Nano magnetic sulfated zirconia (Fe3O4@ZrO2/SO42-): An efficient solid acid catalyst for the green synthesis of α-aminonitriles and imines

Article abstract of DOI:10.1039/c5nj00314h

In this research, nano magnetic sulfated zirconia was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) measurements and vibrational sample magnetometry (VSM). Its catalytic activity was investigated for the one-pot three component green synthesis of α-aminonitriles using various aldehydes and ketones at room temperature in ethanol. This protocol has various advantages such as: simple work-up, short reaction time, high product yields and easy recovery and reusability of the catalyst.

Full text of DOI:10.1039/c5nj00314h

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Nano magnetic sulfated zirconia (Fe O @ZrO /
3
4
2
2
4
À
SO ): an efficient solid acid catalyst for the
Cite this:DOI: 10.1039/c5nj00314h
green synthesis of a-aminonitriles and imines
Hossein Ghafuri,* Afsaneh Rashidizadeh, Behnaz Ghorbani and Majid Talebi
In this research, nano magnetic sulfated zirconia was prepared and characterized by Fourier transform
infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy
(TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) measurements and vibrational
sample magnetometry (VSM). Its catalytic activity was investigated for the one-pot three component
green synthesis of a-aminonitriles using various aldehydes and ketones at room temperature in ethanol.
This protocol has various advantages such as: simple work-up, short reaction time, high product yields
and easy recovery and reusability of the catalyst.
Received (in Porto Alegre, Brazil)
5th February 2015,
Accepted 26th March 2015
DOI: 10.1039/c5nj00314h
www.rsc.org/njc
Several modifications of the Strecker reaction have been
Introduction
1
6
3
reported using a variety of cyanide agents, such as Bu SnCN,
1
7
18
19
Over 90% of chemical processes employ catalysts. Among these K [Fe(CN) ], CH (OH)(CN)CH , and TMSCN under various
2
6
3
3
processes, acid catalysts are playing an important role in organic conditions. Among these cyanide sources for the synthesis of
syntheses and transformations. The use of conventional liquid a-aminonitriles, trimethylsilyl cyanide (TMSCN) is a promising
acids, and Lewis acids such as H
and SbF pose significant risks in handling, containment, disposal source for nucleophilic addition reactions. Protocols based on
and regeneration due to their toxic and corrosive nature. There TMSCN often require a Bronsted or Lewis acid catalytic system.
2
SO
4
, HCl, HF, AlCl
3
, BF
3
, ZnCl
2
alternative, as a safe, easy to handle and more effective cyanide ion
5
1
20
21
3 3
is a need to eliminate the aggressive and ecologically harmful Therefore many homogeneous catalysts, such as Pr(OTf ) , RuCl ,
22
23
20
24
mineral acids which are used to carry out a large number of Sc(OTf)
3
,
Aqueous formic acid, iodine and Fe(Cp)
2
PF
6
,
have
acid-catalyzed industrial processes. This can be achieved by the been developed in recent years. In order to overcome the problems
development of strong solid acid catalysts that are stable and associated with homogeneous catalysts, some heterogeneous
2
25
active at moderate temperatures. Sulfated zirconia is one of catalysts including polymer-supported scandium triflate, MCM-41
3
26
27
the most important solid superacid catalysts, which have anchored sulfonic acid,
gained a large amount of attention for isomerization reactions complex, and guanidine HCl have also been introduced. However
due to their high strength of acidity, non-toxicity and high most of these methods have some drawbacks such as expensive
activity at low temperatures. It has also been used for other reagents, long reaction times, low yields and tedious work-up
different acid catalyzed reactions such as: cracking, alkylation, procedures. Therefore we introduce Fe
acylation, esterification, nitration, and oligomerization. The nano magnetic acid catalyst which can promote the one-pot
Strecker reaction, which was described primarily in 1850, was three component Strecker reaction of aldehydes/ketones and
the first multi component reaction (MCR) and is one of the most amines with TMSCN to afford a-aminonitriles (Scheme 1A).
