Dimethylformamide → 5,6-dichloropyridine-3-carbonyl Chloride

Participants

Reaction Conditions

Reaction Steps

To a well stirred suspension of 5,6-dichloronicotinic acid 5 (600 g, 3.125 mole, Sigma-Aldrich) and DMF (20.0 mL) in dichloroethane (1.2 L) was added drop wise with stirring thionyl chloride (743.56 g, 6.25 mole). The reaction mixture was set up for heating with reflux, fitted with a gas trap filled with saturated aqueous sodium bicarbonate and heated at a temperature of 75° C. until the reaction mixture formed a clear solution, about 3 h. LC/MS of a sample quenched in methanol showed only the presence of the methyl ester. The reaction mixture was cooled to a temperature of about 25° C. and concentrated under reduced pressure to provide 5,6-dichloronicotinoyl chloride 6 as a thick paste.

Provenance & Evidence