Activation of trimethylsilyl cyanide and mechanistic investigation for facile cyanosilylation by solid acid catalysts under mild and solvent-free conditions

Article abstract of DOI:10.1016/j.apcata.2010.06.019

Sulfated-zirconia is found to be a highly efficient heterogeneous solid catalyst in activating trimethylsilyl cyanide (TMSCN) for facile cyanosilylation of aldehydes. A unifying explanation is provided for the cyanosilylation reactions. The unique role of

Full text of DOI:10.1016/j.apcata.2010.06.019

Applied Catalysis A: General 384 (2010) 147–153
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Activation of trimethylsilyl cyanide and mechanistic investigation for facile
cyanosilylation by solid acid catalysts under mild and solvent-free conditions
Boningari Thirupathi, Meghshyam K. Patil, Benjaram M. Reddy∗
Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 607, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Sulfated-zirconia is found to be a highly efficient heterogeneous solid catalyst in activating trimethylsi-
lyl cyanide (TMSCN) for facile cyanosilylation of aldehydes. A unifying explanation is provided for the
cyanosilylation reactions. The unique role of sulfated-zirconia consists of rendering cyanide anions from
TMSCN to C O of aldehydes and providing the corresponding cyanohydrin silyl ethers in quantitative
yields under mild and solvent-free conditions.
Received 16 January 2010
Received in revised form 11 June 2010
Accepted 14 June 2010
Available online 18 June 2010
© 2010 Elsevier B.V. All rights reserved.
Keywords:
Cyanosilylation
Sulfated-zirconia
Mechanistic investigations
Solid acids
Solvent-free synthesis
1. Introduction
[7,10,11]. Because of their importance in organic synthesis and life
science research, a large body of work has been devoted to the
Trimethylsilyl nucleophiles (Me3SiNu) with silicon atoms
attached to carbon, nitrogen, oxygen, or sulfur atoms have long
been recognized as effective alternatives for proton nucleophiles
(HNu) in addition reactions to electrophiles such as aldehydes,
ketones, imines, oxiranes, aziridines, nitrones and polar conjugated
systems [1]. The number of examples of such additions has been
growing steadily over the past 40 years, while the availability of
trimethylsilyl nucleophiles is on the rise and new methods of trans-
formation of silylated pronucleophiles into active nucleophiles
are emerging. The interest in Me3SiNu additions was stimulated
by the properties of the silicon atom, allowing the generation of
active nucleophilic species (Nu−) under different conditions in
comparison to HNu sources. Among all the trimethylsilyl nucle-
ophiles, TMSCN is the best source [2–5], in view of the fact that
the average dissociation energy of Si–C bond is extremely low.
Trimethylsilyl ethers can readily be isolated or transformed into
cyanohydrins by mild acidic hydrolysis. However, cyanohydrins
and their trimethylsilyl ethers are key building blocks for one-step
synthesis of many biologically active compounds [6–8], ferro-
electrics and liquid crystals [9] that are otherwise only obtained
with difficulty. They can easily be converted into various function-
alized ␣-hydroxy acids, ␣-hydroxy aldehydes, ␤-amino alcohols,
␣-cyano ketones, 1,2-diols and other polyfunctional compounds
development of cyanohydrin synthesis. Transfer of a cyano group
from TMSCN to an aldehyde/ketone can be catalyzed by numerous
reagents [12–21], including Lewis acids, Lewis bases, metal alkox-
ides, bifunctional catalysts and inorganic salts. Also a few supported
versions or versions based on room temperature cyanosilylation
reactions [22], activation of TMSCN by N-heterocyclic carbenes
[23], solvent-free cyanosilylations [13,24], and mechanistic studies
for cyanosilylations have recently been described [25]. However,
no zirconia-based solid acid catalyzed activation of trimethylsi-
lyl cyanide for the facile cyanosilylation version has so far been
reported. We are currently exploring application of zirconia-based
solid acid catalysts to organic syntheses because of numerous
advantages [26–30].
In recent years, there has been increasing emphasis on the
design and application of environmental friendly solid acid cata-
lysts to reduce the quantity of toxic wastes. Zirconia-based solid
acid catalysts are finding outstanding applications as active adsor-
bents for various gases and for distraction of hazardous chemicals,
and as catalysts for many organic transformations [31–34]. More
recently, a concerted study from Japan confirmed the super-
acidity of the sulfated-zirconia catalysts [35]. Recently, we have
reported our finding of an efficient zirconia-based solid acid
catalyzed Strecker reaction by TMSCN to ␣-aminonitriles and 1,3-
asymmetric induction in Strecker synthesis towards optical active
␣-aminonitriles [36]. As part of our continued efforts [26–30,36,37]
and to gain more insight into this unprecedented mode of reactivity
of promoted zirconia-based solid acids, we now wish to disclose a
∗
Corresponding author. Tel.: +91 40 27191714; fax: +91 40 27160921.
