Preparation of silica-based ionic liquid an efficient and recyclable catalyst for one-pot synthesis of α-aminonitriles

Article abstract of DOI:10.1007/s10562-011-0696-x

Preparation of N-(3-silicapropyl) imidazolium hydrogen sulfate ([Sipim]HSO₄) as a heterogeneous acidic ionic liquid is described. This heterogeneous ionic liquid was used as catalyst for the synthesis of α-aminonitriles by a one-pot condensation of aldehydes, amines, and trimethylsilyl cyanide at room temperature. Catalyst could be recycled for several times without any additional treatment. Graphical Abstract: A simple and efficient procedure for the preparation of silica-based acidic ionic liquid ([Sipim]HSO₄) is described. This heterogeneous solid acid is employed as a catalyst for the synthesis of a-amino nitriles at room temperature. [Figure not available: see fulltext.]

Full text of DOI:10.1007/s10562-011-0696-x

Catal Lett (2011) 141:1713–1720
DOI 10.1007/s10562-011-0696-x
Preparation of Silica-Based Ionic Liquid an Efficient
and Recyclable Catalyst for One-Pot Synthesis of a-Aminonitriles
•
Maryam Nouri Sefat Dariush Saberi
•
Khodabakhsh Niknam
Published online: 21 September 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Preparation of N-(3-silicapropyl) imidazolium
hydrogen sulfate ([Sipim]HSO4) as a heterogeneous acidic
ionic liquid is described. This heterogeneous ionic liquid
was used as catalyst for the synthesis of a-aminonitriles by
a one-pot condensation of aldehydes, amines, and tri-
methylsilyl cyanide at room temperature. Catalyst could be
recycled for several times without any additional treatment.
Recently, immobilisation processes involving acidic ionic
liquids on solids supports have been designed. The het-
erogenisation of catalysts and reagents can offer important
advantages in handling, separation and reuse procedures.
Based on economic criteria, it is desirable to minimize the
amount of ionic liquid utilized in a potential process. Im-
mobilised acidic ionic liquids have been used as novel solid
catalysts, e.g., for esterification, nitration reactions, acetal
formation and Baeyer–Villiger reaction [13–15].
Keywords Silica-based acidic ionic liquid Á
N-(3-silicapropyl) imidazolium hydrogen sulfate Á
Aldehydes Á Amines Á a-Amino nitriles
The addition of cyanide anion to imines (the Strecker
reaction) [16] provides one of the most important and
straightforward method for the synthesis of a-aminonitr-
iles, which are useful intermediates for the synthesis of
amino acids [17, 18] and nitrogen containing heterocycles
such as thiadiazoles and imidazoles, etc. [19, 20]. The
classical Strecker reaction usually is carried out in aqueous
solution and the work-up procedure is also tedious. Thus,
several modifications of Strecker reaction have been
reported using a variety of cyanide reagents [21, 22], such
as diethyl phosphorocyanidate and a-trimethylsiloxy
nitriles, as well as catalysts such as montmorillonite KSF
clay [23], silica-based scandium(III) [24], SO42-/ZrO2
[25], Fe(Cp)2PF6 [26], InCl3 [27], I2 [28], Fe3O4 [29],
xanthan sulfuric acid [30], [bmim]BF4 [31], silica sulfuric
acid [32], hydrophobic sulfonic acid based nanoreactors
[33], silica-bonded S-sulfonic acid [34], sulfamic acid-
functionalized magnetic Fe3O4 nanoparticles [35] under
various reaction conditions. The use of trimethylsilyl cya-
nide is a safer and more effective cyanide anion source for
the nucleophillic addition reactions of imines under mild
conditions [36, 37]. Furthermore many of these catalysts
are deactivated or sometimes decomposed by amines and
water that exist during imine formation. In order to over-
come these problems, recently one-pot procedures have
been developed for this transformation [38].
