Thionyl Chloride → 2-Chloronicotinic acid

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Reaction Steps

The acid chloride of 2-chloronicotinic acid was prepared by refluxing 11 g. (0.07 mole) of 2-chloronicotinic acid in 80 ml. of thionyl chloride for 1.5 hours. After evaporating to dryness, the oily residue was dissolved in 50 ml. of ether. The ether solution was added to a stirred ice-cold solution of 7.7 g. (0.07 mole) of 3-amino-2-pyridone in 80 ml. of dry pyridine during 15 minutes. After 30 more minutes at ice temperature and 4 hours at room temperature, it was allowed to stand overnight in an open dish. The crystalline residue was extracted with water and the solid residue (12.9 g.) was collected and recrystallized from dimethyl formamide-ether to give gray crystals of 3-(2-chloronicotinoylamino)-2-pyridone, m.p. 295° C.

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