US3706703A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the preparation of cyclic acid anhydrides
Assignee: Gulf Research and Development Co
•
Filing: 1970-11-27
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Granted: 1972-12-19
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Expires: 1990-11-27
Abstract
Abstract A PROCESS IS DEFINED FOR HEATING AN ORGANIC COMPOUND CONTAINING AT LEAST ONE HALF-ESTER OF A DICARBOXYLIC ACID WHERE THE CARBONYL GROUPS ARE DIRECTLY CONNECTED TO ADJACENT INTERNAL ALIPHATIC CARBON ATOMS TO A TEMPERATURE FROM ABOUT 80*C. TO 149*C. TO COVERT THE HALFESTER GROUPS TO CYCLIC ANYDRIDE GROUPS AND A BY-PRODUCT ALCOHOL. THE ORGANIC COMPOUND IS A 1:1 COPOLYMER OF AN ALIPHATIC HYDROCARBON HAVING AT LEAST THREE CARBON ATOMS, SUCH AS 1-HEXANE, AND MALEIC ANHYDRIDE. IF THE ORGANIC COMPOUND CONTAINS BOTH HALF-ESTER AND KIESTER GROUPS, THE RESULTING COMPOUND AFTER HEATING TO A TEMPERATURE FROM 80*C. TO 149*C. WILL CONTAIN ANHYDRIDE AND DIESTER LINKAGES.
Inventors
- 👤 William J Heilman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:17
CPC Classifications
C; C08; C08F; C08F8/00; C08F10/00
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) | 1975-12-19 | 1976-06-19 | 1976-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-19 | 1980-06-19 | 1980-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-19 | 1984-06-19 | 1984-12-19 | $7700.00 | Window Closed / Lapsed |