To prepare p-bromonitrobenzene, the benzene is first subjected to ___ and then ___

Answer

To prepare p-bromonitrobenzene, the benzene is first subjected to **bromination** and then **nitration**.

### Step-by-Step Solution:

1. **Bromination of Benzene**:
- The first step involves brominating benzene. This is done by treating benzene with bromine (Br2) in the presence of a catalyst such as iron (Fe) or iron(III) bromide (FeBr3). The reaction introduces a bromine atom into the benzene ring, resulting in bromobenzene.
- **Reaction**:
\[ \text{C}_6\text{H}_6 + \text{Br}_2 \xrightarrow{\text{Fe}} \text{C}_6\text{H}_5\text{Br} + \text{HBr} \]

2. **Nitration of Bromobenzene**:
- The next step involves the nitration of the bromobenzene. This is achieved by treating bromobenzene with a mixture of concentrated nitric acid (HNO3) and concentrated sulfuric acid (H2SO4). The nitro group (NO2) is introduced into the benzene ring.
- Since the bromine atom is an ortho-para directing group, the nitro group will preferentially add to the para position relative to the bromine atom.
- **Reaction**:
\[ \text{C}_6\text{H}_5\text{Br} + \text{HNO}_3/\text{H}_2\text{SO}_4 \rightarrow \text{C}_6\text{H}_4\text{Br(NO}_2) + \text{H}_2\text{O} \]

3. **Final Product**:
- The final product of this reaction sequence is p-bromonitrobenzene, where the nitro group is located at the para position relative to the bromine atom.

### Summary:
To prepare p-bromonitrobenzene, benzene is first subjected to bromination to form bromobenzene, and then it undergoes nitration to yield p-bromonitrobenzene.