Spidery catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones

Article abstract of DOI:10.1039/c5cy01543j

In this study, a novel fibrous nanosilica (KCC-1) based nanocatalyst (Au, Pd, and Cu) with a high surface area and easy accessibility of active sites was successfully developed by a facile approach. KCC-1 with a high surface area was functionalized with multi-carboxylic hyperbranched polyglycerol groups (HPG) acting as robust anchors so that the metal nanoparticles (Au, Pd, and Cu) were well-dispersed on the fibers of the KCC-1 microspheres without aggregation. Because of the amplification effect of HPG, high loading capacities of the nanocatalysts were achieved. The synthesized KCC-1/HPG/X nanocatalyst exhibited excellent catalytic activity for the synthesis of quinazoline-2,4(1H,3H)-diones from CO₂ and 2-aminobenzonitrile under mild conditions due to the easy accessibility of the active sites. High catalytic activity and ease of recovery from the reaction mixture by using filtration after several reuses without any significant loss of performance are additional eco-friendly attributes of this catalytic system.

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Spidery catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones
Seyed Mohsen Sadeghzadeh
Received (in XXX, XXX) Xth XXXXXXXXX 200X, Accepted Xth XXXXXXXXX 200X
5
DOI: 10.1039/b000000x
In this study, a novel fibrous nano-silica (KCC-1) based nanocatalyst (Au, Pd, and Cu) with high surface area andeasy accessibility of
active sites was successfully developed by a facile approach. KCC-1 with high surfacearea was functionalized with multicarboxylic
hyperbranched polyglycerol groups (HPG) acting as the robust anchors so that the metal nanoparticles (Au, Pd, and Cu) were well-
dispersed on the fibers of the KCC-1 microspheres, without aggregation. Because of the amplification effect of HPG, high loading
10 capacities of the nanocatalysts were achieved. The synthesized KCC-1/HPG/X nanocatalyst exhibited excellent catalyticactivity for the
synthesis of quinazoline-2,4(1H,3H)-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.
55 metal nanoparticles. Then the strength was tested for the
synthesis of quinazoline-2,4(1H,3H)-diones.
15 Introduction
Recently, the use of nanocatalysts has increased rapidly and has
resulted in the development of several active and efficient nano-
catalysts for various protocols.[1–11] These systems have several
advantages over conventional catalysts, such as superior activity
20 and improved stability. Combining metal nanoparticles with a
Experimental
Materials and Methods
60 Chemical materials were purchased from Fluka and Merck in
high purity. Melting points were determined in open capillaries
support of choice provides a large field for the discovery of new,
using an Electrothermal 9100 apparatus and are uncorrected.
highly active nanocatalysts for important and challenging
FTIR spectra were recorded on a VERTEX 70 spectrometer
reactions, which also offer the additional advantage of
(Bruker) in the transmission modein spectroscopic grade KBr
recyclability. Surface functionalized mesoporous materials have
65 pellets for all the powders. The particle size and structure of nano
25 emerged as one of the most important research areas in the field
particle was observed by using a Philips CM10 transmission
of advanced functional materials.
electron microscope operating at 100 KV. Powder X-ray
Fibrous nano-silica (KCC-1), which features a high surface area
diffraction data were obtained using Bruker D8 Advance model
and easy accessibility through its fibers (as opposed to the
with Cu ka radition. The thermogravimetric analysis (TGA) was
traditional use of pores), is reported by Polshettiwar et al. [12].
70 carried out on a NETZSCH STA449F3 at a heating rate of 10 °C
min−1 under nitrogen. 1H and 13C NMR spectra were recorded on
fabrication of noble metalbased catalysts that exhibit high
30 This would be an ideal catalyst support candidate for the
a BRUKER DRX-300 AVANCE spectrometer at 300.13 and
accessibility of active sites and excellent catalytic activity.
