反应详情

A mixture of 9.0 grams (0.040 mole) of 5-bromo-3-cyano-2-hydroxy-4,6-dimethylpyridine in 40 mL of phosphorus oxychloride is stirred, and one drop (catalyst) of N,N-dimethylformamide is added. The reaction mixture is then stirred at ambient temperature for about five hours, and then allowed to stand for about 72 hours. After this time, the reaction mixture is poured into 1000 mL of ice containing about one mL of concentrated hydrochloric acid. The mixture is stirred until the ice melts. The resultant precipitate is collected by filtration and washed with water. The solid is then dried under reduced pressure at about 60° C. An NMR spectrum of the solid indicates that it contains a large amount of starting material. The solid is then dissolved in 25 mL of phosphorus oxychloride, and two drops of N,N-dimethylformamide are added. The mixture is heated to reflux where it is stirred for about 18 hours. After this time, the reaction mixture is poured into 600 mL of ice containing about two mL of concentrated hydrochloric acid. The mixture is stirred until the ice melts. The resultant precipitate is collected by filtration, washed with water, and dried under reduced pressure at about 60° C., yielding 8.6 grams of 5-bromo-2-chloro-3-cyano-4,6-dimethylpyridine. The NMR spectrum is consistent with the proposed structure.

1. stirringThe reaction mixture is then stirred at ambient temperature for about five hours
2. filtrationThe resultant precipitate is collected by filtration
3. washwashed with water
4. customThe solid is then dried under reduced pressure at about 60° C
5. dissolutionThe solid is then dissolved in 25 mL of phosphorus oxychloride
6. additiontwo drops of N,N-dimethylformamide are added
7. temperatureThe mixture is heated
8. temperatureto reflux where it
9. stirringis stirred for about 18 hours
10. additionAfter this time, the reaction mixture is poured into 600 mL of ice containing about two mL of concentrated hydrochloric acid
11. stirringThe mixture is stirred until the ice
12. filtrationThe resultant precipitate is collected by filtration
13. washwashed with water
14. customdried under reduced pressure at about 60° C.