The number of geometrical isomers of the following alkene CH3-CH=CH-CH=CH-CH=CH-Cl is

Name: Problem 162, Chapter 23: A Complete Resource Book in Chemistry for JEE Main
Uploaded: 2021-10-09T08:56:47-08:00
Duration: 1 min 6 s
Channel: Narayan Hari
Description: The number of geometrical isomers of the following alkene CH3-CH=CH-CH=CH-CH=CH-Cl is

step 1 So in this problem, molecule contains three double bonds and the end and the ends are different

The number of geometrical isomers of the following alkene...

Key Concepts

Counting Stereoisomers

Counting stereoisomers for a molecule with multiple double bonds involves determining whether each double bond can independently adopt E or Z configurations. Under the assumption that each double bond is independent and contributes two possible configurations, the maximum number of stereoisomers is given by 2^n, where n is the number of double bonds that can exhibit geometrical isomerism. However, the actual count may be reduced by symmetry or by the nature of substituents attached to the double bonds.

Conjugated Polyenes

Conjugated polyenes are molecules that have alternating double and single bonds, which may interact electronically. In such systems, the spatial arrangement around each double bond still allows for the existence of geometrical isomers. In counting the possible stereoisomers of a conjugated polyene, attention must be paid to the overall molecular symmetry and any overlapping effects that may reduce the independent stereogenicity of each double bond.

Geometrical Isomerism

Geometrical isomerism in alkenes arises due to the restricted rotation around a carbon–carbon double bond. This leads to different spatial arrangements (such as cis and trans, or more generally E and Z) of groups attached to the double?bonded carbons. Each double bond can potentially exhibit such stereoisomerism if it has two distinct substituents on each carbon, resulting in multiple isomers when several double bonds are present in a molecule.

E/Z Nomenclature

The E/Z nomenclature is a system used to describe the configuration of double bonds in alkenes. It assigns configurations based on the Cahn-Ingold-Prelog priority rules, where 'E' (from the German 'entgegen') indicates that the higher-priority substituents on the two carbons are on opposite sides of the double bond, and 'Z' ('zusammen') signifies that they are on the same side. This method is particularly useful for molecules where the simple cis/trans descriptor may be ambiguous or inapplicable.

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