Ionic liquid immobilized onto fibrous nano-silica: A highly active and reusable catalyst for the synthesis of quinazoline-2,4(1 H,3 H)-diones

Article abstract of DOI:10.1016/j.catcom.2015.09.016

In this study, a novel fibrous nano-silica (KCC-1) supported ionic liquid (KCC-1/IL) with high surface area and easy accessibility of active sites was successfully developed by a facile approach. The synthesized KCC-1/IL nanocatalyst exhibited excellent catalytic activity for the synthesis of quinazoline-2,4(1 H,3 H)-diones from CO₂ and 2-aminobenzonitriles under mild conditions to the easy accessibility of the active sites. A high catalytic activity and ease of recovery from the reaction mixture by using filtration and several reuses without any significant loss in performance are additional eco-friendly attributes of this catalytic system.

Full text of DOI:10.1016/j.catcom.2015.09.016

Catalysis Communications 72 (2015) 91–96
Contents lists available at ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Ionic liquid immobilized onto fibrous nano-silica: A highly active and
reusable catalyst for the synthesis of quinazoline-2,4(1 H,3 H)-diones
Seyed Mohsen Sadeghzadeh
Department of Chemistry, College of Sciences, Sina Masihabadi Student Research, P.O. Box 97175-615, Neishabour, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 14 August 2015
Received in revised form 20 September 2015
Accepted 21 September 2015
Available online 25 September 2015
In this study, a novel fibrous nano-silica (KCC-1) supported ionic liquid (KCC-1/IL) with high surface area and
easy accessibility of active sites was successfully developed by a facile approach. The synthesized KCC-1/IL
nanocatalyst exhibited excellent catalytic activity for the synthesis of quinazoline-2,4(1 H,3 H)-diones from
CO and 2-aminobenzonitriles under mild conditions to the easy accessibility of the active sites. A high catalytic
2
activity and ease of recovery from the reaction mixture by using filtration and several reuses without any signif-
icant loss in performance are additional eco-friendly attributes of this catalytic system.
Keywords:
KCC-1
©
2015 Elsevier B.V. All rights reserved.
Quinazoline-2,4(1 H,3 H)-dione
Nanoparticle
One-pot synthesis
Green chemistry
Fibrous nano-silica
1
. Introduction
nano-silica (KCC-1), which features a high surface area and easy acces-
sibility through its fibers (as opposed to the traditional use of pores), is
reported by Polshettiwar et al. [19] This would be an ideal catalyst sup-
port candidate for the fabrication of noble metal-based catalysts that ex-
hibit high accessibility of active sites and excellent catalytic activity. In
this article, we designed and synthesized ionic liquid functionalized
KCC-1. Then the strength was tested for the synthesis of quinazoline-
2,4(1 H,3 H)-diones.
Quinazoline-2,4(1 H,3 H)-diones are an important class of pharma-
ceutical intermediates. Synthesis of quinazoline-2,4(1 H,3 H)-diones
using CO and 2-aminobenzonitriles as raw materials has attracted con-
siderable interest, and various kinds of catalysts have been used to pro-
mote the reactions, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
2
[1], Cs
[3], MgO/ZrO
[Bmim]Ac [7], and so on. However, these reaction systems are more or
2
CO
3
[2], 1-butyl-3-methylimidazolium hydroxide ([Bmim]OH)
2
[4], 1,1,3,3-tetramethylguanidine (TMG) [5], ZnCl [6],
2
2. Experimental
less subjected to some drawbacks, such as long reaction time, high pres-
sure of CO
catalysts.
2
, use of organic solvents, and difficulty in recycling the
2.1. Materials and methods
Recently, the use of nanocatalysts has increased rapidly and has
resulted in the development of several active and efficient nano-
catalysts for various protocols [8–18]. These systems have several ad-
vantages over conventional catalysts, such as superior activity and im-
proved stability. Combining metal nanoparticles with a support of
choice provides a large field for the discovery of new, highly active
nanocatalysts for important and challenging reactions, which also
offer the additional advantage of recyclability. Surface functionalized
mesoporous materials have emerged as one of the most important re-
search areas in the field of advanced functional materials. Fibrous
Chemical materials were purchased from Fluka and Merck in high
purity. Melting points were determined in open capillaries using an
Electrothermal 9100 apparatus are uncorrected. FTIR spectra were re-
corded on a VERTEX 70 spectrometer (Bruker) in the transmission
mode in spectroscopic grade KBr pellets for all the powders. The particle
size and structure were observed by using a Philips CM10 transmission
electron microscope operating at 100 KV. Powder X-ray diffraction data
was obtained using Bruker D8 Advance model with Cu ka radiation. The
thermogravimetric analysis (TGA) was carried out on a NETZSCH
−
1
STA449F3 at a heating rate of 10 °C min under nitrogen. The magnetic
measurement was carried out in a vibrating sample magnetometer
(
VSM) (4 in., Daghigh Meghnatis Kashan Co., Kashan, Iran) at room
E-mail address: seyedmohsen.sadeghzadeh@gmail.com.
