4,5,6-Trichloronicotinic acid synthesis
- Product Name:4,5,6-Trichloronicotinic acid
- CAS Number:847608-28-0
- Molecular formula:C6H2Cl3NO2
- Molecular Weight:226.44
Yield:-
Reaction Conditions:
with hydrogenchloride;sodium hydroxide;triethylamine in tetrahydrofuran;methanol;trichlorophosphate;
Steps:
9 Synthesis of 7-(4-bromo-2-chlorophenylamino)-8-chloroimidazo[1,2-a]pyridine-6-carboxylic acid (30)
5-Chloro-4,6-dihydroxynicotinic acid ethyl ester (8.05 g, 37 mmol) was suspended in phosphorous oxychloride (30 mL, 296 mmol). The mixture was cooled to 0° C. and triethylamine (5.16 mL, 37.0 mmol) was added. The reaction was heated to 60° C. for three hours. The solution was cooled to room temperature, poured onto ice, stirred for 15 minutes and extracted with ethyl acetate (2*) and diethyl ether (1*). The combined organic extracts were washed with brine (3*), dried over Na2SO4 and concentrated to a brown liquid. The crude product was passed through a plug of silica gel eluding with dichloromethane. 4,5,6-trichloronicotinic acid ethyl ester, the desired product was obtained as a yellow liquid (7.76 g, 82%). Sodium hydroxide (1.0 M solution, 61.0 mL, 61.0 mmol) was added to a solution of 4,5,6-trichloronicotinic acid ethyl ester (7.76 g, 30.5 mmol) in 4:1 THF/MeOH (150 mL). After stirring for 30 minutes, the reaction was acidified to pH 1 by addition of concentrated HCl, diluted with ethyl acetate, washed with water (3*) and brine (2*), dried over Na2SO4 and concentrated to provide the desired product, 4,5,6-trichloro-nicotinic acid, as an off white solid (6.77 g, 98%).
References:
US2005/54701,2005,A1
181261-73-4
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