反应详情

A mixture of 1.96 g of benzo-1,2,3-thiadiazole-7-carbaldehyde, 1.24 g of malonic acid and 6 ml of pyridine are heated for 26 hours at 120° C., with 2 further additions of 0.6 g portions of malonic acid after 4 and 7 hours. The mixture is then cooled, poured into ice-water and acidified with concentrated hydrochloric acid. The precipitate which has formed is filtered off and dissolved in dilute sodium hydroxide solution, the mixture is washed three times with methylene chloride, and the aqueous phase is subsequently acidified once more, using hydrochloric acid. The precipitate obtained is filtered off, washed with water and dried in vacuo, resulting in 11 g of the title compound of m.p. 199°-202° C.

1. temperatureThe mixture is then cooled
2. customThe precipitate which has formed
3. filtrationis filtered off
4. dissolutiondissolved in dilute sodium hydroxide solution
5. washthe mixture is washed three times with methylene chloride
6. customThe precipitate obtained
7. filtrationis filtered off
8. washwashed with water
9. customdried in vacuo