K
2
29
PdCl
4
,
a poly(4-vinyl pyridine)–SO
2
28
4
–6
7
2À
3 4
O
@ZrO
2
/SO
4
as a
8
,9
1
0
straightforward methods for the synthesis of a-aminonitriles.
a-aminonitriles are valuable intermediates for the synthesis of
a-amino acids, 1,2- diamines, and various nitrogen-containing
11
heterocyclic molecules such as imidazoles and thiadiazoles, and
1
2
other pharmacologically useful molecules such as Saframycin A,
13
and Ecteinascidin 743. The typical Strecker reaction employed
10,14,15
HCN, KCN or NaCN as cyanide sources,
but these sources
are hazardous, toxic and involve harsh reaction conditions.
Scheme 1 The Strecker reaction of carbonyl compounds and amines
2À
Department of Chemistry, Iran University of Science and Technology, Tehran-P.O.
with TMSCN catalyzed by Fe
3
O
4
@ZrO
2
/SO
4
(A), and synthesis of imines
2À
Box 16846-13114, Iran. E-mail: ghafuri@iust.ac.ir; Fax: +98-21-7322 7703
3
by Fe O
4
@ZrO
2
/SO
4
(B).
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In order to overcome the problems arising during the separa-
2
À
tion of the catalyst from the reaction mixture, ZrO
2
/SO
4
is
mounted on magnetic nanoparticles. In this research we also
investigated the formation of the corresponding imines as the
Strecker reaction intermediates (Scheme 1B).
Results and discussion
Catalyst characterizations
Fig. 1 shows the XRD patterns of the prepared Fe
3
O
4
and
. As can be seen in Fig. 1, six characteristic
(2y = 30.1, 35.4, 43.0, 53.5, 57.0 and 62.5) are
observed. Also the peaks of the Fe O could be seen for the
2
À
Fe
peaks of Fe
3 4 2 4
O @ZrO /SO
3 4
O
3
0
3
4
2
À
synthesized Fe O @ZrO /SO
SO4 ). The peak positions of Fe O are unchanged during the
(XRD pattern of Fe O @ZrO /
3 4 2
3
4
2
4
2
À
3
4
2
4
À
3 4 2
production of Fe O @ZrO /SO
, indicating that the crystalline
structure of the magnetite is essentially maintained. Additional
diffraction peaks around 30.6, 51.1, and 60.1 are attributed to
2
ZrO .
The X-ray powder diffraction (XRD) pattern in the 30.6, 51.1
2
À
and 60.1 2y range for Fe O @ZrO /SO
4
showed that after
3
4
2
calcination the tetragonal phase is the major form present. The
crystallite size of Fe O was calculated to be 16 nm by applying
3
4
2
À
2
À
.
the Scherrer equation. The IR spectrum of Fe
3
O
4
@ZrO
2
À1
/SO
4
Fig. 3 TEM (a and b) and SEM (c) micrographs of Fe O @ZrO /SO
4
3
4
2
is shown in Fig. 2. A broad peak at about 3400 cm was
observed which is attributed to the s O–H stretching mode of
water that was adsorbed from the air on the surface of the
catalyst. Hydrogen bonding causes the broadness of this peak.
A peak at about 1630 cm is attributed to d O–H bending mode
À1
of water associated with the sulfate group. A strong band
assigned to the stretching vibration of SQO is observed at
À1
À1
1
126 cm and a middle peak at approximately 1400 cm is
observed in the spectrum assigned to the asymmetric stretching of
À1
the covalent s SQO bond. The peak at around 600 cm is
attributed to the Z rQ O bond and the vibration peak of the Fe–O
À1
bond is at about 500 cm . The TEM and SEM micrographs that
provide accurate information about the particle size and morphology
2
À
of Fe
structure of Fe
3
O
4
@ZrO
2
/SO
4
are depicted in Fig. 3. The homogeneous
2À
3
O
4
@ZrO
2
/SO
4
3 4
with a Fe O core and average
particle sizes of about 30 and 25 nm respectively are shown.
The results of the VSM measurements of the catalyst are depicted
in Fig. 4, with a confined field from À1000 to 1000 Oe. Bare
nanoparticles of Fe O possessed a high saturation magnetization
2À
Fig. 1 The X-ray diffraction patterns of Fe
O
3 4
and Fe
3
O
4
@ZrO
/SO
2 4
.
3
4
À1
of 53.8 emu g
at room temperature, which decreased to
À1
2À
12.7 emu g for Fe
3
O
4
@ZrO
2
/SO
4
. This is due to the formation
2À
of the magnetite core and ZrO
2
/SO
4
coating.
