Adding of `Cl_2` to benzene in the presence of `AlCl_3` is an example of

Options

A. Addition
B. Halogenation
C. Substitution
D. Elimination

Explanation

To solve the question regarding the addition of \( Cl_2 \) to benzene in the presence of \( AlCl_3 \), we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding the Reactants**:
- We have benzene, which is a stable aromatic hydrocarbon.
- We are adding chlorine gas (\( Cl_2 \)) to benzene.
- The presence of \( AlCl_3 \) is crucial as it acts as a catalyst.

2. **Role of \( AlCl_3 \)**:
- \( AlCl_3 \) is a Lewis acid, which means it can accept electron pairs.
- In this reaction, \( AlCl_3 \) acts as a halogen carrier. It interacts with \( Cl_2 \) to facilitate the generation of a more reactive species.

3. **Formation of Electrophile**:
- When \( AlCl_3 \) reacts with \( Cl_2 \), it abstracts one chlorine atom, forming \( AlCl_4^- \) and a chlorine cation (\( Cl^+ \)).
- The \( Cl^+ \) ion is a strong electrophile, which is essential for the next step.

4. **Electrophilic Substitution Mechanism**:
- The \( Cl^+ \) electrophile attacks the benzene ring.
- This results in the substitution of one hydrogen atom on the benzene ring with a chlorine atom.

5. **Product Formation**:
- The product of this reaction is chlorobenzene, where one of the hydrogen atoms in benzene is replaced by a chlorine atom.
- The overall reaction can be summarized as:
\[ C_6H_6 + Cl_2 \xrightarrow{AlCl_3} C_6H_5Cl + HCl \]

6. **Type of Reaction**:
- Since the reaction involves the substitution of a hydrogen atom in benzene with a chlorine atom, it is classified as an **electrophilic substitution reaction**.

### Final Answer:
Adding \( Cl_2 \) to benzene in the presence of \( AlCl_3 \) is an example of **electrophilic substitution**.

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