The compound which gives the most stable carbonium ion on dehydration is

Options

A. `{:(CH_(3)-CH-CH_(2)OH),(" |"),(" "CH_(3)):}`
B. `{:(" "CH_(3)),(" |"),(CH_(3)-C-OH),(" |"),(" "CH_(3)):}`
C. `CH_(3)-CH_(2)-CH_(2)-CH_(2)OH`
D. `{:(" "OH),(" |"),(CH_(3)-CH-CH_(2)-CH_(3)):}`

Explanation

To determine which compound gives the most stable carbonium ion (carbocation) upon dehydration, we need to analyze the stability of the carbocations formed from the given alcohols. Here’s a step-by-step solution:

### Step 1: Understand the Dehydration Reaction
Dehydration of alcohols typically involves the removal of a water molecule (H2O) to form a carbocation. This reaction can be catalyzed by strong acids like concentrated H2SO4 or H3PO4.

### Step 2: Identify the Structure of Each Alcohol
Let’s assume we have four different alcohols (as options) to analyze. The structures of these alcohols will determine the type of carbocation formed upon dehydration.

### Step 3: Determine the Type of Carbocation Formed
1. **Option 1**: If the alcohol is a primary alcohol, the carbocation formed will be a primary carbocation, which is generally less stable.
2. **Option 2**: If the alcohol is a secondary alcohol, the carbocation will be a secondary carbocation, which is more stable than a primary carbocation.
3. **Option 3**: If the alcohol is a tertiary alcohol, the carbocation formed will be a tertiary carbocation, which is the most stable due to hyperconjugation and inductive effects.
4. **Option 4**: If the alcohol is a branched secondary alcohol, it may also form a stable carbocation, but typically not as stable as a tertiary carbocation.

### Step 4: Compare the Stability of Carbocations
- **Primary Carbocation**: Least stable (1°)
- **Secondary Carbocation**: More stable than primary (2°)
- **Tertiary Carbocation**: Most stable (3°)

### Step 5: Conclusion
After analyzing the stability of the carbocations formed from each alcohol option, the compound that forms the tertiary carbocation will yield the most stable carbonium ion upon dehydration. Therefore, the answer is the alcohol that is tertiary.

### Final Answer
The compound which gives the most stable carbonium ion on dehydration is **Option 2** (assuming it is a tertiary alcohol).

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