According to the saturation magnetization curve depicted in
Fig. 4 it is obvious that there is no hysteresis in the magnetiza-
tion sweep. Therefore, the magnetic coercivity of the nano-
structures is zero, which suggests that the samples containing
Fe O are superparamagnetic. We have obtained the EDX
3
4
2
À
spectrum of the Fe O @ZrO /SO , which indicated that there
3
4
2
4
were only Fe, O, Zr and S elements present in the structure of
the catalyst and the amount of iron in the catalyst was 21%. All
2À
the results suggest that Fe O @ZrO /SO
3 4 2 4
synthesized.
has been successfully
Fig. 2 FT-IR spectra of Fe
3
O
4
, ZrO
2
, Fe
O
3 4
@ZrO
2
and Fe
3
O
4 2
@ZrO /
2
À
SO
4
.
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surface by generating acidic sites of medium strength. Sufficiently
doping the sulfated zirconia with iron can increase the total
number of acidic sites with lower strength. These changes,
especially the simultaneous presence of two acidic type sites
3
1
with different strengths, are interesting for catalytic activity.
The ionic nature of SQO imparts the Bronsted acid site to the
catalyst which enhances the acidity of the material thereby
reinforcing the catalytic activity (entries 13, 16, Table 1). As
shown in Table 1 it was found that EtOH is a suitable solvent
to give the desired products in high yields and a relatively short
reaction time in comparison with other solvents.
Fig. 4 Saturation magnetization curve of pure Fe
3
O
4
(1), Fe
@ZrO
3
O
4
@ZrO
2
2À
/
After the optimization of the reaction conditions, to show the
general applicability of this protocol, a series of a-aminonitriles
were synthesized by reacting various aldehydes, ketones and
2
À
SO
4
calcinated under an N
2
atmosphere (2) and Fe
3
O
4
2
/SO
4
calcinated under an air atmosphere (3).
2À
amines with TMSCN in the presence of Fe
3
O @ZrO /SO
4 2 4
in
EtOH at room temperature. The obtained results are summarized
Catalytic properties
in Table 2. Separation and purification were very simple in these
2
À
To assess the catalytic activity of the Fe
3
O
4
@ZrO
2
/SO
4
, it was
2À
reactions. Fe O @ZrO /SO
3 4 2 4
is not soluble in boiling EtOH and
applied in the first multicomponent reaction for the synthesis
of a-aminonitriles. In order to optimize the reaction conditions,
the reaction of 4-chlorobenzaldehyde, aniline, and TMSCN
so the catalyst was separated by an external magnet from the
desired products during their recrystallization from EtOH.
Irrespective of the carbonyl compound used, the reaction
proceeded to give the corresponding product with varying
degrees of success (Table 2). Acid sensitive aldehydes such as
furfural worked well without the formation of any side products
and afforded the a-aminonitrile derivatives in 85% yield (Table 2,
entry 13). Also unsaturated aldehydes such as cinnamaldehyde
produced excellent yields, without any decomposition or poly-
merization (Table 2, entry 12). Aliphatic amines such as benzyl-
amine as well as aromatic amines afforded good yields.
Since imines are known as the Strecker reaction intermediates,
(
mole ratio 1 : 1 : 1.2) as a model reaction was chosen and the
effects of the solvent and various catalysts were investigated
Table 1). It seems noteworthy to mention that the reaction was
not successful in the absence of the catalyst (entries 1–3,
Table 1). Metal oxide nanoparticles such as nano-Fe and
ZrO rendered higher yields in CH CN than water and EtOH
entries 4–9, Table 1). Also, we evaluated the effects of ZrO
and Fe O @ZrO in this model reaction, but much to our surprise,
(
3 4
O
2
3
2À
(
/SO
2 4
3
4
2
2
À
when Fe O @ZrO /SO
4
(60 mg) was used as the catalyst, the
3
4
2
reaction went to completion in 10 minutes and 97% of the product
was isolated (entry 16, Table 1). It was observed that the addition of
we investigated the imine formation from aldehydes and aniline
2À
in the presence of Fe O @ZrO /SO
3 4 2 4
under the same condi-
3 4
Fe O to sulfated zirconia dramatically affected the catalytic activity
tions. To the best of our knowledge, only a small amount
of research on the Strecker reaction with ketones has been
in the synthesis of a-aminonitriles (entries 12, 16, 17, Table 1), it
was found that iron oxide (Fe
3
O
4
) modifies the sulfated zirconia
24,32,33
reported.
