US2806856A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of pyrrolidone
Assignee: Arnold Hoffman & Co Inc
•
Filing: 1954-04-29
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Granted: 1957-09-17
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Expires: 1974-04-29
Abstract
No abstract record available.
Inventors
- 👤 Charles A Robinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:52
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
63 words
A PROCESS FOR REMOVING IMPURITIES FROM PYRROLIDONE WHICH COMPRISES HEATING THE PYRROLIDONE TO A TEMPPERATURE NOT ABOVE THE DISTILLATION TEMPERATURE, FIRST WITH A CARBOXYLIC ACID ANHYDRIDE SELECTED FROM THE GROUP CONSISTING OF LOWER ALIPHATIC HYDROCARBON AND MON-NUCLEAR AROMATIC HYDROCARBON CARBOXYLIC ACID ANHYDRIDES, AND THEN WITH A NON-OLATILE STRONGLY BASIC COMPOUND AND SEPARATING THE PYRROLIDONE BY DISTILLATION FROM THE PRODUCTS FORMED BY SAID TREATMENT.
Claim 2
Dependent Claim
63 words
A PROCESS FOR REMOVING IMPURITIES FROM PYRROLIDONE WHICH COMPRISES HEATING THE PYRROLIDONE TO A TEMPPERATURE NOT ABOVE THE DISTILLATION TEMPERATURE, FIRST WITH A CARBOXYLIC ACID ANHYDRIDE SELECTED FROM THE GROUP CONSISTING OF LOWER ALIPHATIC HYDROCARBON AND MON-NUCLEAR AROMATIC HYDROCARBON CARBOXYLIC ACID ANHYDRIDES, AND THEN WITH A NON-OLATILE STRONGLY BASIC COMPOUND AND SEPARATING THE PYRROLIDONE BY DISTILLATION FROM THE PRODUCTS FORMED BY SAID TREATMENT.
References Cited (Backward Citations)
US2524136A
Cited
US2547494A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1960-09-16 | 1961-03-18 | 1961-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-09-16 | 1965-03-18 | 1965-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-09-16 | 1969-03-18 | 1969-09-17 | $7700.00 | Window Closed / Lapsed |