. All rights reserved.
Keywords:
Nanoparticle
MCM-41
Ionic liquid
Catalyst
Friedlander
Quinoline
1. Introduction
surface area (>1000 m2 g−1) and high thermal stability (ca. 900 °C)
[10]. This compound has been used as support in the preparation
Recently, room temperature ionic liquids have attracted consider-
able attention due to their special characteristics including unique
solvation properties, high thermal stability, ease of handling, wide
liquid range and negligible vapor pressure (10−8 bar) [1,2]. These
compounds have been used as both catalyst and solvent in various
kinds of reactions. These applications require large amounts of ionic
liquids as expensive materials [3,4]. In addition, the high viscosity of
ionic liquids can induce mass transfer limitations if the chemical reac-
tion is fast, in which case the reaction takes place only within the
narrow diffusion layer and not in the bulk of the ionic liquid. This
problem can be avoided by immobilizing a thin film of ionic liquid
on the surface and/or pores of a high surface area support [4]. The
supported catalyst thus combines the advantages of ionic liquids
and heterogeneous support. This process can transfer the desired
catalytic properties of the ionic liquids to solid catalyst.
of solid acid catalysts for organic transformations [11,12]. Recently,
several reports have been published describing the use of the immo-
bilized ionic liquids on mesoporous silica of MCM-41 [13,14].
In this research we report the preparation, characterization and
catalytic application of nanosized MCM-41 supported n-butanesulfonic
acid pyridinium hydrogensulfate ((BSPY)HSO4/MCM-41), as catalyst in
Friedlander synthesis of quinolines (Scheme 1). The novel multi SO3H
functionalized ionic liquids have been synthesized as protic ionic liquid
and employed in many organic transformations [15–18]. However, less
attention has been paid to the immobilization of this type of protic
ionic liquids on the solid support.
2. Experimental methods
2.1. Materials and methods
Various mineral oxides such as silica [5], alumina [6], titania [7]
and zirconia [8] have been used as the support for preparation of
solid catalyst. Since the discovery of mesoporous molecular sieves in
1992 [9], the use of nanosized mesoporous materials has attracted
considerable attention due to their highly ordered porous structure
and very high surface area. Among the various types of mesoporous
silica, MCM-41 exhibits a highly ordered hexagonal array of one-
dimensional mesopores with a pore diameter of 15–100 Å, high
All chemicals were commercial products. All reactions were mon-
itored by TLC and all yields refer to isolated products. 1H and 13C NMR
spectra were recorded in CDCl3 on a Bruker DRX-500 AVANCE
(500 MHz for 1H and 125.72 MHz for 13C) spectrometer. Infrared
spectra of the catalysts and reaction products were recorded on a
Bruker FT-IR Equinax-55 spectrophotometer in KBr with absorption in
cm−1. XRD patterns were recorded on a Bruker D8 ADVANCE X-ray
diffractometer using nickel filtered Cu Kα radiation (λ=1.5406 Å).
The 2θ angles were scanned from 1.5° to 10°. The morphology was
studied using a Philips XL30 scanning electron microscopy. The BET
surface area was performed using Micromeritics model Gemini 2375V
⁎
Corresponding author. Tel.: +98 351 8122659; fax: +98 351 8210644.
E-mail address: abdollahi@yazduni.ac.ir (M. Abdollahi-Alibeik).
1566-7367/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.catcom.2012.02.004

14
M. Abdollahi-Alibeik, M. Pouriayevali / Catalysis Communications 22 (2012) 13–18
Scheme 1. The Friedlander synthesis of quinolines in the presence of 23% (BSPY)HSO4/MCM-41.
4.02 from the nitrogen adsorption isotherms at −170 °C. All samples
were degassed at 130 °C under flowing nitrogen for 1.5 h. Specific
surface area (SBET) was calculated from adsorption data using BET
equation at P/P°=0.1–0.3, and pore volume (Vpore) was calculated
based on Barret–Joyner–Halenda (BJH) method.
