3-fluoro-2-methyl-1-oxidopyridin-1-ium

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A nitration mixture of 30% oleum (55 ml) and fuming nitric acid (90 ml) was added dropwise with cooling and stirring to a solution of 2-methyl-3-fluoropyridine-N-oxide (13.3 g) in concentrated sulphuric acid (48 ml) at 10°-15°. The solution was stirred at room temperature for 1.5 hours and then for 2 hours at 100°. After cooling, the mixture was poured onto ice, basified (ammonium carbonate) and extracted with dichloromethane. After drying (K2CO3), the extracts were evaporated to dryness to give 2-methyl-3-fluoro-4-nitropyridine-N-oxide (12.12 g) m.p. 170°-175°. was added dropwise with cooling for 2 hours at 100° After cooling the mixture was poured onto ice extracted with dichloromethane After drying (K2CO3) the extracts were evaporated to dryness

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Sodium nitrite (15.3 g) was added to a stirred solution of 3-amino-2-picoline (20 g) in 40% fluoroboric acid (215 ml) at -5° to -10°. The mixture was stirred for 2 hours at -10° followed by a further 2 hours at room temperature, after which time, the solution was basified (NaOH) and extracted with dichloromethane. The extracts were back-washed with water (pH 6 HCl) to remove some unreacted amine and, after drying (K2CO3), m-chloroperbenzoic acid (35.7 g) was added and the mixture allowed to stand for 16 hours. Ammonia gas was passed through the solution and the precipitated benzoate salts filtered off. The filtrate was evaporated to dryness to give 2-methyl-3-fluoropyridine-N-oxide (13.36 g) m.p. softens 55° melts 80°. followed by a further 2 hours at room temperature extracted with dichloromethane The extracts were back-washed with water (pH 6 HCl) to remove some unreacted amine after drying (K2CO3), m-chloroperbenzoic acid (35.7 g) was added to stand for 16 hours the precipitated benzoate salts filtered off The filtrate was evaporated to dryness