反应详情

43 g of 4-chloro-7-nitro-1,2-benzisothiazole and 16 g of sodium hydroxide powder in 400 ml of ethanol are stirred for 1 hour at 70° C. When the mixture has cooled, 500 ml of water are added, the batch is neutralized with dilute sulfuric acid whilst cooling with ice, and the product which has precipitated is filtered off. The filter cake is then washed with a little ice-cold methanol, and dried. 34 g (86% of theory) of 7-nitro-4-hydroxy-1,2-benzisothiazole are obtained, melting at 284° C. (with decomposition) after one recrystallization from n-butanol.

1. temperatureWhen the mixture has cooled
2. temperaturewhilst cooling with ice
3. customthe product which has precipitated
4. filtrationis filtered off
5. washThe filter cake is then washed with a little ice-cold methanol
6. customdried