A Photostable Pyrethroid

Synthetic Pyrethroid Use Patterns, Properties, and Environmental Effects

“…In particular, esters of chrysanthemic acid dihalovinyl analogues were found to display much improved photostabilities compared to the esters of chrysanthemic acid (11,12). The first commercial photostable synthetic pyrethroid based on this approach was permethrin, synthesized in the early 1970s.…”

Properties and applications of pyrethroids.

“…However, 3-phenoxybenzyl alcohol is accessible by a variety of routes and is less expensive, compensating in some circumstances for the lower insecticidal activity of its esters. At Rothamsted Experimental Station in 1972 an exceptionally valuable combination of properties was found in the esters (permethrin) of 3-phenoxybenzyl alcohol with the cis-and transdichlorovinyl acids (9,10,46,47) analogs of chrysanthemic acid with chlorine in place of methyl in the isobutenyl side chain. Not only was permethrin more active against many insect species than would have been predicted from experience with other esters of the acidic and alcoholic components, but it was also very much more stable in air and light than other potent pyrethroids and had lower mammalian toxicity than the 5-benzyl-3-furylmethyl esters of the same acid (9,17,18,48).…”

“…A further advance in developing synthetic pyrethroids was made independently in Great Britain and Japan in 1969 when it was recognized that mr-substituted derivatives of benzene could reproduce the stereochemistry of the furylmethyl unit and a phenoxy group could replace the benzyl side chain (7,9,11 range of acids than 5-benzyl-3-furylmethyl alcohol-for example, the cis-thiolactone ester corresponding to Kadethrin is not a good knockdown agent (45). The chrysanthemate (phenothrin) is one third to one half as active as the 5-benzyl-3-furylmethyl ester to most insect species (7,11).…”

“…This limited potential has changed dramatically in the past two to three years, for workers in Great Britain (9,10) and Japan (11)(12)(13) have shown that the photolabile centers of the molecular framework of pyrethroids may be replaced with alternative groups giving much greater overall stability in air and light, while the features essential for the great insecticidal activity and low mammalian toxicity are retained. As a consequence of these advances, a range of new insecticides is being developed.…”

Separation and Determination of Diastereomers of λ-Cyhalothrin by Normal Phase-Liquid Chromatography Using a CN Column

“…10,11 HPLC is used when GC is not suitable for various reasons of thermal lability and volatility. The GC method of analysis normally merges the 4 chromatographic peaks of λ-cyhalothrin into one.…”