Select the most stable intermediate

Options

A.
B.
C.
D.

Explanation

To determine the most stable carbocation intermediate among the given options, we can follow these steps:

### Step 1: Identify the Types of Carbocations
Carbocations can be classified based on the number of alkyl groups attached to the positively charged carbon atom. The stability order is:
- Tertiary (3°) > Secondary (2°) > Primary (1°) > Methyl (0°)

### Step 2: Analyze the Given Structures
The question provides different structures of carbocations with varying alkyl groups:
1. Carbocation with one CH3 group (Primary)
2. Carbocation with one CH2Me group (Secondary)
3. Carbocation with one CHMe2 group (Tertiary)
4. Carbocation with one CMe3 group (Tertiary)

### Step 3: Determine the Stability Based on Alkyl Groups
- The first structure has one alkyl group (CH3), making it a primary carbocation.
- The second structure has two alkyl groups (CH2Me), making it a secondary carbocation.
- The third structure has three alkyl groups (CHMe2), making it a tertiary carbocation.
- The fourth structure has four alkyl groups (CMe3), making it a tertiary carbocation as well.

### Step 4: Evaluate the Inductive Effect
The stability of carbocations is also influenced by the inductive effect (I effect) of the alkyl groups. Alkyl groups are electron-donating, which helps stabilize the positive charge on the carbocation. The more alkyl groups attached, the greater the stability due to the +I effect.

### Step 5: Compare the Stability
- The first structure (Primary) has the least stability due to having only one alkyl group.
- The second structure (Secondary) is more stable than the first due to having two alkyl groups.
- The third structure (Tertiary) is more stable than the second due to having three alkyl groups.
- The fourth structure (Tertiary with four alkyl groups) is the most stable due to having the maximum number of alkyl groups providing +I effect.

### Conclusion
Based on the analysis, the most stable intermediate is the one with the structure containing CMe3, which is the fourth option.

### Final Answer
**D option (CMe3) is the most stable intermediate.**

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