Fluorobenzene is prepared by treating benzene diazonium chloride with fluoroboric acid and heating the product obtained. This reaction is known as:

Options

A. Schiemann reaction
B. Sandmeyer reaction
C. Gattermann reaction
D. Ullmann reaction.

Answer

To determine the name of the reaction in which fluorobenzene is prepared by treating benzene diazonium chloride with fluoroboric acid, we can break down the process step by step.

### Step-by-Step Solution:

1. **Identify the Reactants**: The reaction begins with benzene diazonium chloride (C6H5N2Cl) and fluoroboric acid (HBF4). The diazonium salt is a key intermediate in many aromatic substitution reactions.

2. **Reaction Mechanism**: When benzene diazonium chloride is treated with fluoroboric acid, the HBF4 dissociates into H+ and BF4-. The BF4- ion acts as a source of fluoride ions.

3. **Substitution Reaction**: The fluoride ion (F-) from BF4- replaces the chloride ion (Cl-) in the diazonium salt. This is a nucleophilic substitution reaction where the nucleophile (F-) attacks the positively charged carbon of the diazonium group.

4. **Formation of Fluorobenzene**: After the substitution occurs, the product formed is fluorobenzene (C6H5F). During this process, nitrogen gas (N2) is released as a byproduct, and HCl is also formed.

5. **Name of the Reaction**: The overall reaction is known as the **Balz-Schiemann reaction**. This name is attributed to the chemists who first described this method of synthesizing aryl fluorides from diazonium salts.

### Final Answer:
The reaction in which fluorobenzene is prepared by treating benzene diazonium chloride with fluoroboric acid is known as the **Balz-Schiemann reaction**.