Process for preparing racemized cyclopropanecarboxylic acids or their derivatives

摘要

The present invention is to provide the process for preparing racemized cyclopropanecarboxylic acids or their acid anhydrides from the corresponding optically active, particularly levo-rotatory, cyclopropanecarboxylic acid anhydrides. The racemization is effected by the treatment of the optically active acid anhydride with a Lewis acid. Thus, the present racemization process enables more efficient commercial production of dextro-rotatory cyclopropanecarboxylic acids, which are the more effective acid component of pyrethroidal insecticides, when combined with an optical resolution process.