E-mail addresses: bmreddy@iict.res.in, mreddyb@yahoo.com (B.M. Reddy).
0926-860X/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2010.06.019

148
B. Thirupathi et al. / Applied Catalysis A: General 384 (2010) 147–153
at 353 K for 2 h and subsequently flushed with He (60 ml min−1
)
at 373 K for 2 h to remove the physisorbed ammonia. The heat-
ing rate for the TPD measurements, from ambient to 1023 K, was
10 K min−1. The scanning electron microscopy (SEM) analysis was
carried out with a Hitachi model-520 instrument. The finely pow-
dered samples were mounted on a silver sample holder with the
help of an adhesive to make the sample surface conductive and
were coated with gold metal at 10 mm Hg pressure. X-ray photo-
electron spectroscopy (XPS) measurements were conducted with
a Kratos Axis 165 instrument with a dual anode (Mg and Al)
apparatus using the Mg K␣ source. The carbon 1 s binding energy
(283.7 eV) was used as reference for determining the binding ener-
gies.
Scheme 1. Well-designed zirconia-based solid acid catalysts for synthesis of
trimethylsilyl ethers by using TMSCN under solvent-free conditions.
facile solid acid catalyzed cyanosilylation reaction between TMSCN
and aldehydes under mild and solvent-free conditions by activating
TMSCN and aldehydes (Scheme 1). This reaction serves as a good
example to show that a silicon-based reagent such as TMSCN can
be activated by zirconia-based solid acid catalysts for nucleophilic
addition reactions. In this work, we synthesized zirconia-based
solid acid catalysts and investigated the cyanosilylation of various
aldehydes under solvent-free conditions at ambient temperature.
The reaction mechanism has also been investigated in detail to
understand the role of sulfated-zirconia catalyst by different char-
acterization techniques.
2.3. Activity studies
All chemicals employed in this study were commercially avail-
able and were used without further purification. A mixture
of aldehyde (1 mmol), TMSCN (1.2 mmol) and sulfated-zirconia
(SO42−/ZrO2) solid acid catalyst (50 mg) was stirred at room tem-
perature for an appropriate time under N2 atmosphere. Caution:
TMSCN must be used in a well-ventilated hood due to its toxic-
ity and moisture sensitive nature. After completion of the reaction,
as indicated by TLC, the reaction mixture was filtered and washed
with ethyl acetate (3 × 5 mL). The combined organic layers were
dried over anhydrous Na2SO4, concentrated in vacuum and puri-
fied by column chromatography on silica gel using ethyl acetate
and hexane as eluent to afford pure trimethylsilyl ethers. All prod-
ucts were identified by comparing their spectral data with that in
the literature [18,22,24,38].
2. Experimental section
2.1. Catalyst preparation
Zirconium hydroxide was prepared first from zirconium oxy-
chloride by hydrolysis with dilute aqueous ammonia solution. For
this purpose, the requisite quantity of ZrOCl2·8H2O (Loba Chime,
GR grade) was dissolved in doubly distilled water. To this clear
solution, aqueous NH3 was added dropwise with vigorous stirring
until the pH of the solution reached 8. The obtained precipitate
was washed with hot distilled water several times until free from
chloride ions and dried at 393 K for 24 h. On the resulting hydrous
zirconium hydroxide, sulfate, molybdate and tungstate promot-
ers were deposited by a wet impregnation method. To incorporate
these promoters, we used sulfuric acid, ammonium heptamolyb-
date and ammonium metatungstate (Aldrich, AR Grade) as the
precursors, respectively. Detailed procedures for the preparation
of these catalysts could be found elsewhere [26–30,36,37].
3. Results and discussion
Incorporation of various promoters (sulfate, molybdate and
tungstate) into Zr(OH)4 gel during synthesis showed a strong influ-
ence on the bulk and surface properties of the zirconia. XRD and
Raman spectroscopy results revealed that addition of promot-
ers enhance tetragonal zirconia phase and surface acidity [37].
Ammonia-TPD results indicated that impregnated sulfate ions
show a strong influence and enhance the acidity of zirconia, which
is followed by molybdate promoter [37].
2.2. Catalyst characterization
The powder X-ray diffraction (XRD) patterns of the synthesized
catalysts were recorded on a Siemens D-5000 diffractometer by
using Cu K␣ radiation source and a scintillation counter detector.
The XRD phases present in the samples were identified with the
help of Powder Diffraction File-International Center for Diffrac-
tion Data (PDF-ICDD). The FTIR spectra were recorded on a Nicolet
740 FTIR spectrometer, using KBr discs, with a nominal resolu-
tion of 4 cm−1 and averaging 100 spectra. The BET surface areas
were determined by N2 physisorption at liquid-N2 temperature
on a Micromeritics Gemini 2360 instrument. Prior to analysis, the
samples were oven dried at 393 K for 12 h and flushed with Argon
gas for 2 h. Raman spectra were recorded at ambient tempera-
ture on a DILOR XY spectrometer equipped with a CCD detector.
