Chlorination of methane proceeds by

Options

A. Electrophilic substitution
B. Nucelophilic substitution
C. Free radical mechanism
D. None of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Reaction:**
The chlorination of methane involves the reaction of methane (CH₄) with chlorine (Cl₂) in the presence of light. The overall reaction can be represented as:
\[ \text{CH}_4 + \text{Cl}_2 \xrightarrow{\text{light}} \text{Products} \]

2. **Initiation Step:**
The reaction begins with the initiation step where chlorine molecules (Cl₂) are dissociated into chlorine free radicals (Cl•) due to the energy provided by light. This can be represented as:
\[ \text{Cl}_2 \xrightarrow{\text{light}} 2 \text{Cl}• \]

3. **Propagation Steps:**
In the propagation steps, the chlorine free radicals react with methane. The first reaction involves a chlorine radical abstracting a hydrogen atom from methane, leading to the formation of hydrochloric acid (HCl) and a methyl free radical (CH₃•):
\[ \text{Cl}• + \text{CH}_4 \rightarrow \text{HCl} + \text{CH}_3• \]
The methyl free radical can then react with another chlorine molecule to produce chloromethane (CH₃Cl) and regenerate another chlorine radical:
\[ \text{CH}_3• + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{Cl}• \]

4. **Termination Steps:**
The reaction can terminate when two free radicals combine to form stable products. For example:
- Two chlorine radicals can combine to form chlorine gas:
\[ 2 \text{Cl}• \rightarrow \text{Cl}_2 \]
- A chlorine radical can react with a methyl radical to form chloromethane:
\[ \text{Cl}• + \text{CH}_3• \rightarrow \text{CH}_3\text{Cl} \]
- Two methyl radicals can combine to form ethane (C₂H₆):
\[ 2 \text{CH}_3• \rightarrow \text{C}_2\text{H}_6 \]

5. **Conclusion:**
The chlorination of methane proceeds via a free radical mechanism, characterized by initiation, propagation, and termination steps. This mechanism leads to a mixture of products, including chloromethane, dichloromethane, trichloromethane, and carbon tetrachloride.

**Final Answer:**
The chlorination of methane proceeds by a free radical mechanism.

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