Abstract: The invention provides a process for the preparation of esters [2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]ethoxy]acetic acid, of the formula (I) ##STR1## wherein X represents a halogen atom and R represents a lower alkyl group comprising reacting:(a) a compound of the formula (II) ##STR2## (b) a compound of the formula (III) ##STR3## and (c) a tertiary amine as a solvent and as an acid scavengerat a temperature of at least 100.degree. C., wherein X is a halogen atom, X' is selected from the group consisting of bromine and chlorine and R is a lower alkyl group.