Sulfamic acid-functionalized magnetic Fe3O4 nanoparticles as an efficient and reusable catalyst for one-pot synthesis of α-amino nitriles in water

Article abstract of DOI:10.1016/j.apcata.2011.01.018

Grafting of chlorosulfuric acid on the amino-functionalized Fe ₃O₄ nanoparticles afforded sulfamic acid-functionalized magnetic Fe₃O₄ nanoparticles (SA-MNPs) as a novel organic-inorganic hybrid heterogeneous catalyst, which was characterized by XRD, FT-IR, TGA, TEM, and elemental analysis. The catalytic activity of SA-MNPs was probed through one-pot synthesis of α-amino nitriles via three-component couplings of aldehydes (or ketones), amines and trimethylsilyl cyanide in water, at room temperature. The heterogeneous catalyst could be recovered easily and reused many times without significant loss of its catalytic activity.

Full text of DOI:10.1016/j.apcata.2011.01.018

Applied Catalysis A: General 395 (2011) 28–33
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Sulfamic acid-functionalized magnetic Fe3O4 nanoparticles as an efficient and
reusable catalyst for one-pot synthesis of ␣-amino nitriles in water
M.Z. Kassaee∗, Hassan Masrouri, Farnaz Movahedi
Department of Chemistry, Tarbiat Modares University, P.O. Box 14155-4838, Tehran, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Grafting of chlorosulfuric acid on the amino-functionalized Fe3O4 nanoparticles afforded sulfamic
acid-functionalized magnetic Fe3O4 nanoparticles (SA-MNPs) as a novel organic–inorganic hybrid hetero-
geneous catalyst, which was characterized by XRD, FT-IR, TGA, TEM, and elemental analysis. The catalytic
activity of SA-MNPs was probed through one-pot synthesis of ␣-amino nitriles via three-component cou-
plings of aldehydes (or ketones), amines and trimethylsilyl cyanide in water, at room temperature. The
heterogeneous catalyst could be recovered easily and reused many times without significant loss of its
catalytic activity.
Received 20 November 2010
Received in revised form 8 January 2011
Accepted 10 January 2011
Available online 14 January 2011
Keywords:
Magnetic nanoparticles
Sulfamic acid
© 2011 Elsevier B.V. All rights reserved.
Heterogeneous catalysis
␣-Amino nitriles
1. Introduction
On the other hand, acid catalysts are used in a variety of organic
transformations, including aldol condensations, hydrolyses, acyla-
Mounting interest is recently expressed for surface function-
alization of nanocatalysts in which the nanoscale architecture of
active centers plays a dominant role in determining their effi-
ciency and selectivity [1–5]. Surface functionalized iron oxide
magnetic nanoparticles (MNPs) are a kind of novel functional
materials, which have been widely used in biotechnology and
catalysis [6–13]. Good biocompatibility and biodegradability as
well as basic magnetic characteristics could be denoted for
functional organic materials grafted to MNPs. Magnetic nanocat-
alysts can easily be separated and recycled from the products
by an external magnet. Moreover, their catalytic performance is
enhanced, for the available surface area of the nonporous MNPs
is external and the internal diffusion is practically avoided. The
silane agents such as 3-aminopropyltriethyloxysilane (APTES),
p-aminophenyl trimethoxysilane (APTS), and mercaptopropyltri-
ethoxysilane (MPTES) are often considered as potential candidates
for modifying the surface of MNPs directly. Such surface modi-
fication enhances the biocompatibility and provides rather high
density surface functional endgroups which allow for connecting
to other metals, polymers or biomolecules [14–17]. Existence of
many hydroxyl groups on the MNPs surface leads to reaction with
alkoxysilane reagents and formation of Si–O bonds which support
terminal functional groups available for immobilization of other
substances [18–20].
