A kind of synthetic method of cis lanbda-cyhalothric acid

The invention discloses a kind of synthetic method of cis lanbda-cyhalothric acid, with suitable, trans- 3- (2,2- bis- chloro- 3,3,3- trifluoro propyls) -2,2- diformazan cyclopropyl carboxylic esters are (cis：Trans=60-90：10-40), the aqueous solution of alkali is raw material, in the presence of phase transfer catalyst, by obtaining cis lanbda-cyhalothric acid after high temperature saponification elimination with pressure, inorganic acid acid adjustment, organic solvent recrystallization.Traditional normal pressure saponification is eliminated and is adjusted to high temperature saponification elimination with pressure by the inventive method, and adds phase transfer catalyst, trans time acid can be changed into cis lanbda-cyhalothric acid, cis：Trans >=99:Content >=99.0% of cis lanbda-cyhalothric acid in 1, i.e. product；This process increases yield, yield is more than 80%, and side reaction is few, and synthesis lanbda-cyhalothric acid raffinate amount is few.