75.46 MHz, BRUKER DRX-400 AVANCE spectrometer at
The metal nanocatalysts can be immobilized on the support
400.22 and 100.63 MHz, respectively. Elemental analyses for C,
through two approaches. The one is to deposit the presynthesized
75 H, and N were performed using a Heraeus CHN–O-Rapid
35 metal nanoparticles onto the support by chemical adsorption.[13,
analyzer. The purity determination of the products and reaction
14] This approach allows the fine control over the size and shape
monitoring were accomplished by TLC on silica gel polygram
of the metal nanoparticles, but the whole operationsteps are
SILG/UV 254 plates. Mass spectra were recorded on Shimadzu
GCMS-QP5050 Mass Spectrometer.
tedious; and moreover, the adsorbed nanocatalysts are easy to be
leached from the KCC-1 support during the catalytic reaction.
80
40 The other is to directly grow metal nanoparticles on the KCC-1
support using the pregrafted organic functional molecules or
polymers as a stabilizer.[15] That this method is much better to
General procedure for the preparation of KCC-1 NPs
KCC-1 nanoparticles were prepared by a simple method in our
previous work.[17] TEOS (2.5 g) was dissolved in a solution of
hold the metal nanoparticles.
cyclohexane (30 mL) and 1-pentanol (1.5 mL). A stirred solution
85 of cetylpyridinium bromide (CPB 1 g) and urea (0.6 g) in water
Quinazoline-2,4(1H,3H)-diones are important heterocyclic
45 compounds used in the pharmaceutical and biotechnology
(30 mL) was then added. The resulting mixture was continually
industries. They are also useful building blocks for the production
stirred for 45 min at room temperature and then placed in a
of active pharmaceutical intermediates, anti-diabetes agents, anti-
teflon-sealed hydrothermal reactor and heated 120 °C for 5 h. The
hypertensives, anti-alpha adrenergic receptors and other
silica formed was isolated by centrifugation, washed with
biologically important compounds such as FK 366 (Zenarestat),
90 deionized water and acetone, and dried in a drying oven. This
50 KF 31327 molecules, Prazosin (Minipress®), Bunazosin
material was then calcined at 550 °C for 5 h in air.
(Detantol®) and Doxazosin (Cardenalin®).[16]
In this article, we designed and synthesized hyperbranched
General procedure for the preparation of KCC-1/HPG NPs
polyglycerol (HPG)-functionalized KCC-1 by surface-initiated
ring-opening polymerization of glycidol to in situ growth of
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For Synthesis of KCC-1/HPG NPs, 2 mmol of KCC-1 NPs were
dispersed in a mixture of 80 mL of toluene, and 1.0 mmol of
potassium methylate (CH3OK), followed by the addition of 10
mL of anhydrous dioxane. 2.0 g of Glycidol was added dropwise
Compound (2c): Obtained as a white solid. Mp>300 oC. IR; 3201,
3063, 1711, 1679, 1632, 1498, 1441, 1290, 881 cm-1; 1H NMR; δ,
ppm: 7.21 (q, J=8.8 Hz, 1H), 7.50–7.59 (m, 2H), 11.18 (s, 1H),
11.39 (s, 1H); 13CNMR; δ, ppm: 111.9, 115.2, 117.7, 122.8,
5
over a period of 1 h. After vigorous stirring for 2 h, the final 70 137.9, 149.8, 155.8, 158.6, 162.7.
suspension was repeatedly washed, filtered for several times and
dried at 60 °C in the air.
Compound (2d): Obtained as a white solid. Mp>300 oC. IR;
3200, 3061, 1709, 1671, 1481, 1430, 1282, 875 cm-1; 1H NMR; δ,
ppm: 7.15 (d, J=8.8 Hz, 1H), 7.70 (d, J=8.8 Hz, 1H), 7.83 (s, 1H),
General procedure for the preparation of KCC-1/HPG/Au NPs
10 KCC-1/HPG/Au NPs structures were prepared by reaction of 75 11.36 (s, 2H); 13CNMR; δ, ppm: 115.9, 117.2, 125.5, 126.3,
KCC-1/HPG NPs with HAuCl4•3H2O. First, 0.05 g of KCC-
1/HPG NPs was dispersed into 5 cm-1 of a 0.1 M gold precursor
(HAuCl4•3H2O; 99.99%; Aldrich) solution and the solution was
stirred by a mechanical stirrer for 1.5 h to ensure sufficient
15 adsorption of HAuCl4•3H2O by the KCC-1/HPG NPs. Then, The
catalyst KCC-1/HPG/Au NPs were collected by filtration and
washed with ethanol and deionized water in sequence.