1 Introduction
In the recent years, ionic liquids have become a powerful
alternative to conventional molecular organic solvents due
to their particular properties, such as undetectable vapor
pressure and the ability to dissolve many organic and
inorganic substances [1]. One type is Brønsted acidic task-
specific ionic liquids (BAILs). Among these ionic liquids
-
possessing HSO4 as a counteranion find a broad appli-
cation in organic synthesis, acting as both solvents and
catalysts [2, 3]. The acidic nature of these ionic liquids as
catalysts has been exploited for many other important
organic reactions and chemical production [4–12].
Electronic supplementary material The online version of this
article (doi:10.1007/s10562-011-0696-x) contains supplementary
material, which is available to authorized users.
M. Nouri Sefat Á D. Saberi Á K. Niknam (&)
Chemistry Department, Faculty of Sciences, Persian Gulf
University, 75169 Bushehr, Iran
e-mail: khniknam@gmail.com; niknam@pgu.ac.ir
123

1714
M. Nouri Sefat et al.
2 Results and Discussion
Along the line of our studies in application of ionic liquids
as a catalyst in chemical transformations [9–12] herein, we
wish to describe the preparation of N-(3-silicapropyl)
imidazolium hydrogen sulfate ([Sipim]HSO4) as illustrated
in Scheme 1, and then used as catalyst for the synthesis of
a-amino nitriles.
The thermogravimetric analysis (TGA) curves of [Si-
pim]HSO4 show the mass loss of organic materials as they
decompose upon heating (Fig. 1). The initial weight loss
from the [Sipim]HSO4 up to 126 °C is due to removal of
physically adsorbed solvent and surface hydroxyl groups.
The weight loss of about 4% between 200 and 450 °C is
contributed to the thermal decomposition of organic
groups. The covalent chemical bonds connection made the
catalyst owned high thermal stability.
Fig. 1 TGA of the [Sipim]HSO4
silicapropyl)-N-methyl imidazolium hydrogen sulfate
[Sipmim]HSO4 [15] gave the best results with respect to
catalytic loading, reaction time and yields (Table 1, enties
Figure 2 shows Fourier transform infrared (FT-IR)
spectra for [Sipim]HSO4. The major peaks for silica (SiO2)
are broad anti symmetric Si–O–Si stretching from 1300 to
1010 cm-1 and symmetric Si–O–Si stretching near
820–780 cm-1. For sulfuric acid functional group, the FT-
IR absorption range of the O=S=O asymmetric and sym-
¨
1,5). These results demonstrate that Bronsted acid counter
ions perform better than other counter ions. The role of the
counter ions was explored when ILs were used as catalysts.
Ionic liquids with the HSO4-counter ion give better results
than H2PO4- with respect to time and yield. This is due to
the acidic power of HSO4- over H2PO4-. When -OTf was
used as the counter ion there was no product formation
even after 24 h (Table 1, entry 13), and very low yield
(10%) in the case of N-methylimidazolium triflate
(Table 1, entry 11). While in the case of [Sipim]OTf or
[Sipmim]OTf as catalysts, this condensation was accom-
plished in 180 and 110 min with 70% and 85% yields,
respectively (Table 1, entries 3 and 7). These results
clearly demonstrate the role of counter ions in the catalytic
activity of their corresponding supported and non-sup-
ported one.
metric stretching modes lie in 1170 and 1060 cm-1
,
respectively, the S–O stretching mode lies around
590 cm-1. FT-IR spectrum shows the overlap asymmetric
and symmetric stretching bands of SO2 with Si–O–Si
stretching bands in the silica functionalized alkyl-sulfuric
acid. The spectrum also shows a broad OH stretching
absorption around 3600 to 2600 cm-1. The NH stretching
is shown around 3150 cm-1 and NH bending 1650 cm-1
.
The BET surface area using nitrogen adsorption iso-
therms at the temperature of liquid nitrogen which gave the
results of as,BET 1.11 m2 g-1 and the total pore volume
0.1737 cm3 g-1 (see supplementary material).
