Synthesis and characterization of pyridine-4-carboxylic acid-functionalized Fe3O4 nanoparticles as a magnetic catalyst for the synthesis of tetrahydrobenzo[b]pyran derivatives under solvent-free conditions

Article abstract of DOI:10.1080/15533174.2016.1219870

Pyridine-4-carboxylic acid (PYCA)-functionalized Fe₃O₄ nanoparticles as an organic–inorganic hybrid heterogeneous catalyst was fabricated and characterized by Fourier transform infrared, X-ray powder diffraction, thermogravimetric an

Full text of DOI:10.1080/15533174.2016.1219870

Synthesis and Reactivity in Inorganic, Metal-Organic, and
Nano-Metal Chemistry
ISSN: 1553-3174 (Print) 1553-3182 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt20
Synthesis and characterization of pyridine-4-
carboxylic acid functionalized Fe O nanoparticles
3
4
as a magnetic catalyst for synthesis of
tetrahydrobenzo[b]pyran derivatives under
solvent-free conditions
Sakineh Asghari & Majid Mohammadnia
To cite this article: Sakineh Asghari & Majid Mohammadnia (2016): Synthesis and
characterization of pyridine-4-carboxylic acid functionalized Fe O nanoparticles as a magnetic
3
4
catalyst for synthesis of tetrahydrobenzo[b]pyran derivatives under solvent-free conditions,
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, DOI:
10.1080/15533174.2016.1219870
To link to this article: http://dx.doi.org/10.1080/15533174.2016.1219870
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Synthesis and characterization of pyridine-4-carboxylic acid functionalized Fe O4
3
nanoparticles as a magnetic catalyst for synthesis of tetrahydrobenzo[b]pyran derivatives
under solvent-free conditions
a,b,*
a
Sakineh Asghari , Majid Mohammadnia
Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar,
7416-95447, Iran
Nano and Biotechnology Research Group, University of Mazandaran, Babolsar, Iran
Corresponding author. E-mail:s.asghari@umz.ac.ir
a
4
b
*
Abstract
Pyridine-4-carboxylic acid (PYCA) functionalized Fe O nanoparticles as an organic–inorganic
3
4
hybrid heterogeneous catalyst was fabricated and characterized by FT-IR, XRD, TGA, TEM,
SEM and VSM techniques. The catalytic activity of the magnetic catalyst was probed through
one-pot synthesis of tetrahydrobenzo[b]pyran derivatives from three component reactions of
aromatic aldehydes, malononitrile and dimedone under solvent-free conditions. Simple
procedure, high yields, short reaction time and environmentally benign method are advantages of
this protocol. The catalyst was readily separated using an external magnet and reusable without
significant loss of its catalytic efficiency.
Keywords
Nanomagnetic catalyst, Pyridine-4-carboxylic acid, Tetrahydrobenzo[b]pyran, Aldehydes,
Malononitrile, Dimedone
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Introduction
Environmentally benign, economical, practical and efficient processes for the catalyst
separation and reuse have been increasingly important goals in the chemical community [1].
Magnetic nanoparticles are efficient, readily available, high-surface-area resulting in high
catalyst loading capacity and outstanding stability heterogeneous supports for catalyst. They
show identical and sometimes even higher activity than their corresponding homogeneous
analogues [2-4]. Magnetic nanocatalysts can easily be separated and recycled from the products
by an external magnet [5]. Surface functionalized iron oxide magnetic nanoparticles (MNPs) are
a kind of novel functional materials, which have been widely used in biotechnology and catalysis
[
6-8]. Good biocompatibility and biodegradability as well as basic magnetic characteristics could
be denoted for functional organic materials grafted to MNPs [9-11].
Multi-component reactions (MCRs) have proven to be a valuable asset in organic and
medicinal chemistry [12-15]. Such protocols can use for drug design, and drug discovery because
of their simplicity, efficiency, and high selectivity [16, 17]. MCRs can reduce the number of
steps and present advantages, such as low energy consumption and little to no waste production,
leading to desired environmentally friendly processes. Synthesis of bioactive and complex
molecules should be facile, fast, and efficient with minimal workup in this methodology [16-18].
