Patent US3873573A successfully refreshed from Google Patents.
US3873573A
Expired / Lapsed
US
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Phthalide compounds
Assignee: ESCO Co A Ltd PARTNERSHIP OF MICHIGAN LP
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Filing: 1973-06-29
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Granted: 1975-03-25
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Expires: 1993-06-29
Abstract
Abstract Processes for the synthesis of phthalides and fluorans are disclosed. New isolatable intermediate phthalides have been found which serve as precursors to the production of fluorans. The products of this invention are synthesized from keto acids and phenolic amines, wherein the mole ratio of the keto acids to the phenolic amines is in excess of 1:1. Not only is product yield greatly improved, but usual condensation times of 24 hours and longer have been reduced to about 5 hours.
Inventors
- 👤 Sheldon Farber
- 👤 Troy E Hoover
- 👤 David B Mcquain
- 👤 Arthur J Wright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:50
CPC Classifications
C; C07; C07D; C07D307/00; C07D307/77; C07D307/87; C07D307/88; C07D307/885; C09; C09B; C09B11/00; C09B11/04; C09B11/10; C09B11/24
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
6 words
A PHTHALIDE REPRESENTED BY THE FORMULA:
Claim 2
Dependent Claim
6 words
A PHTHALIDE REPRESENTED BY THE FORMULA:
Claim 3
Dependent Claim
13 words
A phthalide according to claim 1 wherein the phthalide is 3, 3-(4-diethylamino-2-hydroxyphenyl) (5-anilino-2-methoxy-4-methylphenyl)phthalide.
References Cited (Backward Citations)
US499927A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |