2-Chloronicotinic acid → 2-Methoxynicotinic acid

Participants

Reaction Conditions

Reaction Steps

A stainless steel stirred autoclave was charged sequentially with methanol (2.8 l.), sodium methoxide (259 g.) (in portions, keeping the temperature less than 35° C.), and 2-chloro-3-pyridinecarboxylic acid (190 g.). The autoclave was sealed and the reaction mixture heated at 110° C. (50 psig) for 48 hours. The reaction mixture was cooled to 25° C. and discharged from the autoclave. Solids were recovered by filtration. Concentration of the filtrate gave a second crop. These process steps were repeated until virtually all of the methanol had been removed. The several crops of solids were combined, taken up in 2.5 liters of water and acidified with conc. hydrochloric acid to pH 2.7 keeping the temperature below 20° C. The precipitated product was granulated for 30 minutes at 15° C. and recovered by filtration (141 g.). Purified title product was obtained by recrystallization from ethyl acetate-hexane (120.5 g., m.p. 148°-150° C.).

Provenance & Evidence