US2820824A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of neutral tetracycline
Assignee: Wyeth Holdings LLC
•
Filing: 1957-04-15
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Granted: 1958-01-21
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Expires: 1977-04-15
Abstract
No abstract record available.
Inventors
- 👤 Joseph F Weidenheimer
- 👤 Ritter Lawrence
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:01
CPC Classifications
C; C07; C07C; C07C233/00
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
119 words
THE PROCESS OF PRODUCING ESSENTIALLY TASTELESS TETRACYCLINE NEUTRAL WHICH COMPRISES ADJUSTING THE PH OF AN AQUEOUS SLURRY OF IMPURE TETRACYLINE PREPARED BY CATALYTICALLY REDUCTIVELY DECHLORINATING CHLORETETRACYCLINE WITH HYDROGEN IN THE PRESENCE OF A NOBLE METAL CATALYST TO A PH OF BETWEEN 0.5-2 SO AS TO DISSOLVE THE TETRACYCLINE, ADDING A FILTER AID THERETO, FILTERING, ADDING TO THE FILTRATE FROM ABOUT 0.9 PERCENT TO ABOUT 15 PERCENT BASED ON THE WEIGHT OF THE TETRACYCLINE OF A COMPOUND SELECTED FROMM THE GROUP CONSISTING OF ALKALI METAL SULFITES, AMMONIUM SULFITE AND MIXTURES THEREOF, AND ADJUSTING THE PH OF THE RESULTING AQUEOUS SOLUTION TO NOT MORE THAN ABOUT 3 WHEREUPON PURIFIED ESSENTIALLY TASTELESS TETRACYCLINE NEUTRAL CRYSTALLIZERS THEREFROM AND THE IMPURITIES REMAIN IN SOLUTION.
Claim 2
Dependent Claim
119 words
THE PROCESS OF PRODUCING ESSENTIALLY TASTELESS TETRACYCLINE NEUTRAL WHICH COMPRISES ADJUSTING THE PH OF AN AQUEOUS SLURRY OF IMPURE TETRACYLINE PREPARED BY CATALYTICALLY REDUCTIVELY DECHLORINATING CHLORETETRACYCLINE WITH HYDROGEN IN THE PRESENCE OF A NOBLE METAL CATALYST TO A PH OF BETWEEN 0.5-2 SO AS TO DISSOLVE THE TETRACYCLINE, ADDING A FILTER AID THERETO, FILTERING, ADDING TO THE FILTRATE FROM ABOUT 0.9 PERCENT TO ABOUT 15 PERCENT BASED ON THE WEIGHT OF THE TETRACYCLINE OF A COMPOUND SELECTED FROMM THE GROUP CONSISTING OF ALKALI METAL SULFITES, AMMONIUM SULFITE AND MIXTURES THEREOF, AND ADJUSTING THE PH OF THE RESULTING AQUEOUS SOLUTION TO NOT MORE THAN ABOUT 3 WHEREUPON PURIFIED ESSENTIALLY TASTELESS TETRACYCLINE NEUTRAL CRYSTALLIZERS THEREFROM AND THE IMPURITIES REMAIN IN SOLUTION.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-01-20 | 1961-07-22 | 1962-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-01-20 | 1965-07-22 | 1966-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-01-20 | 1969-07-22 | 1970-01-21 | $7700.00 | Window Closed / Lapsed |