Balz-Schiemann reaction.

Explanation

### Step-by-Step Solution for Balz-Schiemann Reaction

1. **Starting Material**: The reaction begins with aniline (C6H5NH2). Aniline is an aromatic amine that will undergo diazotization.

2. **Diazotization**: Aniline is treated with nitrous acid (HNO2), which is usually generated in situ from sodium nitrite (NaNO2) and a mineral acid (like HCl). The reaction converts the amino group (-NH2) of aniline into a diazonium salt (C6H5N2+). The reaction can be represented as:
\[ C6H5NH2 + HNO2 \rightarrow C6H5N2^+ + 2H2O \]
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