Patent · US Expired

Process for the preparation of certain enantiomeric pairs of .alpha.-cyano-3-phenoxy-4-fluoro-benzyl permethrate

US4544508A · kind A · utility

4Cited by

5References

3Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Rainer Fuchs · Halver, DE
Klaus Naumann

Key dates

Filing date	Jan 9, 1985
Grant date	Oct 1, 1985
Priority date	—
Expiry date	Jan 9, 2005

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC07C255/53
WIPO fieldOrganic fine chemistry
WIPO sectorChemistry

Abstract

A process for the preparation of the enantiomeric pairs (1R-3R-.alpha.S+1S-3S-.alpha.R) and (1R-3S-.alpha.S+1S-3R-.alpha.R) from a mixture of all 8 stereoisomers of the compound .alpha.R/S-cyano-3-phenoxy-4-fluorobenzyl 3R/S-(2,2-dichlorovinyl)-2,2-dimethyl-1R/S-cyclopropanecarboxylate, comprising dissolving the mixture in a secondary or tertiary alkylamine having 2-6 C atoms per alkyl radical, subjecting the solution to crystallization whereby the enantiomeric pairs (1R-3R-.alpha.S+1S-3S-.alpha.R) and (1R-3S-.alpha.S+1S-3R-.alpha.R) crystallize out from the solution, and separating the crystallized material. The crystals are enriched in the most active components.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.