temperature. NMR spectra were recorded in CDCl on a Bruker Avance
3
http://dx.doi.org/10.1016/j.catcom.2015.09.016
1566-7367/© 2015 Elsevier B.V. All rights reserved.

92
S.M. Sadeghzadeh / Catalysis Communications 72 (2015) 91–96
Table 1
Physicochemical properties of the silica-supported ionic liquid nanocatalysts and of the
precursor materials.
Entry
Material
Surface area
BJH PV
BJH PS
[nm]
IL loading
[wt.%]
2
−1
[cm g−1]
3
[m g
]
1
KCC-1/IL
281
0.50
6.8
22.2
DRX-400 MHz instrument spectrometer using TMS as internal standard.
The purity determination of the products and reaction monitoring was
accomplished by TLC on silica gel polygram SILG/UV 254 plates.
Fig. 2. FTIR spectra of (a) KCC-1 NPs, and (b) KCC-1/IL NPs.
2
.2. General procedure for the preparation of KCC-1 NPs
In this study, KCC-1 was successfully synthesized by a traditional hy-
was removed, the resulting mixture was filtered, after which the filtrate
drothermal method [20]. TEOS (2.5 g) was dissolved in a solution of cy-
clohexane (30 mL) and 1-pentanol (1.5 mL). A stirred solution of
cetylpyridinium bromide (CPB 1 g) and urea (0.6 g) in water (30 mL)
was then added. The resulting mixture was continually stirred for
was dried under vacuum at 100 °C.
2.5. General procedures for preparation of quinazoline-2,4(1 H,3 H)-diones
4
5 min at room temperature and then placed in a teflon-sealed hydro-
2
-aminobenzonitrile (1 mmol), and KCC-1/IL NPs (0.0007 g) were
added. The autoclave was closed, purged twice with CO
gas, pressur-
ized with 0.8 MPa of CO and then heated at 70 °C for 60 min. Then
thermal reactor and heated at 120 °C for 5 h. The silica formed was iso-
lated by centrifugation, washed with deionized water and acetone, and
dried in a drying oven. This material was then calcined at 550 °C for 5 h
in air.
2
2
the reactor was cooled to ambient temperature, and the resulting mix-
ture was transferred to a 50 mL round bottom flask. Upon completion,
the progress of the reaction was monitored by TLC when the reaction
was completed, EtOH was added to the reaction mixture and the KCC-
2
.3. General procedure for the preparation of KCC-1/3-chloropropylsilane
NPs
1
/IL NPs were separated by distillation under vacuum. Then the solvent
was removed from solution under reduced pressure and the resulting
product purified by recrystallization using n-hexane/ethyl acetate.
KCC-1 (2 mmol) and THF (20 mL) were mixed together in a beaker,
and then NaH (20 mmol) was dispersed in to the mixture by
ultrasonication. 3-chloropropyltriethoxysilane (22 mmol) was added
drop-wise at room temperature and stirred for another 16 h at 60 °C.
The resultant products were collected and washed with ethanol and de-
ionized water in sequence, and then dried under vacuum at 60 °C for 2 h
for further use.
3. Results and discussion
This procedure was adapted to functionalize KCC-1 thus affording
silica-supported ionic liquid catalysts: KCC-1/IL nanocatalysts involved
several steps (Scheme 2). The fibers of silica support have many Si–
OH groups on the surfaces; thus, it was expected that the silica support
could be easily functionalized with 3-chloropropyltriethoxysilane to
form KCC-1/3-chloropropylsilane NPs. Then, fibrous nano-silica sup-
ported ionic liquid (silica support/IL), which is featured with easy acces-
sibility of active sites and high catalytic activity, was synthesized by a
simple, cost-effective procedure.
