US4562152A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for obtaining pure L-leucine
Assignee: Evonik Operations GmbH
•
Filing: 1984-05-22
•
Granted: 1985-12-31
•
Expires: 2004-05-22
Abstract
Abstract Pure L-leucine is obtained from an aminoacid mixture which contains at least 45 weight percent L-leucine, at most 40 weight percent L-isoleucine and at most 25 weight percent of other aminoacids by acetylating the mixture, precipitating the acetylation product by acidification, subjecting the acetylation product to a saponification by an L-aminoacid acylate until 30 to 95% of the N-acetyl-L-leucine employed is saponified and isolating the L-leucine from the saponification mixture.
Inventors
- 👤 Axel Kleemann
- 👤 Jurgen Martens
- 👤 Horst Weigel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:10
CPC Classifications
C; C07; C07C; C07C227/00; C07C227/38; C07C227/40; C07C231/00; C07C231/02; C12; C12P; C12P13/00; C12P13/04; C12P13/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
133 words
A process of obtaining pure L-leucine from an aminocarboxylic acid mixture containing at least 45 weight percent L-leucine, at most 40 weight percent L-isoleucine and at most 25 weight percent of other aminocarboxylic acids, in each case based on the dry material comprising: (a) acetylating the aminoacid mixture, (b) precipitating a mixture of N-acetylaminoacids enriched in N-acetyl-L-leucine from the crude mixture of acetylation products, (c) subjecting this N-acetyl-L-leucine enriched mixture in aqueous solution having a concentration between 0.1 and 1.5 moles/l of N-acetyl-L-leucine at a pH between 6 and 8 and a temperature between 10° and 40° C. in the presence of an effector of hydrolysis by a L-aminoacid acylase until 30 to 95% of the N-acetyl-L-leucine is hydrolyzed to the free aminoacid, and (d) isolating pure L-leucine from the crude hydrolysis mixture.
Claim 2
Dependent Claim
133 words
A process of obtaining pure L-leucine from an aminocarboxylic acid mixture containing at least 45 weight percent L-leucine, at most 40 weight percent L-isoleucine and at most 25 weight percent of other aminocarboxylic acids, in each case based on the dry material comprising: (a) acetylating the aminoacid mixture, (b) precipitating a mixture of N-acetylaminoacids enriched in N-acetyl-L-leucine from the crude mixture of acetylation products, (c) subjecting this N-acetyl-L-leucine enriched mixture in aqueous solution having a concentration between 0.1 and 1.5 moles/l of N-acetyl-L-leucine at a pH between 6 and 8 and a temperature between 10° and 40° C. in the presence of an effector of hydrolysis by a L-aminoacid acylase until 30 to 95% of the N-acetyl-L-leucine is hydrolyzed to the free aminoacid, and (d) isolating pure L-leucine from the crude hydrolysis mixture.
Claim 3
Dependent Claim
47 words
A process according to claim 1 including the step of recrystallizing the mixture of N-acetylamino acids precipitated in step (b) from water, a water miscible aliphatic alcohol having 1 to 4 carbon atoms or a mixture of water and such an alcohol before proceeding with step (c).
Claim 4
Dependent Claim
31 words
A process according to claim 2 wherein the effector is the ions Ca 2+ , Fe 2+ , Mn 2+ , Mg 2+ , Zn 2+ , or Co 2+ .
Claim 5
Dependent Claim
15 words
A process according to claim 3 wherein the effector is employed as the chloride salt.
Claim 6
Dependent Claim
13 words
A process according to claim 4 wherein the salt is CoCl 2 .
Claim 7
Dependent Claim
31 words
A process according to claim 1 wherein the effector is the ions Ca 2+ , Fe 2+ , Mn 2+ , Mg 2+ , Zn 2+ , or Co 2+ .
Claim 8
Dependent Claim
15 words
A process according to claim 6 wherein the effector is employed as the chloride salt.
Claim 9
Dependent Claim
13 words
A process according to claim 7 wherein the salt is CoCl 2 .
References Cited (Backward Citations)
US3841966A
Cited
US4259441A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-12-30 | 1989-07-01 | 1989-12-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-30 | 1993-07-01 | 1993-12-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-30 | 1997-07-01 | 1997-12-31 | $7700.00 | Window Closed / Lapsed |