Photochemical chlorination of alkane is initiated by a process of -

Options

A. Pyrolysis
B. Substitution
C. Homolysis
D. Peroxidation

Answer

To answer the question "Photochemical chlorination of alkane is initiated by a process of," we need to understand the steps involved in the photochemical chlorination of alkanes.

### Step-by-Step Solution:

1. **Understanding Photochemical Chlorination**:
- Photochemical chlorination is a reaction where chlorine reacts with alkanes in the presence of light (usually UV light). This process leads to the substitution of hydrogen atoms in alkanes with chlorine atoms.

2. **Identifying the Steps**:
- The process of photochemical chlorination consists of three main steps:
1. Initiation
2. Chain Propagation
3. Chain Termination

3. **Focusing on the Initiation Step**:
- The initiation step is crucial as it generates the reactive species that will propagate the reaction. In photochemical reactions, this step is typically initiated by the absorption of light.

4. **Mechanism of Initiation**:
- In the case of chlorination, the initiation occurs through the homolytic cleavage of the chlorine molecule (Cl₂) when it absorbs light. This process results in the formation of two chlorine free radicals (Cl•).
- The reaction can be represented as:
\[ \text{Cl}_2 \xrightarrow{\text{light}} 2 \text{Cl}• \]
- This homolytic bond fission is what initiates the free radical chain reaction.

5. **Conclusion**:
- Therefore, the photochemical chlorination of alkanes is initiated by the process of **homolytic bond cleavage** or **homolysis** of chlorine molecules, resulting in the formation of chlorine free radicals.

### Final Answer:
Photochemical chlorination of alkane is initiated by the process of **homolytic bond cleavage (homolysis)**.

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