A mixture of 17.9 g of 1-(4-methoxy-phenyl)-3-(4-piperidyl)-2-imidazolidinone and 11.7 g of 1-(2-methoxyphenyloxy)-2,3-epoxypropane in 200 ml of isopropyl alcohol is refluxed for 6 hours. The mixture is thereafter acidified with 5 N methanolic hydrochloric acid and concentrated under reduced pressure. The residue is freed from moisture still adhering to it by treatment with toluene. Recrystallisation of the residue from methanol with the addition of activated charcoal yields the 1-{1-[2-hydroxy-3-(2-methoxyphenoxy)-propyl]-4-piperidyl}-3-(4-methoxy-phenyl)-imidazolidin-2-one-hydrochloride as a white crystalline substance with a melting point of 214°-215° C. The 1-(4-methoxy-phenyl)-3-(4-piperidyl)-2-imidazolidinone used as starting material can be prepared as follows: A mixture of 61.5 g of 4-methoxy-aniline and 51.3 g of 2-bromoethylamine-hydrobromide in 125 ml of methyl ethyl ketone is refluxed for 5 hours with stirring. The viscous suspension is thereafter evaporated to dryness under reduced pressure. The residue is suspended in 150 ml of isopropanol and then collected by filtration. The filter cake is washed with three 50 ml portions of isopropanol and with two 50 ml portions of diethyl ether. The crystalline product is made alkaline with a concentrated aqueous ammonia solution and extracted with five 50 ml portions of chloroform. The extracts are dried over sodium sulphate and concentrated under reduced pressure. The oily residue crystallises after trituration to give the 1-(4-methoxyphenyl)-ethylenediamine with a melting point of 64° C.
