Sumitomo Chemical Company, Limited

Toshiko Honda

Nobushige Itaya

Akio Higo

Fukashi Horiuchi

A novel process for preparing cis-chrysanthemic acid comprising (1) hydrolysis of trans-.delta.-halogenodihydrochrysanthemic acid or ester thereof under neutrally kept condition with an alkaline earth metal carbonate, (2) conversion of the obtained trans-.delta.-hydroxydihydrochrysanthemic acid ester into a mixture of cis-chrysanthemic acid and iso-cis-chrysanthemic acid by reacting with a strong base, and (3) separation of the cis-chrysanthemic acid from the mixture by selective conversion of the iso-cis-chrysanthemic acid with water in the presence of an acid catalyst into cis-dihydrochrysanthemolactone, followed by separation of the cis-chrysanthemic acid from the lactone with a caustic alkali and an acid. The present process is very useful for converting (-)-trans-chrysanthemic acid which is obtained, as a main remainder of racemic chrysanthemic acid prepared industrially, after (+)-trans-chrysanthemic acid was used for preparation of (+)-trans-chrysanthemic acid ester having a high insecticidal activity, into (+)-cis-chrysanthemic acid which is industrially valuable for preparation of insecticides.

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Osaka, Japan

Toshiko Honda