Patent US3613291A successfully refreshed from Google Patents.
Patent US2964535A successfully refreshed from Google Patents.
US2964535A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of nu-methyl pyrrolidone
Assignee: Monsanto Chemicals Ltd
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Filing: 1957-07-22
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Granted: 1960-12-13
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Expires: 1977-07-22
Abstract
No abstract record available.
Inventors
- 👤 Howard E Clements
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 21:38
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
44 words
A PROCESS FOR THE REMOVAL OF BUTYROLACTONE FROM NMETHYL PYRROLIDONE CONTAINING MINOR AMOUNTS OF BUTYROLACTONE WHICH COMPRISES CONTACTING SAID N-METHYL PYRROLIDONE WITH AN AQUEOUS SOLUTION OF AN ALKALI METAL HYDROXIDE AND THEREAFTER DISTILLING SAID TREATED MIXTURE TO RECOVER N-METHYL PYRROLIDONE SUBSTANTIALLY FREE OF BUTYROLACTONE.
Claim 2
Dependent Claim
44 words
A PROCESS FOR THE REMOVAL OF BUTYROLACTONE FROM NMETHYL PYRROLIDONE CONTAINING MINOR AMOUNTS OF BUTYROLACTONE WHICH COMPRISES CONTACTING SAID N-METHYL PYRROLIDONE WITH AN AQUEOUS SOLUTION OF AN ALKALI METAL HYDROXIDE AND THEREAFTER DISTILLING SAID TREATED MIXTURE TO RECOVER N-METHYL PYRROLIDONE SUBSTANTIALLY FREE OF BUTYROLACTONE.
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) | 1963-12-13 | 1964-06-13 | 1964-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-12-13 | 1968-06-13 | 1968-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-12-13 | 1972-06-13 | 1972-12-13 | $7700.00 | Window Closed / Lapsed |