Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1998-09-21
2000-07-11
Geist, Gary
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
560 8, 560 76, 560 96, 560129, 560231, C07C 6934, C07C 6902, C07C 6900
Patent
active
060875275
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for producing an alkyl carboxylate from a carboxylic acid and an alcohol. The present invention is especially suitable for producing an alkanedioic acid dialkyl ester using an alkanedioic acid as the carboxylic acid, and the alkanoedioic acid dialkyl ester can be suitably used as an intermediate product of drugs, agricultural chemicals, perfumes, dyes, liquid crystal materials, high molecular materials, etc.
BACKGROUND ARTS
As a method for producing an alkanedioic acid dialkyl ester in the presence of an acid catalyst, it is known to esterify an alkanedioic acid and a monohydric alcohol in the presence of sulfuric acid (Japanese Patent Laid-Open (Kokai) No. 63-243060). Furthermore, as a method for producing an ester using a solid acid catalyst, it is known to esterify a carboxylic acid and an alcohol using an ion exchange resin as a catalyst (Japanese Patent Laid-Open (Kokai) No. 63-297340).
However, according to the production method of Japanese Patent Laid-Open (Kokai) No. 63-243060, the gross yield of the alkanedioic acid dialkyl ester is as low as about 85 to 95% and the purity is as low as about 90 to 98%. Furthermore, the isolation and purification of the produced alkanedioic acid dialkyl ester requires a step of neutralizing the acid catalyst by an alkali and a step of distillation in a high vacuum of about 13 to 53 Pa (0.1 to 0.4 Torr) in a high temperature range of 117.degree. C. to 201.degree. C., and the method does not allow a highly pure alkanedioic acid dialkyl ester to be obtained economically at a high yield.
DISCLOSURE OF THE INVENTION
The inventors studied intensively to solve these problems, and as a result, found that an alkanedioic acid dialkyl ester can be obtained at a high purity of 99% or more with the amount of the alcohol used kept smaller, by removing the water produced in the reaction system in a dehydration step established halfway in the esterification reaction and restarting the esterification reaction, to complete the esterification reaction.
Furthermore, they found that if a solid acid catalyst is used as the acid catalyst, the produced alkanedioic acid dialkyl ester can be easily separated from the acid catalyst. Thus, the present invention has been completed.
The present invention is a method for producing an alkyl carboxylate, in which a carboxylic acid and a monohydric alcohol are esterified by reaction in the presence of an acid catalyst, comprising the steps of removing the reaction solution from contact with the acid catalyst and removing the water produced in the reaction system in a dehydration step established halfway in the esterification reaction, with the reaction solution kept away from contact with the acid catalyst, and restarting the esterification reaction, in the presence of the acid catalyst to complete the esterification reaction.
THE MOST PREFERRED EMBODIMENTS OF THE INVENTION
In the present invention, it is preferable to conduct the dehydration step when the reaction solution is kept away from contact with the acid catalyst. If the dehydration step is established with the reaction solution kept in contact with the acid catalyst, an ester hydrolyzing reaction may occur and this will lower the ester yield.
In the present invention, the method for keeping the reaction solution away from contact with the catalyst halfway in the esterification reaction is not especially limited. Neutralization or filtration, etc. can be used.
In the present invention, the number of dehydration steps established in the esterification reaction is not especially limited, but it is preferable that the number of dehydration steps is 1 to 3 in view of working efficiency. If the number of dehydration steps is 4 or more, the working efficiency tends to decline.
In the present invention, as for the timing of the aforementioned dehydration step or steps established in the esterification reaction, when the number of dehydration steps established halfway in the esterification reaction is one, the time when the conver
REFERENCES:
Melvin Newman; An Advanced Organic Laboratory Course; Macmillan, New York; pp. 8-11, 1972.
Hasebe Akio
Imamura Shinzo
Niwa Atsushi
Nobuhiko Ito
Deemie Robert W.
Geist Gary
Miller Austin R.
Soda Aromatic Co., Ltd.
Toray Industries Inc.
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