tions, nucleophilic additions, etc. However, several drawbacks such
as separation problems, reactor corrosion, waste neutralization and
the incapability for reuse have depreciated the reactions catalyzed
by soluble liquid acids [21]. Consequently, there has been consid-
erable interest in the development of stable, reusable, and highly
active solid acids [22–24] as environmentally benign replacements
for their homogeneous counterparts. During the last few years, sul-
famic acid (NH2SO3H, SA), a dry nonhygroscopic, nonvolatile, and
odorless solid has been considered as an efficient heterogeneous
catalyst substitute for conventional acidic catalysts [25–28]. Ketal
formation or acetalization [29], esterification [25], nitrile formation
[30], tetrahydropyranylation of alcohols [31] and transesterifica-
tion of ␤-ketoesters [32] are among the reactions carried out in the
presence of sulfamic acid.
In this study, we report immobilization of sulfamic acid groups
on the synthesized magnetic Fe3O4 nanoparticles to achieve
sulfamic acid-functionalized magnetic nanoparticles as a new het-
erogeneous catalyst for one-pot synthesis of ␣-amino nitriles via
three-component couplings of aldehydes (or ketones), amines and
trimethylsilyl cyanide in water, at room temperature.
2. Experimental
2.1. Chemicals and instruments
The reagents and solvents used in this work were obtained
from Fluka or Merck and used without further purification.
Nanostructures were characterized using a Holland Philips Xpert
∗
Corresponding author. Tel.: +98 912 1000392; fax: +98 21 88006544.
E-mail address: kassaeem@modares.ac.ir (M.Z. Kassaee).
0926-860X/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2011.01.018

M.Z. Kassaee et al. / Applied Catalysis A: General 395 (2011) 28–33
29
X-ray powder diffraction (XRD) diffractometer (CuK, radiation,
2.3. Preparation of MNPs coated by (3-aminopropyl)-
triethoxysilane
ꢀ = 0.154056 nm), at a scanning speed of 2◦/min from 10◦ to 100◦
(2ꢁ). The particle size and morphology were investigated by a
JEOL JEM-2010 transmission electron microscope (TEM) on an
accelerating voltage of 200 kV. FT-IR measurements were per-
formed using KBr disc on a Thermo IR-100 infrared spectrometer
(Nicolet). Elemental analyses for C, H and N were performed
using a Heraeus CHN–O–Rapid analyzer. The thermogravimet-
ric analysis (TGA) curves are recorded using a PL-STA 1500
device manufactured by Thermal Sciences. The 1H- and 13C-
spectra were measured at 500.1, and 125.7 MHz, respectively,
on a Bruker DRX 500-Avance FT-NMR instrument with CDCl3 as
a solvent.
The obtained MNPs powder (1.5 g) was dispersed in 250 mL
ethanol/water (volume ratio, 1:1) solution by sonication for
30 min, and then APTES (99%, 2.5 mL) was added to the mix-
ture. After mechanical agitation under N2 atmosphere at 40 ◦C for
4 h, the suspended substance was separated with centrifugation
(RCF = 13,200 × g for 30 min). The settled product was re-dispersed
in ethanol by sonication and then was isolated with magnetic
decantation for 5 times. The precipitated product (APTES–MNPs)
was dried at room temperature under vacuum.
2.4. Preparation of sulfamic acid-functionalized magnetic Fe3O4
nanoparticles (SA-MNPs)
2.2. Preparation of the magnetic Fe3O4 nanoparticles (MNPs)
The APTES–MNPs (500 mg) were dispersed in dry CH2Cl2 (3 mL)
by ultrasonic bath for 10 min. Subsequently, chlorosulfuric acid
(0.8 mL) was added dropwise over a period of 30 min at room tem-
perature. Hydrogen chloride gas evolved from the reaction vessel
immediately. Then, the as prepared functionalized MNPs nanopar-
ticles were separated by magnetic decantation and washed three
times with dry CH2Cl2 to remove the unattached substrates.
