US2985665A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of phthalic anhydride
Assignee: Pittsburgh Chemical Co
•
Filing: 1956-10-03
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Granted: 1961-05-23
•
Expires: 1976-10-03
Abstract
No abstract record available.
Inventors
- 👤 Raymond J Lawn
- 👤 Craig C Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:57
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
50 words
A PROCESS FOR THE PURIFICATION OF CRUDE PHTHALIC ANHYDRIDE PREPARED BY THE CATALYTIC OXIDATION OF A MEMBER OF THE GROUP CONSISTING OF NAPHTHALENE AND ORTHO XYLENE CONTAINING SMALL AMOUNTS OF RGANIC COLOR-FORMING IMPURITIES WHICH COMPRISES PASSING THE CRUDE PHTHALIC ANHYDRIDE IN MOLTEN FORM THROUGH A BED OF GRANULAR ACTIVATED CARBON.
Claim 2
Dependent Claim
50 words
A PROCESS FOR THE PURIFICATION OF CRUDE PHTHALIC ANHYDRIDE PREPARED BY THE CATALYTIC OXIDATION OF A MEMBER OF THE GROUP CONSISTING OF NAPHTHALENE AND ORTHO XYLENE CONTAINING SMALL AMOUNTS OF RGANIC COLOR-FORMING IMPURITIES WHICH COMPRISES PASSING THE CRUDE PHTHALIC ANHYDRIDE IN MOLTEN FORM THROUGH A BED OF GRANULAR ACTIVATED CARBON.
References Cited (Backward Citations)
US1301388A
Cited
US1693915A
Cited
US1898688A
Cited
US2118918A
Cited
US2275660A
Cited
US2518312A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1964-05-22 | 1964-11-21 | 1965-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-05-22 | 1968-11-21 | 1969-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-05-22 | 1972-11-21 | 1973-05-23 | $7700.00 | Window Closed / Lapsed |