Patent US2925425A successfully refreshed from Google Patents.
US2925425A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Oxidation of phthalide and mixtures thereof to phthalic anhydride
Assignee: Celanese Corp
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Filing: 1957-05-21
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Granted: 1960-02-16
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Expires: 1977-05-21
Abstract
No abstract record available.
Inventors
- 👤 Jr Leo L Contois
- 👤 Hopkins W Tatum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:04
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/16; C07C51/31; C07C51/313
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
45 words
PROCESS WHICH COMPRISES PASSING OXYGEN THROUGH A LIQUID COMPRISING AT LEAST 5% BY WEIGHT OF EACH OF PHTHALIDE, O-TOLUIC ACID AND O-XYLENE IN THE PRESENCE OF AN OXIDATION CATALYST TO PRODUCE A LIQUID PHASE MIXTURE CONTAINING PHTALIC ANHYDRIDE AND REMOVING PHTHALIC ANHYDRIDE FROM SAID MIXTURE.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-02-15 | 1963-08-17 | 1964-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-02-15 | 1967-08-17 | 1968-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-02-15 | 1971-08-17 | 1972-02-16 | $7700.00 | Window Closed / Lapsed |