Acetic Anhydride → 5-Formamido-1-(2-hydroxyethyl)pyrazole

Participants

Reaction Steps

A mixture of acetic anhydride (44.5 ml) and formic acid (22.3 ml) was stirred at ambient temperature for an hour. To this mixture was added 1-(2-hydroxyethyl)-5-aminopyrazole (30 g) at 0°-10° C., and the mixture was stirred under ice-cooling for 30 minutes. The mixture was poured into ice-cold water, adjusted to pH 10.5 with 40% aqueous potassium carbonate, and stirred under ice-cooling for 30 minutes. The mixture was extracted with a mixture of tetrahydrofuran and ethyl acetate 6 times. The organic layer was dried over magnesium sulfate and evaporated in vacuo to give 1-(2-hydroxyethyl)-5-formamidopyrazole (30.8 g).

Provenance & Evidence