At first, we investigated the reaction of benzaldehyde
with aniline and trimethylsilyl cyanide in the presence of
different ionic liquid catalysts. As shown in Table 1, ionic
liquids and silica-based ionic liquids accomplished this
condensation at room temperature. [Sipim]HSO4 and N-(3-
To study the effect of catalyst loading of [Sipim]HSO4
on the condensation reaction of aldehydes, amines, and
trimethylsilyl cyanide as the corresponding a-amino
nitriles the reaction of benzaldehyde and aniline with
Scheme 1 Preparation of silica
propyl imidazolium hydrogen
sulfate ([Sipim]HSO4)
OH
OH
O
O
O
O
O
O
a
b
c
Cl
Si
Si
N
NH
Cl
OH
O
O
d
Si
N
NH
HSO4
O
([Sipim]H2SO4)
(a)
(c)
(b) Imidazole, toluene (dry), 24 h, reflux;
(d) CH2Cl2 (dry, H2SO4 (97%), 48 h, reflux
(MeO)3Si-(CH2)3-Cl, toluene(dry), Et3N, reflux, 48 h;
o
Dry under vaccum (50 C), 4 h;
123

Preparation of Silica-Based Ionic Liquid
1715
Fig. 2 FT-IR of the [Sipim]HSO4
TMSCN was chosen as a model reaction (Table 2). To
illustrate the need of [Sipim]HSO4 for these reactions we
examined the strecker reaction of benzaldehyde with ani-
line and TMSCN in the absence of this catalyst. In this case
the reaction did not proceed even after 24 h (Table 2, entry
1). Obviously, [Sipim]HSO4 is an important component of
the reaction.
a-amino nitrile 1e in very good yield (Table 4, entry 5).
Aliphatic aldehydes such as 2-methylpropanal and pentanal
gave the corresponding products 1n and 1o in 82 and 80%
yields, respectively (Table 4, enties 14, 15). Secondary
amine such as morpholine treated with benzaldehyde under
optimized conditions gave corresponding product 1p in 80%
yield (Table 4, entry 16). Bis-amino nitrile was obtained by
the reaction of benzaldehyde (2 mmol) with piperazine
(1.5 mmol) and TMSCN (2.4 mmol) in the presence of
[Sipim]HSO4 (0.4 g) gave corresponding product 1q in 60%
yield (Table 4, entry 17). Also, we investigated the reaction
of ketones such as acetophenone and 4-methylacetophenone
with aniline under optimized conditions. In these cases the
condensation of ketones proceeded only about 45–50%
conversion (Table 4, entries 18, 19).
The model reaction was also examined in various sol-
vents as well as under solvent-free conditions in the pres-
ence of 0.2 g mmol-1 of [Sipim]HSO4 (Table 3).
The results showed that the efficiency and the yield of
the reaction in EtOH were higher than those obtained in
other solvents or under solvent-free conditions. Therefore,
we employed the optimized conditions {aldehyde
(1 mmol), amine (1.2 mmol), TMSCN (1.2 mmol), [Si-
pim]HSO4 (0.2 g) and EtOH (2 mL)} for the synthesis of
a-amino nitriles in this one-pot three-component conden-
sation (Scheme 2).
The possibility of recycling the catalyst was examined
using the reaction of benzaldehyde and aniline with
TMSCN under the optimized conditions. Upon completion,
as indicated by TLC, the reaction mixture was filtered and
the remaining washed with warm ethanol (3 9 5 mL).
After cooling, the corresponding a-amino nitrile products
were obtained which were purified by recrystallization
from hot ethanol. The recovered catalyst was dried and
reused for subsequent runs. Table 5 shows the catalyst after
being recycled four times. The catalyst was recovered with
high yield (90–91).
