The dehydration of 1-butanol gives

Options

A. 1-butene as the main product
B. 2-butene as the main product
C. equal amounts of 1-butene and 2-butene
D. 2-methyl propene

Answer

To solve the question regarding the dehydration of 1-butanol, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of 1-Butanol**:
- 1-butanol is a straight-chain alcohol with the molecular formula C4H10O. Its structure can be represented as:
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{OH} \]

2. **Understand Dehydration**:
- Dehydration of an alcohol involves the removal of a water molecule (H2O). This typically occurs when the hydroxyl group (-OH) is removed along with a hydrogen atom from an adjacent carbon atom.

3. **Formation of Carbocation**:
- Upon dehydration, the -OH group leaves, resulting in the formation of a carbocation. In the case of 1-butanol, the initial carbocation formed is a primary carbocation (1°), which is less stable.
- The reaction can be represented as:
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{C}^+\text{H}_2 \]

4. **Rearrangement to Form a More Stable Carbocation**:
- The primary carbocation can rearrange to form a more stable secondary carbocation (2°) by a hydride shift. This involves the migration of a hydrogen atom from an adjacent carbon to the positively charged carbon.
- The rearrangement results in:
\[ \text{CH}_3\text{CH}^+\text{CH}_2\text{CH}_3 \]

5. **Formation of Alkenes**:
- After the formation of the more stable carbocation, the next step involves the elimination of a proton (H+) to form a double bond, resulting in the formation of alkenes.
- Two possible alkenes can be formed:
- If the proton is removed from the carbon adjacent to the carbocation, 1-butene is formed:
\[ \text{CH}_2=\text{CH}\text{CH}_2\text{CH}_3 \quad (\text{1-butene}) \]
- If the proton is removed from the carbocation carbon, 2-butene is formed:
\[ \text{CH}_3\text{CH}=\text{CH}\text{CH}_3 \quad (\text{2-butene}) \]

6. **Determine Major Product**:
- Among the products formed, 2-butene is more stable due to being more substituted (having more alkyl groups attached to the double bond), which stabilizes the double bond. Therefore, the major product of the dehydration of 1-butanol is:
\[ \text{2-butene} \]

### Final Answer:
The dehydration of 1-butanol gives **2-butene** as the major product.

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