Chapter 5, Problem 28PP

Interpretation Introduction

Interpretation:

The structural formulas for all the stereoisomers of $1,3-\text{dimethylcyclopentane}$ are to be written. Pairs of enantiomers and meso compounds are to be labelled.

Concept introduction:

The moleculesthat 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 moleculesthat 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.

Stereoisomers that are mirror images of each other are enantiomers.

Achiral molecules that contains chiral centres and have a plane of symmetry are called meso compounds.

Meso compounds are optically inactive.

In double bond or cyclic compounds, if two same functional groups are present on the same side of the double bond or cyclic compound, the given compound can be labeled as cis.

If the two functional groups are present on the different sides of the double bond or cyclic compound, the given compound can be labeled as Trans.

Cis-trans isomerism exists in the compounds in which similar groups are present on the adjacent carbon atoms.