Naked Fe3O4 nanoparticles were prepared by chemical copre-
cipitation of Fe3+ and Fe2+ ions with
a molar ratio of 2:1
[33]. Typically, FeCl3·6H2O (5.838 g, 0.0216 mol) and FeCl2·4H2O
(2.147 g, 0.0108 mol) were dissolved in 100 mL deionized water
at 85 ◦C under N2 atmosphere and vigorous mechanical stirring
(500 rpm). Then, 10 mL of 25% NH4OH was quickly injected into
the reaction mixture in one portion. The addition of the base to the
Fe2+/Fe3+ salt solution resulted in the formation of the black pre-
cipitate of MNPs immediately. The reaction continued for another
25 min and the mixture was cooled to room temperature. The black
precipitate was washed with doubly distilled water and 0.02 M
solution of NaCl through magnetic decantation. Practically, the NaCl
solution helped delete the excess amount of ammonia providing a
better and faster decantation of suspended Fe3O4 nanoparticles in
water, when an external magnet was used. The average diameter
of obtained MNPs was estimated around 14 nm by transmission
electron microscopy (TEM).
2.5. General procedure for the synthesis of ˛-amino nitriles
To a 10 mL round-bottomed flask were added aldehyde (or
ketone) (1.0 mmol), amine (1.0 mmol), TMSCN (1.1 mmol), H2O
(3 mL) and SA-MNPs (20 mg) sequentially. The suspension was
stirred vigorously at room temperature followed by appropriate
times of stirring. The progress of the reaction was monitored by TLC
(eluent:EtOAc/n-hexane, 30:70). After the reaction was completed,
the catalyst was separated by an external magnet and reused as
Scheme 1. Preparation steps for fabricating sulfamic acid-functionalized magnetic Fe3O4 nanoparticles.

30
M.Z. Kassaee et al. / Applied Catalysis A: General 395 (2011) 28–33
Fig. 2. TGA curve of (a) MNPs, (b) APTES–MNPs and (c) SA-MNPs.
Fig. 1. XRD patterns of (a) MNPs, (b) APTES–MNPs and (c) SA-MNPs.
weight loss of APTES-modified magnetite NPs appears about 2.8%
at 270–430 ◦C which is contributed to the thermal decomposition
of the 3-aminopropyl groups. For SA-MNPs, there is a well-defined
mass weight loss of 4.9% between 250 and 465 ◦C related to the
breakdown of the SA moieties. On the basis of these results, the
well grafting of APTES and SA groups on the MNPs is verified.
Fig. 3 shows Fourier transform infrared (FT-IR) spectra for mag-
netic Fe3O4 nanoparticles (MNPs), APTES–MNPs, and SA-MNPs. The
FT-IR bands at low wavenumbers (≤700 cm−1) come from vibra-
tions of Fe–O bonds of iron oxide, in which for the bulk Fe3O4
samples appear at 570 and 375 cm−1 but for Fe3O4 nanoparticles at
624 and 572 cm−1 as a blue shift, due to the size reduction [37,38].
The FT-IR spectra of APTES–MNPs and SA-MNPs show Fe–O vibra-
tions in the same vicinity. The introduction of APTES to the surface
of MNPs is confirmed by the bands at 1126 and 1001 cm−1 assigned
to the Si–O stretching vibrations. The broad band at 3392 cm−1 is
referred to the N–H stretching vibration [39]. The presence of the
anchored propyl group is confirmed by C–H stretching vibrations
that appear at 2918 and 2846 cm−1. Reaction of APTES–MNPs with
chlorosulfuric acid produces SA-MNPs in which the presence of sul-
fonyl moiety is asserted with 1217 and 1124 cm−1 bands in FT-IR
spectra.
such for the next experiment. Consequently the crude product was
extracted from the aqueous phase by EtOAc (3× 5 mL), and then
the organic layer was washed with saturated brine and dried over
anhydrous MgSO4. Finally the solvent was removed and the desired
␣-amino nitrile obtained through a column of silica gel.
