Patent US2939869A successfully refreshed from Google Patents.
US2939869A
Expired / Lapsed
US
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Pyrrolidone purification
Assignee: 3M Co
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Filing: 1958-01-27
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Granted: 1960-06-07
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Expires: 1978-01-27
Abstract
No abstract record available.
Inventors
- 👤 Norman G Carlson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:56
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16; C08; C08G; C08G69/00; C08G69/02; C08G69/08; C08G69/14; C08G69/24
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
28 words
IN THE PROCESS FOR THE PURIFICATION OF 2-PYRROLIDONE PRODUCED BY THE ACTION OF AMMONIA OF BUTYROLACTONE, THE STEP WHICH COMPRISES TREATING CRUDE PYRROLIDONE WITH AN ALKALI METAL HYDRIDE.
Claim 2
Dependent Claim
28 words
IN THE PROCESS FOR THE PURIFICATION OF 2-PYRROLIDONE PRODUCED BY THE ACTION OF AMMONIA OF BUTYROLACTONE, THE STEP WHICH COMPRISES TREATING CRUDE PYRROLIDONE WITH AN ALKALI METAL HYDRIDE.
References Cited (Backward Citations)
US2828307A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-06-07 | 1963-12-07 | 1964-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-06-07 | 1967-12-07 | 1968-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-06-07 | 1971-12-07 | 1972-06-07 | $7700.00 | Window Closed / Lapsed |