A mixture of 8.8 parts of α-ethylbenzoylacetic acid ethyl ester and 5,3 parts of N-methyl-piperidyl-4-hydrazine is allowed to stand for 30 min at 22°C, after which the mixture is heated for 5 hours to 130°C under a pressure of 12 mm. After 4 hours 1-(N-methylpiperidyl-4)-3-phenyl-4-ethylpyrazolone-5 begins crystallize out. The reaction mixture is allowed to cool, after which the crystal mass is triturated with ether and then recrystallized from methanol-ether or from acetone. Melting point 159-161°C.