3. Results and discussion
3.1. Characterization of the prepared SA-MNPs
Scheme
1 presents the synthetic strategy for SA-MNPs;
naked magnetic Fe3O4 nanoparticles were prepared through
chemical coprecipitation method, and subsequently were coated
with 3-aminopropyltriethoxysilane (APTES) to achieve amino-
functionalized magnetic nanoparticles. Ultimately, the reaction
of amino groups with chlorosulfuric acid led to sulfamic
acid-functionalized magnetic Fe3O4 nanoparticles (SA-MNPs). Ele-
mental analysis showed the S content to be 8.93%. Typically a
loading at ca. 0.32 mmol/g was obtained. Furthermore, when the
prepared SA-MNPs catalyst was placed in an aqueous NaCl solution
(1 M, 25 mL) the pH dropped instantaneously to ≈1.97, indicat-
ing an ion exchange between sulfamic acid protons and sodium
ions, and an ion exchange capacity was found to be 0.31 mmol/g of
sulfamic acid groups which is in good agreement with the results
obtained from TGA and back-titration.
TEM micrographs provide more accurate information on the
particle size and morphology of MNPs and SA-MNPs (Fig. 4).
The X-ray diffraction patterns of MNPs, APTES–MNPs and SA-
MNPs are shown in Fig. 1. The position and relative intensities
of all peaks confirm well with standard XRD pattern of Fe3O4
(JCPDS card No. 85-1436) indicating retention of the crystalline
cubic spinel structure during functionalization of MNPs. A weak
broad band (2ꢁ = 18–27◦) appeared in the APTES–MNPs and the
SA-MNPs which could be assigned to the amorphous silane shell
formed around the magnetic cores [34]. The average MNPs core
diameter was calculated to be 14 nm from the XRD results by
Scherrer’s equation, D = kꢀ/ˇ cos ꢁ, where k is a constant (gener-
˚
ally considered as 0.94), ꢀ is the wavelength of Cu Ka (1.54 A), ˇ is
the corrected diffraction line full-width at half-maximum (FWHM),
and ꢁ is Bragg’s angle [35].
The thermogravimetric analysis (TGA) curves of the MNPs,
APTES–MNPs and SA-MNPs show the mass loss of the organic mate-
rials as they decompose upon heating (Fig. 2). The initial weight
loss from the MNPs up to 126 ◦C is due to the removal of physically
adsorbed solvent and surface hydroxyl groups. The weight loss of
about 2.2% between 260 and 355 ◦C may be associated to the ther-
mal crystal phase transformation from Fe3O4 to ␥-Fe2O3 [36]. The
Fig. 3. The comparative FT-IR spectra for (a) MNPs, (b) APTES–MNPs and (c) SA-
MNPs.

M.Z. Kassaee et al. / Applied Catalysis A: General 395 (2011) 28–33
31
Fig. 4. TEM images of (a) MNPs and (b) SA-MNPs.
Table 1
The naked Fe3O4 nanoparticles show slight agglomeration, which
could be related to the absence of surfactants and the lack of any
repulsive force between the MNPs. For both the pristine and SA-
functionalized nanoparticles, the average diameter of the core is
around 14 nm with an approximate spherical shape, which is in
accord with the XRD pattern. There is no detectable outer shell
within the sensitivity limit of TEM (Fig. 4b). A reasonable expla-
nation might be that silanization with APTES results in to the
formation of a monolayer Si–O network which is too thin to be
recognized.
