Ga-TUD-1: A new heterogeneous mesoporous catalyst for the solventless expeditious synthesis of α-aminonitriles

Article abstract of DOI:10.1016/j.apcata.2010.10.030

The high surface area three-dimensional porous catalyst has been prepared and characterized by TEM, BET S.A, low angle XRD, ²⁹Si MAS NMR, NH₃ TPD techniques. A simple, efficient and rapid method for the green synthesis of α-aminonitriles has been demonstrated over a new mesoporous gallosilicate catalyst Ga-TUD-1. The solventless technique has been applied for the synthesis of a range of compounds with variable functionality with excellent yield and selectivity. The catalyst has been recycled four times with reproducible yield.

Full text of DOI:10.1016/j.apcata.2010.10.030

Applied Catalysis A: General 392 (2011) 111–117
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Ga-TUD-1: A new heterogeneous mesoporous catalyst for the solventless
expeditious synthesis of ␣-aminonitriles
Bikash Karmakara, Apurba Sinhamahapatrab, Asit Baran Pandab, Julie Banerjia,∗∗
,
Biswajit Chowdhuryc,∗
a Centre of Advanced Studies on Natural products including Organic Synthesis, Department of Chemistry, University of Calcutta, 92, A.P.C. Road, Kolkata 700009, India
b Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat, India
c Department of Applied Chemistry, Indian School of Mines, Dhanbad 826004, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 July 2010
Received in revised form 26 October 2010
Accepted 28 October 2010
Available online 4 November 2010
The high surface area three-dimensional porous catalyst has been prepared and characterized by TEM,
BET S.A, low angle XRD, 29Si MAS NMR, NH3 TPD techniques. A simple, efficient and rapid method for the
green synthesis of ␣-aminonitriles has been demonstrated over a new mesoporous gallosilicate catalyst
Ga-TUD-1. The solventless technique has been applied for the synthesis of a range of compounds with
variable functionality with excellent yield and selectivity. The catalyst has been recycled four times with
reproducible yield.
Keywords:
© 2010 Elsevier B.V. All rights reserved.
Mesoporous gallosilicate
Strecker reaction
Multicomponent synthesis
Recyclable
1. Introduction
ardous and special caution has to be taken during their use. It
has been observed that use of Me3SiCN could override all these
In the recent years the development of simple and environmen-
tally benign protocols involving atom and step economic strategies
for the synthesis of organic compounds has attracted considerable
global attention [1]. Thus special importance has been focussed
on multicomponent reactions adopting green methodologies. The
Strecker reaction [2,3] is one of the most important multicompo-
nent reactions in organic chemistry for the direct one-pot synthesis
of ␣-aminonitriles which are of significance to synthetic chemists.
They serve as efficient precursors for the synthesis of natural and
unnatural ␣-amino acids which are in turn of significant biological
importance. Different nitrogen containing heterocycles like imida-
zoles, thiadiazoles [4,5] and bioactive molecules like Saframycin A
[6] can be synthesized using ␣-aminonitriles. These are the starting
materials for the synthesis of several short-acting opioid anal-
getics [7]. The simplest and most economical way to synthesize
␣-aminonitriles is the nucleophilic addition of cyanide anions to
imines [2]. A number of cyanating agents has been utilized earlier
such as, alkaline cyanides, Et2AlCN, Bu3SnCN, (EtO)2POCN, acetone
cyanohydrin [8–12]. However, most of them are found to be haz-
problems as it is safe to handle and is also an effective cyanide
source [13]. Despite intensive efforts to improve the methodol-
ogy with different catalysts, [14–22] the development of green
process involving solid acid catalyst still remains a challenge. More-
over, these homogeneous catalytic processes suffer from a serious
drawback involving the separation and recovery of the catalysts.
Therefore, the heterogeneous alternative systems have become
more important.
After the discovery of MCM-41 material by mobil researchers
the research on mesoporous family has been enriched by ZSM,
HMM, SBA and TUD-1 materials. High thermal stability, three-
dimensional sponge like structure and higher porosity and surface
to volume ratio of the TUD-1 materials the use of mesoporous to
use either as support [23] or the metal doped TUD-1 [24] to the dif-
ferent reactions. It has been shown for the last two decades that
gallium containing catalysts [25,26] are relevant materials for a
series of technologically important processes, such as light alkane
dehydrogenation and aromatization (Cyclar process), hydrocarbon
isomerization, reduction of nitrogen oxides by hydrocarbons and
carbon dioxide hydrogenation to methanol [27–29]. In this commu-
nication we report, the Ga grafted TUD-1 as a new heterogeneous
catalyst for one-pot three component condensation of an amine,
aldehyde and trimethylsilyl cyanide in solventless condition for
the expeditious synthesis of ␣-aminonitriles (Scheme 1). The reac-
tion was completed in short time with high yields and the catalyst
∗
Corresponding author. Tel.: +91 326 223 5663; fax: +91 326 222 4072.
Corresponding author. Tel. 91 33 2350 8386; fax: +91 33 2351 9755.
E-mail addresses: juliebanerji47@gmail.com (J. Banerji),
∗∗
biswajit chem2003@yahoo.com (B. Chowdhury).