The spectra were recorded in the range of 4000–100 cm−1 and
at a spectral resolution of 2 cm−1 using the 514.5 nm excitation
line from an argon ion laser (Spectra Physics, USA). The temper-
ature programmed desorption (TPD) measurements were carried
out on an Auto Chem 2910 instrument (Micromeritics, USA). A
thermal conductivity detector was used for continuous monitoring
of the desorbed ammonia; the areas under the peaks were inte-
grated using GRAMS/32 software. Prior to TPD studies, samples
were pretreated at 473 K for 1 h in a flow of ultra pure helium gas
(40 ml min−1). After pretreatment, the sample was saturated with
At the beginning, we initiated our investigation with the
screening of various catalysts by making use of different sol-
vents, varying the amount of catalyst, and using different catalysts
obtained by varying the calcination temperature and preheating
temperature during synthesis of catalysts. We selected foremost
a commonly used aldehyde, benzaldehyde, for cyanosilylation.
The results obtained are summarized in Table 1. Preliminary
experiments in various solvents revealed that reaction pro-
gresses very well under solvent-free conditions (Table 1, Entries
4 and 5) in comparison to the results for different solvents,
namely, CH3CN, CH2CH2Cl2 and THF (Table 1, Entries 1–3). Indeed,
sulfated-zirconia (SO42−/ZrO2) was found to be more efficient
than molybdated-zirconia (MoOx/ZrO2) and tungstated-zirconia
(WOx/ZrO2) catalysts (Table 1, Entries 4, 9, and 10). The calcina-
tion temperature of the catalyst also caused a divergence in the
yield of the product (Table 1, Entries 11 and 12). Furthermore, an
increase in the amount of catalyst showed a significant increase in
the yield of the products (Table 1, Entries 5–8). Of course, we could
not observe any conversion in the absence of catalyst (Table 1, Entry
14), even after stirring for few days. Similar observation of no activ-
ity in the absence of catalyst and influence of other parameters was
also made earlier in the literature under identical reaction condi-
tions identical to these employed in the present study [5]. These
results clearly emphasize the role of promoted zirconia catalyst.
10% ultra pure anhydrous ammonia gas (balance He, 75 ml min−1
)

B. Thirupathi et al. / Applied Catalysis A: General 384 (2010) 147–153
149
Table 1
Search for optimal catalysts and reaction conditionsa.
Sr. no.
Catalyst
Amount of catalyst (mg)
Solvent
Time (min)
Yield (%)b
BET SA (m2 g−1
)
NH3 desorbed (ml/g)
1.
2.
3.
4.
5.
6.
7.
8.
SO42−/ZrO2
SO42−/ZrO2
SO42−/ZrO2
SO42−/ZrO2
SO42−/ZrO2
SO42−/ZrO2
SO42−/ZrO2
SO42−/ZrO2
WO3/ZrO2
MoO3/ZrO2
SO42−/ZrO2
SO42−/ZrO2
SO42−/ZrO2
–
50
50
50
50
50
40
30
20
50
50
50
50
50
–
ACN
EDC
THF
–
–
–
–
–
–
–
120
120
120
120
120
120
120
120
120
120
120
120
90
56
62
25
67
82
55
43
36
55
59
76
88
100
100
100
100
100
100
100
100
94
35
–
–
100
–
16
16
16
16
16
16
16
16
09
11
–
c
9.
10.
11.
12.
13.
14.
d
e
–
–
–
–
–
16
–
∼100f
NR
g
–
NR: no reaction.
a
Reagents and reaction conditions; benzaldehyde (1 mmol) TMSCN (1.2 mmol), 2 ml solvent.
b
c
d
e
f
Yields evaluated by 1H NMR spectroscopy.
Preheating at 523 K.
Calcination at 973 K.
Calcination at 1073 K.
Reaction of 90 min.
g
Seven days.
FTIR spectra, the C N stretching was observed at 2189 cm−1 for
free TMSCN molecules, which is consistent with the reported val-
ues [45,46]. When sulfated-zirconia was immersed in the TMSCN
solution and then the residue was filtered off, rinsed with chlo-
In order to examine the possibility of recyclability, after the
reaction we removed the solid catalyst conveniently by simple fil-
tration from the reaction mixture. The wet catalyst was reused for
next reaction without any washing. Each catalyst could be easily
recovered and reused for at least 5 cycles with trivial changes in
the catalytic activity. Recycling experiments were examined for the
cyanosilylation of benzaldehyde at room temperature (Fig. 1).
With these “green” conditions in hand, we then explored
the scope of this new promoted zirconia-based solid acid cat-
alyzed cyanosilylation reaction (Scheme 1 and Table 2). We also
investigated the role of aldehyde in this reaction. Aromatic alde-
hydes having electron withdrawing and donating substituents,
heteroaromatic and vinyl aldehydes are found to be active for
cyanosilylation reaction with sulfated-zirconia offering good to
better yields (62–96%) within short reaction times (50–200 min).
Moreover, the reaction conditions are mild enough to perform the
reaction in the presence of acid sensitive substrates, such as fur-
furaldehyde and cinnamaldehyde without any decomposition or
polymerization (Table 2, Entries 6 and 10). In the meantime, we also
investigated the role of a catalyst to activate TMSCN and aldehydes
towards cyanosilylation reactions.
roform, and analyzed by FTIR spectroscopy, the peak of the C
N
stretching appeared at 2338 cm−1. The C N stretching band was
blue-shifted by 149 cm−1. The blue shift indicate the adsorption
and interaction of TMSCN on the surface of sulfated-zirconia, and
the linear coordination (␴ bonding) through the lone-pair electrons
of the nitrogen atom results in an increase of the C N stretching
frequency compared with that of the free trimethylsilyl cyanide
molecule. In other words, the blue shift can be attributed to the
effect of nitrogen to metal cation (Zr+) electron donation. Notably,
the stretch of the cyanide anion in water occurs at 2080 cm−1 and
the coordination of the anion at a metal always increases the fre-
quency of this absorption [47]. This phenomenon suggests that
the cyanide ligand has significantly interacted with the Zr4+ ions,
which are Lewis acidic centres on the surface of the catalyst. We
perceive a strong absorption band in the range of 900–1300 cm−1
.
It is suggested that this band is the result of superimposition of
two absorption peaks. One is the strong 1156 cm−1 peak attributed
to the Zr–N stretching vibration, suggesting that there may be an
electronic change from nitrogen to Zr+ Lewis acidic center. Com-
parison with other oxides leads us to suggest that the cationic
charge borne by the metallic cation is of prime importance for the
acid strength in the catalyst [48]. The other is the 1213 cm−1 line
caused by the C–N and Si–CH3 stretching vibration [49]. There are
3.1. Mechanistic investigation
Recent studies suggest that the activation of n-butane for iso-
merization of alkanes, the activation of CO for carbonylation of ben-
zene and methane, and the activation of alkanes for alkene forma-
tion are promoted by adsorption on the sulfated-zirconia catalyst
[39–42]. Based on these reports, we contemplated that trimethylsi-
lyl cyanide could be activated by adsorption on the sulfated-
zirconia solid acid catalyst for cyanosilylation of aldehydes.
Spectroscopic studies were used to understand the interactions
between trimethylsilyl cyanide and the surface of the sulfated-
zirconia catalyst. From the studies of metal cyanide complexes
and the cyanide adsorbed on the metal surfaces by using elec-
tron energy-loss spectroscopy (EELS), XPS and other techniques,
it has been proposed that the linear coordination (␴ bonding)
through the lone-pair electrons of the nitrogen atom results in an
increase of the C N stretching frequency compared with that of the
free trimethylsilyl cyanide molecule [43,44]. We investigated the
adsorption of TMSCN and benzaldehyde on the surface of sulfated-
zirconia by using FTIR (Fig. 2) and XPS techniques (Fig. 3). In the
Fig. 1. Recyclability of SO42−/ZrO2 catalyst.

150
B. Thirupathi et al. / Applied Catalysis A: General 384 (2010) 147–153
Table 2
a
Cyanosilylation of a variety of aldehydes in presence of SO42−/ZrO2
.
Entry
1.
Aldehyde
Product
Time (min)
Yield (%)b
96
300
2.
3.
100
150
88
81
4.
5.
90
93
91
200
6.
7.
50
65
92
87
8.
9.
90
95
86
120
10.
70
75
a
Reagents and reaction conditions; aldehyde (1 mmol), TMSCN (1.2 mmol) under N2 atmosphere at room temperature.
Isolated yields of pure products.
b
no peaks observed at ∼1500 cm−1 and ∼2100 cm−1, which would
be attributed to N–H bending and Si–H stretching, suggesting that
there is no transfer of hydrogen from sulfated-zirconia to TMSCN.
The peak at 700–800 cm−1 is attributed to Si–C stretching or Si–CH3
rocking or wagging [50].
