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1. WO2014093565 - PROCÉDÉS AMÉLIORÉS D'ISOLEMENT D'ACIDE 4-AMINO-3-CHLORO-6-(4-CHLORO-2-FLUORO-3-MÉTHOXYPHÉNYL)PYRIDINE-2-CARBOXYLIQUE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

WHAT IS CLAIMED IS:

1. A process for the isolation of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3- methoxyphenyl)pyridine-2-carboxylic acid which comprises:

(a) neutralizing an aqueous solution of an alkali metal or alkaline earth metal salt of 4- amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid with an excess of 85 - 99 percent formic acid at a temperature from about 45 to about 90 °C to produce an aqueous mixture of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3- methoxyphenyl)pyridine-2-carboxylic acid;

(b) cooling the aqueous mixture of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3- methoxyphenyl)pyridine-2-carboxylic acid to about 10 to about 25 °C to crystallize the 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid, and

(c) collecting the crystalline 4-amino-3-chloro-6-(4-chloro-2-fluoro-3- methoxyphenyl)-pyridine-2-carboxylic acid.

2. A process for the preparation and isolation of 4-amino-3-chloro-6-(4-chloro-2- fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid which comprises:

(a) contacting an ester of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3- methoxyphenyl)pyridine-2-carboxylic acid of Formula I


in which

R1 represents H or C(0)CH3, and

R2 represents CrC12 alkyl or an unsubstituted or substituted C7-Cn arylalkyl

with an aqueous solution of an alkali metal or alkaline earth metal hydroxide in a C1-C4 alcohol at a temperature from about 45 to about 100 °C to produce an aqueous alcoholic

solution of the alkali metal or alkaline earth metal salt of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid,

(b) optionally removing most of the C1-C4 alcohol from the aqueous alcoholic solution of the alkali metal or alkaline earth metal salt of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid,

(c) neutralizing the aqueous solution of the alkali metal or alkaline earth metal salt of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid with an excess of 85 - 99 percent formic acid at a temperature from about 45 to about 90 °C to produce an aqueous mixture of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid,

(d) cooling the aqueous mixture of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid to about 10 to about 25 °C to crystallize the 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid, and

(e) collecting the crystalline 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acid.