反应详情

Combine 2-hydroxy-1-(2-ethoxyethyl)-1H-benzimidazole (36.4 g, 177 mmol) and phosphorous oxychloride (72 mL) and reflux. After 30 minutes, cool to ambient temperature and pour the reaction mixture onto crushed ice. Adjust the pH to about 9 using aqueous 50% sodium hydroxide solution. Extract three times with ethyl acetate. Combine the organic layers and extract with brine. Dry the organic layer over Na2SO4, filter, and evaporate in vacuo to give a residue. Chromatograph the residue on silica gel eluting with ethyl acetate to give the 2-chloro-1-(2-ethoxyethyl)-1H-benzimidazole.

1. additionpour the reaction mixture
2. customonto crushed ice
3. extractionExtract three times with ethyl acetate
4. extractionextract with brine
5. dry with materialDry the organic layer over Na2SO4
6. filtrationfilter
7. customevaporate in vacuo
8. customto give a residue