Hydrochloric Acid → 3-Chloro-5-methoxypicolinic acid

In a 2-L round bottom flask, the methyl 3-chloro-5-methoxypicolinate (19.1 g, 95 mmol) was suspended in MeOH (104 ml). Aqueous 1N sodium hydroxide (104 ml, 104 mmol) was added. An air-cooled condenser was attached, and the reaction flask was heated in a 50° C. oil bath. After 1.5 h, the reaction was concentrated to remove the MeOH until a yellow sludge remained. The sludge was dissolved in 110 ml of water. The aqueous phase was extracted with diethyl ether (50 ml), which was discarded. The aqueous phase was acidified with aqueous hydrogen chloride (23 ml, 114 mmol), which caused extensive precipitation. The sludgy aqueous mixture was extracted with DCM in 6×250 ml. The organic layer were dried over MgSO4 and concentrated to yield 3-chloro-5-methoxypicolinic acid (17.88 g, 95 mmol, 100%) as a yellow solid. MS m/z=188 (M+H).