Optimization of the SA-MNPs catalyzed model reaction for synthesis of ␣-amino
nitriles.a
Entry
Catalyst
Solvent
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Nano-Fe3O4 (10 mol%)
Nano-Fe3O4 (10 mol%)
Nano-ZnO (10 mol%)
Nano-ZnO (10 mol%)
Nano-TiO2 (10 mol%)
Nano-TiO2 (10 mol%)
Nano-ZrO2 (10 mol%)
Nano-ZrO2 (10 mol%)
NH2SO3H (10 mol%)
NH2SO3H (10 mol%)
NH2SO3H (10 mol%)
SA-MNPs (20 mg)
SA-MNPs (20 mg)
SA-MNPS (20 mg)
SA-MNPs (20 mg)
SA-MNPs (20 mg)
SA-MNPs (10 mg)
SA-MNPs (50 mg)
No catalyst
CH3CN
H2O
CH3CN
H2O
CH3CN
H2O
CH3CN
H2O
CH3CN
–
H2O
CH3CN
Toluene
–
EtOH
H2O
90
90
60
120
60
120
45
120
30
20
90
30
120
90
30
10
20
75
68
86
64
90
71
85
58
81
90
62
93
42
95
86
97
72
98
18
3.2. Evaluation of the catalytic activity of SA-MNPs through the
synthesis of ˛-amino nitriles
␣-Amino nitriles are significantly important intermediates for
the synthesis of a wide variety of amino acids, amides, diamines,
nitrogen-containing heterocycles and other biologically active
molecules. Therefore, we investigated catalytic activity of SA-MNPs
as a heterogeneous catalyst in one-pot synthesis of ␣-amino nitriles
through three-component reaction of aldehydes (or ketones),
amines, and trimethyl cyanide (Scheme 2). For this purpose, the
reaction of benzaldehyde, aniline and TMSCN as a simple model
reaction was probed to establish the feasibility of the strategy and
optimize the reaction conditions. Various catalysts including nano
metal oxides, sulfamic acid, and SA-MNPs were evaluated for this
model reaction, and the results are summarized in Table 1. Metal
oxide nanoparticles such as nano-Fe3O4, ZnO, TiO2 and ZrO2 ren-
dered higher yields in CH3CN than water, for somewhat the later
seemed to poison the nano catalyst. Among the used catalysts SA-
MNPs rendered the highest yield. Indeed, Fe3O4 nanoparticles as
well as sulfamic acid (NH2SO3H) would catalyze the reaction per
H2O
H2O
H2O
10
240
a
Reaction conditions: Benzaldehyde (1 mmol), aniline (1 mmol), trimethylsilyl
cyanide (1.2 mmol), catalyst, solvent (3 mL), room temperature.
b
Isolated yields.
se, with 75 and 81% yield, respectively. Yet, their combination in
the form of SA-MNPs boosts the yield to 98%.
To appraise the effects of media, we carried out the condensation
of benzaldehyde, aniline and TMSCN in various organic solvents
by using SA-MNPs (20 mg per 1 mmol of reactants) as the cat-
alyst (Table 1, entries 12–16). It should be noted that SA-MNPs
Scheme 2.

32
M.Z. Kassaee et al. / Applied Catalysis A: General 395 (2011) 28–33
Table 2
Table 3
One-pot synthesis of ␣-amino nitriles by the Strecker reaction of aldehydes, amines,
One-pot synthesis of ␣-amino nitriles using various ketones, amines, and TMSCN in
and TMSCN in the presence of SA-MNPs in water.a
the presence of SA-MNPs as a catalyst in water.a
Entry
Ketone
Amine
Product
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
9
4a
4b
4c
4d
4e
4f
4g
4h
4b
4d
4e
4g
2a
2a
2a
2a
2a
2a
2a
2a
2b
2b
2b
2b
5a
5b
5c
5d
5e
5f
5g
5h
5i
0.5
0.5
2
1
1
1
2
10
0.5
1
97
96
85
93
91
95
86
64
95
95
90
84
Entry
R
Amine
Product
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Ph
2a
2a
2a
2a
2a
2a
2a
2a
2a
2a
2a
2b
2b
2b
2c
2c
2d
2d
2d
2e
2e
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
3q
3r
10
10
15
15
25
10
20
30
15
30
30
10
10
45
30
30
15
15
20
45
45
97
95
91
92
88
93
92
85
95
90
88
98
93
90
95
96
93
91
87
96
94
4-Cl-C6H4
3-Cl-C6H4
4-Me-C6H4
2-Me-C6H4
4-MeO-C6H4
2-Furyl
2-Thienyl
4-Br-C6H4
i-Pr
10
11
12
5j
5k
5l
2
4
a
n-Pr
Ph
Reaction conditions: Ketones (1 mmol), amines (1 mmol), trimethylsilyl cyanide
(1.2 mmol), SA-MNPs (20 mg), H2O (3 mL), room temperature.
b
4-Cl-C6H4
Cinnamyl
Ph
4-MeO-C6H4
Ph
4-Me-C6H4
2-Furyl
Ph
Isolated yields.