A study of the physicochemical properties (specific surface area, cu-
mulative pore volume, and pore size) of KCC-1/IL is reported in Table 1.
High ionic liquid loading (22.2 wt.%, Table 1) could be obtained under
identical preparation conditions for all support.
2
.4. General procedure for the preparation of KCC-1/IL NPs
First, hexamethylenetetramine (100 mmol) and KCC-1/3-chloro-
propylsilane (5 mmol) were dissolved in dry ethanol (50 mL) under
stirring. The resulting mixture was refluxed for 24 h under nitrogen pro-
tection. After removal of ethanol in vacuum, the solid residue was dis-
solved in water. The obtained solution was concentrated under
vacuum and then extracted with ethanol–tetrahydrofuran. Subsequent-
ly, ion exchange with sodium tetrafluoroborate (110 mmol) in ethanol/
water was performed for 48 h at ambient temperature. After the solvent
Fig. 1. SEM image of the fresh KCC-1/IL NPs (a), TEM images of the fresh KCC-1/IL NPs (b), and TEM images of KCC-1/IL NPs after ten reuses (c).

S.M. Sadeghzadeh / Catalysis Communications 72 (2015) 91–96
93
Table 3
Application of the silica support/ILs for the catalytic synthesis of quinazoline-2,4(1 H,3 H)-
a
dione.
Entry
Catalyst
Yield (%)b
1
2
3
4
5
KCC-1/IL/Cl
KCC-1/IL/FeCl
KCC-1/IL/HSO
67
78
42
86
97
4
4
KCC-1/IL/H
KCC-1/IL/BF
2
PW12
4
O
40
a
Reaction conditions: 2-aminobenzonitrile (1 mmol), silica support/ILs NPs (0.001 g),
1.5 MPa, at 120 °C under solvent-free conditions after 2 h.
Isolated yields.
and CO
2
b
and 1568 cm− associated with C–H and C–C stretching appeared, re-
1
spectively (Fig. 2b).
X-ray diffraction patterns and the infrared spectra of KCC-1/IL NPs
have been measured in order to obtain more information about their crys-
tallographic features and molecule structures. The XRD patterns of KCC-1
NPs, and as-prepared KCC-1/IL NPs catalyst were shown in Fig. 3a. The
broad peak between 20 and 30° corresponds to amorphous silica.
TGA experiments were carried out by heating samples under air up
to 800 °C in order to check the amount of the encapsulated fibrous
nano-silica, and ionic liquid, and obtain information on their thermal
stability. As seen in Fig. 3b, two weight loss stages were observed in
flow air. About 9.7 wt.% weight loss was observed in the first stage
(
40–250 °C) corresponding to the loss of small molecules such as phys-
ically absorbed water. In the second stage (400–600 °C), weight loss is
about 19.2 wt.%, which can be attributed to the pyrolysis of cross-
linking organic group derivatives.
2
The N adsorption–desorption isotherms of all samples (Fig. 3c) ex-
hibit type-IV isotherms with an obvious H1-type hysteresis loop, reveal-
ing strong evidence of mesoporous cylindrical or rod-like pores. These
results indicate that the mesoporous texture of the materials was pre-
served during the surface modification, which was due to the loading
of the functional group in KCC-1 and KCC-1/IL NPs. A considerable de-
crease in height of the capillary condensation step about the final prod-
uct is observed with respect to decrease in average pore diameter, pore
volume and surface area (Table 2).
Five separated reactions were examined in the presence of KCC-1/IL/
Fig. 3. (a) XRD pattern of KCC-1/IL NPs; (b) TGA diagram of KCC-1/IL NPs; and
Cl, KCC-1/IL/BF
PW12 40. The results of these studies showed that KCC-1/IL/Cl, KCC-
/IL/FeCl , KCC-1/IL/HSO , and KCC-1/IL/H PW12 40 as catalysts gave
the desired product in average to good yield (42–86%) (Table 3, entries
4 4 4
, KCC-1/IL/FeCl , KCC-1/IL/HSO , and KCC-1/IL/
(c) Adsorption–desorption isotherms of KCC-1 and KCC-1/IL NPs.
