Question

The most stable conformation of Y and that of Z are

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is B

To determine the most stable conformation of compounds Y and Z, we need to analyze their structures in terms of steric hindrance and stability.

For cyclohexane derivatives like Y and Z, the stability is influenced by the position of bulky substituents (in this case, the tert-butyl groups) on the chair conformation.

1. Cyclohexane prefers to adopt a chair conformation because it minimizes torsional strain and steric hindrance.
2. In the chair conformation, substituents can occupy axial (vertical) or equatorial (horizontal) positions.
3. The equatorial position is more stable than the axial position, particularly for bulky groups, because it experiences less steric hindrance.
4. For compound Y:

   

   Both tert-butyl groups should ideally occupy equatorial positions to minimize steric interactions.
5. For compound Z:

   

   Both tert-butyl groups should also be in equatorial positions for maximum stability.
6. Comparing the provided options:
   1. Option 1: Shows both bulky groups in axial positions, leading to instability due to steric clash.
   2. Option 2: Incorrect representation as per stable conformation logic.
   3. Option 3: Correct representation with both tert-butyl groups in the equatorial position.
   4. Option 4: Similar to option 1, high steric hindrance due to axial positions.
7. Conclusion: The most stable conformation for both Y and Z has tert-butyl groups in the equatorial position, reducing steric strain.