2.84 (s, 3H), 4.11 (q, 2H, J=7.1 Hz), 7.41 (m, 2H), 7.47 (dt, 1H, J=
0.8, 7.2 Hz), 7.53 (m, 3H), 7.62 (d, 1H, J=8.2 Hz), 7.77 (dt, 1H, J=1.3,
7 Hz), 8.13 (d, 1H, J=8.5 Hz). 13C NMR (125.7 MHz, CDCl3):
δ=14.06, 24.15, 61.78, 125.61, 126.9, 126.95, 127.87, 128.66, 128.91,
129.165, 129.80, 130.76, 136. 14, 146.84, 155.05, 168.82.
2.2. Preparation of MCM-41 nanoparticles
3. Results and discussion
The synthesis of nanosized MCM-41 was carried out using tetraethyl
orthosilicate (TEOS) as the Si source, cetyltrimethylammonium bromide
(CTAB) as the template and ammonia as the pH control agent with the
gel composition of SiO2:CTAB:NH4OH:H2O=22.5:2.74:53.5:11.11.
In a typical procedure, to a solution of CTAB (1 g, 2.74 mmol) in
deionized water (200 mL), aqueous ammonia (25 wt.%) was added
until the pH of the solution was adjusted to 10.5. Then TEOS (5 mL)
was added dropwise at 70 °C for 1 h and the mixture was allowed
to cool to room temperature and was stirred for 12 h. The solid was
separated by centrifuge and washed with distilled water (20 mL)
and EtOH (2×10 mL) respectively. The solid was dried in an oven at
120 °C for 1 h and then calcined at 550 °C for 4 h.
3.1. The catalyst preparation
Nanosized MCM-41 was prepared by sol–gel method. The
(BSPY)HSO4/MCM-41 catalysts with various loading amounts of
(BSPY)HSO4 were prepared. For this purpose, suspensions of the MCM-
41 and (BSPY)HSO4 with various molar ratios of (BSPY)HSO4:MCM-41
in a constant amount of acetone were stirred for 12 h. The suspensions
were centrifuged and washed many times with acetone and then dried
in an oven at 120 °C. The details of conditions for catalyst preparation
are listed in Table 1.
As shown in Table 1, loading amounts of (BSPY)HSO4 present in
the MCM-41 were found to be 5, 14, 23 and 28 wt.%.
2.3. Preparation of 23 wt.% (BSPY)HSO4/MCM-41
3.2. Characterization of materials
(BSPY)HSO4 as protic ionic liquid was synthesized according to
reported procedure [18]. To a suspension of the MCM-41 (60 mg) in
acetone (1 mL), (BSPY)HSO4 (0.0626 g) was added and the mixture
was stirred for 12 h. The catalyst was separated by centrifuge, washed
with acetone (4×2 mL) and dried in an oven at 120 °C for 2 h.
The MCM-41 and the prepared catalysts were characterized by
SEM, XRD, FT-IR and BET techniques.
The SEM image of MCM-41 (Fig. 1) shows spherical nanoparticles
with the size of less than 100 nm.
The FT-IR spectra of MCM-41, (BSPY)HSO4 and (BSPY)HSO4/MCM-41
with different loading amounts of (BSPY)HSO4 are shown in Fig. 2. As
shown in Fig. 2a, pure (BSPY)HSO4 exhibited characteristic peaks of
alkyl sulfonate and hydrogensulfate at 1230, 1170, 1058, 1028, 885,
854 and 594 cm−1 and the peaks of pyridine ring at 1489, 1651 and
684 cm−1. FT-IR spectrum of MCM-41 (Fig. 2b) shows typical IR
bands at 1080 and 812 cm−1 corresponding to stretching Si\O and
460 cm−1 corresponding to bending Si\O\Si. In the FT-IR spectra of
5–23% (BSPY)HSO4/MCM-41 (Fig. 2c–f), apart from the main peaks
of MCM-41, additional peaks corresponding to functional group of
2.4. Catalytic activity of (BSPY)HSO4/MCM-41 in Friedlander synthesis
A mixture of o-aminobenzophenone (1 mmol), ketone or β-
diketone (1.2 mmol) and (BSPY)HSO4/MCM-41 (70 mg) was heated
at 100 °C. After completion of the reaction (monitored by TLC, eluent;
n-hexane:EtOAc, 8:2), EtOH (2 mL) was added, the catalyst was
separated and washed with EtOH (3×2 mL). After addition of water,
the product was precipitated with high purity. Further purification
was achieved by recrystallization in EtOH. The pure quinolines were
obtained in 78–95% yields.