H
1
2
O
4
4
2
O
The TEM and SEM images of the KCC-1/IL catalysts were shown in
1–4). A similar reaction in the presence of KCC-1/IL/BF
4
as a non-
Fig. 1. As can be seen from Fig. 1a and b, the KCC-1/IL NPs had a consis-
tent particle size range of 150–170 nm. Subsequently, ionic liquid was
coated on the KCC-1 to form KCC-1/IL (Fig. 1b). The recyclability test
was stopped after ten runs. Comparison of TEM images of used catalyst
Table 4
a
(Fig. 1c) with those of the fresh catalyst (Fig. 1b) showed that the mor-
Synthesis of quinazoline-2,4(1 H,3 H)-dione by KCC-1/IL NPs in different solvents.
phology and structure of KCC-1/IL NPs remained intact after ten recov-
eries. Low agglomeration of KCC-1/IL NPs can be seen.
Yield (%)b
Entry
Solvent
EtOH
1
2
3
4
5
6
7
8
9
73
85
–
32
48
72
60
64
–
51
83
46
–
The reactions were monitored by FTIR, as shown in Fig. 2. For un-
2
H O
−
1
modified KCC-1, the band at 1100 cm was assigned to the vibration
of the Si–O bonds (Fig. 2a). After the supported ionic liquid on the sur-
CH
THF
CH Cl
3
CN
−
1
face of KCC-1, two bands at 2931 and 2890 cm associated with C–H
stretching significantly enhanced. Meanwhile, two new bands at 1486
2
2
EtOAc
DMF
Toluene
n-Hexane
Table 2
10
11
12
CHCl
3
a
Textural parameters of prepared compounds.
DMSO
MeOH
Dioxane
Solvent-free
Entry
Catalyst/cycle
reusability
Specific surface
area (m /g)
Pore volume
(cm /g)
Average pore
radius (nm)
2
3
13
14
97
1
2
KCC-1
KCC-1/IL
593
510
0.802
0.682
2.09
1.27
a
Reaction conditions: 2-aminobenzonitrile (1 mmol), KCC-1/IL NPs (0.001 g), and CO
2
1
.5 MPa, at 120 °C of solvents after 2 h.
a
b
Calculated by the BJH method.
Isolated yields.

94
S.M. Sadeghzadeh / Catalysis Communications 72 (2015) 91–96
Fig. 4. (a) Effect of the amount of the catalyst on yield of quinazoline-2,4(1 H,3 H)-dione; (b) Effect of temperature on yield of quinazoline-2,4(1 H,3 H)-dione; (c) Effect of CO
2
pressure
dependence with KCC-1/IL NPs catalyst system; and (d) Effect of time on yield of quinazoline-2,4(1 H,3 H)-dione.
supported catalyst gave the desired product in excellent yield (97%) due
to the formation of by-products (Table 3, entry 5). Comparison of KCC-
We compared the catalytic performance of our catalyst with litera-
ture reported catalysts for the synthesis of quinazoline-2,4(1 H,3 H)-
dione (Table 6). Table 6 clearly demonstrates that lower temperature,
the minimum amount of catalyst, lower pressure of carbon dioxide
and shorter reaction time were required for the synthesis of
quinazoline-2,4(1 H,3 H)-dione, using KCC-1/IL NPs, while an appropri-
ate, highly perfect, performance of the present catalyst was observed for
this reaction.
1
4 4
/IL/BF with other ionic liquid, demonstrates the advantage of BF as
anion obtained the highest efficiency.
Having proved correct and complete synthesis of the catalysts, the
catalysts performance and stability with the synthesis of quinazoline-
2
,4(1 H,3 H)-dione tested. In order to optimize the reaction conditions
and obtain the best catalytic activity, the reaction of CO and 2-
2
aminobenzonitrile was used as a model, and was conducted under dif-
ferent reaction parameters such as amount of the catalyst, temperature,
time, and solvent. Initially, the model reaction was carried out in several
solvents to investigate the efficiency of the catalyst. In this study, it was
found that conventional heating at 70 °C under solvent-free (Table 4) in
These observations indicated that the catalysts were stable and
could tolerate the present reaction conditions. The recyclability of cata-
lysts was examined using the model reaction under identical conditions.
After the required time, the catalysts were recovered from the reaction
mixture by filtration, washed with ethyl acetate, and subsequently dried
at 100 °C then reused. After ten consecutive reuses, KCC-1/IL NPs exhib-
ited almost identical catalytic activity (Fig. 5a). The recyclability test was
stopped after ten runs. Comparison of TEM images and FT-IR spectra
(Figs. 1c and 5b) of used catalyst with those of the fresh catalyst (Figs.
