US4020069A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of aromatic tetracarboxylic acids
Assignee: General Electric Co
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Filing: 1975-07-25
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Granted: 1977-04-26
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Expires: 1995-07-25
Abstract
Abstract Aromatic tetracarboxylic acids can be prepared by effecting reaction between a 4-nitro-N-alkylphthalimide with an aromatic dihydroxy compound in the presence of potassium carbonate as a catalyst and using dimethyl sulfoxide as a solvent.
Inventors
- 👤 Donald S. Johnson
- 👤 Howard M. Relles
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:31
CPC Classifications
C; C07; C07C; C07C323/00; C07C65/00; C07C65/21; C07C65/24
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
95 words
The process of making a tetracarboxylic acid of the formula ##STR13## which comprises (1) simultaneously effecting reaction under substantially anhydrous conditions and in an inert atmosphere at a temperature within the range of from about 110° to 200° C between a nitrophthalimide of the formula ##STR14## with bisphenol-A, the said reaction being conducted in a dimethyl sulfoxide solvent and in the presence of potassium carbonate in a mol ratio of from 2.1 to 3 mols of the latter per mol of bisphenol-A, and converting the resulting bisimide product by hydrolysis to the abovedescribed tetracarboxylic acid.
Claim 2
Dependent Claim
95 words
The process of making a tetracarboxylic acid of the formula ##STR13## which comprises (1) simultaneously effecting reaction under substantially anhydrous conditions and in an inert atmosphere at a temperature within the range of from about 110° to 200° C between a nitrophthalimide of the formula ##STR14## with bisphenol-A, the said reaction being conducted in a dimethyl sulfoxide solvent and in the presence of potassium carbonate in a mol ratio of from 2.1 to 3 mols of the latter per mol of bisphenol-A, and converting the resulting bisimide product by hydrolysis to the abovedescribed tetracarboxylic acid.
References Cited (Backward Citations)
US3879428A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-04-25 | 1980-10-25 | 1981-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-25 | 1984-10-25 | 1985-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-25 | 1988-10-25 | 1989-04-26 | $7700.00 | Window Closed / Lapsed |