A mixture of 5.0 g (0.0357 g/mol) of ρ-fluorophenylethyl alcohol, 2.0 g (0.007 g/mol) of 5-chloro-2,4-disulphamylaniline, 2.0 g (0.0068 g/mol) of potassium bichromate and 15 ml of concentrated hydrochloric acid (0.176 g/mol) and 25 ml of water is heated under reflux for 1 h. The mixture is allowed to cool, and 15 ml of ether are added to separate the excess of ρ-fluorophenylethyl alcohol. The aqueous layer is decanted and frozen for 2 h and the precipitate is separated, washed with water and dried in vacuum over phosphoric anhydride. There are collected 1.35 g (yield 47.5%) of the 1,1-dioxide of 3-ρfluorophenyl-methyl-7-sulphamyl-6-chloro-3,4-dihydrobenzo-1,2,4-thiadiazine, which when recrystallised from 30 ml of 50% alcohol on "Norit" active carbon takes the form of a white crystalline substance, melting point is 239°C.
