RACEMIZATION OF OPTICALLY ACTIVE CHRYSANTHEMUM-MONOCARBOXYLIC ACIDS

摘要

PURPOSE:To efficiently obtain an optically active substance useful as an acid component of a low-toxic rapid-acting insecticides without leading to other derivatives, by reacting optically active chrysanthemum-monocarboxyic acids with bromine in the presence of a peroxide or azo compound and racemizing the above-mentioned acids. CONSTITUTION:A compound expressed by the formula (R is H, 1-20C alkyl, cycloalkyl or aralkyl; the asterisk mark indicates asymmetric carbon) is reacted and racemized with bromine in the presence of a peroxide (preferably diacyl peroxides) or an azo compound (preferably azonitriles) in an amount of 1/10-20mol based on 1mol bromine at 40-100 deg.C for several min-7hr. The (-) isomer after separating the (+) isomer useful for producing insecticides can be racemized by this method and effective reutilization as a raw material for optical resolution can be readily carried out.