PROCESS FOR PRODUCING UNSATURATED CARBOXYLIC ACIDS WITH 2E, 4E CONFIGURATION

A process for the preparation of 2E,4E carboxylic acids of the general formula (wherein X stands for hydrogen, hydroxy or C1-4alkoxy) from 2Z,4E carboxylic acids of the general Formula VII (wherein X is as stated above) comprises isomerizing the 2Z,4E carboxylic acid of the general Formula VII or an alkali metal or ammonium salt thereof, in the melt or in the presence of an inert solvent, in the presence of a catalyst comprising a free electron-pair, and thereafter separating the carboxylic acid of the general Formula I in the form of the ammonium salt thereof without removing the catalyst. The process is readily feasible and there is no need to remove the catalyst. The compounds of the Formula I are known intermediates useful in the preparation of known selective insecticides.