Sulfuric Acid → 1-Methyl-3-(4-carbamoyl-3-(dimethylamino)-5-isothiazolyl)urea

Participants

Reaction Steps

A mixture of 11.2 g of 1-methyl-3-(4-cyano-3-(dimethylamino)-5-isothiazolyl)urea and 20 ml of concentrated sulfuric acid was heated at 85°-90° for 11/2 hours. The reaction mixture was poured into 300 ml of ice-water and the solid precipitate was collected by filtration. The solid was washed with water and a small amount of cold ethanol. The nmr spectrum of this solid (m.p. 243°, decomposes) indicated it to be the bisulfate salt of 1-methyl-3-(4-carbamoyl-3-(dimethylamino)-5-isothiazolyl)urea. The water-sulfuric acid filtrate was concentrated under reduced pressure, the concentrate was cooled and a solid precipitate was collected by filtration. This solid was combined with the bisulfate salt described above and was stirred with a saturated solution of sodium bicarbonate. A new solid was collected by filtration and purified by recrystallization from ethanol to give 9.2 g of 1-methyl-3-(4-carbamoyl-3-(dimethylamino)-5-isothiazolyl)urea; m.p. 221°. The nmr spectrum was consistent with the assigned structure.

Provenance & Evidence