Question

The molecule that gets inter-converted into its enantiomer, upon ring flipping in its chair conformation, is _ _ _.

• A. cis-1,2-dimethylcyclohexane
• B. cis-1,3-dimethylcyclohexane
• C. cis-1,4-dimethylcyclohexane
• D. trans-1,2-dimethylcyclohexane

Hint:

Only those cyclohexane derivatives form enantiomers on ring flip which lose symmetry and become chiral after axial–equatorial interchange

Answer 1

The Correct Option is A

Step 1: Understand ring flipping in cyclohexane.
In chair conformation, ring flipping converts axial bonds into equatorial bonds and vice versaHowever, the relative positions (cis/trans) remain unchanged

Step 2: Condition for enantiomer formation.
A molecule forms its enantiomer upon ring flipping only if the flipped structure becomes a non-superimposable mirror imagei.e., chirality is generated

Step 3: Analyze each option.
cis-1,2-dimethylcyclohexane On ring flipping, axial and equatorial positions interchange leading to a mirror image configurationThus, it forms its enantiomer
cis-1,3-dimethylcyclohexane This has symmetry and remains identical after flipping
cis-1,4-dimethylcyclohexane Possesses plane of symmetry, so no enantiomer is formed
trans-1,2-dimethylcyclohexane Does not produce a mirror image on flipping

Step 4: Conclusion.
\[ \boxed{\text{cis-1,2-dimethylcyclohexane}} \]