Next, we prepared a range of a-amino nitriles under the
optimized conditions (Table 4). Both aromatic and aliphatic
aldehydes reacted with amines and TMSCN in the presence of
[Sipim]HSO4 and [Sipmim]HSO4 in this one-pot condensa-
tion to afford excellent yields of corresponding a-amino
nitriles. Moreover, aldehydes with electron-withdrawing
groups or electron-donating, i.e., 3-nitrobenzaldehyde or
4-methoxybenzaldehyde, and 3,4,5-trimethoxy-benzalde-
hyde were converted into the corresponding a-amino nitriles
1f–1k in high yields (Table 4, entries 6–11). The acid sensi-
tive substrate thiophene-2-carbaldehyde gave the expected
Finally, a comparative study of [Sipim]HSO4 with other
recently reported catalysts for condensation of benzalde-
hyde and aniline with TMSCN as a model compound was
123

1716
M. Nouri Sefat et al.
Table 1 Condensation of benzaldehyde, aniline and TMSCN in the presence of different ionic liquids at room temperature
Entry
Catalyst
Catalyst loading (g)
Time (min)
Yield (%)b
0.2 (0.16 mmol of H+)
N
sio2
sio2
NH
HSO4
0.2
0.2
N
N
NH
H2PO4
100
sio2
NH
OTf
0.2
0.2
0.2
0.2
N
N
sio2
sio2
NH
Cl
130
N
HSO4
sio2
sio2
N
N
H2PO4
N
N
OTf
N
0.2
sio2
N
120
80
Cl
0.2 (1.1 mmol)
0.2 (0.72 mmol)
0.2 (0.81 mmol)
0.2 (1.2 mmol)
0.2 (0.86 mmol)
HN
N
HSO4
HN
N
H2PO4
HN
HN
N
24h
24h
TfO
NH
HSO4
12
3
0
HN
NH
TfO
trace
Reaction conditions; benzaldehyde (1 mmol), aniline (1.5 mmol), TMSCN (1.2 mmol), EtOH (2 mL), room temperature
a
Isolated yield
made which revealed that [Sipim]HSO4 is an equally
efficient and reusable catalyst (Table 6).
available and cheap starting materials, catalyzed efficiently
the synthesis of a-amino nitriles by a one-pot three-compo-
nent condensation of aldehydes, amines, and trimethylsilyl
cyanide. The catalyst shows high thermal stability and was
In conclusion, it has shown that silica propyl imidazolium
hydrogen sulfate which can be prepared from commercially
Table 2 Condensation of
Entry
Catalyst
Amount of catalyst (g)
Time (min)
Yield (%)a
benzaldehyde, aniline and
TMSCN in the presence of
different amounts of
[Sipim]HSO4
1
2
3
4
5
6
7
Catalyst-free
[Sipim]HSO4
[Sipim]HSO4
[Sipim]HSO4
[Sipim]HSO4
[Sipmim]HSO4
[Sipmim]HSO4
–
24 h
75
0
50
80
90
85
85
95
0.05
0.1
0.2
0.3
0.1
0.2
75
Reaction conditions:
benzaldehyde (1 mmol), aniline
(1.5 mmol), TMSCN
(1.2 mmol), EtOH (2 mL),
room temperature
75
75
75
75
a
Isolated yield
123

Preparation of Silica-Based Ionic Liquid
1717
silica chemically bonded with imidazolium ([Sipim]Cl)
Table 3 Condensation of benzaldehyde (1 mmol), aniline
(1.5 mmol) and TMSCN (1.2 mmol) in different solvents in the
presence of [Sipim]HSO4 (0.2 g)
was dried under vacuum at 50 °C for 4 h [15].
