反应详情

To 1.0g. of 7-amino-6-chloro-1-ethyl-2-methyl-5-trifluoromethylbenzimidazole (Example IV) dissolved in 10 ml. of concentrated H2SO4 was added 1.0g. of paraformaldehyde. The resultant mixture was stirred at 80°C. for 2 hours and then poured onto ice. The resultant brown solution was made basic by addition of concentrated NH4OH, precipitating a light brown solid. The mixture was extracted with chloroform and the chloroform extracts washed with water and dried over Na2SO4. After removal of the chloroform by evaporation, the residue was extracted with hexane and the hexane extract distilled to dryness. The solid residue was recrystallized from hexane to give 0.77g. (73.3%) of the desired product, m.p. 116.5°-119°C.

1. additionpoured onto ice
2. customprecipitating a light brown solid
3. extractionThe mixture was extracted with chloroform
4. washthe chloroform extracts washed with water
5. dry with materialdried over Na2SO4
6. customAfter removal of the chloroform
7. customby evaporation
8. extractionthe residue was extracted with hexane
9. extractionthe hexane extract
10. distillationdistilled to dryness
11. customThe solid residue was recrystallized from hexane
12. customto give 0.77g