Benzene reacts with excess of chlorine in presence of ultraviolet light to produce

Options

A. Hexachlorobenzene
B. p-Dichlorobenzene
C. Hexachlorocyclohexane
D. Chlorobenzene

Answer

To solve the question regarding the reaction of benzene with excess chlorine in the presence of ultraviolet light, we can break it down into the following steps:

### Step 1: Understand the Reactants
- **Benzene (C6H6)**: A cyclic hydrocarbon with a stable structure due to resonance.
- **Chlorine (Cl2)**: A diatomic molecule that can react with benzene under specific conditions.

### Step 2: Identify the Reaction Conditions
- The presence of **ultraviolet (UV) light** indicates that the reaction will proceed via a free radical mechanism. UV light provides the energy needed to break the Cl-Cl bond in chlorine, generating chlorine radicals.

### Step 3: Mechanism of the Reaction
- **Initiation**: UV light causes the dissociation of Cl2 into two chlorine radicals (Cl•).

\[ \text{Cl}_2 \xrightarrow{UV} 2 \text{Cl}• \]

- **Propagation**: The chlorine radicals react with benzene to form chlorobenzene and another chlorine radical. This process can continue, leading to further chlorination.

\[ \text{C}_6\text{H}_6 + \text{Cl}• \rightarrow \text{C}_6\text{H}_5\text{Cl} + \text{HCl} \]

- This process can repeat, with additional chlorine radicals attacking the chlorobenzene, leading to multiple substitutions.

### Step 4: Final Product Formation
- Under excess chlorine and UV light, the reaction can continue until all hydrogen atoms in benzene are replaced by chlorine atoms. The final product will be **hexachlorocyclohexane (C6Cl6)**, which is formed when all six hydrogen atoms in benzene are substituted by chlorine.

### Conclusion
- Therefore, the product of the reaction of benzene with excess chlorine in the presence of ultraviolet light is **hexachlorocyclohexane**.

### Final Answer:
The correct answer is **hexachlorocyclohexane**.

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