PROCESS FOR PREPARING MIXTURES OF CYPERMETRIN ISOMERS Russian patent published in 1995 - IPC

FIELD: chemistry of cypermetrin, more particularly a process for preparing isomers thereof. SUBSTANCE: the product: cypermetrin isomers of formula 1 in which carbon atoms designated as 1,3, and alpha relate to the chiral carbon atom; the wavy line represents cis-or trans-configuration with respect to the cyclopropane ring, the product comprising theoretically possible eight cypermetrin isomers contains at least 95% para 1 R trans-S and IS trans-R isomers (1b) of isomers 1b at a 1a to 1b ratio of from 55:45 to 25:75. Reagent 1: a mixture of cypermetrin isomers (having purity of at least 90% ) containing trans-isomers or a pair of cis-isomers (1b), and other trans-isomers or a pair of isomers (1a+1b) at an undesirable ratio. Reaction conditions: asymmetric conversion of the second order is carried out in the presence of an amine and a protonic solvent at a temperature ranging from zero to 25 C. . EFFECT: more efficient preparation process. 9 cl, 4 tbl