US2517563A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synthetic tricarboxylic acid and method of preparation
Assignee: Hercules Powder Co
•
Filing: 1946-05-04
•
Granted: 1950-08-08
•
Expires: 1966-05-04
Abstract
No abstract record available.
Inventors
- 👤 George C Harris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:29
CPC Classifications
C; C07; C07C; C07C61/00; C07C61/16; C07C61/28; C07C61/29
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
82 words
IN THE METHOD FOR THE PREPARATION OF LEVOPIMARIC-6, 8A-TRANSENDOSUCCINIC ACID HAVING THE STRUCTURAL FORMULA SET FORTH IN CLAIM 13, THE STEP WHICH COMPRISES HEATING IN WATER SOLUTION AT 150-300*C. A MATERIAL HAVING THE STRUCTURAL FORMULA OF THE DIELS-ALDER ADDUCT OF LEVOPIMARIC ACID AND MALEIC ANHYDRIDE TOGETHER WITH A SUFFICIENT AMOUNT OF ALKALINE MATERIALS TO NEUTRALIZE THE ADDUCT COMPLETELY, HEATING BEING CONTINUED FOR A PERIOD OF TIME SUFFICIENT TO EFFECT SUBSTANTIALLY COMPLETE ISOMERIZATION OF THE MALEIC GROUP OF ATOMS TO THE FUMARIC GROUP.
Claim 2
Dependent Claim
9 words
LEVOPIMARIC-6, 8A-TRANSENDOSUCCINIC ACID WHICH HAS THE FOLLOWING STRUCTURAL FORMULA:
Claim 3
Dependent Claim
9 words
LEVOPIMARIC-6, 8A-TRANSENDOSUCCINIC ACID WHICH HAS THE FOLLOWING STRUCTURAL FORMULA:
References Cited (Backward Citations)
US2351949A
Cited
US2383933A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-08-07 | 1954-02-06 | 1954-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-08-07 | 1958-02-06 | 1958-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-08-07 | 1962-02-06 | 1962-08-08 | $7700.00 | Window Closed / Lapsed |