摘要 |
A process is described by which the pair of cyhalothrin isomers represented by (R)- alpha -cyano-3-phenoxybenzyl (1R,cis)-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcycl opropane carboxylate and its enantiomer is converted by base catalyzed epimerization in solution into the insecticidally more useful isomer pair represented by (S)- alpha -cyano-3-phenoxybenzyl (1R,cis)-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcycl opropane carboxylate and its enantiomer, which may be caused to crystallize out from the solution. |