Name: Diastereomers and Meso Compounds
Uploaded: 2019-07-19
Duration: 10 min 31 s
Description: Here, we will see how compounds with multiple stereocenters may be achiral if they have an internal plane of symmetry or an inversion centre. Let's explore.

Question

Draw structures of all geometric isomers of $1, 2, 3 - trichlorocyclopentane$ .

Accepted Answer

The systematic understanding and evaluation of geometrical isomerism for any given substrate will be as follows $: -$

Concept of geometrical isomerism $: -$

There should be presence of frozen $C - C$ bond rotation for which two types of system may be present.

$1 .$ Presence of unsymmetrical double bond with different substituent or species for which $C - C$ bond rotation is not possible due to $π -$ bond.

$2 .$ Presence of unsymmetrical $C - C$ bond of alicyclic ring where different substituent are present around the $σ -$ bond of cyclic ring. Here $C - C$ bond rotation is not possible due to cyclic ring structure.

Evaluation of geometrical isomerism in substituted cyclopentyl substrate $: -$

Here $3$ chloro substituents are present on sigma bond of cyclopentane ring where $C - C$ bond rotation is not possible due to rigid and strained cyclic structure of cyclopentane ring. Hence, here $3$ stereocentre combinations for geometrical isomerism are possible as cis $-$ dichloro cyclopentane and other is trans $-$ dichloro cyclopentane.

Calculation of geometrical isomers $: -$

For this given substrate since $3$ stereocentres are present on $C - C$ bond of cyclopentane ring. Hence, here cis and trans isomers or syn and anti isomers are possible for all three stereocentre related to three chloro substituents present at $1^{st}, 2^{nd} & 3^{rd}$ position of ring. The number of geometrical isomers is $2^{n}$ where $n = 3$ and it is number of stereocentre.

Number of geometrical isomers $=$ $2^{n} = 2^{3} = 8$

All other isomers are representation of these three isomers only.

Draw structures of all geometric isomers of $1, 2, 3 - trichlorocyclopentane$ .

Important Questions on Isomerism

Learn and Prepare for any exam you want !

Draw structures of all geometric isomers of 1, 2, 3-trichlorocyclopentane.

Important Questions on Isomerism

Learn and Prepare for any exam you want !

Draw structures of all geometric isomers of $1, 2, 3 - trichlorocyclopentane$ .