0926-860X/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2010.10.030

112
B. Karmakar et al. / Applied Catalysis A: General 392 (2011) 111–117
R'
N
of any solvent at room temperature for certain period. After com-
pletion of the reaction as indicated by TLC, the reaction mixture
was diluted with DCM and centrifuged to separate the catalyst. The
reaction mixture was washed with water and dried over anhydrous
MgSO4. Concentration of the organic layers under reduced pres-
sure and purification by column chromatography using 100–200
mesh silica gel (ethyl acetate/hexane) afforded the pure product.
The isolated compounds were characterized by mp, IR, NMR spec-
trometry and elemental analysis. Characterization data of some of
the representative compounds are provided below.
O
R
Ga-TUD-1
H
N
R''
+
+
Me3SiCN
R'
R
H
R''
Solvent less, rt
CN
Scheme 1. Strecker type synthesis of ␣-aminonitriles.
could be reused four consecutive times without significant loss in
activity.
2. Experimental
2.3.1. 2-(N-anilino)-2-phenylacetonitrile
Yield 186 mg; White solid, mp 74–75 ◦C; IR (KBr): 3337, 3028,
2237, 1597, 1507, 1282, 1243, 1109, 752, 693 cm−1; 1H NMR (CDCl3,
300 MHz): ı 3.9 (bs, 1H), 5.44 (s, 1H), 6.78 (d, J = 7.6 Hz, 2H), 6.9 (t,
J = 7.4 Hz, 1H), 7.14 (t, J = 7.8 Hz, 2H), 7.27–7.5 (m, 3H), 7.51–7.63
(m, 2H); 13C NMR (CDCl3, 75.5 MHz): ı 50.2, 114.19, 118.16, 120.31,
127.24, 129.33, 129.52, 129.56, 133.96, 144.66; Found: C, 80.74; H,
5.76; N, 13.51. Calc. for C14H12N2: C, 80.77%; H, 5.77%; N, 13.46%.
2.1. General
For the characterization of reaction products the 1H NMR
(300 MHz) and 13C NMR (75.5 MHz) spectra were done on a
Bruker-AVANCE 300 DIGITAL MHz NMR spectrometer using TMS
as internal standard. IR spectra were obtained using a Perkin
Elmer RX-1 spectrophotometer. Melting point was determined
(uncorrected) on a Köfler Block apparatus. During catalyst char-
acterizations the Transmission Electron Microscope (TEM) images
were collected using JEOL JEM 2100 microscope. Samples were pre-
pared by mounting ethanol dispersed samples on carbon coated
Cu grids. Powder X-ray diffraction study was done in the low
2.3.2. 2-(N-anilino)-2-(3-nitrophenyl)acetonitrile
Yield 144 mg; Yellow solid, mp 76–78 ◦C; IR (KBr): 3337, 3093,
2373, 2230, 1604, 1538, 1351, 1240, 1091, 751, 689 cm−1 1H NMR
;
(CDCl3, 300 MHz): ı 4.20 (d, J = 6.0 Hz, 1H), 5.58 (d, J = 6.3 Hz, 1H),
6.78 (d, J = 8.1 Hz, 2H), 6.95 (t, J = 7.4 Hz, 1H), 7.29 (t, J = 8.0 Hz, 2H),
7.68 (t, J = 8.0 Hz, 1H), 8.0 (d, J = 7.8 Hz, 1H), 8.31 (d, J = 7.8 Hz, 1H),
8.51 (s, 1H); 13C NMR (CDCl3, 75.5 MHz): ı 44.4, 109.6, 110.9, 114.5,
116.44, 120.72, 129.6, 144.0, 146.1; Found: C, 66.47; H, 4.33; N,
16.61. Calc. for C14H11N3O2: C, 66.40%; H, 4.35%; N, 16.60%.
о
angle region 2ꢀ range 1–7 with a Philips X’pert X-ray diffrac-
tometer using Cu K␣ radiation (ꢁ = 1.54178 A). TPD measurements
were conducted on a Micromeritics Autochem-II chemisorption
analyzer. In this measurement about 200 mg of the catalyst being
˚
о
о
pre-treated in helium at 250 C for 30 min and then at 350 C for
1 h, was taken on a U-shaped sample tube. Then ammonia was
adsorbed (100 torr) on the catalyst for 1 h and the measurement
2.3.3. 2-(N-anilino)-2-(4-chlorophenyl)acetonitrile
Yield 157 mg; White solid, mp 108–110 ◦C; IR (KBr): 3299, 3024,
о
was carried out in the temperature range 100–900 C. 29Si MAS
1146, 1915, 1598, 1490, 1092, 817, 753, 708 cm−1 1H NMR (CDCl3,
;
NMR was performed using a Bruker Avance II-500 NMR spectrom-
eter (500 MHz) equipped with a magic angle spin probe at room
temperature. Nitrogen adsorption/desorption measurements were
performed at 77 K by using a ASAP 2010 Micromeritics instrument,
300 MHz): ı 3.9 (bs, 1H), 5.27 (s, 1H), 6.61 (d, J = 7.7 Hz, 2H), 6.76 (t,
J = 7.4 Hz, 1H), 7.12 (t, J = 7.1 Hz, 2H), 7.29 (d, J = 8.6 Hz, 2H), 7.39 (d,
J = 8.5 Hz, 2H); 13C NMR (CDCl3, 75.5 MHz): ı 49.7, 114.34, 117.8,
120.6, 128.6, 129.5, 129.6, 132.5, 135.6, 144.37; Found: C, 69.33; H,
4.52; N, 11.51. Calc. for C14H11N2Cl: C, 69.28%; H, 4.54%; N, 11.55%.
after degassing the sample under vacuum (10−2 torr) at 250 C for
о
3 h. The surface area was determined by BET equation and pore size
distribution were determined using BJH model of cylindrical pore
approximation.
