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

Participants

Reaction Conditions

Reaction Steps

To a well stirred suspension of 5,6-dichloronicotinic acid 11 (600 g, 3.125 mole) and N,N-dimethylformamide (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 75° C. until the reaction mixture formed a clear solution, about 3 h. LC/MS of a sample quenched in methanol showed only methyl ester. The reaction mixture was cooled to ambient and concentrated under reduced pressure to yield 5,6-dichloronicotinoyl chloride 12 as a thick paste.

Provenance & Evidence