134.8, 139.5, 149.9, 161.9.
Results and discussion
The synthesis of KCC-1/HPG/X nanocatalysts involved several
80 steps (Scheme 1). The fibers of KCC-1 has many Si–OH groups
on thesurfaces; thus, it was expected that the KCC-1 could be
easily functionalized with glycidol to form KCC-1/HPG.
Furthermore, hyperbranched polyglycerol groups on the KCC-
1/HPG could serve as aggregation centers for the growth of metal
85 nanoparticles on the surface of KCC-1.
General procedure for the preparation of KCC-1/HPG/Pd NPs
20 A 100 mL round-bottom flask was charged with 0.5 g of KCC-
1/HPG nanocomposite, 0.1 g of Pd(OAc)2 and 50 mL of
acetonitrile, after which it was ultrasonically dispersed for 30
min. Subsequently, the fresh NaBH4 solution (0.2 M, 10 mL) was
added dropwise into the abovementioned suspension. The product
25 was isolated by centrifugation, washed repeatedly with deionized
water and ethanol, and dried in a vacuum.
OEt
(KCC-1)
EtO
Si
OEt
OEt
General procedure for the preparation of KCC-1/HPG/Cu NPs
KCC-1/HPG NPs (0.5 g) was ultrasonically dispersed in H2O(50
30 mL), and subsequently CuCl2•2H2O (0.1 g) was added. After
beingstirred for about 30 min, excess amount of NaBH4 solution
wasadded dropwise. Then the Cu NPs were formed and anchored
on the KCC-1/HPG NPs. Thus, the KCC-1/HPG/Cu NPs
nanocatalyst was obtained by centrifugation and finally dried
35 invacuum.
O
OH
HO
HO
O
O
O
O
O
O
O
O
O
HO
HO
OH
X = Au, Pd, Cu
OH
O
O
O
HO
HO
O
O
O
O
OH
OH
O
O
General Procedure for the Synthesis of quinazoline-2,4(1H,3H)-
diones
HO
HO
HO
HO
OH
HO
HO
OH
OH
OH
2-aminobenzonitrile (1 mmol), KCC-1/HPG/X (X =Au, Pd, Cu)
40 (0.4 mol%) and water were added. The autoclave was closed,
purged twice with CO2 gas, pressurized with 1 MPa of CO2 and
Scheme 1 Schematic illustration of the synthesis for KCC-1/HPG/X (X
=Au, Pd, Cu) NPs.
o
then heated at 70 C for 25 min. Then the reactor was cooled to
90
ambient temperature, and the resulting mixture was transferred to
a 50 mL round bottom flask. Upon completion, the progress of
45 the reaction was monitored by TLC when the reaction was
completed, EtOH was added to the reaction mixture and the
KCC-1/HPG/X was separated by filtration under vacuum. Then
the solvent was removed from solution under reduced pressure
and the resulting product purified by recrystallization using n-
50 hexane/ethyl acetate.
The reactions were monitored by FTIR, as shown in Figure 1. For
unmodified KCC-1, the band at 1100 cm−1 was assigned to the
vibration of the Si-O bonds (Figure 1a). After the ringopening
polymerization of glycidol on the surface of KCC-1, two bands at
95 2931 and 2890 cm−1 associated with C-H stretching significantly
enhanced. Meanwhile, two new bands at 1486 and 1568 cm−1
associated with C-H and C-C stretching appeared, respectively
(Figure 1b). Though the IR spectrum of the KCC-1/HPG/X (X
=Au, Pd, Cu) catalyst demonstrates that almost no change occurs
100 after immobilization of gold, palladium, and copper on the KCC-
1/HPG surface (Figure 1c-e), but it was clearly observed that the
metal nanoparticles was dispersed on the surface of KCC-1/HPG
from the TEM image of the KCC-1/HPG/X (X =Au, Pd, Cu)
(Figure 2).
