Which of the following alcohols will give the most stable carbocation during dehydration ?

Options

A. 2- Methyl-1- propanal
B. 2-Methyl-2-propanol
C. 1 - Butanol
D. 2-Butanol

Explanation

To determine which of the given alcohols will yield the most stable carbocation during dehydration, we need to analyze the stability of the carbocations formed from each alcohol upon dehydration.

### Step-by-Step Solution:

1. **Identify the Alcohols**: The alcohols given in the question are:
- 2-methyl-1-propanol
- 2-methyl-2-propanol
- 1-butanol
- 2-butanol

2. **Understand Dehydration Reaction**: Dehydration of alcohols typically involves the removal of a water molecule (H₂O) in the presence of an acid, often concentrated sulfuric acid (H₂SO₄). This process leads to the formation of a carbocation intermediate.

3. **Determine the Type of Carbocation Formed**:
- **2-methyl-1-propanol**: Upon dehydration, this alcohol forms a primary carbocation.
- **2-methyl-2-propanol**: This alcohol forms a tertiary carbocation, which is the most stable type of carbocation.
- **1-butanol**: This alcohol also forms a primary carbocation upon dehydration.
- **2-butanol**: This alcohol forms a secondary carbocation upon dehydration.

4. **Stability of Carbocations**: The stability of carbocations increases in the following order:
- Primary < Secondary < Tertiary
The more alkyl groups attached to the positively charged carbon, the more stable the carbocation due to hyperconjugation and inductive effects.

5. **Conclusion**: Among the alcohols analyzed:
- 2-methyl-1-propanol forms a primary carbocation.
- 2-methyl-2-propanol forms a tertiary carbocation (most stable).
- 1-butanol forms a primary carbocation.
- 2-butanol forms a secondary carbocation.

Thus, **2-methyl-2-propanol** will give the most stable carbocation during dehydration.

### Final Answer:
**2-methyl-2-propanol** gives the most stable carbocation during dehydration.