Entry
Catalyst
Time (min)
Yield (%)a
4.2 Preparation of Silica Propyl Imidazolium
Hydrogen Sulfate [Sipim]HSO4
1
2
3
4
5
6
EtOH
75
165
165
165
60
90
70
60
25
85
85
H2O
Into the three-necked round bottom flask equipped with
stirrer, ice bath condenser, and thermometer [Sipim]Cl
(3.0 g) was suspended in dry CH2Cl2 (20 mL). During
vigorous stirring, concentrated H2SO4 (97%) (2.9 mmol)
was added drop by drop at 0 °C. Then the mixture was
warm up to the room temperature, and was refluxing for
48 h. When the formed HCl was completely distilled of the
condenser the solution was cooled and the CH2Cl2 was
removed under vacuum. To remove any water from the
reaction mixture 10 mL of benzene was added to the crude
ionic liquid and stirred for 3 h with magnetic stirrer at
50 °C. Formed azeotrope was distilled of yielding [Si-
pim]HSO4. Elemental analysis showed the S content to be
2.57%; C, 10.90%; H, 2.10%; N, 3.1%. According to S
content the number of H? sites of [Sipim]HSO4 is
0.8 mmol g-1. In addition, when [Sipim]HSO4 (0.2 g) was
placed in an aqueous NaCl solution (25 mL), the solution
pH dropped virtually instantaneously to pH 1.43, as ion
exchange occurred between protons and sodium ions.
CH2Cl2
n-Hexane
CH3CN
Solvent-free
165
The reaction was carried out in 2 mL of solvent at rt
a
Isolated yield
recovered and reused without any noticeable loss of activity.
The mild reaction conditions and simplicity of the procedure
offers improvements over many existing methods.
3 Experimental Section
Chemicals were purchased from Fluka, Merck and Aldrich
Chemical Companies. For recorded NMR spectra we using
Bruker (400 MHz) and Bruker (500 MHz) Avance DRX in
pure deuterated CDCl3 solvent with tetramethylsilane
(TMS) as internal standards. All the products were char-
acterized by comparison of their IR, H NMR and 13C
1
4.2.1 General Procedure
NMR spectroscopic data and their melting points with
reported values [16–35].
A mixture of aldehyde (1 mmol), amine (1.5 mmol), tri-
methylsilyl cyanid (1.2 mmol), and [Sipim]HSO4 (0.2 g,
0.16 mmol of H?) in EtOH (2 mL) was stirred at room
temperature for appropriate time (Table 4). After comple-
tion of the reaction, as indicated by TLC, the reaction
mixture was filtered and the remaining washed with warm
ethanol (3 9 5 mL). After cooling, the corresponding a-
amino nitrile products were obtained which were purified
by recrystallization from hot ethanol. The recovered cata-
lyst was dried and reused for subsequent runs.
4 Preparation of Catalyst
Chloropropyl silica was prepared by a known procedure as
previously reported [15].
4.1 Preparation of Silica Propyl Imidazolium Chloride
[Sipim]Cl
Silicapropyl chloride (10.0 g) was added to a flask con-
taining 100 mL of anhydrous toluene and a large excess of
imidazole (10.0 g). The reaction mixture was refluxed with
stirring for 24 h. Then, the reaction mixture was cooled to
room temperature, transferred to a vacuum glass filter, and
washed with toluene, ethanol, and methanol in turn. The
4.2.2 Spectral Data of New Compounds
2-[N-(4-Methylanilino)]-2-(3,4,5-trimethoxyphenyl)aceto-
nitrile 1j: IR (KBr): 3360, 3320, 2990, 2943, 2843, 2220,
1600, 1520, 1130, 820 cm-1. 1H NMR (500 MHz, CDCl3):
Scheme 2 Synthesis of a-
amino nitrile derivatives
catalyzed by [Sipim]HSO4
N
SiO2
NH
HSO4
R1-C-NH-R2
CN
R1-CHO
1 mmol
+
R2-NH2 + TMSCN
1.2 mmol
EtOH, rt
15-160 min
1.5 mmol
1a-q
R1= aliphatic, aromatic; R2= primary, secondary
123

