Acetone on addition to methyl magnesium bromide forms a complex, which on decomposition with acid gives X and `Mg(OH)Br.` Which one of the following is X?

Options

A. `CH_(3)OH`
B. `(CH_(3))_(3)COH`
C. `(CH_(3))_(2)CHOH`
D. `CH_(3)CH_(2)OH`

Answer

To solve the problem, we will follow the steps of the reaction between acetone and methyl magnesium bromide (a Grignard reagent) and identify the product formed after hydrolysis.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- Acetone (CH₃COCH₃) is a ketone with the structure:
```
CH3 - C(=O) - CH3
```
- Methyl magnesium bromide (CH₃MgBr) is a Grignard reagent.

2. **Formation of the Grignard Complex**:
- When acetone reacts with methyl magnesium bromide, the nucleophilic methyl group (CH₃⁻) from the Grignard reagent attacks the electrophilic carbon of the carbonyl group (C=O) in acetone.
- This results in the formation of a tetrahedral intermediate:
```
CH3 - C(OH)(CH3) - CH3
```
- The magnesium bromide ion (MgBr⁺) associates with the oxygen atom, leading to a complex:
```
CH3 - C(OH)(CH3) - CH3 + MgBr⁺
```

3. **Decomposition with Acid**:
- Upon hydrolysis (decomposition with acid), the tetrahedral intermediate undergoes protonation and rearrangement.
- The negative charge on the oxygen atom is neutralized by a proton (H⁺) from the acid, forming an alcohol:
```
CH3 - C(OH)(CH3) - CH3 → (CH3)3C - OH (tert-butyl alcohol)
```
- The magnesium bromide ion combines with hydroxide ions (OH⁻) from the acid to form:
```
Mg(OH)Br
```

4. **Identify the Product X**:
- The product X formed after hydrolysis is tertiary butyl alcohol, which has the structure:
```
(CH3)3C - OH
```

### Conclusion:
The final product X is **tertiary butyl alcohol**.

### Answer:
**X = Tertiary butyl alcohol (Option B)**