反应详情

117.5 g. of 4-ethoxy-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid (0.5 mol.) are slowly added with stirring to 300 ml. of thionyl chloride. The mixture is refluxed for 4 hours, excess thionyl chloride is removed in vacuo and the residue dissolved in 500 ml. anhydrous diethylether. The undissolved material is filtered off and the filtrate intensively cooled. The acid chloride precipitates; it is filtered under suction and washed well with cold water. Yield 105 g. (80%), m.p. 72°-73°.

1. temperatureThe mixture is refluxed for 4 hours
2. customexcess thionyl chloride is removed in vacuo
3. dissolutionthe residue dissolved in 500 ml
4. filtrationThe undissolved material is filtered off
5. temperaturethe filtrate intensively cooled
6. customThe acid chloride precipitates
7. filtrationit is filtered under suction
8. washwashed well with cold water