反应详情

The process of UK-P No. 2 225 320 (Chem. Abstr., 113, 191395s) aims at the elimination of the disadvantages of the above known processes by preparing cetirizine from the {2-[4-(α-phenyl-p-chlorobenzyl)piperazin-1-yl]}ethanol of the formula III which is converted to the potassium salt with potassium tert-butylate. The potassium salt is reacted with sodium chloro-acetate to obtain cetirizine dihydrochloride in a yield of 48.8%. In addition, 5.1% of a second generation product are obtained. Also an improved process is described for the preparation of the {2-[4-(α-phenyl-p-chlorobenzyl)piperazin-1-yl]}ethanol of the formula III according to which 1-[(4-chlorophenyl)phenyl-methyl]piperazine of the formula VI is reacted with ethylene chlorohydrine in a yield of 90.4%, the total yield of the synthesis, referred to the piperazine derivative of the formula VI, is merely 48.7%.