Compounds containing tetrahydrobenzo[b]pyran, has been of considerable interest to chemists
because they may contribute to potential pharmacological activities [19], such as spasmolytic,
diuretic, anti-coagulant, anti-cancer, antiancaphylactia activities [20-23]. However, some of the
reported methods require prolonged reaction time, reagents in stoichiometric amounts and
generate unsatisfactory yields of the products [24-29].
2
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In the present study, we present our results on the preparation and characterization of
magnetic, pyridine-4-carboxylic acid (PYCA) functionalized Fe O nanoparticles (Fe O –
3
4
3
4
PYCA) and its catalytic application for three-component synthesis of tetrahydrobenzo[b]pyran
derivatives from aromatic aldehydes, malononitrile and dimedone under solvent-free conditions
(Scheme 1).
Experimental
Chemicals and materials
Melting points were measured on an Electrothermal 9100 apparatus. The X-ray powder
diffraction (XRD) of the catalyst was carried out on a Philips PW 1830 X-ray diffractometer
with CuKα source (λ=1.5418 Å) in a range of Bragg’s angle (10-80°) at room temperature.
Scanning electron microscope (SEM) analyses were taken using VEGA//TESCAN KYKY-EM
3
200 microscope (acceleration voltage 26 kV). Transmission electron microscopy (TEM)
experiments were conducted on a Philips EM 208 electron microscope. Thermo gravimetric
analysis (TGA) was recorded on a Stanton Red craft STA-780 (London, UK). NMR spectra were
1
13
recorded with a Bruker DRX-400 AVANCE instrument (400.1 MHz for H, 100.6 MHz for C).
The spectra were measured in DMSO-d as solvent. IR spectra were recorded on an FT-IR
6
Bruker vector 22 spectrophotometer. Magnetic measurements were performed using vibration
sample magnetometer (VSM, MDK, and Model 7400) analysis.
3
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General Procedure
Preparation of the magnetic Fe O nanoparticles (MNPs)
3
4
FeCl .6H O (4.865 g, 0.018 mol) and FeCl ·4H O (1.789 g, 0.0089 mol) were added to
3
2
2
2
1
00 mL deionized water and sonicated until the salts dissolved completely. Then, 10 mL of 25%
NH OH (10 mL) was added quickly into the reaction mixture in one portion under N
4
2
atmosphere at room temperature followed by stirring about 30 min with mechanical stirrer. The
black precipitate was washed with doubly distilled water (five times).
Preparation of pyridine-4-carboxylic acid functionalizedFe O nanoparticles(Fe O –
3
4
3
4
PYCA)
The obtained MNPs powder (1 g) was dispersed in 150 mL water solution by sonication
for 30 min, and then 0.010 mol (0.123 g) of PYCA was added to the above mixture which a
o
black suspension was formed. This suspension was then refluxed at 100 C for 6 h, with vigorous
stirring. Fe O –PYCA nanoparticle was separated from the aqueous solution by magnetic
3
4
decantation, washed with distilled water several times and then dried in an oven overnight
Scheme 2). Whole synthesis was done under N atmosphere.
(
2
General procedure for the synthesis of tetrahydrobenzo[b]pyran derivatives under solvent-
free conditions
A mixture of aromatic aldehydes (1 mmol), malononitrile (1 mmol, 0.066 g) and
o
dimedone (1 mmol, 0.140 g) and Fe O –PYCA nanoparticles (15 mol %) as a catalyst at 70 C
3
4
was stirred under solvent-free conditions for the 29-34 min. After completion of the reaction,
monitored by TLC, the reaction mixture was cooled to room temperature. Then, the reaction
4
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mixture was dissolved in dichloromethane (10 mL) and subsequent Fe O –PYCA nanoparticle
3
4
catalyst was separated by an external magnet at 5 min. The solution containing the product was
evaporated and the residue solid was recrystallized using diethylether and the product obtained
as a white powder. Finally, the isolated catalyst was washed several times with dried CH Cl ,
2
2
o
dried under vacuum at 60 C to give the pure Fe O –PYCA nanoparticle catalyst.
