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 solve the question regarding the major products of acid-catalyzed dehydration of 2-methylcyclohexanol and butan-1-ol, we will follow these steps:

### Step 1: Identify the Structure of 2-Methylcyclohexanol
2-Methylcyclohexanol is a secondary alcohol with the hydroxyl (-OH) group attached to the second carbon of a cyclohexane ring. The structure can be represented as follows:

```
CH3
|
CH2-CH
/ \
CH2 CH
| /
CH2-CH
```

### Step 2: Mechanism of Dehydration
The dehydration of alcohols typically occurs via an E1 mechanism when an acid is present. In this case, 2-methylcyclohexanol will lose a water molecule (H2O) to form a carbocation.

### Step 3: Formation of Carbocation
Since 2-methylcyclohexanol is a secondary alcohol, it will first form a secondary carbocation. However, this carbocation can rearrange to form a more stable tertiary carbocation through a hydride shift. The hydride shift involves the movement of a hydrogen atom from an adjacent carbon to the carbocation.

### Step 4: Rearrangement to Tertiary Carbocation
The hydride shift results in the formation of a tertiary carbocation, which is more stable than the secondary carbocation. The structure of the tertiary carbocation can be represented as follows:

```
CH3
|
CH2-CH
/ \
CH2 C+
| /
CH2-CH
```

### Step 5: Elimination to Form Alkene
The tertiary carbocation will then lose a proton (H+) to form an alkene. The major product of this dehydration reaction will be 1-methylcyclohexene.

### Step 6: Identify the Structure of Butan-1-ol
Butan-1-ol is a primary alcohol with the hydroxyl group at the first carbon. Its structure is:

```
CH3-CH2-CH2-CH2OH
```

### Step 7: Mechanism of Dehydration for Butan-1-ol
The dehydration of butan-1-ol will also occur via an E1 mechanism. However, since it is a primary alcohol, it will initially form a primary carbocation, which is less stable. Therefore, it will undergo rearrangement to form a more stable carbocation.

### Step 8: Formation of Carbocation
In the case of butan-1-ol, a hydride shift can occur, leading to the formation of a secondary carbocation.

### Step 9: Elimination to Form Alkene
The secondary carbocation will then lose a proton to form the major product, which will be 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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