Characterization data
Compound (2a): Obtained as a white solid. Mp>300 oC. IR; 3261,
3049, 2853, 1699, 1667, 1628, 1440, 759 cm-1; 1H NMR; δ, ppm:
55 7.17–7.21 (m, 2H), 7.66 (t, J=7.7 Hz, 1H), 7.85 (d, J=7.7 Hz,
1H), 11.11 (s, 1H), 11.28 (s, 1H); 13CNMR; δ, ppm: 114.4, 115.1,
122.3, 127.1, 135.0, 140.6, 150.4, 162.4.
Compound (2b): Obtained as a white solid. Mp>300 oC. IR;
60 3197, 3063, 1739, 1698, 1610, 1478,1436,1281, 830 cm-1; 1H
NMR; δ, ppm: 7.69 (d, J=8.7 Hz, 1H), 7.78 (dd, J=8.8 Hz, J=2.3
Hz, 1H), 7.93 (d, J=2.3 Hz, 1H), 11.26 (s, 1H), 11.43 (s, 1H);
13CNMR; δ, ppm: 113.9, 115.9, 117.9, 129.0, 137.7, 140.0, 150.2,
161.4.
65
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(Figure 3b), and 2θ = 43.3°, 50.4° and 74.1° reflection of Cu
30 (JCPDS No. 04-0836) (Figure 3c) crystal were observed for
KCC-1/HPG/Au, KCC-1/HPG/Pd, and
KCC-1/HPG/Cu,
respectively, confirming the successful growth of metal particles
on the surface of KCC-1/HPG again.
Figure 1 FT-IR spectra of KCC-1 (a), KCC-1/HPG (b), KCC-1/HPG/Au
(c), KCC-1/HPG/Pd (d), and KCC-1/HPG/Cu (e).
35
Figure 3 Powder XRD patterns of KCC-1/HPG/Au (a), KCC-1/HPG/Pd
(b), and KCC-1/HPG/Cu (c).
5
The TEM images of the KCC-1 NPs, KCC-1/HPG, and KCC-
1/HPG/X (X =Au, Pd, Cu) catalysts were shown in Figure 2. As
can be seen from the Figure 2a, the KCC-1 NPs had a consistent
particle size range of 150-170 nm. Subsequently, hyperbranched
polyglycerol was coated on the KCC-1 to form KCC-1/HPG
To assess the exact impact of the presence of HPG in the catalyst,
40 the KCC-1/HPG/X (X =Au, Pd, Cu) compared with KCC-1/X (X
=Au, Pd, Cu). The loading amount of Au, Pd, and Cu in KCC-
1/HPG/X and KCC-1/X as determined by inductively coupled
plasma mass spectrometry (ICP-MS). The amount of motionless
nano particle in KCC-1/HPG/X was about twice KCC-1/X. By
45 comparing these values prove to be the HPG efficiency (Table 1).
10 core-shell particles (Figure 2b) through ring-opening
polymerization of glycidol. Moreover, after anchoring of Au, Pd,
and Cu, the metal nanoparticles are clearly distinguishable with
the difference in their contrast. As we can see, the as-prepared
metal nanoparticles are spherical without obvious aggregation.
15
Table 1 The loading amount of Au, Pd, and Cu in KCC-1/HPG/X and
KCC-1/X.
Entry
Catalyst
KCC-1/HPG/Au
KCC-1/HPG/Pd
KCC-1/HPG/Cu
KCC-1/Au
wt %
3.1
2.9
3.3
1.9
1.7
2.1
1
2
3
4
5
6
KCC-1/Pd
KCC-1/Cu
50 Having proved correct and complete synthesis of the catalysts,
the catalysts performance and stability with the synthesis of
quinazoline-2,4(1H,3H)-dione tested. In order to optimize the
reaction conditions and obtain the best catalytic activity, the
reaction of CO2 and 2-aminobenzonitrile was used as a model,
55 and was conducted under different 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
Figure 2 TEM images of KCC-1 (a), KCC-1/HPG (b), KCC-1/HPG/Au
(c), KCC-1/HPG/Pd (d), and KCC-1/HPG/Cu (e).
