process for separating the acid dextro - trans - pyréthrique of acid dextro - trans - (2,2-dimethyl - (methoxycarbonyl) cyclopropyl) use a mixture of the two compounds in

摘要

Dextro-trans-pyrethric acid is prepared by half-saponifying dimethyl dextro-trans-chrysanthemum dicarboxylate with an equimolar amount of alkali metal hydroxide or lower alcoholate; treating the mixture of monomethyl esters with an equimolar amount of quinine to form the salts thereof, fractionally crystallizing with an organic solvent to separate the quinine salts of dextro-trans-pyrethic acid from that of dextro-trans-b -(2,2-dimethyl-3-methoxy - carbonyl - cyclopropyl) methacrylic acid and hydrolysing to yield the acid.