US3829444A
Expired / Lapsed
US
⏱️ 0.0 years remaining
4-azidocarbonylphthalic anhydride,4-isocyanatophthalic anhydride,and 4-lower alkoxycarbonamido phthalic anhydride
Assignee: Pharmacia and Upjohn Co
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Filing: 1972-02-22
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Granted: 1974-08-13
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Expires: 1992-02-22
Abstract
Abstract THE COMPOUNDS 4-AZIDOCARBONYLPHTHALIC ANHYDRIDE, 4ISOCYANATOPHTHALIC ANHYDRIDE, AND THE LOWER-ALKYL CARBAMATES OBTAINED BY REACTING THE LATTER ISOCYANATE WITH A LOWER-ALIPHATIC ALCOHOL, ARE DESCRIBED. A PROCESS FOR THE PREPARATION OF A POLYIMIDE BY HEATING THESE COMPOUNDS ALONE OR IN ADMIXTURE WITH OTHER POLYISOCYANNATES IS ALSO DESCRIBED. THE 4-AZIDOCARBONYLPHTHALIC ANHYDRIDE IS AN INTERMEDIATE FOR THE 4-ISOCYANATOPHTHALIC ANHYDRIDE.
Inventors
- 👤 R Richter
- 👤 H Ulrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:44
CPC Classifications
C; C07; C07D; C07D307/00; C07D307/77; C07D307/87; C07D307/89; C08; C08G; C08G18/00; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1035
Claims Analysis
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References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |