| 摘要 |
PURPOSE:To carry out the racemization of an optically active chrysanthemum- monocarboxylic acid, easily in high yield, and to obtain a racemic chrysanthemum-monocarboxylic acid useful as a raw material of phyrethroidal insecticides, by reacting the optically active acid in the presence of aluminum bromide and an organic hydroperoxide. CONSTITUTION:Chrysanthemum-monocarboxylic acid of formula which is an acid component of the esters of pyrethroidal insecticides such as pyrethrin useful as low-toxic rapid-acting insecticides, is racemized in the presence of a aluminum bromide and an organic hydroperoxide, preferably in an inert solvent at -30- +100 deg.C for 10min-10hr to obtain racemic chrysanthemum-monocarboxylic acid rich in the trans-isomer having higher insecticidal activity in the from of an ester. EFFECT:The process is suitable for the use in an industrial scale. The inert (-)- chrysanthemum-monocarboxylic acid separated in various optical resolution processes can be utilized directly in high efficiency. Furthermore, the consumption of aluminum bromide can be decreased remarkably by the use of only a small amount of the organic hydroperoxide. |