20 X-ray diffraction patterns and the infrared spectra of KCC-
1/HPG/X (X =Au, Pd, Cu) NPs have been measured in order to
obtain more information about their crystallographic features and
molecule structures. The XRD patterns of KCC-1 NPs, and as-
prepared KCC-1/HPG/X (X =Au, Pd, Cu) NPs catalyst were
25 shown in Figure 3. The broad peak between 20–30° corresponds
to amorphous silica. Moreover, new peaks at 2θ = 38.2°, 44.4°,
64.6° and 77.6° reflection of Au (JCPDS 04-0784) (Figure 3a),
2θ = 40.1°, 46.5° and 68° reflection of Pd (JCPDS 05-0681)
o
found that conventional heating at 70 C in water in 25 min at 1
60 bar CO2 pressure in the presence 0.4 mol% of KCC-1/HPG/X (X
=Au, Pd, Cu) is more efficient, with respect to reaction time and
yield of the desired quinazoline-2,4(1H,3H)-dione. But it was in
o
the presence of 1 mol% KCC-1/ X (X =Au, Pd, Cu) at 100 C in
water in 40 min at 1.5 bar CO2 pressure. View the terms easier to
65 reaction in the presence of HPG, proof of its efficiency (Figure 4-
7).
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Figure 4 Effect of the catalyst concentration: 2-aminobenzonitrile (1
mmol), and CO2 2 Mpa in different amounts of KCC-1/HPG/X (X =Au,
Pd, Cu) and KCC-1/X (X =Au, Pd, Cu) at 100 oC in 60 min in water.
Figure 7 Effect of time on yield of quinazoline-2,4(1H,3H)-dione: 2-
aminobenzonitrile (1 mmol), KCC-1/HPG/X (X =Au, Pd, Cu) and KCC-
1/X (X =Au, Pd, Cu) (1.2 mol%), CO2 1.5 Mpa at 100 oC in water.
5
20
In order to study the catalytic activity of various KCC-1/HPG/X
(X = Au, Cu, Pd, Ag, Pt, Mn, Ni, Zn, and Co) of metal
nanoparticles as catalyst, we examined their efficiency on the
reaction of 2-aminobenzonitrile, and carbon dioxide (Table 2).
25 The catalytic activity of these various nanoparticles was found to
be of the order Au > Cu > Pd > Ag > Pt > Mn > Ni > Zn > Co.
Therefore, we chose nanoparticles of Au, Cu, and Pd for the
synthesis of quinazoline-2,4(1H,3H)-dione.
30 Table 2 The effect of KCC-1/HPG/X (X = Metal nanoparticles) for the
synthesis of quinazoline-2,4(1H,3H)-dione.
Entry
Metal
nanoparticles
Yielda (%)
1
2
3
4
5
6
7
8
9
Au
Cu
Pd
Co
Mn
Ni
Zn
Ag
Pt
94
91
87
57
73
70
68
83
74
Figure 5 Effect of temperature on yield of quinazoline-2,4(1H,3H)-dione:
2-aminobenzonitrile (1 mmol), KCC-1/HPG/X (X =Au, Pd, Cu) and
KCC-1/X (X =Au, Pd, Cu) (1.2 mol%), CO2 2 Mpa in 60 min in water.
10
a Yields refer to isolated pure product.