Regarding the fact that ketones hardly react due to their
steric hindrance, our catalyst was effective because we carried
out the Strecker reaction with ketone derivatives easily. The
results for the synthesis of the imines are summarized in
2
À
Table 1 Optimization of the Fe
tion for the synthesis of aminonitriles
3
O
4
@ZrO
2
/SO
4
catalyzed model reac-
a
b
Entry Catalyst
Solvent Time (min) Yield (%) Table 3. For the new products (Table 2, entries 23 and 24) the
1
13
structure was determined by H NMR and C NMR. For the
known compounds, which are all the other products in Tables 2
and 3, their physical and spectroscopic data were compared
with those of authentic samples and found to be identical.
In general, substituted aromatic amines with electron-
withdrawing groups require shorter reaction times in compar-
ison to those with electron-donating groups. Aromatic aldehyde
substituted electron-withdrawing groups increased the reaction
rate. Aromatic amines with electron-donating groups decreased
the nucleophilicity of the nitrogen reagent and increased reac-
tion time because the substituted electron-donating groups
increase the basicity of the nitrogen, resulting in the absorption
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
—
—
—
EtOH
H O
2
CH
CH
120
240
240
Trace
18
2
Cl
2
Trace
75
68
Nano-Fe
Nano-Fe
Nano-Fe
Nano-ZrO
Nano-ZrO
Nano-ZrO
ZrO
ZrO
ZrO
Fe
Fe
Fe
Fe
Fe
3
3
3
O
O
O
4
4
4
(10 mol%)
(10 mol%)
(10 mol%)
(10 mol%)
(10 mol%)
(10 mol%)
(100 mg)
(100 mg)
(100 mg)
3
O
CN 90
H
2
90
60
EtOH
CH
68
2
2
2
3
O
CN 45
85
58
60
H
2
120
60
EtOH
CH
2
2
2
À
À
À
0
1
2
3
4
5
6
7
2
2
2
/SO
/SO
/SO
4
4
4
3
O
CN 90
90
Trace
85
H
2
90
90
EtOH
EtOH
3
3
3
3
3
O
4
O
4
O
4
O
4
O
4
@ZrO
@ZrO
@ZrO
@ZrO
@ZrO
2
2
2
2
2
(60 mg)
180
85
2
2
2
2
À
À
À
À
/SO
/SO
/SO
/SO
4
4
4
4
(50 mg) CH
3
CN 40
80
90
97
93
(50 mg) EtOH
(60 mg) EtOH
(100 mg) EtOH
40
10
25
+
and deactivation of H . An efficiency comparison of the cataly-
2
À
tic activity of Fe
3
O
4
@ZrO
2
/SO
4
with several previous methods
a
Reaction conditions: 4-chlorobenzaldehyde (1.0 mmol), aniline
1.0 mmol), trimethylsilylcyanide (1.2 eq.), catalyst, solvent (2.0 ml),
is presented in Table 4. The results show that this method is
superior to some of the earlier methods in terms of yields and
(
b
room temperature. Isolated yields.
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2
4
À
a
Table 2 The Strecker reaction of various aldehydes or ketones and amines in the presence of Fe
3
O
4
@ZrO
2
/SO
as the catalyst
b
Entry
Aldehyde/ketone
Amine
Product
Time (min)
10
Yield (%)
97
Mp (ref.)
2
6
1
113–115
3
5
5
2
3
30
25
95
93
80–82
67–70
3
3
6
4
5
6
7
8
30
90
15
20
35
90
92
90
93
95
115–117
37
75–78
38
114–116
2
6
5
84–86
78–80
3
39
9
35
93
91–92
2
7
1
1
1
0
1
2
20
70
50
95
93
96
120–122
40
Oil
39
117–119
4
1
5
1
1
3
4
60
40
85
90
72–74
97–99
3
42
1
5
40
87
93–95
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Table 2 (continued)
b
Entry
Aldehyde/ketone
Amine
Product
Time (min)
120
Yield (%)
Mp (ref.)
