Coupling of benzene diazonium chloride with `1-`naphthol in alkaline medium will give:

Options

A.
B.
C.
D.

Answer

To solve the question regarding the coupling of benzene diazonium chloride with 1-naphthol in alkaline medium, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Reactants**:
- We start with benzene diazonium chloride, which is formed from aniline (aminobenzene) reacting with nitrous acid (generated from sodium nitrite and hydrochloric acid). The structure of benzene diazonium chloride is represented as C6H5-N2^+Cl^-.

2. **Formation of Benzene Diazonium Chloride**:
- The reaction occurs at low temperatures (0-5 degrees Celsius) to stabilize the diazonium salt. The reaction can be summarized as:
\[ \text{C6H5-NH2} + \text{NaNO2} + \text{HCl} \rightarrow \text{C6H5-N2}^+ \text{Cl}^- \]

3. **Understanding 1-Naphthol**:
- 1-Naphthol (or alpha-naphthol) has the structure of a naphthalene ring with a hydroxyl (–OH) group at the first position. It can be represented as:
\[ \text{C10H8O} \quad (\text{with } -OH \text{ at position 1}) \]

4. **Coupling Reaction**:
- In the presence of an alkaline medium, the hydroxyl group of 1-naphthol can act as a nucleophile. The diazonium ion (C6H5-N2^+) will couple with the naphthol at the para position relative to the hydroxyl group.

5. **Product Formation**:
- The coupling reaction leads to the formation of an azo compound. The structure of the product can be represented as:
\[ \text{C6H5-N=N-C10H7OH} \quad (\text{with the } -OH \text{ at para position}) \]
- This product is known for its vibrant orange-red color, commonly referred to as an azo dye.

6. **Final Answer**:
- The product of the coupling of benzene diazonium chloride with 1-naphthol in alkaline medium is an orange-red azo dye.