2.3.4. 2-(N-anilino)-2-(4-methylphenyl)acetonitrile
Yield 163 mg; White solid, mp 74–76 ◦C; IR (KBr): 3306, 3026,
2244, 1598, 1509, 1289, 1243, 1107, 755, 685 cm−1; 1H NMR (CDCl3,
300 MHz): ı 2.24 (s, 3H), 3.85 (bs, 1H), 5.22 (s, 1H), 6.6 (d, J = 7.7 Hz,
2H), 6.74 (t, J = 7.4 Hz, 1H), 7.12 (t, J = 8.0 Hz, 4H), 7.62 (d, J = 8.1 Hz,
2H); 13C NMR (CDCl3, 75.5 MHz): ı 21.1, 50.05, 114.13, 118.33,
120.18, 127.14, 129.53, 129.95, 131.05, 139.56, 144.75; Found: C,
81.11; H, 6.27; N, 12.59. Calc. for C15H14N2: C, 81.08%; H, 6.31%; N,
12.61%.
2.2. Sol–gel synthesis of Ga-TUD-1 catalyst
The mesoporous Ga-TUD-1 catalyst was prepared following a
simple non hydrothermal sol–gel procedure. Tetraethyl orthosil-
icate (TEOS) and gallium (III) nitrate were used as the precursor
for silica and gallium respectively. In the typical procedure gallium
nitrate was added to the TEOS and stirred at room temperature.
A mixture of triethanolamine (TEA) and water was added to it
dropwise and then triethyl ammonium hydroxide (TEAOH) (20%
aqueous solution) was added slowly to the mixture to reach pH
10. The final molar ratio of the reagents was 1.0Si:xGa (x = 0.02,
0.04, 0.06):3.0TEA:0.3TEAOH:15H2O. The clear solution was aged
for 24 h at room temperature. It was then dried at 115 ◦C for 16 h
and finally calcined at 700 ◦C for 12 h at the rate of 2 ◦C/min under
the flow of air [30]. The nature of the synthesized calcined product
was amorphous. The material was further characterized employing
different physicochemical techniques.
2.3.5. 2-(N-anilino)-2-(4-cyanophenyl)acetonitrile
Yield 189 mg; white solid; IR (KBr): 3432.7, 2927.2, 2232.0,
1604.3, 1504.2, 1218.7, 768 cm−1 1H NMR (CDCl3, 300 MHz): ı
;
4.12 (d, J = 6.9 Hz, 1H), 5.54 (s, 1H), 6.76 (d, J = 8.4 Hz, 2H), 6.95 (t,
J = 7.5 Hz, 1H), 7.29 (t, J = 7.4 Hz, 2H), 7.77 (s, 4H); 13C NMR (CDCl3,
75.5 MHz): ı 49.98, 113.71, 114.58, 117.13, 121.06, 127.95, 129.7,
133.08, 138.94, 143.98; Found: C, 82.53; H, 5.09; N,19.31. Calc. for
C15H11N3: C, 82.56%; H, 5.04%; N, 19.27%.
2.3.6. 2-(N-anilino)-2-(4-methoxyphenyl)acetonitrile
2.3. Representative experimental procedure for the synthesis of
˛-aminonitriles
Yield 156 mg; Pale yellow solid, mp 92–94 ◦C; IR (KBr): 3358,
3058, 2225, 1601, 1497, 1466, 1254, 1167, 1036, 757 cm−1 1H
;
NMR (CDCl3, 300 MHz): ı 3.77 (s, 3H), 3.82 (s, 1H), 5.29 (s, 1H),
6.7 (d, J = 7.7 Hz, 2H), 6.85 (t, J = 7.4 Hz, 1H), 6.9 (d, J = 8.8 Hz, 2H),
7.2 (t, J = 7.0 Hz, 2H), 7.44 (d, J = 8.7 Hz, 2H); 13C NMR (CDCl3,
75.5 MHz): ı 49.7, 55.4, 114.11, 114.63, 118.39, 120.17, 126.0, 128.6,
A mixture of aldehyde (206 mg, 2.0 mmol), amine (186 mg,
2.0 mmol), trimethylsilyl cyanide (243 mg, 2.6 mmol) and Ga-TUD-
1 catalyst (20 mg) was stirred at room temperature in the absence

B. Karmakar et al. / Applied Catalysis A: General 392 (2011) 111–117
113
129.53, 144.73, 160.43; Found: C, 75.67; H, 5.87; N, 11.73. Calc. for
15H14N2O: C, 75.63%; H, 5.88%; N, 11.76%.