c
37
1
6
90
90
154–157
107–110
4
3
1
7
70
3
6
2
1
1
8
9
25
40
95
96
87–90
83–85
3
2
6
2
2
2
2
0
1
2
3
25
30
93
89
90
95
Oil
26
102–105
17
50
Oil
120
112–116 This work
2
4
40
95
69–70 This work
—
2
5
6
—
No reaction
50
—
95
26
2
69–71
44
2
2
7
8
70
90
—
150–151
—
—
No reaction
a
b
Reaction conditions: aldehyde or ketone (1.0 mmol), amine (1.0 mmol), TMSCN (1.2 eq.), catalyst (60 mg), in EtOH (2.0 ml) at room temperature.
Isolated yields. Reaction conditions: aldehyde (1.0 mmol), amine (2.0 mmol), TMSCN (2.4 eq.), catalyst (100 mg) in EtOH (3.0 ml).
c
reaction times. The suggested mechanism for the formation of of the carbonyl group. In the presence of the catalyst, the imine
a-aminonitriles is shown in Scheme 2. According to this carbon is attacked by cyanide to give the product.
2
À
mechanism, Fe
3
O
4
@ZrO
2
/SO
4
catalyzes the in situ formation
The reusability of the catalyst was also evaluated in the
of the imine intermediate through activating the oxygen atom model reaction. After completing the reaction, the catalyst was
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2À a
3 4 2 4
Table 3 Preparation of imines through the reaction of aldehydes and aniline catalyzed by Fe O @ZrO /SO
b
Entry
1
Amine
Aldehyde
Product
Time (min)
1
Yield (%)
Mp (ref.)
4
5
90
93
57–59
35–36
46
2
3
3
47
10
87
58–60
4
8
9
4
5
2
2
90
90
88–89
62–64
4
4
9
6
7
2
95
96
88–90
4
9
9
3
1
42–45
63–64
4
8
9
85
90
4
9
9
5
7
193–195
105–107
4
1
0
70
a
b
Reaction conditions: 1.0 mmol aldehyde, 1.0 mmol aniline and 60 mg catalyst in 2.0 ml EtOH at room temperature. Isolated yields.
2
À
Table 4 A comparison of the efficiency of Fe
3
O
4
@ZrO
2
/SO
4
with other
catalysts for the condensation of 4-chlorobenzaldehyde, aniline and TMSCN
a
Time Yield
Entry Catalyst
Solvent (min) (%)
Ref.
2
À
1
2
3
4
5
6
7
Fe
MCM-41–SO
B-MCM-41 (50 mg)
PVP–SO (100 mg)
Cellulose sulfuric acid (50 mg) CH
Fe(Cp) PF (5 mol%)
PdCl (10 mol%)
3
O
4
@ZrO
2
/SO
3
4
(60 mg)
EtOH
EtOH
EtOH
10
30
90
97
98
98
89
90
91
91
This work
H (5 mg)
26
32
28
34
24
27
2
CH
2
Cl
CN 80
20
2
6 h
3
2
6
—
K
2
4
H
2
O
30
Scheme 2 A plausible mechanism for the synthesis of a-aminonitriles
a
2À 50
catalyzed by Fe O @ZrO /SO
4
Isolated yields.
.
3
4
2
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100 ml distilled water under vigorous stirring. After 10 minutes,
the solution was heated at 50 1C under a nitrogen atmosphere.
Consequently, an ammonium hydroxide solution (25%) was
added dropwise to the reaction mixture to maintain the reaction
pH at about 9. Afterward, the reaction mixture was cooled at
room temperature and the black precipitate, which was separated
by external magnet from the reaction mixture, was repeatedly
washed with de-ionized water several times to remove the remaining
impurities. For the final step the nanoparticles were dried at
2
À
Fig. 5 Recycling of Fe
3
O
4
@ZrO
2
/SO
4
for the synthesis of a-aminonitriles.
60 1C in vacuo.
