Patent EP0002998A1 successfully refreshed from Google Patents.
US3972888A
Expired / Lapsed
US
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Process for the preparation of 1-hydroxy-pyridones
Assignee: Hoechst AG
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Filing: 1974-08-23
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Granted: 1976-08-03
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Expires: 1994-08-23
Abstract
Abstract Method for making 6-substituted-1-hydroxy-2-pyridones, which may also be substituted in one or more of the 3-, 4-, and 5-positions, by reaction of the corresponding 2-pyrone with hydroxylamine or its salts in the presence of imidazole or a 2-aminopyridine which may be mono- or di-methyl substituted.
Inventors
- 👤 Gerhard Lohaus
- 👤 Walter Dittmar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 11:28
CPC Classifications
C; C07; C07D; C07D213/00; C07D213/02; C07D213/89; C07D213/04; C07D213/24; C07D213/44; C07D213/46; C07D213/50
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
204 words
The method of making a 1-hydroxy-2-pyridone of the formula ##SPC3## wherein R 1 is straight-chain or branched alkyl having 1 to 17 carbon atoms, alkenyl having 2 to 17 carbon atoms, cycloalkyl having 3 to 8 carbon atoms, cyclohexylalkyl having 1 to 2 carbon atoms in the alkyl, furyl, or furylvinyl, or is phenyl, phenylalkyl having 1 to 4 carbon atoms in the alkyl, phenylalkenyl having 2 to 4 carbon atoms in the alkenyl, benzhydryl, phenoxymethyl, phenylmercaptomethyl, or phenylsulfonylmethyl, all of which may be at least mono-substituted in the phenyl nucleus by methyl, methoxy, amino, nitro, methoxycarbonyl, cyano, or halogen, R 2 is hydrogen, lower alkyl, lower alkenyl, lower alkinyl, or benzyl; R 3 is hydrogen, lower alkyl, or phenyl; R 4 is hydrogen, lower alkyl, lower alkenyl, methoxymethyl, benzyl, chlorine, or bromine, which comprises reacting a 2-pyrone of the formula ##SPC4## wherein R 1 -R 4 have their earlier meanings, at a temperature from room temperature to 150°C., with from 1 to 10 mol equivalents, per mol of 2-pyrone, of hyroxylamine or a salt thereof in the presence of 1 to 20 mols, per mol of hydroxylamine or of hydroxylamine salt, of imidazole, a 2-aminopyridine, or of a mono- or dimethyl substituted 2-aminopyridine.
Claim 2
Independent Claim
204 words
The method of making a 1-hydroxy-2-pyridone of the formula ##SPC3## wherein R 1 is straight-chain or branched alkyl having 1 to 17 carbon atoms, alkenyl having 2 to 17 carbon atoms, cycloalkyl having 3 to 8 carbon atoms, cyclohexylalkyl having 1 to 2 carbon atoms in the alkyl, furyl, or furylvinyl, or is phenyl, phenylalkyl having 1 to 4 carbon atoms in the alkyl, phenylalkenyl having 2 to 4 carbon atoms in the alkenyl, benzhydryl, phenoxymethyl, phenylmercaptomethyl, or phenylsulfonylmethyl, all of which may be at least mono-substituted in the phenyl nucleus by methyl, methoxy, amino, nitro, methoxycarbonyl, cyano, or halogen, R 2 is hydrogen, lower alkyl, lower alkenyl, lower alkinyl, or benzyl; R 3 is hydrogen, lower alkyl, or phenyl; R 4 is hydrogen, lower alkyl, lower alkenyl, methoxymethyl, benzyl, chlorine, or bromine, which comprises reacting a 2-pyrone of the formula ##SPC4## wherein R 1 -R 4 have their earlier meanings, at a temperature from room temperature to 150°C., with from 1 to 10 mol equivalents, per mol of 2-pyrone, of hyroxylamine or a salt thereof in the presence of 1 to 20 mols, per mol of hydroxylamine or of hydroxylamine salt, of imidazole, a 2-aminopyridine, or of a mono- or dimethyl substituted 2-aminopyridine.
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) | 1979-08-03 | 1980-02-02 | 1980-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-03 | 1984-02-02 | 1984-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-03 | 1988-02-02 | 1988-08-03 | $7700.00 | Window Closed / Lapsed |