Table 4
Reusability of the SA-MNPs catalyst.a
3s
3t
3u
Entry
Yield (%)
Recovery of SA-MNPs (%)
Refresh
97
96
96
94
91
99
99
98
98
98
4-Br-C6H4
1
2
3
4
a
Reaction conditions: Aldehydes (1 mmol), amines (1 mmol), TMSCN (1.2 mmol),
SA-MNPs (20 mg), water (3 mL), room temperature.
b
Isolated yields.
a
Reaction conditions: Benzaldehyde (1 mmol), aniline (1 mmol), trimethylsilyl
cyanide (1.2 mmol), SA-MNPs (20 mg), H2O, room temperature.
showed good catalytic activity in a variety of organic solvents such
as acetonitrile and ethanol, where over than 80% conversion was
obtained. Nevertheless, the reaction in water is very clean and this
is the solvent of choice, environmentally appreciable.
To investigate the effect of the catalyst concentration, system-
atic studies are carried out in the presence of different amounts of
the catalyst (0, 5, 20, 50 mg) in water, affording ␣-amino nitriles
with 18%, 72%, 97%, and 98% isolated yields, respectively. Thus, the
best yield is found in the presence of just 20 mg SA-MNPs, and the
use of higher amounts of catalyst (50 mg) does not improve the
result to an appreciable extent (Table 1, entry 18).
the reactions proceeded relatively slowly (Table 3, entry 8). All
products were characterized on the basis of their spectroscopic data
such as FT-IR, 1H and 13C NMR spectra.
The catalytic activity and the ability to recycle and reuse SA-
MNPs were studied in this system (Table 4). The catalyst was
separated by an external magnet and was reused as such for subse-
quent experiments under similar reaction conditions. Yields of the
product decreased only slightly after four times reuse of catalyst.
A comparison for the efficiency of the catalytic activity of SA-
MNPs with several pervious methods is presented in Table 5. The
results show that this method is superior to some of the earlier
methods in terms of yields and reaction times.
The reaction can tolerate
a wide range of aliphatic and
aromatic aldehydes carrying either electron-donating or electron-
withdrawing substituents in the ortho, meta and para positions.
Acid sensitive aldehydes such as furfuraldehyde worked well with-
out the formation of any side products and gave the ␣-amino nitrile
derivative in 92% yield (Table 2, entry 7). Aliphatic amines such as
benzylamine and butylamine as well as aromatic amines gave good
yields (Table 2). Inspired by the results obtained with aldehydes
(products 3a–3u), we then investigated whether these simple pro-
tocols were also valid for the Strecker reaction with ketones. Thus,
various aliphatic and aromatic ketones, regardless of differences
in the electronic characters, smoothly reacted with aniline and
TMSCN to give the corresponding products in good to high yields,
after short reaction times (products 5a–5l). Cyclopentanone and
cyclohexanone both rapidly underwent the condensation within
15 min in excellent yields (Table 3, entries 1 and 2). Sterically hin-
dered ketones, such as benzophenone, also reacted with aniline and
TMSCN to give the corresponding products in good yields, although
Table 5
Comparison of catalytic activity of SA-MNPs with several known catalysts.a
Entry Catalyst
Conditions
Yield (%) Ref.
