Hydrogen Bromide → 2-Bromo-3,5-dichloro-6-methylpyridine

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Reaction Conditions

Reaction Steps

2-Amino-3,5-dichloro-6-methylpyridine (3.54 g, 20 mmol) was suspended in aqueous 48% HBr solution at rt and the mixture was cooled to −20° C. This suspension was maintained at −20° C. while bromine (2.87 mL, 56 mmol) was added dropwise. The resultant paste was stirred for 30 minutes at this temperature before the dropwise addition of a cooled solution of sodium nitrite (3.59 g, 52 mmol) in water (5 mL). At this point the reaction mixture was allowed to warm to rt. After stirring for a further 60 minutes, the mixture was again cooled to −20° C. and treated with a solution of sodium hydroxide (16 g, 0.4 mol) in water (20 mL). This mixture was extracted with ethyl acetate and the organic layer washed with water and then brine solution. The organic solution was dried over MgSO4, filtered and the residue obtained from solvent evaporation was purified using silica gel chromatography [eluent: 10% ethyl acetate in hexane]. 2-Bromo-3,5-dichloro-6-methylpyridine 1-4 (2.14 g, 45%) was obtained as a solid.

Provenance & Evidence