3
4
Selected spectra for some known product are given below:
-Amino-4-(4-chlorophenyl)-3-cyano-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran
Table 2, entry 2) : white solid; mp =210-211 °C. IR (KBr): νmax= 3380 and 3182 (NH ), 2189
2
(
(
2
-1
1
CN), 1676 (C=O), 1218 (C–O) cm .; H NMR (400.13 MHz, DMSO-d ): δ = 0.92 and 1.03 (2s,
6
6
H, 2CH ), 2.12 and 2.30 (AB quartet, 2H, J = 16.0 Hz, CH ), 2.52 (m, 2H, CH ), 4.19 (s, 1H,
3 2 2
1
3
CH), 7.07 (s, 2H, NH ), 7.17 (d, 2H, J =8.4 Hz, 2CHarom), 7.35 (d, 2H, J = 8.4 Hz, 2CHarom); C
2
NMR (100.6 MHz, DMSO-d ): δ = 27.7, 29.2, 32.7, 36.2, 51.8, 58.9, 113.4, 121.4, 129.8, 130.7,
6
1
2
32.9, 144.7, 159.5, 163.8, 196.6.
-Amino-3-cyano-4-(4-cyanophenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran
(Table 2, entry 4) : white solid; mp =226-228 °C. IR (KBr): νmax= 3353 and 3213 (NH ), 2231
2
-1
1
(
CN), 1655 (C=O), 1214 (C–O) cm .; H NMR (400.13 MHz, DMSO-d ): δ = 0.95 and 1.03 (2s,
6
6
2
H, 2CH ), 2.10 and 2.25 (AB quartet, 2H, J = 8.1 Hz), 2.51 (m, 2H, CH ), 4.29 (s, 1H), 7.14 (s,
3
2
1
3
H, NH ), 7.35 (d, 2H, J =8.1 Hz), 7.75 (d, 2H, J = 8.1 Hz, 2CH ); C NMR (100.6 MHz,
2
arom
DMSO d ): δ = 27.7, 29.1, 32.5,36.6, 50.8, 58.2, 110.4, 112.5, 119.7, 120.3, 129.4, 133.1, 151.2,
6
1
2
59.3,163.8, 196.6.
-Amino-3-cyano-4-(4-methylphenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetra-hydrobenzo[b]pyran
(
Table 2, entry 6) : white solid; mp =213-214 °C. IR (KBr): νmax= 3426 and 3329 (NH ), 2191
2
5
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-1
1
(
CN), 1677 (C=O), 1207 (C–O) cm .; H NMR (400.13 MHz, DMSO-d ): δ = 0.91 and 1.03 (2s,
6
6
1
H, 2CH ), 2.08 and 2.25 (AB quartet, 2H, J = 16.0 Hz), 2.26 (s, 3H, CH ), 2.50 (s, 2H), 4.11 (s,
3 3
1
3
H), 6.98 (s, 2H, NH ), 7.01 (d, 2H, J =8.0 Hz), 7.09 (d, 2H, J = 8.0 Hz, 2CHarom);
C
2
NMR(100.6 MHz, DMSO-d ): δ = 21.5, 27.7, 29.3, 32.7, 36.1, 50.9, 59.4, 113.8,120.9, 127.8,
6
1
29.9, 136.6, 142.9, 159.7, 163.8, 196.9.
Results and discussion
Characterization of the prepared Fe O –PYCA nanoparticles
3
4
X-ray diffraction (XRD) analysis
Phase investigation of the supported catalyst was performed by XRD and result presented
in Fig. 1. The result shown in Fig. 1 was fitted for observed six peaks with the following miller
indices: (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), and (4 4 0). The XRD pattern indicates that
Fe O –PYCA nanoparticles,is broadened owing to semicrystalline, indicating that the PYCA
3
4
have been successfully supported on Fe O nanoparticle. The average MNPs corediameter was
3
4
calculated to be about 11 nm from the XRD results by Scherrer’s equation, D = k λ/β cosө,
where k is a constant (generally considered as 0.94), λ is the wavelength of Cu Ka (1.54 ˚A), β
isthe corrected diffraction line full-width at half-maximum (FWHM), and ө is Bragg’s angle [30-
3
1] (figure 1).
