Patent US2418908A successfully refreshed from Google Patents.
Patent US3655740A successfully refreshed from Google Patents.
US3655740A
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Method for producing aminonaphthalene sulphonic acids
Assignee: Bayer AG
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Filing: 1968-07-22
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Granted: 1972-04-11
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Expires: 1988-07-22
Abstract
Abstract COMPOUNDS OF THE FORMULA 1-R,5-(HO3S-),7-NH2-NAPHTHALENE IN WHICH R IS -OH OR -NH2 ARE PREPARED BY NITRATING 1-NITRONAPHTHALENE-5-SULFONIC ACID IN OLEUM TO GIVE 1,7DINITRONAPHTHALENE-5-SULFONIC ACID, REDUCING THE LATTER TO 1,7-DIAMINONAPHTHALENE-5-SULFONIC ACID AND OPTIONALLY EXCHANGING IN KNOWN MANNER THE 1-POSITIONED AMINO GROUP FOR A HYDROXY GROUP. THESE COMPOUNDS ARE USEFUL AS INTERMEDIATES IN THE PREPARATION OF AZOMETHINE DYESTUFFS, E.G. BY CONDENSATION WITH AROMATIC ALDEHYDES.
Inventors
- 👤 Horst Nickel
- 👤 Fritz Suckfull
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:29
CPC Classifications
C; C07; C07C; C07C309/00; A; A01; A01N; A01N43/00; A01N43/64; A01N43/66; A01N43/68; A01N43/70; C10; C10M; C10M2219/00; C10M2219/04; C10M2219/044
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) | 1975-04-11 | 1975-10-11 | 1976-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-11 | 1979-10-11 | 1980-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-11 | 1983-10-11 | 1984-04-11 | $7700.00 | Window Closed / Lapsed |