10
F. Shirini et al. / Catalysis Communications 18 (2012) 5–10
Time(min) Yield(%)
Table 4
Compared performance of various catalysts in the trimethylsilylation of benzyl alcohol.
9
5
1
00
91
8
8
8
6
8
2
Catalyst / condition
Catalyst
loading
Time
(min)
Yield
(%)
Ref.
8
0
8
6
4
2
0
0
0
0
0
(mg)
TiO
2
–HClO
4
/ CH
3
CN, r.t.
5
1
97
Present
method
8
Sulfonic acid-functionalized ordered
nanoporous silica / CH Cl , r.t.
SiO –HClO /CH CN, r. t.
PW12 40/neat, 55–60 °C
Montmorillonite K 10/neat, r.t.
19
80
100
2
2
2
4
3
50
28
100
87.5
87.5
15
2
98
90
92
70
90
95
9
5
5
1
2
3
3
H
3
O
23
21
102
13
10
11
13
16
16
19
1
2
3
4
5
6
Fe(HSO
Fe(HSO
Nanocrystalline TiO
4
)
)
3
/ CH
/ Neat, 90–100 °C
/CH CN, r.t.
3
CN, reflux
Run
4
3
2
3
Fig. 6. Reusability of the catalyst.
we believe it would be a useful addition to the available organic
methodologies.
by trimethylsilylation of 4-chlorobenzyl alcohol in the presence
of the recycled reagent, which gave the requested product in 95, 91,
8
8, 86, 82 and 80% yields after six runs. The average time for 6 con-
Acknowledgement
secutive runs was 3.2 min and 100% conversion for all, which clearly
demonstrates the practical recyclability of this catalyst (Fig. 6). The
IR of the recovered catalyst after the fourth run showed the same
spectra of unused catalyst, which shows the catalyst remained
unchanged after four uses.
In all reactions, we have studied, fast evolution of ammonia gas was
observed. With these observations we have proposed a mechanism in
which the generation of NH
We are thankful to the University of Guilan Research Council for
the partial support of this work.
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3 2 4
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Scheme 2. Proposed mechanism of the reaction.