Chapter 17.8, Problem BQ

Interpretation Introduction

Interpretation: The correct sterochemical descriptor for the substitution pattern of the cyclopropane ring in permethrin and bifentrin has to be determined.

Concept introduction:

Cis compounds are the geometrical isomers with the organic groups on the same side of the double bond.

The double bond of alkenes form a rigid structure around which the atoms cannot rotate as in alkenes. This leads to a form of isomerism referred to as cis-trans isomers.

In a cis isomer, groups are attached on the same side of the double bond while in the Trans isomer the groups are attached on the opposite sides.

Simple representation of cis and Trans isomer is as follows,

Permethrin and bifenthrin are the synthetic pyretherenoids now in common use in household and agricultural products.

Their structures are given below,