反应详情

Ethyl 3-hydroxypyridazine-6-carboxylate [22.00 g, 0.13 mol, prepared from 3-hydroxypyridazine-6-carboxylic acid according to the procedure of Libermann, D. and Rouaix, A. (Bull. Soc. Chim . Fr. 1959, 1793-1798)] and phosphorous oxychloride (122 mL, 1.31 mol) were heated at 110° C. (via an oil bath) for 1 h. The mixture was cooled and concentrated under reduced pressure, which removed the excess phosphorous oxychloride. The residue was dissolved into chloroform, cooled, and carefully washed with saturated sodium bicarbonate solution. The chloroform extract was dried (MgSO4) , filtered, concentrated and recrystallized from ethyl acetate-diisopropyl ether to afford ethyl 6-chloro-3-pyridazinecarboxylate as tan needles, mp 145°-150° C.

1. temperatureThe mixture was cooled
2. concentrationconcentrated under reduced pressure, which
3. customremoved the excess phosphorous oxychloride
4. dissolutionThe residue was dissolved into chloroform
5. temperaturecooled
6. washcarefully washed with saturated sodium bicarbonate solution
7. extractionThe chloroform extract
8. dry with materialwas dried (MgSO4)
9. filtrationfiltered
10. concentrationconcentrated
11. customrecrystallized from ethyl acetate-diisopropyl ether