1718
M. Nouri Sefat et al.
Table 4 Preparation of various a-amino nitriles in the presence of [Sipim]HSO4 as a solid acid at room temperature
Entry
R1
R2
Product
Time
(min)
Yield
(%)b
mp
Lit. mp
(oC)
(oC)
H
H
C
N
81-83[30]
CN
1
2
C6H5-
C6H5-
C6H5-
75
60
90
80-82
1a
H
C
H
N
Cl
4-Cl-
CN
90(98)c
111-112[23]
112-114
C6H4-
1b
Cl
3
4
H
C
H
N
Cl
Br
117[34]
115-
2,4-(Cl)2-
C6H3-
CN
115-117
C6H5-
80
70
1c
H
H
C
N
4-Br-
CN
C6H5-
C6H5-
C6H5-
C6H5-
65
68
75
15
95
85
101-103
100-102
89-92
99-100[22]
C6H4-
1d
5
6
7
NH
CN
2-
S
[26]
98-
100
Thienyl-
1e
H
C
H
N
3-O2N-
C6H4-
CN
89-92[34]
O2N
MeO
85
1f
H
H
N
C
CN
4-MeO-
C6H4-
95(95)c
95-97
95[23]
94-
1g
H
H
8
9
C
N
Me
MeO
4-MeO-
C6H4-
4-Me-
C6H4-
CN
20
20
98
90
[35]
109-112
147-149
1h
MeO
MeO
MeO
H
C
H
N
3,4,5-
(MeO)3-
C6H5-
CN
147-149[34]
C6H5-
1i
MeO
MeO
10
11
H
C
H
3,4,5-
(MeO)3-
C6H2-
Me
N
4-Me-
C6H4-
CN
60
70(70)c
149-152
86-88
MeO
-
1j
MeO
H2
H
H
C
3,4,5-
N
C
MeO
MeO
CN
[34]
(MeO)3
C6H2-
-
Ph-CH2-
160
90
86-
88
1k
123

Preparation of Silica-Based Ionic Liquid
1719
Table 4 continued
Entry
12
R1
R2
Product
Time
(min)
Yield
(%)b
mp
Lit. mp
(oC)
(oC)
H
C
H
CH3
N
CN
4-Me-
[34]
C6H5-
20
85
-
102
104
102-104
C6H4-
1l
Cl
13
H
C
H
N
CH3
Cl
2,4-(Cl)2-
C6H3-
4-Me-
C6H4-
CN
120
90(90)c
111-114
-
1m
H2
C
H
C
H
14
15
N
Colorless oil
Colorless oil[27]
CN
iso-C3H7-
n-C4H9
C6H5-
Ph-CH2-
C6H5-
120
120
210
82(84)c
80
1n
NH
[28]
NC
55-57
56-
68-
58
1o
H
C
16
17
N
O
[27]
CN
1p
N
O
HN
83
69-71
69
H
C
HC
CN
N
CN
C6H5-
120
60(70)c
N
N
233-235
-
1q
CN
NH
18
19
O
C6H5-
C6H5-
300
360
45d
50d
[26]
139-141
140-142
140-
142
1r
CN
NH
O
[26]
142-
144
1s
Reaction conditions: aldehyde (1 mmol), aniline (1.5 mmol), TMSCN (1.2 mmol), [Sipim]HSO4 (0.2 g, equal to 0.16 mmol of H?), EtOH (2 mL),
a
room temperature Isolated yield
b
The yields in parenthesis were catalyzed by [Sipmim]HSO4
c
GC conversion
d (ppm) 2.32 (s, 3H), 3.78 (s, 1H), 3.90 (s, 9H), 5.37 (s,
Table 5 Reusability of [Sipim]HSO4 on the example condensation
reaction of benzaldehyde, aniline and TMSCN at room temperature
1H), 6.75 (d, 2H, J = 7.3 Hz), 6.84 (s, 2H), 7.12 (d, 2H,
J = 7.3 Hz). 13C NMR (125 MHz, CDCl3): d (ppm) 20.94,
51.39, 56.72, 61.32, 104.74, 115.02, 118.71, 130.51,
139.32, 154.22. Anal. Calcd for C18H20N2O3: C, 69.21; H,
6.45; N, 8.97. Found: C, 69.02; H, 6.49; N, 8.70.
