Process for the preparation of {2-[4-(alpha-phenyl-p-chlorobenzyl)piperazin-1-yl]ethoxy} acetic acid and novel intermediates therefor

The invention refers to a novel process for the preparation of cetirizine of formula (I) as well as to novel {2-[4-(alpha-phenyl-p-chloro-benzyl)piperazin-1-yl]ethoxy}acetamides of formula II, wherein R1 and R2 represent, independently, a C1-4 alkyl group optionally substituted by a phenyl group, a C2-4 alkenyl group or a cyclohexyl group, or R1 and R2 form together with the adjacent nitrogen atom a morpholino group. According to the novel process, an acetamide of formula (II) is hydrolized, if desired in the presence of a phase transfer catalyst, to obtain cetirizine.