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ChemicalBook CAS DataBase List 5,6-Dichloronicotinic acid
41667-95-2

5,6-Dichloronicotinic acid synthesis

2synthesis methods
5,6-DICHLORONICOTINIC ACID ETHYL ESTER

401566-69-6

5,6-Dichloronicotinic acid

41667-95-2

The general procedure for the synthesis of 5,6-dichloropyridine-3-carboxylic acid from 5,6-dichloronicotinic acid ethyl ester was as follows: in a solvent mixture of tetrahydrofuran (THF), methanol (MeOH) and water (50 mL, 4:1:1, v/v/v), ethyl 5,6-dichloronicotinic acid ethyl ester (1.0 g, 4.5 mmol) and aqueous sodium hydroxide 2N solution (6.75 mL, 13.5 mmol). The reaction mixture was stirred at room temperature for 0.5 hours. Upon completion of the reaction, the mixture was concentrated to remove the organic solvent. Subsequently, the mixture was acidified with 2N hydrochloric acid to a pH of about 2. The acidified mixture was extracted with ether (30 mL x 3). The organic layers were combined, washed with water (50 mL x 3), dried over anhydrous sodium sulfate, and concentrated to give 5,6-dichloropyridine-3-carboxylic acid (800 mg, 91% yield) as a white solid.LCMS (ESI) m/z: 192.0 [M + H]+.

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Yield:41667-95-2 91%

Reaction Conditions:

Stage #1: ethyl 5,6-dichloronicotinatewith sodium hydroxide in tetrahydrofuran;methanol;water at 20; for 0.5 h;
Stage #2: with hydrogenchloride in water;

Steps:

33.1 Preparation of 5,6-dichloronicotinic acid

A mixture of ethyl 5,6-dichloronicotinate (1.0 g, 4.5 mmol) and aqueous NaOH (2 N, 6.75 mL, 13.5 mmol) in a mixed solvents of THF/MeOH/water (50 mL, 4/1/1) was stirred at room temperature for 0.5 h.
After concentration, the mixture was acidified with 2 N HCl to pH around 2.
The resulting mixture was extracted with ether (30 mL*3).
The organic layer was washed with water (50 mL*3), dried over Na2SO4, and concentrated to afford 5,6-dichloronicotinic acid (800 mg, 91% yield) as a white solid. LCMS (ESI) m/z: 192.0 [M+H]+.

References:

US2013/317000,2013,A1 Location in patent:Paragraph 0368-0369

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