When `3,3-`dimethyl`-2-`butanol is heated with `H_(2)SO_(4)` the major product obtained is

Options

A. 2, 3-dimethyl 2-butene
B. cis and trans isomers of 2, 3-dimethyl 2-butene
C. 2, 3-dimethyl 1-butene
D. 3, 3-dimethyl 1-butene

Answer

To determine the major product formed when 3,3-dimethyl-2-butanol is heated with H₂SO₄, we can follow these steps:

### Step 1: Understand the Structure of 3,3-Dimethyl-2-butanol
3,3-Dimethyl-2-butanol has the following structure:
- It is a four-carbon alcohol (butanol) with the hydroxyl (OH) group on the second carbon.
- There are two methyl (CH₃) groups attached to the third carbon.

The structure can be represented as:
```
CH3
|
CH3-C-CH-CH3
|
OH
```

### Step 2: Protonation of the Alcohol
When 3,3-dimethyl-2-butanol is heated with H₂SO₄, the sulfuric acid donates a proton (H⁺) to the hydroxyl group (OH), converting it into a better leaving group (water, H₂O). This results in the formation of a carbocation.

### Step 3: Formation of the Carbocation
The protonation leads to the formation of a carbocation at the second carbon:
```
CH3
|
CH3-C⁺-CH-CH3
|
H2O
```
This carbocation is a secondary carbocation.

### Step 4: Rearrangement of the Carbocation
To stabilize the carbocation, a methyl shift can occur. The methyl group from the third carbon can shift to the second carbon, resulting in the formation of a more stable tertiary carbocation:
```
CH3
|
CH3-C-CH3
|
C⁺
```

### Step 5: Elimination of Water
Once the more stable tertiary carbocation is formed, a hydrogen atom is eliminated from the adjacent carbon (the third carbon), leading to the formation of a double bond:
```
CH3
|
CH3-C=CH2
```

### Step 6: Naming the Product
The final product is 2,3-dimethyl-2-butene. The double bond is located between the second and third carbons, and there are two methyl groups on the second carbon.

### Final Answer
The major product obtained when 3,3-dimethyl-2-butanol is heated with H₂SO₄ is **2,3-dimethyl-2-butene**.

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