Abstract: The present invention relates to a process for the selective separation of esters of the general formula IIA--COOR.sup.1 IIfrom mixtures containing the cyclopropane carboxylic acid esters of the general formula I ##STR1## in addition to the said esters of the general formula II by reacting the said mixture with an amine of the general formula III ##STR2## when removing the acid amides formed from the esters of the general formula II by washing the mixture with water of removing the esters of the general formula I by distillation.The compounds of the general formula I are the intermediates of herbicides. The requested purity of the herbicides can be achieved if pure intermediates are used.

Abstract: The invention relates to a process for the preparation of enantiomers of trans vinyl-cyclopropane carboxylic acids of the formula I, ##STR1## wherein R is a methyl group or chlorine atom, by resolution of racemic trans compound or mixture of racemic cis and trans compounds by using (+)- or (-)-N-(1-formamido-2,2,2-trichloroethyl)-piperazine as a resolving agent in a polar solvent then separating the crystallizing salt of (+)-trans carboxylic acid and (-)-resolving agent or (-)-trans carboxylic acid and (+)-resolving agent from the mother liquor by filtration and obtaining the enantiomers by acidifying the mother liquor or the salts suspended in water followed by extraction with a solvent and evaporation.The products so obtained may be used as starting materials for the preparation of insecticides.

Abstract: The invention relates to a new process for the preparation of cyclopropanecarboxylic acids of the formula (I) ##STR1## wherein X and Y independently stand for halogen, by the alkaline hydrolysis of the corresponding alkyl esters having 1 to 6 carbon atoms in the alkyl moiety, in or without a water-miscible organic solvent, in the presence of a phase transfer catalyst. The hydrolysis is carried out with a 2 to 50% by weight aqueous alkali hydroxide solution. If desired, under suitable conditions the cis/trans ratio of the original ester can be altered in the end products. The cyclopropanecarboxylic acids of the formula (I) are obtained in a high purity and are useful intermediates of insecticidally active pyrethroids.