2.5. Physical and spectroscopic data for selected compound
2.5.1. Ethyl-2-methyl-4-phenylquinoline-3-carboxylate (3a)
MP: 100–101 °C (Lit. [19], 100–101 °C). IR (KBr): υmax: 2978, 1711,
1561, 1444, 1402, 1297, 1237, 1182, 1130, 1070, 767, 700, 623,
603 cm−1 1H NMR (500 MHz, CDCl3): δ=1.00 (t, 3H, J=7.1 Hz),
.
Table 1
Preparation of (BSPY)HSO4/MCM-41 with various loading amounts of (BSPY)HSO4/
MCM-41.
Entry
Mole ratio of
(BSPY)/HSO4:MCM-41
Amount of (BSPY)/HSO4 on
the MCM-41 (wt.%)
1
2
3
4
1:20
1:10
1:5
5
14
23
28
1:2
Fig. 1. The SEM image of MCM-41.

M. Abdollahi-Alibeik, M. Pouriayevali / Catalysis Communications 22 (2012) 13–18
15
Table 2
(a)
Textural properties of MCM-41 and (BSPY)HSO4/MCM-41 catalysts.
Entry Catalyst
SBET (m2 g−1
)
Total pore volume
(mL g−1
)
1
2
3
4
MCM-41
1153
444
110
948
0.84
0.39
0.17
0.62
(b)
(c)
23% (BSPY)HSO4/MCM-41
28% (BSPY)HSO4/MCM-41
Recovered 23% (BSPY)HSO4/MCM-41
(d)
peaks at 1651, 1489, 727 and 684 cm−1 are assigned to the pyridine
ring of (BSPY)HSO4, while the characteristic peaks of sulfate around
1230, 1170, 1058 and 1028 cm−1 may overlap with the strong peak
of MCM-41 around 1080 cm−1 resulting in increase of intensity and
broadening of this peak of MCM-41. The peaks at 885 and 854 cm−1
are assigned to a stretching frequency of C\S and S\O bond of sulfate.
These results indicated that ionic liquid is dispersed on the surface of
MCM-41.
(e)
(f)
Fig. 3 shows the XRD pattern of MCM-41 and 5–23 wt.% (BSPY)HSO4/
MCM-41. As shown in Fig. 3a, MCM-41 exhibited a strong peak at
2θ=2.32° which corresponded to the characteristics of hexagonal or-
dering and two weak peaks at 2θ=4.04, 4.64°. In the XRD patterns of
5–23 wt.% (BSPY)HSO4/MCM-41 (Fig. 3b–c), intensity of the peak at
2θ=2.32° was decreased and its width was increased with an increase
in loading amount of (BSPY)HSO4, which means that the hexagonal
mesostructures are less ordered due to dispersion of ionic liquid mole-
cules in the mesoporous channels of MCM-41.
2000
1600
1200
800
400
Wavenumber (cm-1)
Fig. 2. FT-IR spectra of (a) (BSPY)HSO4, (b) MCM-41, (c) 5 wt.% (BSPY)HSO4/MCM-41,
(d) 14 wt.% (BSPY)HSO4/MCM-41, (e) 23 wt.% (BSPY)HSO4/MCM-41, and (f) 28 wt.%
(BSPY)HSO4/MCM-41.
