p-bromoaniline is prepared from aniline via

Options

A. direct bromination of aniline in presence of Lewis acid
B. bromination of acetanilide followed by hydrolysis
C. direct bronination of aniline in presence of light
D. amination of bromine.

Answer

To prepare p-bromoaniline from aniline, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Starting Material**:
The starting material is aniline, which has the structure C6H5NH2.

2. **Choose the Method**:
We will use the method of bromination of acetanilide followed by hydrolysis. This is because direct bromination of aniline is not effective due to the deactivation of the ring by the amino group.

3. **Convert Aniline to Acetanilide**:
First, we need to convert aniline (C6H5NH2) to acetanilide (C6H5NHCOCH3). This can be done by reacting aniline with acetic anhydride or acetyl chloride. The reaction is as follows:
\[ \text{C6H5NH2} + \text{(CH3CO)2O} \rightarrow \text{C6H5NHCOCH3} + \text{CH3COOH} \]

4. **Bromination of Acetanilide**:
Next, we perform bromination on acetanilide using bromine (Br2) in the presence of a Lewis acid like AlBr3. The nitrogen atom in acetanilide donates its lone pair, increasing the electron density at the ortho and para positions of the benzene ring. The electrophilic bromine (Br+) will preferentially attack the para position due to steric hindrance from the acetyl group:
\[ \text{C6H5NHCOCH3} + \text{Br2} \xrightarrow{\text{AlBr3} } \text{C6H4BrNHCOCH3 (para)} \]

5. **Hydrolysis of Brominated Acetanilide**:
Finally, we perform acid hydrolysis on the brominated acetanilide to convert the acetamido group back to an amino group. This is done using an acid like H3O+:
\[ \text{C6H4BrNHCOCH3} + \text{H3O+} \rightarrow \text{C6H4BrNH2} + \text{CH3COOH} \]

6. **Final Product**:
The final product of this reaction is p-bromoaniline (C6H4BrNH2).

### Conclusion:
Thus, p-bromoaniline is prepared from aniline via the bromination of acetanilide followed by hydrolysis.

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