反应详情

49 g (0.226 mol) of 4,5-dichloroisatin are suspended in 200 ml of acetic acid and 200 ml of acetic anhydride, treated over a period of 50 minutes at a temperature between 80° and 90° with 37.65 g (0.376 mol) of chromium trioxide and the mixture is subsequently cooled to 5°. The precipitated material is filtered off under suction, washed with water and dried. There is obtained 5,6-dichloroisatoic acid anhydride of melting point 280°-283°.

1. temperaturethe mixture is subsequently cooled to 5°
2. filtrationThe precipitated material is filtered off under suction
3. washwashed with water
4. customdried