(CDCl3, 300 MHz): ı 3.92 (bs, 1H), 5.09 (d, J = 1.5 Hz, 1H), 6.29 (dd,
J = 5.1 Hz, J = 15.9 Hz, 1H), 6.79 (d, J = 8.1 Hz, 2H), 6.91 (t, J = 7.4 Hz,
1H), 7.06 (d, J = 15.9 Hz, 1H), 7.28–7.46 (m, 7H); 13C NMR (CDCl3,
75.5 MHz): ı 47.78, 114.4, 118.13, 120.41, 120.96, 126.93, 128.83,
128.94, 129.59, 134.9, 135.13, 144.4; Found: C, 82.09; H, 5.93; N,
11.93. Calc. for C16H14N2: C, 82.05%; H, 5.98%; N, 11.96%.
C
2.3.7. 2-(N-anilino)-2-(3-methoxyphenyl)acetonitrile
Yield 150 mg; Pale yellow solid, mp 64–66 ◦C; IR (KBr): 3353,
2968, 2838, 2226, 1934, 1601, 1497, 1327, 1255, 1166, 1036, 757,
686 cm−1 1H NMR (CDCl3, 300 MHz): ı 3.76 (s, 3H), 4.0 (bs, 1H),
;
5.32 (s, 1H), 6.7 (d, J = 7.8 Hz, 2H), 6.83 (t, J = 7.5 Hz, 1H), 6.9 (d,
J = 8.1 Hz, 1H), 7.1 (s, 1H), 7.12 (d, J = 8.1 Hz, 1H), 7.21 (t, J = 7.5 Hz,
2H), 7.3 (t, J = 8.0 Hz, 1H); 13C NMR (CDCl3, 75.5 MHz): ı 50.2,
55.4, 112.75, 114.16, 115.14, 118.13, 119.33, 120.28, 129.55, 130.4,
144.66, 160.3.
2.3.14. 2-(N-anilino)-2-(˛-naphthyl)acetonitrile
Yield 202 mg; White solid, IR (KBr): 3339, 3052, 2241, 1924,
1601, 1507, 1315, 1109, 747 cm−1 1H NMR (CDCl3, 300 MHz): ı
;
4.07 (d, J = 8.1 Hz, 1H), 6.04 (d, J = 7.8 Hz, 1H), 6.87 (d, J = 7.7 Hz, 2H),
6.94 (t, J = 7.4 Hz, 1H), 7.34 (t, J = 7.0 Hz, 2H), 7.53–7.59 (m, 3H),
7.9–7.98 (m, 4H); 13C NMR (CDCl3, 75.5 MHz): ı 48.48, 113.82,
118.16, 118.27, 120.24, 122.76, 125.28, 126.29, 126.58, 127.47,
129.11, 129.70, 130.18, 130.71, 134.09, 144.83; Found: C, 83.69;
H, 5.38; N, 10.79. Calc. for C18H14N2: C, 83.72%; H, 5.43%; N, 10.85%.
2.3.8. 2-(N-anilino)-2-(4-hydroxyphenyl)acetonitrile
Yield 152 mg; Grey solid, mp 120–122 ◦C; IR (KBr): 3341, 3022,
2232, 1602, 1271, 1156, 751 cm−1 1H NMR (CDCl3, 300 MHz): ı
;
4.58 (bs, 1H), 5.28 (s, 1H), 6.70–6.85 (m, 5H), 7.17 (t, J = 7.0 Hz, 2H),
7.32 (d, J = 8.5 Hz, 2H), 9.74 (bs, 1H); 13C NMR (CDCl3, 75.5 MHz): ı
49.19, 113.69, 115.85, 118.54, 119.21, 124.36, 128.25, 129.03, 144.9,
157.99; Found: C, 75.11; H, 5.41; N, 12.38. Calc. for C14H12N2O: C,
75.08%; H, 5.36%; N, 12.41%.
2.3.15. 2-(N-anilino)-3-methylbutanenitrile
Yield 208 mg; colourless oil; 1H NMR (CDCl3, 300 MHz): ı 1.24
(m, 6H), 2.19 (m, 1H), 3.76 (d, J = 9.0 Hz, 1H), 4.06 (q, J = 6.0 Hz, 1H),
6.72 (d, J = 7.5 Hz, 2H), 6.87 (t, J = 7.3 Hz, 1H), 7.26 (t, J = 7.9 Hz, 2H);
13C NMR (CDCl3, 75.5 MHz): ı 18.22, 19.13, 31.64, 52.56, 114.12,
118.66, 119.97, 129.52, 145.11; Found: C, 75.86; H, 8.04; N, 16.09.
Calc. for C11H14N2: C, 75.81%; H, 8.07%; N, 16.12%.
2.3.9. 2-(N-anilino)-2-(4-hydroxy-3-methoxyphenyl)acetonitrile
Yield 125 mg; Yellow solid, mp 106–108 ◦C; IR (KBr): 3377, 3021,
2237, 1604, 1509, 1253, 1208, 1028, 758, 691 cm−1; 1H NMR (CDCl3,
300 MHz): ı 3.93 (bs, 1H), 3.93 (s, 3H), 5.35 (s, 1H), 5.76 (bs, 1H),
6.78 (d, J = 8.5 Hz, 2H), 6.88–6.98 (m, 3H), 7.06 (d, J = 2.0 Hz, 1H),
7.3 (d, J = 7.5 Hz, 2H); 13C NMR (CDCl3, 75.5 MHz): ı 50.08, 56.11,
109.6, 114.13, 114.9, 118.37, 120.26, 120.49, 125.69, 144.72, 146.67,
147.05; Found: C, 70.84; H, 5.56; N, 11.0. Calc. for C15H14N2O2: C,
70.87%; H, 5.51%; N, 11.02%.
