To 60 ml of isopropanol, there are introduced 120 g of 4-ethyl-propiophenone,
28.8g of p-formaldehyde and 107 g of piperidine hydrochloride, and the
resulting mixture is heated to reflux on an oil bath with stirring. The heating is
continued, and when the reaction mixture solidifies, the state being a sign of
completion of the reaction, there are added 500 ml of acetone thereinto. The
solidified mass is pulverized by crush, recovered by filtration and washed with
acetone. 144 g of the crude dry crystalline substance is thus obtained, which
is the hydrochloride of the purposed product. The hydrochloride is
recrystallized from isopropanol, and there are obtained the crystalline needles
having the melting point of 170°C to 172°C.
