Hydrochloric Acid → ethyl 3-amino-1-methyl-1H-pyrazole-4-carboxylate

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Reaction Steps

At room temperature, 100 ml of concentrated hydrochloric acid were added dropwise over a period of 20 min to a suspension of 220 g (0.855 mol) of ethyl 3-(N′-benzylidene-N-methylhydrazino)-2-cyanoacrylate (XVI-1) in 1000 ml of ethanol. The mixture was then heated at the boil for 1 hour. After removal of the solvent, the oily residue was triturated with gentle heating with 200 ml of diethyl ether, resulting in the precipitation of a solid. Filtration with suction gave 149 g (95% of theory) of ethyl 3-amino-1-methyl-1H-pyrazole-4-carboxylate [log P (pH 2.3)=0.72].

Provenance & Evidence