The textural properties of MCM-41, 23 wt.% and 28 wt.% (BSPY)HSO4/
MCM-41 and recovered 23 wt.% (BSPY)HSO4/MCM-41 are listed in
Table 2. As shown in Table 2, the surface area and pore volume
of MCM-41 are 1153 m2 g−1 and 0.84 mL g−1 respectively, in accor-
dance with literature data [20]. The surface area and pore volume
ionic liquid appeared in the patterns. It is noticeable that because of low
intensity, all of the characteristic peaks of (BSPY)HSO4 in the spectra of
the catalysts with lower loading amounts of (BSPY)HSO4 (Fig. 2c and d)
did not appear. However, in the spectra of 23% and 28% (BSPY)HSO4/
MCM-41, more of (BSPY)HSO4 peaks appeared. In these spectra, the
MCM-41
23% (BSPY)HSO4/MCM-41
28% (BSPY)HSO4/MCM-41
500
400
300
(a)
200
(a)
(b)
(b)
(c)
100
(c)
(d)
2
4
6
8
10
0.2
0.4
0.6
0.8
2θ(o)
Relative pressure (p/p°)
Fig. 4. Nitrogen adsorption isotherms of (a) MCM-41, (b) 23% (BSPY)/HSO4/MCM-41,
Fig. 3. XRD patterns of (a) MCM-41, (b) 5 wt.% (BSPY)HSO4/MCM-41, (c) 14 wt.%
and (c) 28% (BSPY)/HSO4/MCM-41.
(BSPY)HSO4/MCM-41, and (d) 23 wt.% (BSPY)HSO4/MCM-41.

16
M. Abdollahi-Alibeik, M. Pouriayevali / Catalysis Communications 22 (2012) 13–18
Table 3
assigned to type IV isotherm. A mesoporous inflection was observed
on the isotherm of MCM-41 at a relative pressure between p/p°=
0.3–0.4 due to capillary condensation. In the isotherm of 23 wt.%
(BSPY)HSO4/MCM-41, mesoporous isotherm (type IV) characteristic
still could be observed, but the inflection becomes shorter corre-
sponding to a reduction in the pore volume. This result is due to
(BSPY)HSO4 dispersion in pore walls that causes lower capillary con-
densation. However, in the isotherm of 28 wt.% (BSPY)HSO4/MCM-41
(Fig. 4c) the condensation region disappeared. This may be due to
extremely full blockage of mesoporous channels of MCM-41 with
(BSPY)HSO4 and the isotherm shows only multilayer adsorption on
the external surface.
Reaction of ethylacetoacetate and 2-aminobenzophenone for the synthesis of quino-
lines in the presence of various amounts of (BSPY)HSO4/MCM-41.
Entry Catalyst (BSPY)HSO4
amount loading on the
(BSPY)HSO4/MCM-41 wt.% Time Conversion
related to reactants
(min) (%)
(mg)
MCM-41 (wt.%)
1
2
3
4
5
6
70
70
70
70
50
5
14
23
28
23
23
21
21
21
21
15
30
120
100
70
180
130
65
100
100
100
b50
100
100
100
decrease after supporting the (BSPY)HSO4 on the MCM-41 surface area
(Table 2, entries 2, 3).
3.3. Catalytic activity of (BSPY)HSO4/MCM-41
Fig. 4 shows N2 adsorption isotherms of MCM-41, and 23 wt.% and
28 wt.% (BSPY)HSO4/MCM-41. The typical curve of MCM-41 could be
The catalytic performance of (BSPY)HSO4/MCM-41 in the
Friedlander synthesis of quinolines by the condensation reaction
Table 4
Reaction of ketones and 2-aminobenzophenone for the synthesis of quinolines in the presence of 23 wt.% of (BSPY)HSO4/MCM-41.
Entry
Aminoarylketone
(1)
Ketone
(2)
Quinoline
(3)
Time
(min)
Yielda
(%)
Mp (°C)
Found
Lit. [ref]
O
O
Ph
N
O
a
Ph
NH2
OEt
OEt
70
45
50
90
210
40
80
70
55
80
93
91
90
87
82
87
94
88
89
91
100–101
100–101 [19]
O
Ph
O
O
b
c
d
e
f
Ph
NH2
108–109
111–112 [19]
N
Ph
O
O
O
O
Ph
NH2
139–140
133–134 [21]
Ph
Ph
CH3
N
Ph
O
Ph
NH2
142–143
138–141 [21]
N
Ph
O
Ph
NH2
133–135
133–135 [21]
N
Ph
O
O
O
O
O
Ph
NH2
144–146
151–153 [21]
N
O
Ph
O
O
C1
Cl
Cl
Cl
Cl
g
h
i
OEt
98–99
102–104 [21]
Ph
OEt
NH2
O
N
Ph
O
C1
C1
C1
155–156
154 [21]
Ph
NH2
O
N
Ph
162–163
159 [19]
Ph
NH2
O
N
Ph
j
97–98
100 [21]
Ph
NH2
N
a
Isolated yields.