1
2
3
4
5
6
7
8
InI3
Water, 0.5 h
CH2Cl2, 14 h
CH2Cl2, 0.5 h
CH2Cl2, 3.5 h
Neat, 15 min
Neat, 12 min
95
94
88
90
94
90
94
[40]
[41]
[42]
[43]
[44]
[45]
[46]
This work
Silica-based scandium (III)
Silica sulfuric acid
Montmorillonite
TlCl3·4H2O
LiBF4
Silica-bonded S-sulfonic acid EtOH, 30 min
SA-MNPs
Water, 10 min 98
a
Reaction conditions: Benzaldehyde (1 mmol), aniline (1 mmol), trimethylsilyl
cyanide (1.2 mmol).

M.Z. Kassaee et al. / Applied Catalysis A: General 395 (2011) 28–33
33
4. Conclusion
[16] C.C. Berry, S. Wells, S. Charles, A.S.G. Curtis, Biomaterials 24 (2003) 4551–
4557.
[17] M.A. Morales, P.V. Finotelli, J.A.H. Coaquira, M.H.M. Rocha-Lea˜o, C. Diaz-Aguila,
E.M. Baggio-Saitovitch, Mater. Sci. Eng. C 28 (2007) 253–257.
[18] H. Cao, J. He, L. Deng, X. Gao, Appl. Surf. Sci. 255 (2009) 7974–7980.
[19] K.C. Barick, M. Aslam, P.V. Prasad, V.P. Dravid, D. Bahadur, J. Magn. Magn. Mater.
321 (2009) 1529–1532.
[20] K. Can, M. Ozmen, M. Ersoz, Colloid Surf. B 71 (2009) 154–159.
[21] A. Corma, H. Garcia, Adv. Synth. Catal. 348 (2006) 1391–1412.
[22] B.M. Reddy, B. Thirupathi, M.K. Patil, J. Mol. Catal. A: Chem. 307 (2009) 154–159.
[23] A.K. Bhattacharya, K.C. Rana, Tetrahedron Lett. 49 (2008) 2598–2601.
[24] S.D. Mitragotri, D.M. Pore, U.V. Desai, P.P. Wadgaonkar, Catal. Commun. 9 (2008)
1822–1826.
[25] B. Wang, Y. Gu, L. Yang, J. Suo, O. Kenichi, Catal. Lett. 96 (2004) 71–74.
[26] B. Wang, Y. Gu, C. Luo, T. Yang, L. Yang, J. Suo, Tetrahedron Lett. 45 (2004)
3369–3372.
[27] J.S. Yadav, P.P. Rao, D. Sreenu, R.S. Rao, V.N. Kumar, K. Nagaiah, A.R. Prasad,
Tetrahedron Lett. 46 (2005) 7249–7253.
Covalent functionalization of sulfamic acid onto the magnetic
Fe3O4 nanoparticles is successfully achieved by a multiple syn-
thetic procedure which is confirmed with XRD, FT-IR, TGA, and TEM.
The most interesting features of the present work include durabil-
ity as well as efficient catalytic activity for one-pot synthesis of
␣-amino nitriles via three-component coupling reactions of alde-
hydes (or ketones), amines and trimethylsilyl cyanide in water, at
room temperature. This method offers several advantages includ-
ing high yield, short reaction time, simple work-up procedure, ease
of separation, and recyclability of the magnetic catalyst, as well as
the ability to tolerate a wide variety of substitutions in the reagents.
[28] M.M. Heravi, L. Ranjbar, F. Derikvand, B. Alimadadi, Mol. Divers. 12 (2008)
191–196.
References
[29] T.S. Jin, G. Sun, Y.W. Li, T.S. Li, Green Chem. 4 (2002) 255–258.
[30] L. Daohua, W. Bi, Huaxe Shijie 41 (2000) 373–377.
[1] R. Anwander, Chem. Mater. 13 (2001) 4419–4438.
[2] S. Kobayashi, R. Akiyama, Chem. Commun. (2003) 449–460.
[3] K. Mori, S. Kanai, T. Hara, T. Mizugaki, K. Ebitani, K. Jitsukawa, K. Kaneda, Chem.