2.3.16. 2-[N-(2-methylanilino)]-2-phenylacetonitrile
Yield 174 mg; White solid; IR (KBr): 3360, 3031, 2236, 1597,
1503, 1448, 1258, 1055, 743, 693 cm−1 1H NMR (CDCl3, 300 MHz):
;
ı 2.09 (s, 3H), 3.81 (s, 1H), 6.78 (q, J = 7.8 Hz, 2H), 7.07 (d, J = 7.2 Hz,
1H), 7.1 (t, J = 8.2 Hz, 1H), 7.4 (m, 3H), 7.56 (m, 2H); 13C NMR (CDCl3,
75.5 MHz): ı 17.4, 50.0, 111.6, 118.3, 120.0, 123.52, 127.2, 129.34,
129.5, 130.5, 134.14, 142.75; Found: C, 81.04; H, 6.34; N, 12.57. Calc.
for C15H14N2: C, 81.08%; H, 6.31%; N, 12.61%.
2.3.10. 2-(N-anilino)-2-(3,4-dimethoxyphenyl)acetonitrile
Yield 144 mg; Pale yellow solid, mp 134–136 ◦C; IR (KBr): 3337,
2933, 2230, 1601, 1512, 1287, 1239, 1141, 1024, 761 cm−1; 1H NMR
(CDCl3, 300 MHz): ı 3.83 (s, 3H), 3.84 (s, 3H), 3.9 (s, 1H), 5.31 (s,
1H), 6.72 (d, J = 8.5 Hz, 2H), 6.83 (t, J = 8.7 Hz, 2H), 6.99 (d, J = 2.1 Hz,
1H), 7.1 (d, J = 9.3 Hz, 1H), 7.2 (t, J = 7.0 Hz, 2H); 13C NMR (CDCl3,
75.5 MHz): ı 50.05, 56.0, 56.02, 110.22, 111.37, 114.27, 118.28,
119.73, 120.37, 126.17, 129.54, 144.57, 149.6, 149.95; Found: C,
71.60; H, 5.99; N, 10.41. Calc. for C16H16N2O2: C, 71.64%; H, 5.97%;
N, 10.45%.
2.3.17. 2-[N-(4-methylanilino)]-2-phenylacetonitrile
Yield 185 mg; White solid, mp 100–102 ◦C; IR (KBr): 3328, 3023,
2242, 1613, 1518, 1282, 801, 697 cm−1 1H NMR (CDCl3, 300 MHz):
;
ı 2.13 (s, 3H), 3.74 (bs, 1H), 5.24 (s, 1H), 6.55 (d, J = 8.2 Hz, 2H),
6.92 (d, J = 7.9 Hz, 2H), 7.29 (d, J = 6.3 Hz, 3H), 7.44 (d, J = 5.4 Hz, 2H);
13C NMR (CDCl3, 75.5 MHz): ı 20.45, 50.7, 118.31, 127.21, 129.26,
129.43, 129.75, 130.03, 134.12, 142.38.
2.3.18. 2-[N-(4-chloroanilino)]-2-phenylacetonitrile
2.3.11. 2-(N-anilino)-2-(3,4,5-trimethoxyphenyl)acetonitrile
Yield 171 mg; White solid, mp 71–72 ◦C; IR (KBr): 3345, 1130,
Yield 137 mg; White solid, mp 130–132 ◦C; IR (KBr): 3350, 2974,
1599, 1495, 1071, 820, 691, 638 cm−1 1H NMR (CDCl3, 300 MHz):
;
2942, 2220, 1599, 1505, 1238, 1129, 1001, 760, 701 cm−1
;
1H NMR
ı 3.99 (bs, 1H), 5.35 (s, 1H), 6.69 (d, J = 7.5 Hz, 2H), 6.85 (t, J = 7.5 Hz,
1H), 7.21 (t, J = 7.2 Hz, 2H), 7.36 (d, J = 8.7 Hz, 2H), 7.47 (d, J = 6.9 Hz,
2H); 13C NMR (CDCl3, 75.5 MHz): ı 49.7, 114.33, 117.79, 120.6,
128.56, 129.51, 129.59, 132.46, 135.6, 144.37; Found: C, 69.24; H,
4.58; N, 11.62. Calc. for C14H11N2Cl: C, 69.28%; H, 4.54%; N, 11.55%.
(CDCl3, 300 MHz): ı 3.7 (s, 3H), 3.72 (s, 3H), 3.73 (s, 3H), 3.9 (s, 1H),
5.21 (s, 1H), 6.64 (d, J = 9.7 Hz, 2H), 6.66 (s, 2H), 6.76 (t, J = 7.3 Hz, 1H),
7.14 (t, J = 8.1 Hz, 2H); 13C NMR (CDCl3, 75.5 MHz): ı 50.05, 56.28,
60.86, 104.35, 112.3, 117.17, 120.38, 129.31, 129.57, 139.31, 144.64,
153.8; Found: C, 68.51; H, 6.01; N, 9.44. Calc. for C17H18N2O3: C,
68.46%; H, 6.04%; N, 9.40%.
