Process for the production of pyridine carboxylic acids
Abstract
Abstract NICOTINIC ACID AND OTHER CARBOXYLIC ACIDS HAVING A PYRIDINE NUCLEUS MAY BE PREPARED BY THE OXIDATION OF FUSED-RING PYRIDINE COMPOUNDS IN THE PRESENCE OF 25 TO 6:: PERCENT EXCESS NITRIC ACID AT TEMPERATURES OF 180* TO 370*C. WITH PRESSURES OF 20 TO 500 ATM. THE NIRIC ACID CONCENTRATION OF THE REACTION MIXTURE IS ADJUSTED TO 10 TO 28 PERCENT TO PRECIPITATE AS CRYSTALLINE HYDDRONITRATE AND SEPARATED FROM THE MIXTURE. THE PH OF AN AQUEOUS SOLUTION OF THE PYRIDINE CARBOXYLIC ACID HYDRONITRATE IS ADJUSTED WITH THE BASIC STARTING MATERIAL TO THE ISOELECTRIC POINT OF THE SPECIFIC PYRIDINE CARBOXYLIC ACID TO PRECIPITATE THE SAME. THE CRYSTALLINE PRECIPITATION IS SEPARATED AND THE MOTHER LIQUORS ARE COMBINED AND RECYCLED AS THE STARTING MATERIAL AFTER ADJUSTMENT OF THE CONCENTRATIONS THEREIN.
Inventors
- 👤 A Stocker
- 👤 O Marti
- 👤 T Pfammatter
- 👤 G Schreiner
Bibliographic Details
Claims Analysis
Total Claims: 0References 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) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |