反应详情

温度

140 °C

To a solution of 1-(5,6-dichloro-pyridin-3-yl)-ethanol 9 (311 g. 1.62 mole) in chlorobenzene (3 L) was added p-toluene sulfonic acid (431 g, 2.5 mole) and the reaction mixture was heated at reflux (about 140° C.) with concomitant removal of water. When the reaction was complete, the mixture was concentrated to about 500 mL, diluted with 2 L water, and extracted with three times (1 L per extraction) ethyl acetate. The organic portions were combined, dried (Na2SO4), concentrated under reduced pressure with low heat, dissolved in 500 mL methylene chloride, and applied to the top of 2 kg silica column. The purified vinyl pyridine was eluted with a 0% to 10% gradient of ethyl acetate in hexane. 178.55 g, of about 100% pure 2,3-dichloro-5-vinylpyridine was collected as a clear oil which solidified upon cooling to 4° C. (63% yield). 1H NMR (400 MHz, CDCl3) δ 8.27 (m, 1H), 7.80 (dd, J=12, 18 Hz, 1H), 6.62 (d, J=18 Hz, 1H), 5.46 (d, J=12 Hz, 1H).

1. temperaturethe reaction mixture was heated
2. customwith concomitant removal of water
3. concentrationthe mixture was concentrated to about 500 mL
4. additiondiluted with 2 L water
5. extractionextracted with three times (1 L per extraction) ethyl acetate
6. dry with materialdried (Na2SO4)
7. concentrationconcentrated under reduced pressure with low heat
8. dissolutiondissolved in 500 mL methylene chloride
9. washThe purified vinyl pyridine was eluted with a 0% to 10% gradient of ethyl acetate in hexane
10. custom178.55 g, of about 100% pure 2,3-dichloro-5-vinylpyridine was collected as a clear oil which
11. temperatureupon cooling to 4° C. (63% yield)