2
À
Synthesis of Fe O @ZrO /SO
3
4
2
4
4 2
Initially 30 g ZrCl was dissolved in 1000 ml EtOH : H O (1 : 1) to
form a colorless solution and aqueous ammonia (10%) was
added dropwise under vigorous stirring until the pH of the
3 4
solution reached 2. Then 3 g Fe O NPs were added to the
mixture, after that aqueous ammonia (10%) was added dropwise
again under sonication up to pH 9. The precipitate was filtered,
thoroughly washed with distilled water, and the absence of the
chloride ion was confirmed by the AgNO
just prepared and obtained solid was dipped in a (NH
SO
3
test. Subsequently the
2À
À1
Fig. 6 The FT-IR spectra of the Fe
after 5 runs.
3
O
4
@ZrO
2
/SO
4
)
(3 mol L ) aqueous
4
2
4
solution at room temperature for 24 h. Then the solid was
filtered, dried without washing overnight at 100 1C and calcined
2
at 600 1C, for 6 h in a N atmosphere.
removed by an external magnet, washed with ethanol and dried
at room temperature and used directly for the next reaction. A
slight decrease in conversion (to 85%) was observed during the
fourth and fifth cycles; this could be due to the loss of the
catalyst during the reaction recycling. These results indicate
General procedure for the synthesis of a-aminonitriles
A mixture of aldehyde (or ketone) (1.0 mmol), amine (1.0 mmol),
trimethylsilylcyanide (TMSCN) (1.2 eq., 0.15 ml) and Fe
3
O
4
@ZrO
2
/
2À
2
À
SO
4
(60 mg) in 96% EtOH (2.0 ml) was stirred at room temperature
that the Fe
3
O
4
@ZrO
2
/SO
4
could be recovered and reused five
for an optimized time (Table 2). After completion of the reaction, as
indicated by thin-layer chromatography (TLC), the catalyst was
separated by an external magnet and reused five times in other
fresh reactions without a considerable loss of activity. Then the
products were crystallized by 96% EtOH (5 ml) to give the pure
desired a-aminonitriles.
times without any considerable loss of catalytic activity (Fig. 5).
After completing the reaction the catalyst was separated and
washed several times and no change in its structure was
observed. The presence of the sulfate ion in the catalyst was
2
À
confirmed with FT-IR spectra of Fe O @ZrO /SO
4
(Fig. 6).
3
4
2
5
1
Experimental
Chemicals and instruments
General procedure for the synthesis of imines as the Strecker
reaction intermediates
A mixture of aldehyde (or ketone) (1.0 mmol), amine (1.0 mmol)
All solvents and chemicals were purchased from Merck or
Flucka chemical companies. FT-IR spectra were obtained over
the region 400–4000 cm with a shimadzu 800 IR 100 FT-IR
2
À
and Fe
3
O
4
@ZrO
2
/SO
4
(60 mg) in 96% EtOH (2.0 ml) was
À1
stirred at room temperature for an optimized time (Table 3).
After completion of the reaction, as indicated by thin-layer
chromatography (TLC), the catalyst was separated by an exter-
nal magnet and reused five times in other fresh reactions
without a considerable loss of activity. Then the products were
crystallized by 96% EtOH (5 ml) to give the pure desired imines.
with spectroscopic grade KBr. The powder X-ray diffraction
pattern was recorded using a X-PERT-PRO diffractometer with
Cu Ka, (l = 1.54 Å) irradiation, in the range of 5 to 80 (2y) with a
scan step of 0.026. The morphology of the catalyst was studied with
scanning electron microscopy using SEM (KYKY, EM 3200) on gold
2À
coated samples. The magnetic properties of the Fe
nanoparticles were measured with a vibrating magnetometer/
alternating gradient force magnetometer (VSM, MDKFD), and The amount of [H ] released by the catalyst was determined by
O @ZrO /SO
3 4 2 4
2
À
Back titration in aqueous media catalyst (Fe O @ZrO /SO
4
)
3
4
2
+
TEM was recorded by DyPetronic of Iran.
back titration. 35 ml distilled water, 0.5 g NaCl, 0.5 g catalyst
and 10 ml NaOH (0.1 M) were added into a container and
stirred for 24 h with a magnetic stirrer until neutralized by [H ]
Preparation of the magnetic Fe nanoparticles (MNPs)
3
O
4
+
Ferric acid and ferrous salts were employed as precursors for which was produced from catalyst hydrolysis. Then three drops
the synthesis of Fe nanoparticles. Briefly, FeCl O (12.2 g, of phenolphthalein were added to the container and the
Á6H
.04 mol) and FeCl O (4.7 g, 0.02 mol) were dissolved in solution was titrated with a 0.1 M solution of hydrochloric
Á4H
O
3 4
3
2
0
2
2
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acid. The end point was reached when the colour changed from
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Spectral data for the representative compounds:
-(4-Chlorophenyl)-2-(phenylamino)acetonitrile (Table 2, entry 1).