The IR spectra of the sulfated-zirconia immersed in the
benzaldehyde solution and taken out, and rinsed with chlo-
roform contained an absorption peak at 1686 cm−1 that could
be attributed to the chemisorption of aldehyde on the sur-
face of sulfated-zirconia catalyst. The C O stretching frequencies
at 1698 cm−1 and 1686 cm−1 correspond to physisorbed and
chemisorbed benzaldehyde [22], respectively. Note that the spec-
trum of neat benzaldehyde also displays a carbonyl stretching
band at 1698 cm−1, which suggests that the benzaldehyde is
chemisorbed on the catalyst surface and that the catalyst is acti-
vating both aldehyde and TMSCN.
The results for sulfated-zirconia were partly obscured by an
intense band at 1392 cm−1 due to a vibration of sulfate groups.
However, the dominant detectable mode of adsorption involved
grafting of trimethysilylcyano groups to Lewis acidic exposed Zr4+
sites at 2338 cm−1. Trimethylsilyl cyanide would be expected to
be protonated at strongly Brønsted acidic sites on the sulfated-
zirconia, but we did not observe any peak related to the same.
No change in the color of the pressed discs in the present IR
cell was observed when trimethylsilyl cyanide was adsorbed on
the sulfated-zirconia. This could be taken as evidence for no
proton transfer from the catalyst to the TMSCN. Colour change
and FTIR results remain as definite indicators of no protona-

B. Thirupathi et al. / Applied Catalysis A: General 384 (2010) 147–153
151
Fig. 2. FTIR spectra of the catalyst before and after reaction: (SZ)–fresh
SO42−/ZrO2 catalyst; (SZ–TMSCN)–SO42−/ZrO2 catalyst after reaction with TMSCN;
(SZ–aldehyde)–SO42−/ZrO2 catalyst after reaction with aldehyde.
tion occurring during TMSCN adsorption on the sulfated-zirconia.
In sulfated-zirconia, the Lewis acidic centers (Zr+) are generally
electron-deficient sites and they are strengthened by the electron-
withdrawing nature of the sulfate groups. TMSCN molecules may
be adsorbed on sulfated-zirconia either in a flat or perpendicular
orientation to the surface. The strong electron-donating charac-
ter of the CN group donates much electron density to Lewis acidic
sites thereby increasing the strength of adsorption at Lewis acidic
surface sites via interaction with the cyanide in a flat orientation.
After high temperature treatments, the sulfated oxide demon-
strates mainly Lewis acidity rather than Brønsted acidity [51].
Morterra et al. [52] have elegantly shown that raising the treat-
ment temperature decreases the Brønsted activity and increases
the Lewis acidity as monitored by IR spectra of adsorbed pyridine.
As already confirmed by IR spectroscopy, the Lewis acidic sites
in sulfated-zirconia are activating the TMSCN for cyanosilylation.
An attempt has therefore been made here to generate a sulfated-
zirconia surface exhibiting a higher level of Lewis acidity than that
of the sulfated-zirconia which had been pretreated at 250 ◦C. Con-
sequently, we carried out the cyanosilylation of aldehyde reaction
with TMSCN as a cyanide source by taking the sulfated-zirconia
catalyst preheated at 350 ◦C, and we observed a greater increase in
the product yield 67–82% within 45 min (Table 1, Entries 4 and 5).
Also, we carried out this reaction by employing sulfated-zirconia
Fig. 3. XPS spectra of the catalysts before and after reaction with TMSCN: (SZ)–fresh
SO42−/ZrO2 catalyst; (SZTMS)–SO42−/ZrO2catalyst after reaction with TMSCN.
catalyst calcined at 650, 700 and 800 ◦C, and we observed great
increments in conversion of aldehydes to cyanosilylated products
(Table 1, Entries 11 and 12). These studies prove that activation of
TMSCN occurred by the adsorption on the surface of Lewis acidic
sites of sulfated-zirconia.
The chemical compositions of the surface layers of sulfated-
zirconia before and after reaction with TMSCN were studied
through XPS analysis to understand whether TMSCN is binding
on surface Brønsted acid sites or Lewis acid sites. The Zr 3d5/2 at

152
B. Thirupathi et al. / Applied Catalysis A: General 384 (2010) 147–153
Scheme 2. Plausible reaction mechanism for cyanosilylation of aldehydes catalyzed by SO42−/ZrO2.
183.51 eV and Zr 3d3/2 at 185.60 eV appeared in the XP spectra of
sulfated-zirconia sample, but these peaks are shifted to lower bind-
ing energies, i.e., Zr 3d5/2 at 181.92 eV and Zr 3d3/2 at 184.11 eV in
the spectra of TMSCN adsorbed sample (SZTMS). It could be due to
changes in electron density around surface zirconium ions, which
are electron-deficient Lewis acidic sites as reported earlier in the lit-
erature [53]. From the peak of the N 1s corresponding to the SZTMS
sample, the peak with a binding energy of 398.00 eV is assigned
to Zr–N bond in conformity with the literature [54]. The Si 2p and
C 1s peaks were observed at 101.08 eV and 283.63 eV, which are
corresponding to the values for SZTMS sample, but these are less
intense peaks. There is no shift in the binding energies in the cases
of O 1s and S 2p this mean that the cyanide source is interacting
only with Lewis acidic sites not with Brønsted sites. XPS results are
also supporting the blue shift of cyanide peak in FTIR spectroscopic
observations. All these results are tending to support an active role
of solid acid and supporting the mechanism presented in Scheme 2
for the formation of cyanosilyl ethers.