No. of run
Yield (%)a
Catalyst recovered (%)
1
2
3
4
5
90
90
88
85
80
91
90
90
89
89
2-[N-(4-Methylanilino)]-2-(2,4-dichlorophenyl)acetoni-
trile 1m: IR (KBr): 3340, 3025, 2240, 1620, 1585, 1515,
1468, 800 cm-1. 1H NMR (500 MHz, CDCl3): d (ppm) 2.32
(s, 3H), 3.95 (brs, 1H), 5.67 (s, 1H), 6.73 (d, 2H, J = 8.2 Hz),
7.11 (d, 2H, J = 8.0 Hz), 7.38 (dd, 1H, J1 = 8.2 Hz,
J2 = 1.6 Hz), 7.53 (d, 1H, J = 1.6 Hz), 7.69 (d, 1H,
J = 8.3 Hz). 13C NMR (125 MHz, CDCl3): d (ppm) 20.96,
Reaction conditions: [Sipim]HSO4 (0.2 g), benzaldehyde (1 mmol),
aniline (1.5 mmol), and TMSCN (1.2 mmol). Time = 75 min
a
Isolated yield
123

1720
M. Nouri Sefat et al.
Table 6 Comparison of the result of condensation reaction of benzaldehyde and aniline with TMSCN in the presence of different catalysts based
on silica
Entry
Catalyst
Catalyst loading (g)
Conditions
Time (min)
Yielda
Ref.
1
2
3
4
5
6
7
8
a
Montmorillonite KSF clay
Silica-based scandium(III)
Xanthene sulfuric acid
Silica sulfuric acid
1.0
rt
210
840
65
90
94
[23]
0.1 (0.03 mmol)
0.1 (0.06 mmol)
0.095 (0.25 mmol)
0.031 (0.017 mmol)
0.2 (0.066 mmol)
0.02 (0.006 mmol)
0.2 (0.16 mmol)
rt
[24]
rt
97
[30]
rt
360
5
88
[32]
SBA-15 supported sulfonic acid
SBSSA
50 °C
100
94
[33]
rt
rt
rt
30
[34]
Sulfamic acid Fe3O4 nanoparticles
[Sipim]HSO4
10
97
[35]
75
90
Present work
Isolated yield
14. Sugimura R, Qiao K, Tomida D, Yokoyama C (2007) Catal
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48.45, 115.21, 117.95, 128.49, 130.30, 130.55, 130.71,
130.76, 130.99, 134.73, 136.82, 142.39. Anal calcd for
C15H12Cl2N2: C, 61.87; H, 4.15; N, 9.62. Found: C, 6.68; H,
4.20; N, 9.44.
[4-(Cyano-phenyl-methyl)-piperazin-1yl]-phenylaceto-
1
nitrile 1q: IR (KBr): 3355, 3050, 2810, 2230 cm-1. H
NMR (500 MHz, CDCl3): d (ppm) 2.52–2.60 (m, 8H), 4.88
(s, 2H), 7.32–7.38 (m, 6H), 7.46–7.50 (m, 4H). 13C NMR
(125 MHz, CDCl3): d (ppm) 48.00, 62.12, 115.47, 128.29,
129.25, 129.54, 132.75. Anal. Calcd for C20H20N4: C,
75.92; H, 6.37; N, 17.71. Found: C, 75.73; H, 6.41; N,
17.60.
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Acknowledgment The authors are thankful to Persian Gulf Uni-
versity Research Council for partial support of this study.
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