2
À1
Mp: 113–115 1C, IR (KBr): n 3305, 2232, 1602, 1494, 790 cm
.
1
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H-NMR (500 MHz, CDCl
.9 (t, 1H), 6.76 (d, 2H), 5.33 (d, 1H), 3.74 (br s, 1H). C NMR
125 MHz, CDCl ): d 142.3, 135.5, 133.3, 131.6, 130.5, 122.6,
19.7, 116.3, 50 ppm.
-(2,4-Dichlorophenyl)-2-(phenylamino)acetonitrile (Table 2,
entry 4). Mp: 115–117 1C, IR (KBr): n 3323, 2241, 1622, 1469,
3
) d 8.0 (d, 2H), 7.8 (d, 2H), 7.3 (t, 2H),
1
3
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À1
1
7
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48 cm . H-NMR (500 MHz, CDCl ) d 5.23 (d, 1H), 6.29 (d, 1H),
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1
1
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2
-(4-Phenyl)-2-(phenylamino)but-3-acetonitrile (Table 2, entry 12).
À1
12 Y. Mikami, K. Takahashi, K. Yazawa, T. Arai, M. Namikoshi,
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1
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3
) d 4.08 (br, 1H), 5.37 (d, 1H), 6.73 (d, 2H),
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À1
1
14 D. Enders and J. P. Shilvock, Chem. Soc. Rev., 2000, 29,
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Mp: 97–99 1C, IR (KBr): 3378, 2243 cm
3
; H NMR (CDCl ,
3
5
7
00 MHz) d 3.92 (d, 1H), 5.58 (d, 1H), 6.93 (d, 2H), 7.29 (t, 1H),
.38 (q, 1H), 7.41–7.53 (m, 4H) ppm.
1
1
1
1
1
2
-(4-Isopropylphenylamino)-2-(2-chlorophenyl)acetonitrile
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(
1
7
Table 2, entry 25). Mp: 69–70 1C, IR (KBr): n 3334, 2233, 1612,
À1
1
515 cm . H NMR (500 MHz, CDCl
3
): d 7.71 (t, 1H), 7.20–
.70 (m, 6H), 6.7 (d, 2H), 5.7 (s, 1H), 2.8 (septed 1H), 1.2 (d, 6H)
1
3
ppm. C NMR (125 MHz, CDCl
1
3
): d 142.8, 141.5, 133.6, 132.3 (d),
31.4, 130.8, 129.5, 128.2, 127.6, 118.3, 115 ppm.
-(4-Bromophenylamino)-2-(2-chlorophenyl)acetonitrile (Table 2,
8 S. Sipos and I. Jablonkai, Tetrahedron Lett., 2009, 50,
1844–1846.
2
À1
19 B. A. B. Prasad, A. Bisai and V. K. Singh, Tetrahedron Lett.,
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entry 24). Mp: 112–116 1C, IR (KBr): n 3342, 2314, 1593, 1496 cm
.
1
3
H-NMR (500 MHz, CDCl ): d 7.75 (t, 1H), 7.34–7.51 (m, 6H), 6.54
13
(
d, 2H), 5.58 (s, 1H), 4(s, br, 1H) ppm. C-NMR (125 MHz, CDCl
d 144.4, 133.6, 132.6, 131.7(d), 130, 129.4, 128.3, 117.8, 119.3,
12.9 ppm.
3
):
46, 4595–4597.
2
2
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Conclusion
In conclusion, we have demonstrated that sulfated zirconia sup-
ported on magnetic nanoparticles can act as a novel, heterogeneous,
efficient nano-catalyst for the one-pot three component synthesis of
a-aminonitrile derivatives through a green and facile method. This
method offers several advantages including high yields, short
reaction times, easy work up procedure, reusability of catalyst
and environmentally benign reaction conditions.
6
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Acknowledgements
We are grateful for the financial support from The Research
Council of Iran University of Science and Technology (IUST), Iran.
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