Adding `Cl_(2)` to benzene in the presence of anhydrous `AlCl_(3)` is an example of

Explanation

To determine the type of reaction that occurs when adding Cl₂ to benzene in the presence of anhydrous AlCl₃, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants in this reaction are benzene (C₆H₆) and chlorine gas (Cl₂), with anhydrous aluminum chloride (AlCl₃) acting as a catalyst.

2. **Understand the Role of AlCl₃**: Anhydrous AlCl₃ is a Lewis acid that helps generate a more reactive electrophile from Cl₂. It does this by forming a complex with Cl₂, which facilitates the generation of Cl⁺ ions (electrophiles).

3. **Electrophilic Substitution Mechanism**: In benzene, the π-electrons are delocalized, making it a stable aromatic compound. When Cl₂ is introduced in the presence of AlCl₃, the Cl₂ molecule interacts with AlCl₃ to produce Cl⁺ ions.

4. **Formation of the Electrophile**: The Cl₂ molecule interacts with AlCl₃, leading to the formation of the electrophile Cl⁺. This electrophile is then able to attack the benzene ring.

5. **Substitution Reaction**: The Cl⁺ ion attacks one of the hydrogen atoms on the benzene ring, leading to the substitution of that hydrogen atom with a chlorine atom. The reaction can be summarized as:
\[ C_6H_6 + Cl_2 \xrightarrow{AlCl_3} C_6H_5Cl + HCl \]

6. **Final Product**: The product of this reaction is chlorobenzene (C₆H₅Cl) and hydrogen chloride (HCl) as a byproduct.

7. **Conclusion**: Therefore, the reaction of adding Cl₂ to benzene in the presence of anhydrous AlCl₃ is classified as an **electrophilic substitution reaction**.