7.77–7.82 (m, 1H). FTIR (Neat): ꢀ 3342, 3113, 1749, 1605, 1433,
1298, 1220, 1024, 989, 743, 682, 618 cm−1; EIMS: m/z calcd for
C12H17NO2Si (M+): 235.
2-Furanyl (trimethylsilyloxy) acetonitrile (Table 2, Entry 6):
1H NMR (CDCl3, 200 MHz): ı = 0.29 (s, 9H), 5.58 (s, 1H), 6.41–6.43
(m, 1H), 6.57–6.6 (m, 1H), 7.4–7.52 (m, 1H). FTIR (Neat): ꢀ 3390,
3092, 2254, 1723, 1319, 1230, 1054, 864, 759, 656 cm−1; EIMS: m/z
calcd for C9H13NO2Si (M+): 195.
2-Thiophenyl (trimethylsilyloxy) acetonitrile (Table 2, Entry
7): 1H NMR (CDCl3, 200 MHz): ı = 0.22 (s, 9H), 5.68 (s, 1H), 6.83–6.86
(dd, 1H), 7.02–7.03 (m, 1H), 7.20–7.22(dd, 1H); FTIR (Neat): ꢀ 3403,
3110, 2251,1653, 1419, 1237, 1031, 847, 712, 667 cm−1; EIMS: m/z
calcd for C9H13NOSSi (M+): 211.
2-Pyridinyl (trimethylsilyloxy) acetonitrile (Table 2, Entry 8):
1H NMR (CDCl3, 300 MHz): ı = 0.36 (s, 9H), 5.63 (s, 1H), 7.35–7.40
(m, 1H), 7.66–7.69 (m, 1H), 7.83–7.90 (m, 1H), 8.63–8.67 (m, 1H);
FTIR (Neat): ꢀ 3418, 3109, 2925, 2147, 1725, 1597, 1450, 1347, 1297,
1246, 1084, 752, 679, 536 cm−1; EIMS: m/z calcd for C10H14N2OSi
(M+): 206.
The spectral data for some of the selected envoy compounds is
given below:
2-(4-Methylphenyl)-2-(trimethylsilyloxy)
acetonitrile
2-Phenyl-2-(trimethylsilyloxy) acetonitrile (Table 2, Entry 1):
1H NMR (CDCl3, 200 MHz): ı = 0.29 (s, 9H), 5.53 (s, 1H), 7.41–7.58
(m, 5H); FTIR (Neat): ꢀ 3436, 3035, 2960, 1696, 1453, 1255, 1194,
1097, 1071, 853, 752, 696 cm−1; EIMS: m/z calcd for C11H15NOSi
(M+): 205.
(Table 2, Entry 9): 1H NMR (CDCl3, 200 MHz): ı = 0.13 (s, 9H),
2.27 (s, 3H), 5.49 (s, 1H), 7.18 (d, 2H) 7.25 (d, 2H); FTIR (Neat): ꢀ
3173, 2926, 1741, 1591, 1438, 1283, 1242, 1110, 1048, 998, 752,
702, 619 cm−1; EIMS: m/z calcd for C12H17NOSi (M+): 219.
2-(4-Nitrophenyl)-2-(trimethylsilyloxy) acetonitrile (Table 2,
Entry 2): 1H NMR (CDCl3, 200 MHz): ı = 0.28 (s, 9H), 5.61 (s,
1H), 7.65–7.68 (m, 2H), 8.23–8.27 (m, 2H); FTIR (Neat): ꢀ 3427,
2976,1954, 1718, 1453, 1270, 1071, 1018, 761, 709 cm−1; EIMS:
m/z calcd for C11H14N2O3Si (M+): 250.
2-(2-Nitrophenyl)-2-(trimethylsilyloxy) acetonitrile (Table 2,
Entry 3): 1H NMR (CDCl3, 300 MHz): ı = 0.29 (s, 9H), 6.20 (s, 1H),
7.93–8.01 (m, 2H), 8.09–8.14 (m, 2H); FTIR (Neat): ꢀ 3402, 3107,
2960, 1701, 1530, 1348, 1256, 1189, 1109, 1071, 851, 789, 738,
698 cm−1; EIMS: m/z calcd for C11H14N2O3Si (M+): 250.