2.3.19. 2-[N-(4-bromoanilino)]-2-phenylacetonitrile
Yield 147 mg; White solid, mp 74–76 ◦C; IR (KBr): 3318, 3066,
2.3.12. 2-(N-anilino)-2-furfurylacetonitrile
2245, 1592, 1500, 1286, 1071, 816, 695 cm−1 1H NMR (CDCl3,
;
Yield 198 mg; White solid, mp 66–68 ◦C; IR (KBr): 3373, 2367,
300 MHz): ı 3.96 (d, J = 7.76 Hz, 1H), 5.23 (d, J = 8.0 Hz, 1H), 6.49 (d,
J = 8.7 Hz, 2H), 7.21 (d, J = 8.7 Hz, 2H), 7.30 (m, 3H), 7.43 (d, J = 3.7 Hz,
2H); 13C NMR (CDCl3, 75.5 MHz): ı 50.2, 112.3, 115.3, 117.8, 127.2,
129.7, 132.3, 133.5, 143.64; Found: C, 58.58; H, 3.78; N, 9.80. Calc.
for C14H11N2Br: C, 58.54%; H, 3.83%; N, 9.76%.
2242, 1605, 1505, 1297, 965, 744, 691 cm−1 1H NMR (CDCl3,
;
300 MHz): ı 3.96 (bs, 1H), 5.5 (s, 1H), 6.44 (m, 1H), 6.69 (d, J = 3.3 Hz,
1H), 6.79 (d, J = 7.8 Hz, 2H), 6.93 (t, J = 7.4 Hz, 1H), 7.3 (t, J = 7.9 Hz,
2H), 7.49 (t, J = 0.9 Hz, 1H); 13C NMR (CDCl3, 75.5 MHz): ı 44.4,
109.61, 110.9, 114.5, 116.44, 120.7, 129.57, 143.97, 144.04, 146.07;
Found: C, 72.76; H, 5.06; N, 13.47. Calc. for C12H10N2O: C, 72.73%;
H, 5.05%; N, 14.14%.
2.3.20. 2-(N-cyclohexylamino)-2-phenylacetonitrile
Yield 157 mg; Pale yellow solid, mp 56–58 ◦C; IR (KBr): 3313,
2927, 2853, 2231, 1449, 1118, 922, 741, 696 cm−1 1H NMR (CDCl3,
;
2.3.13. 2-(N-anilino)-2-cinnamylacetonitrile
300 MHz): ı 1.07–1.74 (m, 10H), 1.94 (d, J = 13.9 Hz, 1H), 2.8 (m,
1H), 4.77 (s, 1H), 7.29–7.43 (m, 3H), 7.46 (d, J = 7.6 Hz, 2H); 13C NMR
(CDCl3, 75.5 MHz): ı 24.23, 24.6, 25.9, 31.9, 33.8, 51.56, 54.8, 119.3,
Yield 142 mg; Yellow solid, mp 116–118 ◦C; IR (KBr): 3351, 3048,
2224, 1604, 1505, 1264, 1147, 978, 897, 750, 692 cm−1 1H NMR
;

114
B. Karmakar et al. / Applied Catalysis A: General 392 (2011) 111–117
Fig. 1. (a) TEM image of the sponge like porous catalyst surface and (b) homogeneous grafting of Ga2O3 nanoparticles over the silica matrix (4 mol% Ga-TUD-1).
127.24, 127.25, 128.9, 133.5; Found: C, 78.47; H, 8.39; N, 13.13. Calc.
for C14H18N2: C, 78.50%; H, 8.41%; N, 13.08%.
300 MHz): ı 1.63–1.74 (m, 4H), 2.44–2.57 (m, 4H), 4.89 (s, 1H),
7.17–7.35 (m, 3H), 7.39 (d, J = 7.3 Hz, 2H); 13C NMR (CDCl3,
75.5 MHz): ı 23.44, 50.25, 59.3, 116.11, 127.65, 128.64, 128.74,
134.26; Found: C, 77.35; H, 7.56; N, 15.11. Calc. for C12H14N2: C,
77.42%; H, 7.53%; N, 15.05%.
2.3.21. 2-(N-piperidino)-2-phenylacetonitrile
Yield 207 mg; Yellow oil; IR (KBr): 3438, 3065, 2938, 1806, 2226,
1450, 1316, 1268, 1100, 736, 696 cm−1 1H NMR (CDCl3, 300 MHz):
;
ı 1.32–1.55 (m, 6H), 2.4 (m, 4H), 4.7 (s, 1H), 7.2–7.43 (m, 3H), 7.51
(d, J = 7.0 Hz, 2H); 13C NMR (CDCl3, 75.5 MHz): ı 23.9, 25.8, 50.9,
63.0, 115.6, 127.8, 128.64, 128.7, 133.5; Found: C, 78.06; H, 7.96; N,
14.03. Calc. for C13H16N2: C, 78.00%; H, 8.00%; N, 14.00%.
3. Results and discussion
3.1. Characterization of the catalyst
In our early communications we reported Ti-TUD-1 as
an effective catalyst for the synthesis of biologically active
bis(indolyl)methanes and trisubstituted electrophilic olefins
2.3.22. 2-(N-morpholino)-2-phenylacetonitrile
Yield 136 mg; heavy oil; IR (KBr): 3451, 2855, 2231, 1730, 1643,
1452, 1250, 1116, 1005 cm−1 1H NMR (CDCl3, 300 MHz): ı 2.59
;
[31,32].
