Claims
- 1. A process for obtaining an optically active L-alpha-amino acid from the corresponding racemic D,L-alpha-aminocarboxylic acids comprising the steps of
- a) chemically acylating the said D,L-alpha-aminocarboxylic acids to produce N-Acetyl-D,L-alpha-aminocarboxylic acids;
- b) adding sufficient base to bring said N-Acetyl-D,L-alpha-aminocarboxylic acids to a pH range of between about 6 and 8 and preferentially deacylating the N-Acetyl-L-alpha-aminocarboxylic acid present in the mixture using a stereo specific acylase to form a composition comprising L-alpha-aminocarboxylic acid, an equimolar amount thereto of acetate, N-Acetyl-D-alpha-aminocarboxylic acid salt and a lesser amount of N-Acetyl-L-alpha-aminocarboxylic acid salt;
- c) separating the composition formed in step (b) into a first fraction containing most of the L-alpha-aminocarboxylic acid and a second fraction comprising N-Acetyl-D-alpha-aminocarboxylic acid salt and an amount of acetate equivalent to the L-alpha-aminocarboxylic acid formed
- d) adding to said second fraction an amount of N-Acetyl-D,L-alpha-aminocarboxylic acid equivalent to the removed L-alpha-aminocarboxylic acid, then removing the acetic acid formed by distillation;
- e) racemizing the mixture of step (d);
- f) subjecting the racemized mixture to the specific deacylation procedure of step (b).
- 2. The process in accordance with claim 1 comprising the steps of concentrating the solution of step (d) to a melt at a pH of between 4.5 and 5.5.
- 3. The process in accordance with claim 2 comprising racemizing the product obtained after concentration and recycling same to enzymatic deacylation.
- 4. The process in accordance with claim 1 comprising racemizing the N-Acetyl-D-.alpha.-aminocarboxylic acid as salt or in a mixture together with free acid in the presence of from 1 to 10 wt % of an acetic anhydride at 100-200.degree. C.
- 5. Process in accordance with claim 4 comprising racemizing at temperatures between 130 and 180.degree. C.
- 6. Process in accordance with claim 1 wherein prior to step (e) the concentrated second fraction is treated with at least 1.1 mol equivalents of acetic anhydride related to the unseparated amount of L-.alpha.-amino carboxylic acid present.
- 7. Process in accordance with claim 6 comprising treating the solution for the acetylation of the unseparated L-amino carboxylic acid with up to 3 equivalents of acetic anhydride relative to the unseparated L-.alpha.-amino carboxylic acid at a pH of between 4 and 8 prior to subjecting the resulting solution to enzymatic splitting.
- 8. Process in accordance with claim 1 wherein the starting materials are selected from the group consisting of D,L-methionine, valine, phenylalanine and norvaline to yield the corresponding L-methionine, valine, phenylalanine and norvaline.
- 9. The process of claim 1 for obtaining an optically active L-alpha-amino acid from the corresponding racemic D,L-alpha-aminocarboxylic acids comprising the additional steps of
- c') acetylating the L-alpha-aminocarboxylic acid present in the second fraction of step (c);
- d') adding to said second fraction acetylated in step c') an amount of N-Acetyl-D,L-alpha-aminocarboxylic acid equivalent to the removed L-alpha-aminocarboxylic acid, then removing the acetic acid formed by distillation;
- e) racemizing the mixture of step (d');
- f) subjecting the racemized mixture to the specific deacylation procedure of step (b).
Priority Claims (1)
Number |
Date |
Country |
Kind |
195 46 532 |
Dec 1995 |
DEX |
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RELATED APPLICATIONS
This application claims priority of PCT Application PCT/EP96/05440 filed Dec. 5, 1996, which claims priority of German Application 1 95 46532.6
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3841966 |
Asai et al. |
Oct 1974 |
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4011263 |
Wagner et al. |
Mar 1977 |
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4602096 |
Karrenbauer et al. |
Jul 1986 |
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Continuations (1)
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Number |
Date |
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Parent |
PCTEP9605440 |
Dec 1995 |
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