US3629328A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of organic acids
Assignee: Celanese Corp
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Filing: 1969-05-20
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Granted: 1971-12-21
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Expires: 1989-05-20
Abstract
Abstract PROCESS FOR PURIFYING RELATIVELY INSOLUBLE CARBOXYLIC ACIDS SUCH AS TEREPHTHALIC ACID BY TREATING THE INSOLUBLE ACID DISSOLVED IN AQUEOUS SOLUTIONS OF WEAK ACID SALTS, THE WEAK ACID SALTS BEING OF LITHIUM, MAGNESIUM, TERTIARY AMINES OR BEING TETRAALKYL QUATERNARY AMMONIUM SALTS. THE INSOLUBLE ACID IS RECOVERED IN THE FREE ACID FORM BY MERELY COOLING THE SOLUTION TO RECRYSTALLIZE THE INSOLUBLE ACID.
Inventors
- 👤 Adin L Stautzenberger
- 👤 Alexander F Maclean
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:52
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/42
Claims Analysis
Total Claims: 0
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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) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |