Preparation of l-3,4-dihydroxy-phenyl-alanine
Abstract
Abstract To an aqueous solution of D,L-N-benzoyl-3,4-dimethoxy-phenylalanine there is added at least one amine selected from the group consisting of D(-)-threo-1-m-nitrophenyl-2-amino-propanediol-1,3, D(-)-threo-1-p-nitrophenyl-2-amino-propanediol-1,3 and D(-)threo-1-phenyl-2-amino-propanediol-1,3 selectively to precipitate the amine salt of the L-stereoisomer which is separated, dissolved and acidified to precipitate the free L-stereoisomer which is saponified to L-3,4-dihydroxy-phenyl-alanine. The mother liquor from the initial precipitation containing the amine salt of the D-stereoisomer and some L-stereoisomer is acidified to precipitate the free stereoisomers, leaving the amine in the acidified solution. The precipitated free stereoisomers are racemized and recycled for recovery of additional L-stereoisomer. The acidified solution of amine is rendered alkaline and steps are taken to regenerate and recycle the free amine.
Inventors
- 👤 G Stoeck
- 👤 W Gradel
- 👤 H Budka
- 👤 F Topfmeier
Bibliographic Details
Claims Analysis
Total Claims: 4References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |