The invention comprises compounds of formula where the several R's are the same and each is hydrogen or methyl, R1 is methyl or ethyl, n is 2 or 3, and Het is either a 7-chloroquinolyl-4-or a 2-chloro-7-methoxyacridyl-5 group. They may be prepared by condensing 4 : 7-dichloroquinoline or 2 : 5-dichloro-7-methoxyacridine with the amino-alkyl piperazine compound, which may be obtained by reduction of the nitrile. In the examples: (1) 1-ethyl-4-(21-amino-11-ethyl)-piperazine is treated with 4 : 7-dichloroquinoline in phenol at 100 DEG C. to give 4 - [21 - (711 - chloro - 411 - quinolylamino) - 11 - ethyl] - 1 - ethylpiperazine, the initial aminopiperazine being prepared by reduction from 1 - ethyl - 4 - cyanomethylpiperazine, which is obtained from chloroacetonitrile and 1-ethylpiperazine; (2) 4-[31-(711-chloro-411-quinolylamino) - 11 - propyl] - 1 - ethylpiperazine is prepared in a similar way, the amine being prepared by reduction of 1-ethyl-4-(21-cyano-11-ethyl) piperazine, obtained from acrylonitrile and 1-ethylpiperazine; (3) 4-[31-(211-chloro-711 methoxy - 511 - acriodylamino) - 11 - propyl] - 1 - ethylpiperazine is prepared; (4) 1-ethyl-2 : 3 : 5 : 6 - tetramethyl - 4 - [21 - (711 - chloro - 411 - quinolylamino) - 11 - ethyl] piperazine is prepared, and the preparations of the aminopiperazine, the nitrile, and 1-ethyl-2 : 3 : 5 : 6-tetramethylpiperazine (by reduction of 2 : 3 : 5 : 6-tetramethylpiperazine iodoethylate) from which the nitrile is prepared, are given; (5 and 6) 1 : 2 : 3 : 5 : 6 - pentamethyl - 4 - [21 - (711 - chloro - 411 - quinolylamino) - 11 - ethyl] piperazine is prepared in two forms corresponding to two isomeric 1 : 2 : 3 : 5 : 6-pentamethyl - 4 - (21 - amino 11-ethyl) piperazines separated via the maleates and prepared from the pentamethyl piperazine and via the nitrile.