Chlorination of methane in the presence of ultraviolet light involves:

Options

A. homolytic cleavage
B. heterolytic cleavage
C. carbocation
D. carbanion

Explanation

To solve the question regarding the chlorination of methane in the presence of ultraviolet light, we can break down the process into several steps:

### Step 1: Understand the Reaction
Chlorination of methane is a free radical substitution reaction where chlorine (Cl2) reacts with methane (CH4) to form chloromethane (CH3Cl) and other chlorinated products. This reaction typically requires ultraviolet (UV) light to initiate the process.

**Hint:** Remember that UV light provides the energy needed to break the Cl-Cl bond in chlorine molecules.

### Step 2: Initiation Step
The reaction begins with the initiation step, where UV light causes the homolytic cleavage of the Cl-Cl bond, generating two chlorine radicals (Cl•).

**Hint:** Look for the formation of free radicals as a key feature of initiation.

### Step 3: Propagation Steps
Once the chlorine radicals are formed, they can react with methane. The propagation steps can be summarized as follows:

1. A chlorine radical (Cl•) abstracts a hydrogen atom from methane (CH4), forming chloromethane (CH3Cl) and a methyl radical (CH3•).

\[ \text{Cl•} + \text{CH}_4 \rightarrow \text{CH}_3\text{Cl} + \text{H•} \]

2. The methyl radical (CH3•) can then react with another chlorine molecule (Cl2) to form more chloromethane and regenerate a chlorine radical.

\[ \text{CH}_3• + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{Cl•} \]

**Hint:** Identify the cyclic nature of the propagation steps where radicals are continuously generated.

### Step 4: Termination Step
The reaction can terminate when two radicals combine to form a stable product. For example, two chlorine radicals can combine to regenerate Cl2, or a methyl radical can combine with a chlorine radical.

**Hint:** Look for the combination of radicals as a way to stop the reaction.

### Step 5: Products of the Reaction
The chlorination of methane can lead to various products, including chloromethane (CH3Cl), dichloromethane (CH2Cl2), trichloromethane (CHCl3), and carbon tetrachloride (CCl4), depending on the reaction conditions and the amount of chlorine used.

**Hint:** Consider how the number of chlorine atoms affects the type of chlorinated products formed.

### Final Summary
The chlorination of methane in the presence of ultraviolet light involves the initiation of chlorine radicals, followed by a series of propagation steps where methane is converted into chlorinated products, and finally, termination steps that lead to stable products.