Claims
- 1. A process for purifying esters of tetrahydropyran-4-carboxylic acid of the formula I ##STR5## where R.sup.1 to R.sup.3 are each C.sub.1 -C.sub.4 -alkyl, and R.sup.2 and R.sup.3 are each additionally hydrogen, from mixtures produced in the reaction of butyrolactones of the formula II ##STR6## where R.sup.2 and R.sup.1 have the above-mentioned meanings, and R.sup.4 is hydrogen, alkyl of 1-6 carbons or acyl of the formula --CO--R.sup.2, with alcohols of the formula R.sup.1 OH in the presence of oxide catalysts, by distillation, which comprises
- a) removing overhead, in a first column with 5-25 theoretical plates with a distillate pressure of 700-1100 mbar and a distillate temperature of 50.degree.-80.degree. C., an alcohol and up to 10% of the water, and
- b) transferring the bottom product from the first column into a second column with 18-40 theoretical plates, into which a water entrainer is metered between plates 15 and 30, and is circulated, and which operates with a distillate pressure of 35-350 mbar and a distillate temperature of 18.degree.-70.degree. C., with the esters of tetrahydropyran-4-carboxylic acid being removed between plates 8 and 18 at 90.degree.-150.degree. C.
- 2. A process for purifying esters of tetrahydropyran-4-carboxylic acid of the formula I as defined in claim 1, wherein the bottom product from the second column is fed into a third column with 5-25 theoretical plates, and the overhead products from the third column are returned at a distillate pressure of 1-100 mbar and a distillate temperature of 90.degree.-140.degree. C. to the synthesis of the esters of tetrahydropyran-4-carboxylic acid.
Priority Claims (1)
Number |
Date |
Country |
Kind |
41 41 221.4 |
Dec 1991 |
DEX |
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Parent Case Info
This application is a c-i-p of application Ser. No. 07/990,285, filed on Dec. 14, 1992 now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4837346 |
Fischer et al. |
Jun 1989 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
990285 |
Dec 1992 |
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