Fourier transform infrared (FT-IR) analysis
The presence of the coating agents on the surface of the magnetite nanoparticles was also
−
1
supported by the FT-IR spectroscopy analysis. The peaks around 2923 and 2853 cm , for
asymmetric and symmetric vibrations of C–H stretching can be obviously found. The adsorption
6
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−
1
peaks at 1629 and 1461 cm corresponds to the asymmetric and symmetric stretching vibration
of COO (carboxylate group) of pyridine-4-carboxylate moiety. The characteristic absorbing
−
1
peaks of Fe O are appeared at 633 and 583 cm , which can be ascribed to the vibrations of Fe–
3
4
O group. Therefore, the obtained data from FT-IR spectroscopy can be confirmed the existence
of the nonmagnetic particle and heterocyclic moiety in the structure of Fe O –PYCA
3
4
nanoparticle (Figure 2).
Thermogravimetric analysis (TGA)
Thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG) were
performed at the range of 25 to 900 ˚C under atmosphere N , to determine the loading of organic
2
groups coated on the surface of the magnetite (Figure 3). TGA curve of the Fe O –PYCA
3
4
nanoparticle shows the mass loss of the organic functional group as it decompose upon heating.
o
The curve shows a weight loss about 3.53% from 900 C, resulting from the decomposition of
functional group grafting to the MNPs surface. The amount of adsorbed pyridine-4-carboxylic
-1
acid calculated by Eq. (1) is 0.4mmol g .
Eq. (1): mmolpyridine-4-carboxylic acid= (weight loss / 100 × Mw pyridine-4-carboxylic acid) ×
1
000 = 0.4mmol
TEM analysis
Morphology of synthesized of Fe O –PYCA nanoparticles were investigated by TEM
3
4
that shown in Figure 4. Particles are observed to have spherical morphology from Fig.4. Average
particle size is estimated about 13 nm from the TEM micrographs, which is in a very good
agreement with the crystallite size estimated from XRD at 11.5 nm. As shown in Fig. 4, a
7
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basically core–shell structure (dark colored core for Fe O nanoparticles and light-colored shell
3
4
for PYCA) was obtained. This is an indication of nearly single crystalline character of Fe O –
3
4
PYCA nanoparticles.
Scanning electron microscope (SEM)
Scanning electron microscopy (SEM) has been a primary tool for determining the size
distribution, particle shape, surface morphology and fundamental physical properties. In Fig. 5,
the SEM image of the Fe O –PYCA nanoparticle is shown (Figure 5). The SEM image of
3
4
Fe O –PYCA showed a spherelike structure.
3
4
Vibrating sample magnetometer (VSM)
The room temperature magnetization curves proved that the Fe O –PYCA nanoparticle is
3
4
super paramagnetic. Saturation magnetization of MNPs was 92.13 emu/g and saturation
magnetization of Fe O –PYCA nanoparticles was 76.89 emu/g. Compared with the uncoated
3
4
Fe O nanoparticle, the saturation magnetization of the Fe O –PYCA nanoparticle obviously
3
4
3
4
decreased because the diamagnetic contribution of the organic group resulted in a low mass
fraction of the Fe O magnetic substance. Even with this reduction in the saturation
3
4
magnetization, the solid could still be efficiently separated from solution with a permanent
magnet (Figure 6).
Catalytic application of Fe O –PYCA nanoparticles
3
4
First, to find optimization conditions, the reaction of benzaldehyde, malononitrile and
dimedone in the presence of the Fe O –PYCA nanoparticles as catalyst was selected as model
3
4
8
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reaction. The reaction was carried out with different amount of Fe O –PYCA nanoparticles as
3
4
o
catalyst (10, 15, 20 mol %) in different temperatures (25, 50, 70 C).