M. Abdollahi-Alibeik, M. Pouriayevali / Catalysis Communications 22 (2012) 13–18
17
Table 5
Comparison of the catalytic activity of (BSPY)HSO4/MCM-41 with other heterogeneous catalysts.
Entry
Catalyst
Amount of the catalyst
Solvent, reaction temp. (°C)
Reaction time (min)
Yield (%)
Ref.
1
2
3
4
5
6
7
(BSPY)HSO4/MCM-41
NaHSO4/SiO2
Amberlyst-15
HClO4/SiO2
Nano Al2O3
70 mg
Solvent-free, 100
Solvent-free, 100
EtOH, reflux
CH3CN, 60
CHCl3, reflux
70
60
150
120
180
20
93
92
89
94
98
82
81
–
200 mg
10% (w/w)
200 mg
0.03 mmol
80 mg
[22]
[23]
[24]
[25]
[26]
[26]
Cellulose sulfuric acid
Starch sulfuric acid
Solvent-free, 100
Solvent-free, 100
80 mg
30
of o-aminobenzophenones and ketones was investigated. Initially,
the optimization experiments were performed in the reaction of
o-aminobenzophenone and ethyl acetoacetate at 100 °C under
solvent-free condition as the model reaction and the results are
shown in Table 3. It is noticeable that the reaction times presented
in Table 3 (except for entry 4) are the times for total conversion of
reactants.
from EtOH. All of the reported yields in Table 4 are isolated yields
(by weight) after recrystallization.
All of the synthesized products are known compounds and were
characterized by comparing their melting points (Table 4) and IR
spectra. Many of the compounds have also been characterized by 1H
and 13C NMR spectroscopy. The characterization detail of selected
compound is shown in Experimental methods section.
To investigate the effect of the loading amount of (BSPY)HSO4
on the catalytic activity of (BSPY)HSO4/MCM-41 in the Friedlander
synthesis, the model reaction was performed in the presence of
70 mg of catalysts with 5–28 wt.% (BSPY)HSO4. As shown in Table 3
(entries 1–4) the reaction times were reduced from 120 to 70 min
with an increase in the loading amount of (BSPY)HSO4 up to
23 wt.%. Further increase in loading up to 28 wt.% results in a drop
in activity and increases the reaction time. These results show that
in terms of reaction time the catalyst with 23 wt.% (BSPY)HSO4
has the best catalytic activity. Low catalytic activity of 28 wt.%
(BSPY)HSO4/MCM-41 compared with 23 wt.% (BSPY)HSO4/MCM-41
is in compliance with the results of BET experiments. This low activity
of the former catalyst is due to high blockage of mesoporous channels
of MCM-41 and thus reaction cannot take place in very low surface of
the heterogeneous catalyst.
In order to optimize the amount of 23 wt.% (BSPY)HSO4 in the
model reaction, various amounts of the catalyst were used in the
reaction and the best result in terms of catalyst loading amount and
the yield of the product was obtained using 70 mg of the catalyst
for the reaction of 1 mmol o-aminobenzophenone in the model reac-
tion with a mole ratio of 1:1.2 for o-aminobenzophenone:ethyl
acetoacetate (Table 3, entries 4–6).
The scope and generality of this methodology is illustrated with
respect to various types of ketones and results are summarized in
Table 4. According to the results of optimization experiments for the
reaction conditions and the amount of the catalyst, the reaction of
various diketones with o-aminobenzophenones was carried out
in the presence of 23 wt.% (BSPY)HSO4/MCM-41 at 100 °C under
solvent-free condition and the corresponding quinolines were obtained
in good to excellent yields (Table 4, entries 3a–3c and 3g–3h). Cyclic
ketones were also reacted with o-aminobenzophenones in the same
reaction conditions to afford the corresponding tricyclic quinolines in
good yields (Table 4, entries 3d–3f and 3i–3j). The difference between
reaction times of various ketones in Table 4 is not clear. This may
be due to the absence of regular functional groups on the ketones.