4. Conclusions
In summary, among the promoted zirconia and other solid acid
catalysts, sulfated-zirconia is found to be the most efficient for the
title reaction. Solvent-free, mild and ambient temperature reac-
tion conditions, experimental simplicity, inexpensive catalyst, high
yield of the products and shorter reaction times are some of the
advantages associated with this methodology. The FTIR and XP
spectroscopic studies suggested that TMSCN is activated for the
cyanosilylation of aldehydes by adsorbing on the Lewis acidic sites
of the sulfated-zirconia catalyst.
2-(4-Cholorophenyl)-2-(trimethylsilyloxy)
acetonitrile
(Table 2, Entry 4): 1H NMR (CDCl3, 200 MHz): ı = 0.25 (s, 9H),
5.43 (s, 1H), 7.34–7.41 (m, 4H). FTIR (Neat): ꢀ 3392, 3118, 2042,
1704, 1462, 1340, 1075, 1018, 788, 629 cm−1; EIMS: m/z calcd for
Acknowledgments
C
11H14ClNOSi (M+): 239.
BT thanks the Department of Science and Technology, New
Delhi, for a Research Fellowship under SERC Scheme (SP/S1/PC-
31/2004). MKP is the recipient of Senior Research Fellowship of
CSIR, New Delhi.
2-(4-Methoxyphenyl)-2-(trimethylsilyloxy)
acetonitrile
(Table 2, Entry 5): 1H NMR (CDCl3, 200 MHz): ı = 0.24 (s, 9H),
2.14 (s, 3H), 5.43 (s, 1H), 7.32–7.42 (m, 2H), 7.47–7.51 (m, 1H),

B. Thirupathi et al. / Applied Catalysis A: General 384 (2010) 147–153
153
References
[29] B.M. Reddy, M.K. Patil, B.T. Reddy, Catal. Lett. 126 (2008) 413–418.
[30] B.M. Reddy, M.K. Patil, G.K. Reddy, B.T. Reddy, K.N. Rao, Appl. Catal. A: Gen. 332
(2007) 183–191.
[31] H. Matsuhashi, T. Tanaka, K. Arata, J. Phys. Chem. B 105 (2001) 9669–9671.
[32] C. Morterra, G. Meligrana, G. Cerrato, V. Solinas, E. Rombi, M.F. Sini, Langmuir
19 (2003) 5344–5356.
[1] G.G. Furin, O.A. Vyazankina, B.A. Gostevsky, N.S. Vyazankin, Tetrahedron 44
(1988) 2675–2749.
[2] S. Kobayashi, S. Nagayama, T. Busujima, Tetrahedron Lett. 37 (1996)
9221–9225.
[33] T. Riemer, H. Knözinger, J. Phys. Chem. 100 (1996) 6739–6742.
[34] B.M. Reddy, M.K. Patil, Chem. Rev. 109 (2009) 2185–2208.
[35] H. Matsuhashi, H. Nakamura, H. Ishihara, S. Iwamoto, Y. Kamiya, J. Kobayashi,
Y. Kubota, T. Yamada, T. Matsuda, K. Matsushita, K. Nakai, H. Nishiguchi, M.
Ogura, N. Okazaki, S. Sato, K. Shimizu, T. Shishido, S. Yamazoe, T. Takeguchi, K.
Tomishige, H. Yamashita, M. Niwa, N. Katada, Appl. Catal. A: Gen. 360 (2009)
89–97.
[36] B.M. Reddy, B. Thirupathi, M.K. Patil, J. Mol. Catal. A: Chem. 307 (2009) 154–159.
[37] B.M. Reddy, P.M. Sreekanth, V.R. Reddy, J. Mol. Catal. A: Chem. 225 (2005)
71–78.
[38] S.T. Kadam, S.S. Kim, Bull. Korean Chem. Soc. 29 (2008) 1320–1322.
[39] X. Li, K. Nagaoka, L.J. Simon, R. Olindo, J.A. Lercher, A. Hofmann, J. Sauer, J. Am.
Chem. Soc. 127 (2005) 16159–16166.
[40] T.H. Clingenpeel, T.E. Wessel, A.I. Biaglow, J. Am. Chem. Soc. 119 (1997)
5469–5470.
[41] M.V. Luzgin, V.A. Rogov, N.S. Kotsarenko, V.P. Shmachkova, A.G. Stepanov, J.
Phys. Chem. C 111 (2007) 10624–10629.
[42] J. Sommer, M. Hachoumy, F. Garin, D. Barthomeuf, J. Vedrine, J. Am. Chem. Soc.
117 (1995) 1135–1136.
[43] H. Ibach, D.L. Mills, Electron Energy Loss Spectroscopy and Surface Vibrations,
Academic, New York, 1982.
[44] C.M. Friend, J. Stein, E.L. Muetterties, J. Am. Chem. Soc. 103 (1981) 767–772.