To further evaluate the efficiency of the catalyst, different control
35 experiments were performed and the obtained data is shown in
table 3. Firstly, two separated reactions were examined in the
presence of KCC-1 and KCC-1/HPG. The results of these studies
showed that any amount of the desired product was not formed
(Table 3, entries 1 and 2). Based on these frustrating results, we
40 continued the research to improve the yield of the product by the
optimization of the reaction conditions. To our delight, the
reaction performed smoothly with the use of KCC-1/HPG/X (X
=Au, Pd, Cu) and X =Au, Pd, Cu as the catalyst, and the KCC-
1/HPG/X (X =Au, Pd, Cu) was more effective than X =Au, Pd,
45 Cu (Table 3, entries 3 and 4). As a result, KCC-1/HPG/X (X
=Au, Pd, Cu) was used in the subsequent investigations because
of its high reactivity, high selectivity and easy separation.
Figure 6 Effect of pressure on yield of quinazoline-2,4(1H,3H)-dione: 2-
aminobenzonitrile (1 mmol), KCC-1/HPG/X (X =Au, Pd, Cu) and KCC-
1/X (X =Au, Pd, Cu) (1.2 mol%) at 100 oC in 60 min in water.
15
50
55
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Table 3. Influence of different catalysts on the reaction of 2-
aminobenzonitrile, and carbon dioxide.a
Table 5 Analysis the amount of Au, Pd, and Cu from KCC-1/HPG/X and
KCC-1/X
.
Entry
Catalyst
Yield
(%)b
-
Entry
Metal (X)
ppm
45
1
2
KCC-1
KCC-1/HPG
-
Au
Pd
Cu
Au
Pd
Cu
94
87
91
96
90
93
Au
Pd
Cu
Au
Pd
Cu
0.3
0.2
0.4
1.1
0.8
0.9
3
X (X =Au, Pd, Cu)
1
2
KCC-1/HPG/X
KCC-1/X
50
4
KCC-1/HPG/X (X =Au, Pd, Cu)
aReaction conditions: 2-aminobenzonitrile (1 mmol), CO2 1.5 Mpa, and
0.4 mol% of catalyst at 80 oC in 2.5 h under solvent-free conditions.
bIsolated yield.
5
55 These observations indicated that the catalysts was stable and
could tolerate the present reaction conditions. The recyclability of
catalysts was examined using the model reaction under identical
conditions. After the required time, the catalysts was recovered
from the reaction mixture by filtration, washed with ethyl acetate,
60 and subsequently dried at 100 ◦C then reused. After ten
consecutive reuses, KCC-1/HPG/X NPs exhibited almost
identical catalytic activity, but it was not for KCC-1/X NPs
(Figure 8). The reason for this difference in yield was designed
Then, it was tested in the conversion of six other 2-
aminobenzonitriles (1a–f) into the synthesis of quinazoline-
2,4(1H,3H)-diones (2a–f) (Scheme 2), results being shown in
10 Table 4. In each case, the quinazoline-2,4(1H,3H)-diones was
obtained with good to excellent isolated yield in the presence of
KCC-1/HPG/X (X =Au, Pd, Cu). But, when KCC-1/X (X =Au,
Pd, Cu) was used as the catalyst, a reaction was still observed,
although the yield of the desired product was low. It is
15 noteworthy, efficiency to over 75% in the presence of KCC-1/X
(X =Au, Pd, Cu) after 40 min. This is another reason of the
performance of HPG with KCC-1.
and
synthesized
hyperbranched
polyglycerol
(HPG)-
65 functionalized KCC-1. For this purpose we selected the reactions
under optimized conditions to evaluate the reactivity of
nanocatalysts at different time at every cycle. The results were
summarized in Figure 9.
H
N
O
NH2
70
CO2
+
NH
R
R
CN
O
1a-f
2a-f
20 Scheme 2 Synthesis of various quinazoline-2,4(1H,3H)-diones.
Table 4 Synthesis of quinazoline-2,4(1H,3H)-dione derivatives catalyzed
by KCC-1/HPG/X (X =Au, Pd, Cu) and KCC-1/X (X =Au, Pd, Cu).