1a,b and 2b) showed that the morphology and structure of KCC-1/IL
NPs remained intact after ten recoveries. In order to know whether
the reaction takes place at the surface of KCC-1/IL NPs or any IL species,
ICP analysis of the remaining mixture after catalyst and product separa-
tion was investigated upon reaction completion. The amount of ionic
liquid leaching after the ten repeated recycling was 4.2%. These
6
2
0 min at 0.8 bar CO pressure in the presence 0.0007 g of KCC-1/IL is
more efficient, with respect to reaction time and yield of the desired
quinazoline-2,4(1 H,3 H)-dione (Fig. 4).
Since KCC-1/IL NPs were the most active of the one-component cat-
alysts, they were tested in the conversion of six other terminal 2-
aminobenzonitriles (1a–f) into the synthesis of quinazoline-
2
5
,4(1 H,3 H)-diones (2a–f) (Scheme 1), results being shown in Table
. In each case, the quinazoline-2,4(1 H,3 H)-diones were obtained
with good to excellent isolated yield after 1 h using 0.0007 g of catalyst
under solvent-free conditions at 70 °C under a constant pressure of car-
bon dioxide.
Table 5
a
Synthesis of quinazoline-2,4(1 H,3 H)-dione derivatives catalyzed by KCC-1/IL NPs.
Entry
R
Product
Yield (%)b
1
2
3
4
5
6
H
Br
F
Cl
Me
NO
2a
2b
2c
2d
2e
2f
97
91
94
92
88
96
2
a
Reaction condition: 2-aminobenzonitrile derivatives (1 mmol), KCC-1/IL NPs (0.0007 g),
Scheme 1. Synthesis of quinazoline-2,4(1 H,3 H)-diones from CO
aminobenzonitriles.
2
and 2-
CO
2
0.8 MPa, 1 h.
Yield refers to isolated product.
b

S.M. Sadeghzadeh / Catalysis Communications 72 (2015) 91–96
95
Scheme 2. Schematic illustration of the synthesis for KCC-1/IL NPs.
observations indicated that the catalyst was stable and could tolerate
the present reaction conditions.
4
. Conclusions
We developed a novel kind of robust catalytic hybrids based on the
ionic liquid functionalized KCC-1 and used it as a nanocatalyst support
for the first time. The ionic liquid was directly grafted from the KCC-1.
These catalysts as an efficient, nontoxic, green, economical and recycla-
2
ble catalytic protocol for the reaction of CO with 2-aminobenzonitriles
to produce quinazoline-2,4(1 H,3 H)-diones in good to excellent yield
under mild reaction condition have been developed. This synthetic
method provides a green way to effectively prepare low-cost ionic liq-
uid based catalysts and is promising for the development of other useful
materials.
Table 6
Comparison of the catalytic efficiency of KCC-1/IL NPs with various catalysts.
Entry Catalyst
MPa
Solvent Temperature Amount
Time Yield
a
(
CO
2
)
(°C)
catalyst
(h)
(%)
[
3]
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
–
Cs
t-BuOK
KF
3
3
3
3
3
3
3
3
–
–
–
–
–
–
–
–
120
120
120
120
120
120
120
120
120
130
200
200
200
200
200
200
200
100
100
100
100
100
80
–
18
18
18
18
18
18
18
–
[3]
2
CO
3
5 mol (%)
5 mol (%)
5 mol (%)
5 mol (%)
5 mol (%)
–
10 mol (%) 18
5 mol (%)
10 mol (%) 12
1 equiv
1 equiv
1 equiv
1 equiv
1 equiv
1 equiv
5 equiv
0.25 equiv
0.25 equiv
0.25 equiv
0.25 equiv
0.25 equiv
0.1 equiv
10
[
[
3]
3]
Fig. 5. (a) Reuses performance of the catalysts; and (b) FT-IR spectrum of recovered KCC-
1/IL NPs.
–
5
[3]
Et
3
N
28
[
[
3]
3]
[Bmim]BF
4
–
–
[Bmim]HSO
[Bmim]OH
TMG
MgO/ZrO
CuCl
HgCl
FeCl
AlCl
SnCl
TiCl
ZnCl
K
Na
KF
KOH
Cs CO
DBU
[Bmim]Ac
KCC-1/IL NPs
4
91[
3]
5]
4]
6]
6]
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DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
–
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