Patent US3812149A successfully refreshed from Google Patents.
US3812149A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of 2-pyrrolidinone
Assignee: Sun Research and Development Co
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Filing: 1972-07-21
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Granted: 1974-05-21
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Expires: 1992-07-21
Abstract
Abstract A PROCESS FOR PREPARING 2-PYRROLIDIONE WHICH COMPRISES REACTING SUCCINIC ACID OR ITS PRECURSOR, HYDROGEN, AND AMMONIA IN AN AQUEOUS SYSTEM AT A MOLE RATIO OF AMMONIA TO ACID OF ABOUT 1.1:1 TO ABOUT 1.7:1, AT A TEMPERATURE OF FROM ABOUT 250* C. TO ABOUT 275* C., AT A PRESSURE OF FROM ABOUT 1500 TO 2000 P.S.I.G., FOR A TIME OF ABOUT 3 TO ABOUT 6 HOURS, AND IN THE PRESENCE OF A RHODIUM CATALYST.
Inventors
- 👤 E Hollstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:49
CPC Classifications
C; C07; C07D; C07D207/00; C07D207/02; C07D207/18; C07D207/22; C07D207/24; C07D207/26
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) | 1977-05-20 | 1977-11-19 | 1978-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-20 | 1981-11-19 | 1982-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-20 | 1985-11-19 | 1986-05-21 | $7700.00 | Window Closed / Lapsed |