64.5 g of 6-methylthiachromane were dissolved in 500 ml of acetic acid and
250 ml of 110-volume hydrogen peroxide were added. The solution was
placed on a water bath for 1.5 hour; it was then diluted with iced water, the
precipitate obtained was recovered, and this was washed and dried. There
were obtained 59.6 g of 6-methylthiachromane-1,1-dioxide (yield: 77.5%;
melting point 79°-81°C).
52 g of this product were added to 250 ml of chlorosulfonic acid and the
mixture was placed on a water bath at a temperature of 70°-75°C for 2
hours. It was allowed to cool and poured onto crushed ice; the product was
extracted by means of chloroform, the extracted solutions were washed and
the chloroform was evaporated. There were obtained 67 g of crude 6-methyl-
7-chloro-sulfonyl-thiachromane-1,1-dioxide (yield: 86%; melting point 158°-
161°C).
47 g of this sulfochloride were introduced into 200 ml of liquid ammonia. The
mixture was left to stand at ambient temperature until the ammonia
evaporated. The residue was taken up in water and the solution was acidified.
The precipitate formed was centrifuged, washed with water and dried. There
were obtained 30.8 g of 6-methyl-7-sulfamido-thiachromane-1,1-dioxide,
recrystallized from 2-methoxy ethanol (yield: 49%; MP: 236°-237°C).
