Chapter 7, Problem 27P

Interpretation Introduction

Interpretation:

The 3d formulas of the given compounds is to be written and name using $E-Z$ configuration or $R-S$ configuration for the isomers of given compounds is to be given.

Concept introduction:

The molecules that are nonsuperimposable or not identical with their mirror images are known as chiral molecules.

A pair of two mirror images that are nonidentical is known as enantiomers, which are optically active.

The stereoisomers that are nonsuperimposable on each other and not mirror images of each other are known as diastereomers.

The achiral compounds in which plane of symmetry is present internally and consists of chiral centres are known as meso compounds, but they are optically inactive.

$E-Z$ configuration is used to designate alkene diastereomers (cis-trans isomers).

First, give priority according to Cahn-Ingold-Prelog convention rules:

The higher the atomic mass, the higher will be the priority.

If priority cannot be assigned according to atomic mass, then assign the priority according to first point of difference.

If both the priority groups are on same side of the double-bonded carbon atom, then it is known as $\left(Z\right)$ configuration.

But if both the priority groups are diagonal to each other, then it is $\left(E\right)$ configuration.

Configuration is used to differentiate between enantiomers.

After giving priority to four groups, rotate the molecule such that the fourth priority group is at the horizontal position.

Now, move from 1-2-3; if it is in clockwise, then it is $\left(R\right)$ configuration and if it is in anticlockwise direction, then it is $\left(S\right)$ configuration.