S. B. Waghmode et al. / Tetrahedron Letters 42 (2001) 3145–3147
3147
Table 3. Acylation of 2-phenylethanol with various car-
boxylic acids over Na–K–ETS-10
Acknowledgements
Nos Acylating
agent
Conversion
Othersa
Acylation
selectivityb
S.B.W. and V.V.T. thank CSIR for research fellow-
ships.
1
2
Acetic acid
Propanoic
acid
97.8
99.4
0.8
1.4
99.2
98.5
References
3
4
5
Octanoic acid 96.8
Nonanoic acid 90.7
Decanoic acid 76.3
6.0
10.2
12.7
93.8
89.8
87.3
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Reaction conditions: temperature=120°C; substrate=5 mmol; acetic
acid=4 mL; other acids=5 mmol; and duration of run=8 h.
a Mainly C-alkylated products.
b Selectivity=(mol% expected product/mol% conversion)×100.
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conversion increases with the basicity of the catalyst.
General procedure for catalyst preparation
ETS-10 was prepared according to the procedure
reported earlier.17 The Si/Ti ratio was 5.61. The ETS-10
sample was converted into different ion-exchanged
forms by exchanging thrice with the required metal
chloride solution (20 mL of 1 M solution/g of catalyst
at 80°C for 3 h). After washing with demineralized
water, filtering and drying, the M-ETS-10 samples
(M=Li, Na, K, Rb, Cs and Ba) were calcined at 500°C
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General procedure for the acylation reaction
All the reactions were carried out in the liquid phase in
a round bottom flask fitted with a cold water con-
denser. Substrate (5 mmol), acetic acid (4 mL) (in the
case of long chain C8–C10 acids, a stoichiometric
amount was used) and 50 mg of catalyst were refluxed
at 120°C for 8 h. Conversions have been calculated on
the basis of alcohol used. The progress of the reaction
was monitored by a gas chromatography (HP-5880)
using a capillary column (HP-5, cross-linked methyl–
silicone gum, 50 m×0.5 mm). After completion, the
reaction mixture was quenched with a saturated solu-
tion of NaHCO3 and extracted with ethyl acetate. The
organic layer was washed with water and brine and the
solvent was evaporated in vacuo to give almost pure
products.
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.