反应详情

To produce 2-amino-3-chloro-5-bromopyridine, chlorine is slowly introduced in the course of 8 hours at about 50° C. into a solution of 25 parts of 2-amino-5-bromopyridine in 70 parts of concentrated hydrochloric acid. After complete reaction, the solution is poured into ice-water, and the unreacted chlorine is decomposed with sodium bisulphite. Whilst ice is added, the solution is adjusted at 15° with 30% sodium hydroxide solution to pH 8 and subsequently stirred for one hour; the precipitate is then filtered off and washed with water. Recrystallisation from cyclohexane yields 28.5 parts (95.4% of theory) of 2-amino-3-chloro-5-bromopyridine in the form of white needles, m.p. 94°-96° C.

1. customAfter complete reaction
2. additionWhilst ice is added
3. filtrationthe precipitate is then filtered off
4. washwashed with water
5. customRecrystallisation from cyclohexane