Ammonia → 2H-1,3-Benzothiazine-2,4(3H)-dione

Participants

Reaction Steps

30 g of thiosalicylic acid and 39 g of triethylamine were dissolved in 125 ml of tetrahydrofuran. The mixed solution was maintained at a temperature of 0 - 5° C., to which 42 g of ethyl chloroformate was added dropwise. The system was allowed to stand for 30 minutes and then, 50 ml of aqueous ammonia (ammonia concentration: 25 - 30%) was added thereto. The resulting solution was allowed to stand over night at room temperatue (about 20 - 30° C.). Then, the solvent used was removed by distillation under reduced pressure, while the residue was filtered off, and recrystallized from ethanol. 21 g of 2H-1,3-benzothiazin-2,4(3H)-dione was obtained. The melting point of the product was 210 - 211° C. (In addition, this product can be also prepared by using as a starting material the ester derivatives of thiosalicylic acid, which are obtained using usual esterification reactions, in a similar manner as above.)

Provenance & Evidence