19798-81-3

626-05-1

141-86-6

19798-81-3

14.1 Preparation of 6-bromo-2-aminopyridine In a steel autoclave equipped with a glass liner, 10.00 g of 2,6-dibromopyridine (42.2 mmol) was suspended in 50 mL of concentrated ammonia. The autoclave was sealed and heated to 190°C using a heating jacket and maintained for 6 hours (pressure was raised to about 25 bar). After the autoclave was cooled and depressurized, the reaction mixture was mixed with 100 mL of ethyl acetate for phase separation. The aqueous phase was extracted twice with ethyl acetate, 100 mL each. the organic phases were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was dissolved in 250 mL of a solvent mixture of cyclohexane/ethyl acetate (1:1, v/v) to remove the by-product 2,6-diaminopyridine. Subsequently, the solution was filtered through a short silica gel column (5 x 20 cm) and washed again with 250 mL of cyclohexane/ethyl acetate (1:1, v/v) mixed solvent. After removal of the solvent under reduced pressure, the residue was sublimated at 90°C and 10-1 mbar to give 6.49 g (37.5 mmol, 88.9% yield) of 6-bromo-2-aminopyridine as a white solid.