In which of the following, homolytic bond fission takes place :

Options

A. Alkaline hydrolysis of ethyl chloride
B. Addition of HBr to double bond
C. Photochlorination of methane
D. Nitration of benzene

Answer

To determine in which of the given reactions homolytic bond fission occurs, we will analyze each option step by step.

### Step 1: Understand Homolytic Bond Fission
Homolytic bond fission is a process where a bond breaks evenly, resulting in the formation of two radicals, each containing one of the shared electrons from the bond. This is different from heterolytic fission, where the bond breaks unevenly, leading to the formation of a cation and an anion.

### Step 2: Analyze Each Option

**Option A: Alkaline Hydrolysis of Ethyl Chloride**
- In this reaction, ethyl chloride (C2H5Cl) reacts with a base (like NaOH) to form ethanol and sodium chloride.
- The bond between carbon and chlorine undergoes heterolytic fission, where the electron pair is taken by the chlorine atom, resulting in the formation of an ethyl cation and a chloride ion.
- **Conclusion**: This reaction does not involve homolytic bond fission.

**Option B: Addition of HBr to Double Bond**
- When HBr adds to an alkene, the double bond breaks and forms a carbocation intermediate.
- The bond between H and Br undergoes heterolytic fission, where the electron pair is transferred to the bromine atom, forming H+ and Br-.
- **Conclusion**: This reaction does not involve homolytic bond fission.

**Option C: Photochlorination of Methane**
- In this reaction, methane (CH4) reacts with chlorine (Cl2) in the presence of light.
- The Cl-Cl bond undergoes homolytic fission, resulting in the formation of two chlorine radicals (Cl•).
- This initiates a free radical chain reaction, where the chlorine radical reacts with methane, leading to the formation of methyl chloride (CH3Cl) and more chlorine radicals.
- **Conclusion**: This reaction involves homolytic bond fission.

**Option D: Nitration of Benzene**
- In the nitration of benzene, benzene reacts with concentrated nitric acid in the presence of sulfuric acid to form nitrobenzene.
- The bond fission in this reaction is heterolytic, as the nitronium ion (NO2+) is formed from nitric acid.
- **Conclusion**: This reaction does not involve homolytic bond fission.

### Final Answer
After analyzing all the options, the only reaction that involves homolytic bond fission is:
**Option C: Photochlorination of Methane.**