2‐Phenyl‐cyclopropane‐1‐carboxylic acids: Researches on plant growth regulators XX. Structure/activity V

By means of their action on the oleate coacervate and of the UV‐absorption spectra the 2‐phenyl‐cyclopropane‐carboxylic acids of m.p. 91° C and 105° C could be identified as the trans‐ and cis‐forms respectively. Of these acids, resembling very closely the trans‐ and cis‐cinnamic acids, the cis‐acid (m.p. 105° C) shows practically the same activity as cis‐cinnamic acid, whereas the trans‐acid, like trans‐cinnamic acid, is inactive. So here spatially equivalent structures are also comparable as to their physiological activity.