Process for the preparation of insecticidal esters of 24-unsaturated acids

Unsaturated carboxylic acid esters < IMAGE > having a 2E,4E stereoconfiguration (wherein X stands for hydrogen, C1-4 alkoxy or hydroxy and R represents C1-4 alkyl), may be prepared by reacting a salt < IMAGE > (wherein M stands for a metal ion or an ammonium ion substituted by one or more alkyl and/or aralkyl group(s) and X has the same meaning as stated above) with an alkyl halide R-Y (wherein Y stands for halogen and R is as stated above) in a polar solvent. The process provides end-products free of isomers in excellent yields, and is readily feasible on an industrial scale. The compounds of the general Formula I are known insecticides. PROCEDIMIENTO DE PREPARACION DE ESTERES DE ACIDOS CARBOXILICOS INSATURADOS. LA INVENCION SE RELACIONA CON UN PROCEDIMIENTO DE PREPARACION DE ESTERES DE ACIDOS CARBOXILICOS INSATURADOS DE FORMULA GENERAL (I), DOTADOS DE UNA ESTEREOCONFIGURACION LE,4E (EN CUYA FORMULA X REPRESENTA HIDROGENO, ALCOXI C1-4 O HIDROXILO Y R REPRESENTA ALQUILO C1-4), QUE COMPRENDE LA REACCION DE UNA SAL DE FORMULA GENERAL (LIX), EN LA QUE M REPRESENTA UN ION METALICO O UN ION AMONICO SUSTITUIDO POR UNO O MAS GRUPOS ALQUILOS Y/O ARALQUILOS Y X TIENE EL MISMO SIGNIFICADO ANTERIORMENTE SEÑALADO, CON UN HALURO ALQUILICO DE FORMULA GENERAL (LXIII), EN LA QUE Y REPRESENTA HALOGENO Y R ES LO QUE SE INDICA ANTERIORMENTE, EN UN DISOLVENTE POLAR.