Select the most stable intermediates :

Options

A.
B.
C.
D.

Answer

To determine the most stable intermediate among the given options, we need to analyze the stability based on hyperconjugation. Here’s a step-by-step solution:

### Step 1: Understand Hyperconjugation
Hyperconjugation refers to the interaction between the electrons in a σ-bond (usually C-H or C-C) and an adjacent empty or partially filled p-orbital or π-bond. This interaction can stabilize carbocations, free radicals, and alkenes.

### Step 2: Analyze Each Compound
We have four compounds (A, B, C, D) with different substituents. We need to evaluate the number of hyperconjugation structures for each compound.

1. **Compound A**: Contains a methyl group attached to an sp² carbon.
- Hyperconjugation: 3 structures (due to the presence of three adjacent C-H bonds).

2. **Compound B**: Contains a dimethyl group attached to an sp² carbon.
- Hyperconjugation: 2 structures (due to the presence of two adjacent C-H bonds).

3. **Compound C**: Contains a thiomethyl group (C-SH) attached to an sp² carbon.
- Hyperconjugation: 0 structures (no adjacent C-H bonds).

4. **Compound D**: Contains a trimethyl group attached to an sp² carbon.
- Hyperconjugation: 1 structure (due to the presence of one adjacent C-H bond).

### Step 3: Compare Stability
Now, we compare the number of hyperconjugation structures:
- **Compound A**: 3 hyperconjugation structures (most stable)
- **Compound B**: 2 hyperconjugation structures
- **Compound C**: 0 hyperconjugation structures (least stable)
- **Compound D**: 1 hyperconjugation structure

### Step 4: Conclusion
Since stability is directly proportional to the number of hyperconjugation structures, **Compound A** is the most stable intermediate.

### Final Answer
**The most stable intermediate is Compound A.**

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