The reaction: `ArN_2Cl overset(Cu//HCl)rarrArCl +N_2 + CuCl` is known as: -

Options

A. Balz Schiemann reaction
B. Sandmeyers reaction
C. Finkelstein reaction
D. Gattermann reaction

Answer

To determine the name of the reaction given by the equation:

\[ \text{ArN}_2\text{Cl} \xrightarrow{\text{Cu/HCl}} \text{ArCl} + \text{N}_2 + \text{CuCl} \]

we can analyze the components and the process involved.

### Step-by-Step Solution:

1. **Identify the Reactants and Products**:
- The reactant is aryl diazonium chloride (ArN₂Cl).
- The products are aryl chloride (ArCl), nitrogen gas (N₂), and copper(I) chloride (CuCl).

2. **Understand the Role of Copper and Hydrochloric Acid**:
- In this reaction, copper acts as a reducing agent and hydrochloric acid provides the chloride ion necessary for the substitution reaction.

3. **Recognize the Type of Reaction**:
- The reaction involves the substitution of the diazonium group (N₂) with a chlorine atom (Cl) from HCl, leading to the formation of aryl chloride.

4. **Relate to Known Reactions**:
- This reaction is characteristic of the Sandmeyer reaction, which involves the conversion of aryl diazonium salts into aryl halides using copper(I) halides in the presence of a halogen acid.

5. **Conclusion**:
- Therefore, the reaction given is known as the **Sandmeyer Reaction**.

### Final Answer:
The reaction \( \text{ArN}_2\text{Cl} \xrightarrow{\text{Cu/HCl}} \text{ArCl} + \text{N}_2 + \text{CuCl} \) is known as the **Sandmeyer Reaction**.

---