The obtained results in Table 1 showed that an optimal condition was 15 mol % of Fe O –PYCA
3
4
o
nanoparticles at 70 C (Table 1, entry 8). Next, various aromatic aldehydes were used in the
reactions that led to the corresponding products in high to excellent yields (Table 2).As shown in
Table 2, the reactions with the aromatic aldehydes including electron-donating or electron-
withdrawing substituents afforded the desired products in high to excellent yields.
Next, various aromatic aldehydes were used in the reactions that led to the corresponding
products in high to excellent yields (Table 2). As shown in Table 2, the reactions with the
aromatic aldehydes including electron-donating or electron-withdrawing substituents afforded
the desired products in high to excellent yields (Table 2).
According to the literature survey [36], the suggested mechanism for the formation of the
products is shown in Scheme 3.
The recycling of the Fe O –PYCA nanoparticles was studied using the model reaction
3
4
(Experimental section). The recovered Catalyst was reused several runs without any loss of its
activities (Fig. 7 and 8).
In order to show the accessibility of the present work, it was compared with several
reported results in the literature in Table 3 [22, 34, 37, 38]. The results show that the
reactions in the presence of Fe O –PYCA nanoparticle were carried out in short times
3
4
(
29-34 min) relative to other catalysts with the similar yields (Table 3).
9
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Conclusions
We were synthesized Fe O –PYCA nanoparticle as an organic–inorganic hybrid
3
4
heterogeneous catalyst and characterized by FT-IR, XRD, TGA, TEM, SEM and VSM
techniques. Size evaluation via various techniques revealed size of Fe O –PYCA nano
3
4
particles around 11–13 nm with nearly single crystalline character. The most interesting
features of the present work include durability as well as efficient catalytic activity for
synthesis of tetrahydrobenzo[b]pyran derivatives via the reaction of an aromatic
◦
aldehydes, malononitrile and dimedone under solvent free at 70 C. The attractive features
of this protocol are simple procedure, inexpensive work up, ease of handling, high yields
of products and use of reusable nanocatalyst.
Acknowledgments
This research was supported by the Research Council of the University of Mazandaran in
Iran.
Supplementary Material
Supplemental data for this article is available at the publisher’s website.
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38] Montazeri, N.; Noghani, T.; Ghorchibeigy, M.; Zoghi, R. Pentafluoropropionic acid: an
efficient and metal-free catalyst for the one-pot synthesis of Tetrahydrobenzo [b] pyran
derivatives, Journal of Chemistry, 2014, 2014, Article ID 596171.
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Table 1. Optimization conditions for reactions of benzaldehyde (1 mmol), malononitrile (1
mmol) and dimedone (1 mmol) in the presence of different amount of Fe3O4–PYCA
nanoparticles as catalyst in diffrent temperatures under solvent-free conditions
Amount
of
Temperature Time Yield
Entry catalyst
mol
o
a
(
C)
(min) (%)
(
%)
1
2
3
4
5
6
7
8
9
10
15
20
10
15
20
10
15
20
25
25
25
50
50
50
70
70
70
100
100 Trace
___
80
75
70
70
40
30
30
37
50
60
75
85
96
96
a
Yields refer to isolated pure product
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Table 2. Three-component reactions of aromatic aldehydes (1 mmol), malononitrile (1 mmol)
