Hydrochloric Acid → 5-Bromo-6-fluoro-2-methylquinoline

Participants

Reaction Conditions

Reaction Steps

A solution of 12.1 kg (75 mole) of 6-fluoro-2-methylquinoline in 33 liters of 1,2-dichloroethane was chilled to 5° C., and 15.0 kg (113 mole) of aluminum chloride was added thereto in portions over 15 minutes. The mixture was purged with nitrogen and then heated to 75° C. A solution of 13.2 kg (82.6 mole) of bromine in 2 liters of 1,2-dichloroethane was added over a period of 5.5 hours. The reaction was maintained at 75° C. during the addition and for an additional 15 minutes after the addition was completed. The reaction was stirred at 70° C. for 23 hours and was then cooled to 10° C. and slowly added to a mixture of 8 kg of 30% hydrochloric acid, 41 liters of water and 31.75 kg of ice. The mixture warmed to 50° C. during the addition. The mixture was heated in reflux and the 1,2-dichloroethane was removed by azeotropic distillation. The remaining aqueous solution was cooled to 60° C. and 12 kg of 10% hydrochloric acid was added. The solution was treated with Celite® (available from Johns-Manville Corp.) and filtered. The filtrate was cooled to 25° C. and 18 kg of 30% hydrochloric acid and 10.22 kg of zinc chloride were added. The resulting slurry was chilled to 5° C. and allowed to stir for several days. The solid was collected and then reslurried with 10 gallons of water. The slurry was chilled to 5° C. and 22 kg of chilled ammonium hydroxide was added. The resulting slurry (pH 10-11) was diluted with 25 gallons of water and the solid was collected, rinsed with water and dried in vacuo at 60° C. to give crude 5-bromo-6-fluoro-2-methylquinoline (84.5% pure by gas chromatography analysis). The material was recrystallized from hexane to give 99.2% pure 5-bromo-6-fluoro-2-methylquinoline.

Provenance & Evidence