Question

Which one of the following compounds can exist as cis-trans isomers?

• A. 2-Methylhex-2-ene
• B. 1,1-Dimethylcyclopropane
• C. 1,2-Dimethylcyclohexane
• D. Pent-1-ene

Hint:

For cis-trans isomerism to occur, the compound must have a double bond with two different groups attached to each of the carbons involved in the double bond.

Answer 1

The Correct Option is A

Cis-trans isomerism occurs when there are two different groups attached to each carbon of a double bond, resulting in non-superimposable mirror images. Let's analyze each compound:
- Option (1) 2-Methylhex-2-ene: The structure has a double bond between C2 and C3, with different groups (methyl and hydrogen) on C2 and C3. This allows for cis-trans isomerism.
- Option (2) 1,1-Dimethylcyclopropane: In this case, both methyl groups are attached to the same carbon (C1) in the cyclopropane ring, and
Thus, cis-trans isomerism is not possible due to the symmetry of the molecule.
- Option (3) 1,2-Dimethylcyclohexane: This compound does not have a double bond and is a saturated hydrocarbon, so cis-trans isomerism does not apply here.
- Option (4) Pent-1-ene: While this compound has a double bond, there are no two different substituents attached to the same carbon in the double bond, so cis-trans isomerism does not exist.

Thus, the correct compound that can exhibit cis-trans isomerism is 2-Methylhex-2-ene.