Mater. 19 (2007) 1249–1256.
[4] A.M. Argo, J.F. Odzak, F.S. Lai, B.C. Gates, Nature 415 (2002) 623–626.
[5] C. Copeˇıret, M. Chabanas, R.P. Saint-Arroman, J.M. Basset, Angew. Chem. Int. Ed.
42 (2003) 156–181.
[31] B. Wang, L. Yang, J. Suo, Synth. Commun. 33 (2003) 3929–3934.
[32] B. Wang, L. Yang, J. Suo, Tetrahedron Lett. 44 (2003) 5037–5039.
[33] X. Liu, Z. Ma, J. Xing, H. Liu, J. Magn. Magn. Mater. 270 (2004) 1–6.
[34] Y. Jiang, J. Jiang, Q. Gao, M. Ruan, H. Yu, L. Qi, Nanotechnology 19 (2008) 75714.
[35] B.D. Cullity, S.R. Stock, Elements of X-ray Diffraction, third ed., Prentice-Hall,
Englewood Cliffs, 2001.
[6] A.H. Lu, E.L. Salabas, F. Schuth, Angew. Chem. Int. Ed. 46 (2007) 1222–1244.
[7] B. Hu, J. Pan, H.L. Yu, J.W. Liu, J.H. Xu, Process Biochem. 44 (2009) 1019–1024.
[8] S. Bai, Z. Guo, W. Liu, Y. Sun, Food Chem. 96 (2006) 1–7.
[9] C.S. Gill, B.A. Price, C.W. Jones, J. Catal. 251 (2007) 145–152.
[10] A. Taher, J.B. Kim, J.Y. Jung, W.S. Ahn, M.J. Jin, Synlett (2009) 2477–2482.
[11] S.C. Tsang, V. Caps, I. Paraskevas, D. Chadwick, D. Thompsett, Angew. Chem. Int.
Ed. 43 (2004) 5645–5649.
[12] O.C. Dalaigh, A.S. Corr, Y. Gun’ko, J.S. Connon, Angew. Chem. Int. Ed. 46 (2007)
4329–4332.
[13] Y. Zhang, Y. Zhao, C. Xia, J. Mol. Catal. A: Chem. 306 (2009) 107–112.
[14] X. Shen, X. Fang, Y. Zhou, H. Liang, Chem. Lett. 33 (2004) 1468–1469.
[15] M. Ma, Y. Zhang, W. Yu, H. Shen, H. Zhang, N. Gu, Colloid Surf. A 212 (2003)
219–226.
[36] R.M. Cornell, U. Schwertmann, The Iron Oxides, VCH, New York, 1996.
[37] Z.M. Rao, T.H. Wu, S.Y. Peng, Acta Phys. Chim. Sin. 11 (1995) 395–399.
[38] R.D. Waldron, Phys. Rev. 99 (1955) 1727–1735.
[39] Z. Xu, Q. Liu, J.A. Finch, Appl. Surf. Sci. 120 (1997) 269–278.
[40] Z.L. Shen, S.J. Ji, T.P. Loh, Tetrahedron 64 (2008) 8159–8163.
[41] B. Karimi, A.A. Safari, J. Organomet. Chem. 693 (2008) 2967–2970.
[42] W.Y. Chen, J. Lu, Synlett (2005) 2293–2296.
[43] J.S. Yadav, B.V.S. Reddy, B. Eshwaraiah, M. Srinivas, Tetrahedron 60 (2004)
1767–1771.
[44] A. Majhi, S.S. Kim, S.T. Kadam, Appl. Organometal. Chem. 22 (2008) 705–711.
[45] U.V. Desai, S.D. Mitragotri, T.S. Thopate, D.M. Pore, P.P. Wadgaonkar, Monatsh.
Chem. 138 (2007) 759–762.
[46] K. Niknam, D. Saberi, M.N. Sefat, Tetrahedron Lett. 51 (2010) 2959–2962.