A similar methodology was followed to synthesize
(t, J = 4.7 Hz, 2H), 3.73 (m, 4H), 4.82 (s, 1H), 7.35–7.45 (m, 3H),
7.50–7.55 (m, 2H); 13C NMR (CDCl3, 75.5 MHz): ı 50.0, 62.44, 66.66,
115.15, 128.0, 128.83, 129.07; Found: C, 68.96; H, 5.74; N, 16.09.
Ga-TUD-1 applying non hydrothermal sol–gel technique using
triethanolamine–water mixture as the structure directing tem-
plate. Physical characterizations of the catalyst were performed
with TEM, low angle XRD, NH3 probed TPD, 29Si MAS NMR and
surface area analysis.
Calc. for C12H10N2O: C, 68.91%; H, 5.81%; N, 16.05%.
2.3.23. 2-(N-pyrrolidino)-2-phenylacetonitrile
The TEM micrographs (Fig. 1) show an irregular sponge like,
three-dimensional arrangement of mesopores. No extra framework
particles were observed from the figure which indicates homoge-
Yield 223 mg; Reddish oil; IR (KBr): 3430, 2967, 2815, 2222,
1702, 1492, 1454, 1271, 1125, 911, 703 cm−1 1H NMR (CDCl3,
;
Fig. 2. TEM mapping image of Si and Ga atom distributions over the catalyst framework for 4 mol% Ga-TUD-1.

B. Karmakar et al. / Applied Catalysis A: General 392 (2011) 111–117
115
Fig. 3. (a) The small angle X-ray diffraction pattern and (b) the NH3 TPD profile of calcined 4 mol% Ga-TUD-1 catalyst.
neous incorporation of gallium oxide nanoparticles (∼5–6 nm) in
-109
the silicate matrix. The uniformly grafted Ga distribution over the
matrix was as also confirmed from TEM mapping image of Si and
Ga atoms (Fig. 2).
-100
The XRD patterns of the Ga-TUD-1 samples showed a single
broad reflection in the low angle region 0≤ 2ꢀ ≤ 2◦ indicating that
the materials were highly mesostructured (Fig. 3a) [33]. For the
measurement of surface acidity the NH3 TPD was performed for the
calcined Ga-TUD-1 which reflected three maxima located at 220 ◦C,
500 ◦C and a distinct shoulder at 890 ◦C (Fig. 3b). These TPD profiles
were similar to those observed for dealuminated large-pore zeo-
lites of the faujasite family. The strength and distribution of acid
sites of both structure types are comparable. Karge et al. [34] found
a large number of both strong and weak Brønsted as well as Lewis
acid sites in dealuminated zeolite which were found to be present
in Ga-TUD-1 catalyst.
-89
-140
-120
-100
-80
-60
29Si MAS NMR measurements were performed with a freshly
calcined sample to obtain detailed information on the change about
the state in the vicinity of the surface. As shown in Fig. 4, the spec-
trum gives a weak single band at −100 ppm (Q3 species), which
was accompanied by extremely weak shoulders at around −109
and −89 ppm. These two components could be ascribed to Q4 and
Q2 silicon species. The three-band nature indicated that hydrolysis
of the siloxane bond took place on the surface and resulted in the
formation of a new hydroxylated species, the geminal-type silanol
groups [35].
δ/ppm
Fig. 4. 29Si NMR spectrum of Ga-TUD-1 catalyst (4 mol%).
solvents was carried out for the reaction with benzaldehyde, ani-
line and TMSCN over Ga-TUD-1 (Table 1). The catalyst showed best
result in solventless condition in terms of productivity and reaction
time. Among the different tested solvents toluene, THF and acetoni-
trile afforded poor results which might be due to their basic nature
The BET specific surface area and BJH isotherm measurement
results demonstrated that the sample is of high surface area
(675 m2 g−1) with a pore size of almost 5 nm and pore volume
0.93 cm3/g.
100
75
50
25
0
3.2. Study of catalytic activity
A very simple methodology was followed in the reaction proto-
col. Mixture of an aldehyde, an amine and TMSCN were stirred in
the absence of solvent at room temperature over Ga-TUD-1 cata-
lyst. The progress was checked by TLC and after work-up excellent
yields of the product was obtained. No other additive was required
to promote the reaction. Prior to work up the reaction mixture was
diluted with CH2Cl2 and it was centrifuged to separate the catalyst.
It was then washed several times with acetone and dried for reuse.
In recycling the catalyst for a representative reaction for consec-
utive four times the activity remained almost unchanged (Fig. 5).
During optimization of the reaction conditions a screening of the
run1
run2
run3
run4
Fig. 5. Reusability study of the catalyst with entry 1, Table 2.

