Russian Journal of Organic Chemistry, Vol. 40, No. 6, 2004, pp. 773–774. Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 6, 2004,
pp. 814–815.
Original Russian Text Copyright © 2004 by Kozhukhova, Kalyuzhnaya, Yatluk, Suvorov.
Dedicated to Full Member of the Russian Academy of Sciences
O.N. Chupakhin on his 70th Anniversary
Synthesis of Esters in the Presence of Chlorosilanes
V. V. Kozhukhova, S. A. Kalyuzhnaya, Yu. G. Yatluk, and A. L. Suvorov
Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences,
ul. S. Kovalevskoi 20, Yekaterinburg, 620219 Russia
e-mail: eop@ios.uran.ru
Received January 23, 2004
Abstract—Esterification of various carboxylic acids with primary alcohols in the presence of chloro(methyl)-
silanes provides a simple and convenient synthetic route to esters.
Carboxylic acid esters constitute an important class
of organic compounds; they are involved in a number
of chemical reactions [1]. Nacao et al. [2] used chloro-
silanes to convert carboxylic acids into the corre-
sponding esters. The reactions were carried out with
respectively, in the pesence of SiCl , SiCl Me,
4 3
SiCl Me , and SiClMe . It is seen that the yield of
2
2
3
ethyl benzoate depends on the number of chlorine
atoms in the chlorosilane. The highest yield was
obtained with chlorotrimethylsilane, while in the case
of tetrachlorosilane the yield was the lowest. These
findings indicate that intermediate product is not
benzoyl chloride (in this case, tetrachlorosilane would
be the most efficient) but the corresponding silyl ester.
Table contains the results of esterification of
various carboxylic acids with lower alcohols in the
presence of chlorotrimethylsilane. Here, the alcohol
structure was crucial. The esterification of benzoic
acid was successful only with unbranched alcohols:
no respective ester was obtained in the reaction with
0
.5 equiv of chlorosilane. However, the scheme given
below shows that 2 equiv of chlorosilane is required to
complete the process. By reaction of oleic acid with
ethanol under the conditions described in [2] we
obtained only 16% of ethyl oleate.
RCOOH
+
R'OH
+
+
2SiCl Me
n 4–n
RCOOR'
(Me4–nCln–1Si) O
+
2HCl
2
n = 1–4.
2
-propanol. Presumably, the latter reacted with chloro-
In the present work we compared for the first time
the reactivity of chlorosilanes and examined the effect
of the carboxylic acid and alcohol structure on the
esterification process. As a result, we developed
a simple and convenient procedure for the synthesis of
a number of esters. The reactions were performed by
heating a mixture of the reactants for 1–1.5 h at the
boiling point. The molar ratio carboxylic acid–chloro-
silane–alcohol was 1:3.5:5. This reactant ratio
allowed us to use even water-containing alcohols, e.g.,
rectified ethanol. The products were isolated by
distillation. In reactions with anhydrous alcohols, the
amount of chlorosilane can be reduced, but it should be
no less than 2 equiv, otherwise the yield decreases.
trimethylsilane to afford isopropyl chloride which was
detected in the distillate. The same factor is likely to be
Synthesis of esters RCOOR' in the presence of chlorotri-
methylsilane
R
R'
Yield, %
72
CH
CH
3
3
(CH
(CH
2
2
)
)
3
10
C
2
C
2
C
2
H
5
5
5
7
CH=CH(CH
2
)
7
H
H
57
C
4
C
6
C
6
C
6
C
6
C
6
H
H
H
H
H
H
9
5
5
5
5
5
(CH
)
2
C
73
CH
3
71
C
C
2
H
H
5
9
86
4
76
3
iso-C H
7
00
The effect of chlorosilane nature was examined in
the synthesis of ethyl benzoate as an example. The
yields of ethyl benzoate were 50, 68, 72, and 86%,
CH
2
C
C
2
H
H
5
5
93
3
-Indenyl
2
50
1
070-4280/04/4006-0773 © 2004 MAIK “Nauka/Interperiodica”