Patent US3658905A successfully refreshed from Google Patents.
US3658905A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the purification of p-aminophenol
Assignee: Rhone Poulenc SA
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Filing: 1969-03-12
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Granted: 1972-04-25
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Expires: 1989-03-12
Abstract
Abstract PARA-AMINOPHENOL, PREPARED BY THE CATALYTIC HYDROGENATION OF NITROBENZENE IN A STRONG ACID MEDIUM, IS PURIFIED BY TREATMENT WITH A LIQUID ALIPHATIC, CYCLOALIPHATIC OR AROMATIC KETONE. THE IMPURE P-AMINOPHENOL MAY BE WASHED WITH AND/OR RECRYSTALLISED FROM KETONES SUCH AS ACETONE, METHYLETHYLKETONE, METHYLISOBUTYLKETONE, CYCLOHEXANONE OR ACETOPHENONE AND THE PURIFIED P-AMINOPHENOL IS FOUND TO REMAIN COLOURLESS OVER SEVERAL MONTHS WHEN STORED WITH STABILISING AGENTS. FURTHER PURIFICATION IS ACHIEVED BY DISSOLVING THE PURIFIED CRYSTALS IN BOILING WATER AND RECRYSTALLISING THE P-AMINOPHENOL FROM THE AQUEOUS PHASE.
Inventors
- 👤 Henri Daunis
- 👤 Marcel Gominet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:02
CPC Classifications
C; C07; C07C; C07C213/00; C07C213/10; C07C213/02
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |