US2547504A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of tetrachlorophthalic anhydrides
Assignee: Monsanto Chemicals Ltd
•
Filing: 1949-08-11
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Granted: 1951-04-03
•
Expires: 1969-08-11
Abstract
No abstract record available.
Inventors
- 👤 George W Steahly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:28
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
59 words
A METHOD OF PURIFYING CRUDE TETRACHLOROPHTHALIC ANHYDRIDE, WHICH COMPRISES HEATING CRUDE TETRACHLOROPHTHALIC ANHYDRIDE IN THE PRESENCE OF AN ALKALINE SALT OF AN ALKALI METAL AT A TEMPERATURE ABOVE ABOUT 260* C. FOR A PERIOD OFTRATIME SUFFICIENT TO PERMIT SEPARATION OF SAID TETRACHLOROPHTHALIC ANHYDRIDE FROM THE IMPURITIES THEREIN BY DISTILLATION, AND THEN SEPARATING SAID TETRACHLOROPHTHALIC ANHYDRIDE THEREFROM IN PURIFIED FROM.
Claim 2
Independent Claim
59 words
A METHOD OF PURIFYING CRUDE TETRACHLOROPHTHALIC ANHYDRIDE, WHICH COMPRISES HEATING CRUDE TETRACHLOROPHTHALIC ANHYDRIDE IN THE PRESENCE OF AN ALKALINE SALT OF AN ALKALI METAL AT A TEMPERATURE ABOVE ABOUT 260* C. FOR A PERIOD OFTRATIME SUFFICIENT TO PERMIT SEPARATION OF SAID TETRACHLOROPHTHALIC ANHYDRIDE FROM THE IMPURITIES THEREIN BY DISTILLATION, AND THEN SEPARATING SAID TETRACHLOROPHTHALIC ANHYDRIDE THEREFROM IN PURIFIED FROM.
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) | 1954-04-02 | 1954-10-02 | 1955-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-04-02 | 1958-10-02 | 1959-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-04-02 | 1962-10-02 | 1963-04-03 | $7700.00 | Window Closed / Lapsed |