Patent ID: 7507852

Claim:
A process for the preparation of gamma-cyhalothrin comprising steps of: a) chlorinating 1R cis-Z 3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cyclopropanecarboxylic acid to give 1R cis-Z 3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cyclopropanecarboxylic acid chloride; b) esterifying 1R cis-Z 3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cyclopropanecarboxylic acid chloride with the (S)-cyanohydrin of 3-phenoxy benzaldehyde (III) thereby to form a reaction mass including gamma-cyhalothrin and HCl; c) using a combination of physical methods and a sub-stoichiometric amount of a base to remove the HCl from said reaction mass.