For each of the following molecules, indicate whether or not cis–trans isomerism is possible.

1. a. 2-Pentene
2. b. l-Chloro-2-pentene
3. c. Chlorocyclopentane
4. d. 1,2-Dichlorocyclopentane

Interpretation:

For the given molecule, whether cis‑trans isomerism is possible has to be indicated.

Concept Introduction:

Alkenes are hydrocarbons that contain at least one double bond in it. There will not be any free rotation of the double bond in alkene. Hence, cis‑trans isomerism is possible. The first and foremost condition for the alkene to exhibit cis‑trans isomerism is that the carbon attached in either end of double bond must have different groups attached to it.

A cis isomer is the one in which the same groups are present on same side of both the carbon atoms present in the double bond.

A trans isomer is the one in which the same groups are present on opposite side of both the carbon atoms present in the double bond.

Cis‑trans isomerism is not possible if any one of the carbon atom bonded to the double bond bears two identical groups.

Cis‑trans isomers are not constitutional isomers but they are stereoisomers.

Given name of the molecule is 2-pentene.

The structure of this can be drawn as,

On seeing the structure of the alkene given above, it is found that two different groups are present on the same carbon (first carbon atom) that is present on the double bond.

This compound possess cis‑trans isomerism...

Interpretation:

For the given molecule, whether cis‑trans isomerism is possible has to be indicated.

Concept Introduction:

Alkenes are hydrocarbons that contain at least one double bond in it. There will not be any free rotation of the double bond in alkene. Hence, cis‑trans isomerism is possible. The first and foremost condition for the alkene to exhibit cis‑trans isomerism is that the carbon attached in either end of double bond must have different groups attached to it.

A cis isomer is the one in which the same groups are present on same side of both the carbon atoms present in the double bond.

A trans isomer is the one in which the same groups are present on opposite side of both the carbon atoms present in the double bond.

Cis‑trans isomerism is not possible if any one of the carbon atom bonded to the double bond bears two identical groups.

Cis‑trans isomers are not constitutional isomers but they are stereoisomers.

Interpretation:

For the given molecule, whether cis‑trans isomerism is possible has to be indicated.

Concept Introduction:

Alkenes are hydrocarbons that contain at least one double bond in it. There will not be any free rotation of the double bond in alkene. Hence, cis‑trans isomerism is possible. The first and foremost condition for the alkene to exhibit cis‑trans isomerism is that the carbon attached in either end of double bond must have different groups attached to it.

A cis isomer is the one in which the same groups are present on same side of both the carbon atoms present in the double bond.

A trans isomer is the one in which the same groups are present on opposite side of both the carbon atoms present in the double bond.

Cis‑trans isomerism is not possible if any one of the carbon atom bonded to the double bond bears two identical groups.

Cis‑trans isomers are not constitutional isomers but they are stereoisomers.

Interpretation:

For the given molecule, whether cis‑trans isomerism is possible has to be indicated.

Concept Introduction:

Alkenes are hydrocarbons that contain at least one double bond in it. There will not be any free rotation of the double bond in alkene. Hence, cis‑trans isomerism is possible. The first and foremost condition for the alkene to exhibit cis‑trans isomerism is that the carbon attached in either end of double bond must have different groups attached to it.

A cis isomer is the one in which the same groups are present on same side of both the carbon atoms present in the double bond.

A trans isomer is the one in which the same groups are present on opposite side of both the carbon atoms present in the double bond.

Cis‑trans isomerism is not possible if any one of the carbon atom bonded to the double bond bears two identical groups.

Cis‑trans isomers are not constitutional isomers but they are stereoisomers.