| 摘要 |
A process for the separation of the cis- and trans-stereoisomers of a substituted vinylcyclopropanecarboxylic acid of the formula <IMAGE> in which R is alkyl with 1 to 4 carbon atoms, halogen, phenyl or phenyl substituted by at least one of alkyl and halogen, and R1 is hydrogen, alkyl with 1 to 4 carbon atoms or halogen, or R and R1, together with the adjacent C atom, form a carbocyclic ring, comprising reacting the free vinylcyclopropanecarboxylic acid in a weakly alkaline aqueous solution with an amount of an amine salt corresponding to the proportion of the cis-isomer present thereby to form a salt precipitate enriched in one of the stereoisomers, separating the precipitant from the supernatant, separately reacting the precipitate and supernatant with a strong acid to liberate the isomeric vinylcyclopropanecarboxylic acid, and recrystallizing at least one of the stereoisomers.
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