The major product of acid catalysed dehydration of 2-methylcyclohexanol and butan-1-ol are respectively

Options

A. 1-methylcyclohexene and but-1-ene
B. 2-methylcyclohexene and but-2-ene
C. 2-methylcyclohexene and butane
D. 1-methylcyclohexene and but-2-ene.

Explanation

To determine the major products of the acid-catalyzed dehydration of 2-methylcyclohexanol and butan-1-ol, we will analyze each compound step by step.

### Step 1: Dehydration of 2-Methylcyclohexanol
1. **Identify the structure**: 2-methylcyclohexanol has a cyclohexane ring with a hydroxyl (-OH) group at the second position and a methyl (-CH₃) group also at the second position.
2. **Protonation of the alcohol**: When 2-methylcyclohexanol reacts with an acid (H⁺), the hydroxyl group gets protonated, forming a better leaving group (water).
3. **Formation of carbocation**: The protonation leads to the formation of a carbocation intermediate. Initially, a secondary carbocation is formed.
4. **Rearrangement**: The secondary carbocation can rearrange to form a more stable tertiary carbocation by a hydride shift from an adjacent carbon.
5. **Elimination**: From the tertiary carbocation, elimination occurs, leading to the formation of an alkene. Two different hydrogens can be removed to form the same product.
6. **Final product**: The major product formed is 1-methylcyclohexene.

### Step 2: Dehydration of Butan-1-ol
1. **Identify the structure**: Butan-1-ol is a straight-chain alcohol with four carbon atoms and a hydroxyl group at the first position.
2. **Protonation of the alcohol**: Similar to the previous reaction, the hydroxyl group is protonated by the acid.
3. **Formation of carbocation**: This leads to the formation of a primary carbocation, which is less stable.
4. **Rearrangement**: The primary carbocation can rearrange to form a more stable secondary carbocation by a hydride shift.
5. **Elimination**: From the secondary carbocation, elimination occurs, resulting in the formation of an alkene. Two different hydrogens can be removed, leading to two possible products.
6. **Major product determination**: According to Zaitsev's rule, the more substituted alkene is favored. The major product formed is but-2-ene.

### Final Answer
The major products of the acid-catalyzed dehydration of 2-methylcyclohexanol and butan-1-ol are:
1. **1-methylcyclohexene** (from 2-methylcyclohexanol)
2. **but-2-ene** (from butan-1-ol)

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