反应详情

HCl (20 g) is heated to 210° C. and 5 g of 7-methoxy-3-methyl-4H-1,2,4-benzothiadiazine-1, 1-dioxide are added. This mixture was kept at about 210° C. for about 11/2 hours. The mixture was then cooled slightly and about 60 ml of ice cold water was added with stirring. This mixture was filtered and the solid washed with 25 ml. of cold water and dried yielding 3.5 g of 7-hydroxy-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide (A). An additional 0.63 g of A was recovered from the filtrate to allowing it to stand in the refrigerator for about one hour. Total yield of this product was 4.13 g (88%), m.p. 333°-336° C. (dec.). ##STR12##

1. customwas kept at about 210° C. for about 11
2. custom2 hours
3. temperatureThe mixture was then cooled slightly
4. filtrationThis mixture was filtered
5. washthe solid washed with 25 ml
6. dry with materialof cold water and dried