反应详情

4-Methoxy-1,2-phenylenediamine (5.00 g, 36 mmol) was dissolved in formic acid (10 ml) and heated at reflux for 2 hours. The solution was allowed to cool to room temperature overnight then treated with calcium carbonate (5.0 g). After dilution with ethanol (150 ml) the mixture was heated at reflux for 1 h then filtered, the residue being washed with hot ethanol (50 ml). The combined filtrates were evaporated at reduced pressure to give an oil from which a solid crystallised. The material was slurried with diethyl ether (50 ml) then filtered to give an orange solid which was recrystallised from ethyl acetate to give 5-methoxybenzimidazole (5.33 g, 99%) as a yellow crystalline solid.

1. temperatureheated
2. temperatureat reflux for 2 hours
3. temperatureat reflux for 1 h
4. filtrationthen filtered
5. washthe residue being washed with hot ethanol (50 ml)
6. customThe combined filtrates were evaporated at reduced pressure
7. customto give an oil from which a solid
8. customcrystallised
9. filtrationthen filtered
10. customto give an orange solid which
11. customwas recrystallised from ethyl acetate