Ammonia → 5-Bromo-2-methylpyridin-1-ium-1-olate

Participants

Reaction Steps

To a solution of 5 -Bromo-2 -methyl-pyridine (71.35 g. 0.41 M) in dichloromethane (350 ml) was added a solution of m-chloroperbenzoic acid (78.83 g, 0.46 M) in dichloromethane (1100 ml), over a period of 2.5 hours. The reaction mixture was stirred at ambient temperature for a further 20 hours, cooled (ice/salt bath) and anhydrous ammonia bubbled into it for 1 hour during which time a white precipitate formed and the temperature of the solution was not allowed to rise above 151°. The reaction mixture was allowed to warm to room temperature, filtered and washed with dichloromethane. The filtrate and washings were combined and washed with Na2SO3 (5 %) solution (2×200 ml), water (2×150 ml), dried (phase separating paper) and evaporated to dryness in vacuo to give an off white solid. Recrystallisation from ethyl acetate gave 5 -bromo-2 -methylpyridine-N-oxide as white crystals, 65.66 g. 84 %. m.p. 116°-118°.

Provenance & Evidence