1 - piperazines bearing a fluoro , chloro , methyl , nitro , hydroxy , methoxy , cyano , amino , methylamino or dimethylamino substituent in the 4 - position of the phenyl ring and being further optionally substituted in the 4 - position of the piperazine ring by tetrahydropyranyl , alkyl , formyl , carboxy , alkanoyl or carboalkoxy , and the acid addition salts thereof , are tranquilizers . a typical embodiment is 1 - piperazine hydrochloride .