反应详情

温度

-40 °C

P.2 4-Nitrobenzisothiazole, 5-nitrobenzisothiazole and 7-nitrobenzisothiazole 300 g of benzisothiazole are added, with cooling, to 750 ml of concentrated sulfuric acid, the solution is cooled to -40° C., and 227.5 g of potassium nitrate are added in portions, in such a manner that the temperature does not rise above room temperature. After standing at room temperature for 15 hours, the reaction mixture is poured onto ice and the solid portion is filtered off and dried. The product is chromatographed on silica gel with tetrahydrofuran:methylene chloride:hexane 5:10:85. After evaporation, there are isolated from the fractions 5.5% of the theoretical yield of 4-nitrobenzisothiazole, 56.5% of the theoretical yield of 5-nitrobenzisothiazole and 36.8% of the theoretical yield of 7-nitrobenzisothiazole (compounds 16, 11 and 1, Table).

1. customdoes not rise above room temperature
2. additionthe reaction mixture is poured onto ice
3. filtrationthe solid portion is filtered off
4. customdried
5. customThe product is chromatographed on silica gel with tetrahydrofuran:methylene chloride:hexane 5:10:85
6. customAfter evaporation, there