反应详情

48.4 g of the ester obtained as described above were stirred with 330 ml of 2N sodium hydroxide solution at 50° C. for 4 hours. The clear yellow solution was cooled down and acidified to pH 3 to 4 by adding 2N hydrochloric acid. The precipitate was filtered by suction, washed with water and dried at 80° C. The crude product obtained was recrystallized from a mixture of dimethylformamide and water (1:1) under clarifying by activated carbon. Thus, 1-(4'-chloro-3'-sulfamoylbenzoyl)amino-5-carboxybenzimidazole-2-thione containing 1 molecule of dimethylformamide was obtained in the form of snow-white tiny crystalls.

1. temperatureThe clear yellow solution was cooled down
2. filtrationThe precipitate was filtered by suction
3. washwashed with water
4. customdried at 80° C
5. customThe crude product obtained
6. customwas recrystallized from a mixture of dimethylformamide and water (1:1)