Method for the production of 2,6-dichloro-5-fluoro-nicotinic acid and coarse and particularly pure 2,6-dichloro-5-fluoro-nicotinic acid

US6441182B1 · kind B1 · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Gunter Rauchschwalbe · Leverkusen, DE
• Bernd Griehsel · Bottrop, DE
• Andreas Sattler · Trostberg, DE
• Karsten von dem Bruch · Leverkusen, DE

Key dates

• Filing date: Dec 6, 2001
• Grant date: Aug 27, 2002
• Expiry date: Dec 6, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D213/80
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a method for the production of 2,6-dichloro-5-fluoronicotinic acid by hydrolyzing 2,6-dichloro-5-fluoro-3-cyanopyridine by(a) dissolving 2,6-dichloro-5-fluoro-3-cyanopyridine at 70 to 90° C. in sulfuric acid having a concentration of 90 to 99% by weight and hydrolyzing the 2,6-dichloro-5-fluoro-3-cyanopyridine at 70 to 100° C. to the corresponding carboxamide,(b) cooling the resultant reaction mixture to a temperature in the range from 10 to 65° C.,(c) metering in water until the concentration of sulfuric acid is 55 to 75% by weight (calculated relative to the sulfuric acid employed in stage (a) and the water employed in stage (c)) while keeping the temperature between 30 and 65° C. during the addition of the first quarter of the water and keeping the temperature between 50 and 80° C. during the addition of the second quarter of the water, and(d) completing hydrolysis of the resultant mixture to 2,6-dichloro-5-fluoronicotinic acid at 70 to 110° C.