Chapter 5, Problem 7Q

Interpretation Introduction

Interpretation:

The reactant in the given reaction, which is optically active and exists as $\left(S\right)$ isomer is to be determined.

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 objects or molecules that are superimposable with their mirror images are achiral objects or molecules and these objects have a centre of symmetry or plane of symmetry.

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.

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

Chiral molecules are capable of rotating plane polarized light

The molecules that are superimposable or identical with their mirror images are known as achiral molecules, and achiral molecules are not capable of rotating the plane-polarised light.

Chiral molecules have different atoms around the central carbon atom. They are usually optically active compounds.

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 the atomic mass, then assign the priority according to first point of difference.

$R-S$ 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.

The conversion of alkenes and alkynes to alkanes is known as hydrogenation reaction.

Hydrogenation reaction occurs with hydrogen in the presence of a metal catalyst.

The reagents used in hydrogenation process are ${\text{H}}_2\text{,Pd,pressure}$, ${\text{H}}_2\text{,Pt,pressure}$ or ${\text{H}}_2\text{,Ni,pressure}$.