Question

Which one of the following isomers is thermodynamically most stable? 

 

• A. A
• B. B
• C. C
• D. D

Hint:

In cyclohexane conformations, {equatorial>axial} for bulky groups due to less steric strain. Always look for the structure minimizing 1,3-diaxial interactions.

Answer 1

The Correct Option is A

Step 1: Identify the structural type.
The question depicts conformers of substituted cyclohexanes. The stability depends on whether the substituents occupy axial or equatorial positions.
Step 2: Recall the rule of stability.
Substituents in the equatorial position are more stable because they minimize 1,3-diaxial repulsions. Hence, the conformer having bulky groups in equatorial positions is thermodynamically most stable.
Step 3: Analyze the options.
Among the given isomers, structure (B) has both substituents in equatorial orientation, resulting in minimal steric hindrance.
Step 4: Conclusion.
Thus, the thermodynamically most stable conformer is (B).