116
B. Karmakar et al. / Applied Catalysis A: General 392 (2011) 111–117
Table 1
Table 3
Screening of solvents in Strecker reaction using Ga-TUD-1 catalysta.
One-pot synthesis of ␣-aminonitriles (4) via condensation of benzaldehydes, amines
and TMSCN at room temperature.
Entry
Solvent
Time (h)
Yield (%)b
Ph
CN
NHR
+
+
PhCHO
RNH2
TMSCN
1
2
3
4
5
6
Toluene
THF
CH3CN
CH2Cl2
EtOH
12
8
5
6
2
52
47
78
85
91
95
.
Entry
Amine
Product
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
9
10
C6H5NH2
4a
4b
4c
4d
4e
4f
4g
4h
4i
0.5
0.5
0.5
0.7
1.0
0.5
2.0
2.0
1.5
1.0
95
89
93
92
90
83
88
90
83
84
Solventless
0.5
2-Me-C6H4NH2
4-Me-C6H4NH2
4-Cl-C6H4NH2
4-Br-C6H4NH2
Cyclohexylamine
Piperidine
a
Reaction condition: 1.0 mmol benzaldehyde, 1.0 mmol aniline, 1.3 mmol
TMSCN, 20 mg catalyst, room temperature stirring.
b
Isolated yield.
which naturally would reduce the catalytic activity. CH2Cl2 and
ethanol took longer time for completion of the reaction. As the ini-
tial step of the reaction is imine formation, the released water takes
part in protonation. 4 mol% Ga loaded TUD-1 matrix was optimized
as the catalyst for the reactions.
Pyrrolidine
Morpholine
Butylamine
4j
Reaction condition: 1.0 mmol benzaldehyde, 1.0 mmol amine, 1.3 mmol TMSCN,
20 mg catalyst, room temperature stirring.
b
Isolated yield.
On reaching the optimized conditions a wide range of ␣-
aminonitriles were synthesized by using different aldehydes and
amines reacting with TMSCN. The results have been shown in
Table 2. Most of the aldehydes reacted efficiently with aniline and
TMSCN in the absence of solvent to furnish the corresponding prod-
ucts in excellent yields (79–95%). A variety of substituents in the
aromatic aldehydes viz., NO2, Cl, CN, OMe, OH, Me are compatible
in this reaction. Heterocyclic aldehydes like furfural, pyridine-2-
carbaldehyde resulted in good yields. Unsaturated aldehyde like
cinnamaldehyde furnished high yield of the product. Encouraged
by the above results we continued the endeavor by treating variety
of amines with benzaldehyde and TMSCN under similar conditions
(Table 3). Different aromatic and aliphatic amines were used in the
reaction and we observed that both the type of amines reacted
smoothly to furnish the corresponding products in moderate to
high yields. However the aliphatic amines reacted at much faster
rate than the aromatic amines due to higher basicity.
can believe that these two factors are largely responsible for its high
catalytic activity. These active sites are symmetrically dispersed
over the ordered 3D pores of the matrix and are easily accessible by
the reactant molecules. The initial step of the reaction being imine
formation is facilitated by the Bronsted sites and further addition
of cyanide ions to imine is accelerated due to the presence of Lewis
acidic Ga3+ ions.
4. Conclusion
An efficient, clean, step economic and one-pot procedure for the
synthesis of ␣-aminonitriles has been demonstrated by the three
component coupling of aldehyde, amine and TMSCN over a new
heterogeneous catalyst Ga-TUD-1 under solventless condition. Fast
reaction, operational simplicity, high yield and reusability of the
catalyst are the striking features of this methodology. Our approach
of using the strong Lewis acidic Ga-TUD-1 catalyst in the Strecker
reaction might open new vistas for its use in different organic trans-
formations in future.
3.3. Mechanistic study
As the NH3 TPD study confirmed the presence of large number of
Bronsted as well as Lewis acidic sites in the Ga-TUD-1 catalyst, we
Acknowledgements
Table 2
One-pot synthesis of ␣-aminonitriles (3) via condensation of aldehydes, aniline and
TMSCN at room temperature.
B.C would like to acknowledge DST, Govt. of India for financial
assistance under fast track young scientist scheme (Proposal num-
ber SR/FTP/ETA-16/2007), New Delhi. J.B would like to thank the
instrumental laboratories, Department of Chemistry, University of
Calcutta, for providing technical facilities.
Ar
CN
NHPh
+
+
RCHO
PhNH2
TMSCN
.
Entry
Aldehyde
C6H5CHO
4-NO2-C6H4CHO
3-NO2-C6H4CHO
4-Cl-C6H4CHO
4-Me-C6H4CHO
4-CN-C6H4CHO
4-OMe-C6H4CHO
3-OMe-C6H4CHO
4-OH-C6H4CHO
3-OH-C6H4CHO
4-OH-3-OMe-C6H4CHO
3,4-di-OMe-C6H3CHO
3,4,5-tri-OMe-C6H2CHO
2-Furfural
Product
Time (h)
Yield (%)b
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6
7
8
3a
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3h
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3k
3l
3m
3n
3o
3p
3q
3r
0.5
0.3
0.5
0.5
1.0
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1.0
1.2
1.5
1.0
2.0
1.0
1.0
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1.0
1.0
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85
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