Entry
R
Product
Yield (%)a,b
KCC-
1/HPG/Au
KCC-
1/HPG/Pd
KCC-
1/HPG/Cu
KCC-
1/Au
KCC-
1/Pd
KCC-
1/Cu
1
2
3
4
5
6
H
Br
2a
2b
2c
2d
2e
2f
96
98
93
95
96
91
90
92
87
89
90
91
93
95
90
92
93
95
87
90
84
88
88
82
82
83
79
81
78
79
85
87
82
84
86
87
F
Cl
Figure 8 Reuses performance of the catalysts.
Me
NO2
aReaction condition: 2-aminobenzonitrile (1 mmol), KCC-1/HPG/X (X
25 =Au, Pd, Cu) and KCC-1/X (X =Au, Pd, Cu) (1.2 mol%), CO2 1.5 Mpa at
100 oC in 40 min in water.
bYield refers to isolated product.
To verify whether or not the catalysis is truly heterogeneous or is
30 due to some leached active species present in the liquid phase, the
model reaction of 2-aminobenzonitrile and carbon dioxide was
carried out under the optimized conditions, and the catalyst was
separated by filtration from the reaction mixture. Inductively
coupled plasma mass spectrometry (ICP-MS) analysis showed
35 that the amount of Au, Pd, and Cu from KCC-1/HPG/X leaching
into the reaction mixture is very low. But it is much more amount
for KCC-1/X. This is proof of the excellent performance HPG
(Table 5).
75 Figure
9 reaction progress vs. conversion of the reaction of 2-
aminobenzonitrile, and carbon dioxide at different cycles of the reaction
under optimized conditions in the presence of: KCC-1/HPG/Au (a);
KCC-1/HPG/Pd (b); KCC-1/HPG/Cu (c); KCC-1/Au (d); KCC-1/Pd (e);
KCC-1/Cu (f).
80
40
Comparison of powder XRD patterns of used catalyst (Figure 10)
with those of the fresh catalyst (Figure 3) showed that the
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9
Q. Yao, Z. H. Lu, Z. Zhang, X. Chen, Y. Lan, Scientific
reports 2014, 4, 7597.
morphology and structure of KCC-1/HPG/X (X =Au, Pd, Cu)
remained intact after eight recoveries.
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Adv. Mater. 2004, 16, 84.
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Figure 10 Powder XRD patterns of recovered KCC-1/HPG/Au (a), KCC-
1/HPG/Pd (b), and KCC-1/HPG/Cu (c).
5
Conclusions
We developed a novel kind of robust catalytic hybrids based on
the hyperbranched polyglycerol-functionalized KCC-1 and used
it as noble metal nanocatalyst supports for the first time. The
17 S. M. Sadeghzadeh, Green Chem., 2015, 17, 3059.
10 HPG was directly grafted from the KCC-1 by surface-initiated
ring-opening polymerization of glycidol. Because of the unique
structure and numerous functional groups of HPG, various
noblemetal nanocatalysts such as Au, Pd, and Cu could be
directly grown on the surface of KCC-1 firmly with ultrasmall
15 and monodisperse size, uniform distribution, and high loading
capacity. These catalysts as an efficient, nontoxic, green,
economical and recyclable catalytic protocol for the reaction of
CO2 with 2-aminobenzonitriles to produce quinazoline-
2,4(1H,3H)-diones in good to excellent yield under mild reaction
20 condition has been developed. To assess the exact impact of the
presence of HPG in the catalyst, the KCC-1/HPG/X (X =Au, Pd,
Cu) compared with KCC-1/X (X =Au, Pd, Cu). The amount of
motionless nano particle in KCC-1/HPG/X was about twice
KCC-1/X. By comparing these values prove to be the HPG
25 efficiency. Also, View the terms easier to produce quinazoline-
2,4(1H,3H)-dione in the presence of HPG, proof of its efficiency.
This is proof of the excellent performance HPG with KCC-1.
Notes and references
30 Department of Chemistry, College of Sciences, Sina Masihabadi Student
Research, P.O. Box 97175-615, Neishabour, Iran. Fax/Tel: +98 561
2502065; E-mail: sadeghzadeh.sm@gmail.com
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Graphical Abstract
Spidery catalyst for the synthesis of quinazoline-2,4(1H,3H)-
diones