[45] S.F. Rach, F.E. Kühn, Chem. Rev. Article ASAP, doi:10.1021/cr800270h.
[46] J.A. Seckar, J.S. Thayer, Inorg. Chem. 15 (1976) 501–504.
[47] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Com-
pounds, 4th ed., Wiley, New York, 1986, pp. 272–280.
[48] F. Babou, G. Coudurier, J.C. Vedrine, J. Catal. 152 (1995) 341–349.
[49] D. Wu, Z. Zhang, D. Fu, W. Fan, H. Guo, Appl. Phys. A 64 (1997) 593–595.
[50] X.C. Wu, R.Q. Cai, P.X. Yan, W.M. Liu, J. Tian, Appl. Surf. Sci. 185 (2002) 262–266.
[51] R. Srinivasan, R.A. Keogh, B.H. Davis, Catal. Lett. 36 (1996) 51–57.
[52] C. Morterra, G. Cerrato, F. Pinna, M. Signoretto, J. Phys. Chem. 98 (1994)
12373–12381.
[3] A. Heydari, P. Fatemi, A. Alizadeh, Tetrahedron Lett. 39 (1998) 3049–3050.
[4] S.K. De, J. Mol. Catal. A: Chem. 225 (2005) 169–171.
[5] S.K. De, R.A. Gibbs, Tetrahedron Lett. 45 (2004) 7407–7408.
[6] M.S. In, M. Cholod, H. Grant (Eds.), Cyanohydrins Encyclopedia of Chemical
Technology, vol. 7, Wiley, New York, 1993, p. 821.
[7] R.J.H. Gregory, Chem. Rev. 99 (1999) 3649–3682.
[8] C. Baleizão, B. Gigante, H. García, A. Corma, Tetrahedron 60 (2004)
10461–10468.
[9] N. Azizi, M.R. Saidi, J. Organomet. Chem. 688 (2003) 283–285.
[10] R.O. Duthaler, A. Hafner, Chem. Rev. 92 (1992) 807–832.
[11] M. North, Tetrahedron: Asymmetry 14 (2003) 147–176.
[12] L. Mei, S.W. Long, H.K. Liang, W.S. Xuan, Appl. Organometal. Chem. 22 (2008)
181–186.
[13] N. Kurono, M. Yamaguchi, K. Suzuki, T. Ohkuma, J. Org. Chem. 70 (2005)
6530–6532.
[14] F. Chen, X. Feng, B. Qin, G. Zhang, Y. Jiang, Org. Lett. 5 (2003) 949–952.
[15] A. Fujii, S. Sakaguchi, Y. Ishii, J. Org. Chem. 65 (2000) 6209–6212.
[16] M. Bandili, P.G. Cozzi, P. Melchiiorre, U.-R. Achille, Tetrahedron Lett. 42 (2001)
3041–3043.
[17] D.A. Evans, G.L. Carroll, L.K. Truesdale, J. Org. Chem. 39 (1974) 914–917.
[18] B. Karimi, L. Ma’Mani, Org. Lett. 6 (2004) 4813–4815.
[19] J.S. Yadav, B.V.S. Reddy, M.S. Reddy, A.R. Prasad, Tetrahedron Lett. 43 (2002)
9703–9706.
[20] N.N. Bhongle, S.A. Wald, C.H. Senanayake, Org. Lett. 3 (2001) 553–556.
[21] X. Liu, B. Qin, X. Zhou, B. He, X. Feng, J. Am. Chem. Soc. 127 (2005) 12224–12225.
[22] S. Horike, M. Dinca, K. Tamaki, J.R. Long, J. Am. Chem. Soc. 130 (2008)
5854–5855.
[23] J.J. Song, F. Gallou, J.T. Reeves, Z. Tan, N.K. Yee, C.H. Senanayake, J. Org. Chem.
71 (2006) 1273–1276.
[24] S.C. George, S.S. Kim, S.T. Kadam, Appl. Organometal. Chem. 21 (2007) 994–998.
[25] W.K. Cho, J.K. Lee, S.M. Kang, Y.S. Chi, H.-S. Lee, I.S. Choi, Chem. Eur. J. 13 (2007)
6351–6358.
[53] I. Takano, S. Isobe, T.A. Sasaki, Y. Baba, Appl. Surf. Sci. 37 (1989) 25–32.
[54] S. Badrinarayanan, S. Sinha, A.B. Mandale, J. Electron Spectrosc. Relat. Phenom.
49 (1989) 303–309.
[26] B.M. Reddy, M.K. Patil, B.T. Reddy, S.-E. Park, Catal. Commun. 9 (2008) 950–954.
[27] B.M. Reddy, M.K. Patil, Curr. Org. Chem. 12 (2008) 118–140.
[28] B.M. Reddy, M.K. Patil, B.T. Reddy, Catal. Lett. 125 (2008) 97–103.