反应详情

温度

100 °C

A suspension of 3-ethoxycarbonyl-7,8-difluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]-naphthyridine (8 g) in 17.5% strength aqueous hydrochloric acid solution (80 cc) and acetic acid (80 cc) is heated with stirring to a temperature in the region of 100° C. for 1 hour and a half. After cooling to approximately 20° C., the solid is drained and washed with water (6×100 cc). After 1 recrystallization in dimethylformamide (160 cc), 7,8-difluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3 -carboxylic acid (6.44 g) is obtained in the form of a yellow solid, decomposing at 360° C.

1. temperatureis heated
2. temperatureAfter cooling to approximately 20° C.
3. washwashed with water (6×100 cc)
4. customAfter 1 recrystallization in dimethylformamide (160 cc)