Synthesis of 4,6-dichloropyridine-2-carboxylic acid [Compound (II-17)]: a mixture of ethyl 4,6-dichloropyridinecarboxylate (0.5 g, 2.43 mmol) with sodium hydroxide (0.11 g, 2.67 mmol) was stirred in 1.1 mL of water and 11 mL of ethanol and reacted for 1 hr at 60 °C. After completion of the reaction, ethanol was removed by distillation and the residue was washed with dichloromethane. The aqueous layer was acidified with dilute hydrochloric acid and extracted with ethyl acetate. The organic phase was washed with saturated brine solution and dried over anhydrous sodium sulfate. A white solid product was obtained, yield: 0.46 g, yield: 98.7%, melting point: 114-116 °C. IR (KBr, cm-1): 3562, 1692, 1557, 1395, 1287, 819.
