Propionic anhydride → HCID 15580734, compound

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Reaction Steps

A mixture of 4.5 g. of 3-amino-1-phenyl-5-p-tolyl-2-pyrazoline (prepared in Example 3), 20.0 ml. of propionic anhydride and 200 mg. of 4-dimethylaminopyridine is heated on a steam bath for 2 hours. The reaction mixture is cooled to room temperature then water is added to separate a solid. The solid is collected then is dissolved in dichloromethane. The solution is passed through a short column of a hydrous magnesium silicate. The effluent is heated to reflux and hexane is added until turbidity appears. The mixture is cooled and filtered to collect a solid. The solid is recrystallized again from 80% ethanol. This material is dissolved in 100 ml. of methanol, then 200 mg. of potassium carbonate is added and the mixture is refluxed for 15 minutes. Water is added until turbidity appears. The mixture is cooled and filtered to collect the solid. The solid is dissolved in dichloromethane. This solution is columnized and recrystallized as described above to yield 2.4 g. of the desired product as colorless needles, m.p. 123.5°-125° C.

Provenance & Evidence