The most stable conformation of 2, 3-dimethyl butane is :

Options

A.
B.
C.
D. none of these

Explanation

To determine the most stable conformation of 2,3-dimethylbutane, we need to analyze the different conformations based on steric interactions, specifically the gauche interactions. Here’s a step-by-step solution:

### Step 1: Identify the Structure
2,3-dimethylbutane has the following structure:
- It consists of a butane backbone (4 carbon atoms) with two methyl (CH3) groups attached to the second and third carbon atoms.

### Step 2: Draw Possible Conformations
We can visualize the different conformations of 2,3-dimethylbutane by rotating around the carbon-carbon bonds. The main conformations to consider are:
- Staggered conformations (where groups are positioned as far apart as possible)
- Eclipsed conformations (where groups are positioned directly in front of each other)

### Step 3: Analyze Each Conformation
- **Conformation A**: This conformation has three gauche interactions (repulsive interactions between the methyl groups).
- **Conformation B**: This conformation has two gauche interactions.
- **Conformation C**: This conformation again has three gauche interactions.

### Step 4: Determine Stability
The stability of a conformation is inversely related to the number of repulsive interactions (gauche interactions in this case). The fewer the gauche interactions, the more stable the conformation.

- Conformation A: 3 gauche interactions (less stable)
- Conformation B: 2 gauche interactions (more stable)
- Conformation C: 3 gauche interactions (less stable)

### Step 5: Conclusion
Since Conformation B has the least number of gauche interactions (only 2), it is the most stable conformation of 2,3-dimethylbutane.

**Final Answer**: The most stable conformation of 2,3-dimethylbutane is **Option B**.

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