反应详情

温度

15 °C

220 parts of the β-acetoxyethyl ester of p-aminobenzoic acid and 333 parts of ammonium thiocyanate are suspended in 1000 parts of acetic acid. The suspension is cooled to 15° C. and then a solution of 176 parts of bromine in 300 parts of acetic acid is gradually added in a period of two hours, without allowing the temperature to exceed 15° C. The mixture is stirred for an hour at 15° C. and then allowed to stand overnight and is subsequently run into 2500 parts of water containing 15 parts of 19° Be hydrochloric acid. Then it is heated to 95° C., filtered at 95° C., and the cooled filtrate is neutralised by the addition of 700 parts of sodium carbonate, filtered again, and the precipitate is washed with 2000 parts of water, drained and dried at 60° C. 215 parts of β-acetoxyethyl ester of 2-amino-benzothiazole-6-carboxylic acid, m.p. 191°-192° C, are thus obtained.

1. customto exceed 15° C
2. temperatureThen it is heated to 95° C.
3. filtrationfiltered at 95° C.
4. additionthe cooled filtrate is neutralised by the addition of 700 parts of sodium carbonate
5. filtrationfiltered again
6. washthe precipitate is washed with 2000 parts of water
7. customdried at 60° C