PROCEDE POUR LA PREPARATION D'UN ACIDE CHRYSANTHEMIQUE D'UNE HAUTE PURETE

The invention relates to a process for the preparation of chrysanthemum-monocarboxylic acid (I) in high purity by alkaline hydrolysis of the C1-C6-alkyl ester of I (II), in the absence of organic solvents and in the presence of a phase transfer catalyst, with 100-150% by weight of the equivalent amount of alkali metal hydroxide which corresponds to the ester (II) when II is to be hydrolysed completely while maintaining the isomer ratio, or with 70-110% by weight of the equivalent amount of alkali metal hydroxide corresponding to the trans-isomer of II if II is to be hydrolysed partially or selectively while changing the ratio of the isomers. I can be used as intermediate for the synthesis of insecticidal pyrethroids. L'INVENTION CONCERNE UN PROCEDE POUR LA PREPARATION D'UN ACIDE CHRYSANTHEMIQUE D'UNE HAUTE PURETE.ON PREPARE L'ACIDE CHRYSANTHEMIQUE PAR HYDROLYSE ALCALINE DES ESTERS D'ALCOYLE CORRESPONDANT CONTENANT DE 1 A 6 ATOMES DE CARBONE DANS LA PORTION ALCOYLE, EN L'ABSENCE DE SOLVANTS ORGANIQUES, EN PRESENCE D'UN CATALYSEUR.L'ACIDE CHRYSANTHEMIQUE EST UN PRODUIT INTERMEDIAIRE UTILE DANS LA PREPARATION DE PYRETHROIDES AYANT UNE ACTIVITE INSECTICIDE.