The most stable confomation of cis-1,4-di-t-buty1 cyclohexane is:

Options

A. (a) Boat
B. (b) Chair
C. (c) Twist boat
D. (d) Half chair

Answer

To determine the most stable conformation of cis-1,4-di-tert-butylcyclohexane, we need to analyze the different conformations of cyclohexane and how the bulky tert-butyl groups affect stability. Here is a step-by-step solution:

### Step 1: Identify the Structure
Cis-1,4-di-tert-butylcyclohexane has two tert-butyl groups located at the 1 and 4 positions of the cyclohexane ring. Since it is in the cis configuration, both bulky groups will be on the same side of the ring.

### Step 2: Consider Different Conformations
Cyclohexane can adopt several conformations:
1. Chair
2. Boat
3. Twisted boat
4. Half-chair

We will analyze the stability of each conformation with respect to the bulky tert-butyl groups.

### Step 3: Analyze the Boat Conformation
In the boat conformation, both tert-butyl groups are positioned in a way that they are close to each other, leading to significant steric hindrance. This results in an unstable conformation due to the repulsion between the bulky groups.

### Step 4: Analyze the Chair Conformation
In the chair conformation, both tert-butyl groups can be positioned in axial positions. However, this also leads to steric hindrance because both bulky groups are pointing out of the plane and are close to each other. Thus, this conformation is also less stable.

### Step 5: Analyze the Twisted Boat Conformation
In the twisted boat conformation, the tert-butyl groups can be positioned such that they are further apart from each other. This reduces steric hindrance and allows for a more stable arrangement. Therefore, this conformation is expected to be more stable than the previous two.

### Step 6: Analyze the Half-Chair Conformation
The half-chair conformation is the least stable due to the strain it introduces. In this conformation, five of the carbon atoms are in the same plane, which is not favorable for bulky groups. Thus, this conformation is the least stable.

### Conclusion
After analyzing all the conformations, the most stable conformation of cis-1,4-di-tert-butylcyclohexane is the **twisted boat conformation**.

### Final Answer
The most stable conformation of cis-1,4-di-tert-butylcyclohexane is the **twisted boat conformation**.

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