and dimedone (1 mmol) in the presence of Fe3O4–PYCA nanoparticles as catalyst (15 mol %) as
o
catalyst under solvent free at 70 C
o
Entr
y
Aldehyde
C H
Product
Time
(min)
Yield
(%)
Melting Point ( C)
Found
Reported
Rf]
[
O
3
3
0
0
96
96
230-231
229–232
CN
6
5
1
2
[32]
Me
O
NH2
Me
Cl
210-211
179-181
208-210
[33]
O
4
-ClC H
CN
6
4
Me
O
NH2
Me
NO2
9
4
180–183
O
3
4
CN
33
29
[34]
4
4
-NO C H
2 6 4
Me
O
NH2
Me
CN
O
-CNC H
6
4
CN
95
91
93
226-228
215-216
213-214
224-227
[
35]
Me
O
NH2
Me
OH
O
5
6
CN
34
32
213–215
32]
4
-OHC H
6
4
[
Me
O
NH2
Me
Me
O
4
-MeC H
CN
6
4
210-212
[33]
Me
O
NH2
Me
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OMe
2
00-202
O
4
-
7
CN
34
92
198–200
OMeC H
6
4
Me
O
NH2
[34]
Me
O
Cl
CN
1
1
94-196
81-182
2
-ClC H
6 4
8
9
32
32
95
91
196–198
Me
O
NH2
Me
[
32]
O
NO2
CN
2
-
180–183
35]
Me
O
NH2
Me
NO C H
2
6
4
[
a
Yields refer to the isolated pure products
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Table 3. Comparison the results of Fe O –PYCA nanoparticle with other catalysts in the
3
4
synthesis of tetrahydrobenzo[b]pyran derivatives
a
Entry
Catalyst
Conditions
Time
Yield (%)
Ref]
[
o
1
2
starch solution (4ml)
50 C
30 min
50 min
92 [33]
86 [34]
2
-
SO /MCM-41 (25
ethanol (4 mL) ,
4
mg)
reflux
3
4
Silica bonded S-
sulfonic acid (0.1 g)
EtOH:H O (50:50
45 min
80 min
90 [37]
90 [38]
2
v/v), reflux
Pentaluoropropionic
acid (PFPA) (35 mol
EtOH:H O (1: 1),
2
R.T
%)
o
5
Fe O –PYCA
70 C, solvent-free
30 min
96
3
4
nanoparticle (15 mol
(Present work)
%)
a
Yields refer to isolated pure products
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Figure 1. XRD powder pattern of Fe O –PYCA nanoparticles
3
4
20
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Figure 2. FT-IR spectra for Fe O nanoparticles, pyridine-4-carboxylic acid and Fe O –PYCA
3
4
3
4
nanoparticles
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Figure 3. TGA thermograms of Fe O –PYCA nanoparticles
3
4
22
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Figure 4. TEM micrographs of Fe O –PYCA nanoparticles
3
4
23
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Figure 5. The SEM images of Fe O –PYCA nanoparticles
3
4
24
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Figure 6. Room temperature magnetization curves of Fe O nanoparticle and Fe O –PYCA
3
4
3
4
nanoparticle
25
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Figure 7. Image showing Fe O –PYCA nanoparticle was can be separated by applied magnetics
3
4
field. A reaction mixture in the absence (left) and presence of a magnetic field (right)
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96
94
93
100
92
90
89
90
80
70
60
50
40
30
20
10
0
1
2
3
4
5
6
Reaction cycles
Figure 8. The recycling of the Fe O –PYCA nanoparticles as catalyst
3
4
27
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R
CHO
O
O
Fe O -PYCA(Catalyst)
3
4
CN
CN
CN
NH2
+
+
Me
Me
Solvent -Free, 70 oC
R
O
O
N
R= H, 4-Cl, 4-NO2, 4-CN, 4-OH,
-CH3, 4-OCH3, 2-Cl, 2-NO2
4
N
O
O
O
O
O
O
Fe O
3
4
Fe O -PYCA
3
=
N
4
O
O
O
O
N
N
Scheme. 1. Synthesis of tetrahydrobenzo[b]pyran derivatives using pyridine-4-carboxylic acid
functionalized Fe O nanoparticles (Fe O –PYCA) as a nanomagnetic catalyst
3
4
3
4
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N
N
water, 100 oC,
O
O
FeCl .6H O (2mmol)
O
3
2
4 2
NH OH, N
N , 6h
+
2
Fe O
O
FeCl .4H O (1mol) 80 oC, 30 min
3
4
O
O
2
2
Fe O
3
4
O
OH
N
N
O
O
O
O
N
N
Scheme. 2. Preparation of Fe O –PYCA nanoparticles
3
4
29
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