However, a plausible explanation is that various reactants have differ-
ent interactions with the surface of the catalyst in mesoporous channels
of MCM-41.
The efficiency of 23 wt.% (BSPY)HSO4/MCM-41 was also compared
with other similar heterogeneous catalytic systems in the same reac-
tion at the same reaction temperature and solvent-free condition
(Table 5). The obtained results indicate the superiority of the present
catalyst in terms of catalyst amount, yield or reaction times.
To investigate reusability of the catalyst, the recovered catalyst
from the model reaction was washed with EtOH and dried in an
oven at 120 °C for 1 h. The recovered catalyst was used in the same
reaction. The results show a decrease of catalyst activity in compari-
son to the first run. This result suggests that deactivation is due to
the leaching of (BSPY)HSO4 from the MCM-41. The leaching was
studied by comparing the FT-IR of the fresh catalyst and recovered
catalyst after the first run (Fig. 5). As shown in Fig. 5b the FT-IR spec-
trum of the recovered catalyst shows very weak characteristic peaks
of ionic liquid in comparison to the fresh catalyst (Fig. 5c). This con-
firms partial leaching of the ionic liquid from the surface of MCM-
41. These results were confirmed by the study of BET surface area
and pore volume of recovered and fresh catalysts. As shown in
Table 2 (entry 4) BET surface area and pore volume of recovered
catalysts were decreased to 947 m2/g and 0.62 mL/g from 444 m2/g
and 0.39 mL/g in fresh catalyst. However, the surface area and pore
volume of recovered catalyst are less than pure MCM-41 and these
results can confirm partial leaching of (BSPY)HSO4 from the support.
(a)
(b)
(c)
The workup and catalyst recovery are very simple. All of the reac-
tions have very high selectivity toward corresponding quinolines
and TLC monitoring shows only trace amounts of byproducts. After
the completion of the reaction (monitored by TLC, eluent; EtOAc:n-
hexane, 20:80), EtOH was added to the reaction mixture and the
catalyst was separated by centrifuge and washed with EtOH. After
evaporation of excess amount of EtOH the crude product was easily
isolated in almost pure state by addition of water and filtration of
the precipitate. Further purification was achieved by recrystallization
2000
1600
1200
800
400
Wavenumber (cm-1)
Fig. 5. FT-IR spectra of (a) MCM-41, (b) 23 wt.% (BSPY)HSO4/MCM-41 after reaction,
and (c) fresh 23 wt.% (BSPY)HSO4/MCM-41.

18
M. Abdollahi-Alibeik, M. Pouriayevali / Catalysis Communications 22 (2012) 13–18
[8] B.M. Devassy, S.B. Halligudi, Journal of Catalysis 236 (2005) 313.
4. Conclusion
[9] C.T. Kresge, M.E. Leonowicz, W.J. Roth, J.C. Vartuli, J.S. Beck, Nature 359 (1992)
710.
In conclusion, we found that (BSPY)HSO4 as protic ionic liquid
could be dispersed highly on the surface of MCM-41 nanoparticles.
The obtained material ((BSPY)HSO4/MCM-41) can be used as solid
acid catalyst for the Friedlander synthesis of quinolines. Easy workup,
green condition, high yield and simple purification make this method
attractive for the synthesis of quinolines.
[10] J.C. Juan, J.C. Zhang, M.A. Yarmo, Journal of Molecular Catalysis A: Chemical 267 (2007)
265.
[11] M. Abdollahi-Alibeik, M. Pouriayevali, Reaction Kinetics, Mechanism and Cataly-
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[12] S. Ajaikumar, A. Pandurangan, Journal of Molecular Catalysis A: Chemical 286
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Acknowledgment
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We are thankful to the Yazd University Research Council for par-
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