Thionyl Chloride → 4-Ethoxy-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid chloride

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Reaction Steps

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°.

Provenance & Evidence