NEW MATERIAL:The compound of formula I (A is group of formula II or III; n is 3 or 4; R is 2-pyridyl or 2-pyrimidinyl) and its acid addition salt.

EXAMPLE: N-{4-[4-(2-Pyrimidinyl)-1-piperazinyl]butyl}phthalimide hydrochloride.

USE: An antianxiety agent having low side effects of central inhibition.

PREPARATION: The objective compound can be prepared by reacting the acid anhydride of formula IV (e.g. phthalic anhydride) with the amine derivative of formula V [e.g. 1-(4-aminobutyl)-4-(2-pyrimidinyl)-piperazine] preferably in an inert organic solvent such as pyridine.