The chlorination of ethane is an example for which type of the following reactions?

Options

A. Nucleophilic substitution
B. Electrophilic substitution
C. Free radical substitution
D. Rearrangement

Answer

To determine the type of reaction that the chlorination of ethane represents, we can follow these steps:

### Step 1: Understand the Reactants and Conditions
The reaction involves ethane (C2H6) and chlorine (Cl2) under photochemical conditions (presence of sunlight or light energy, denoted as Hν).

**Hint:** Identify the reactants and the conditions under which the reaction occurs.

### Step 2: Identify the Mechanism
The chlorination of ethane occurs through a free radical mechanism. This mechanism can be broken down into three main stages: initiation, propagation, and termination.

**Hint:** Look for the stages of the reaction mechanism when free radicals are involved.

### Step 3: Chain Initiation
In the initiation step, chlorine molecules (Cl2) dissociate into two chlorine radicals (Cl•) when exposed to light (Hν). This is represented as:
\[ \text{Cl}_2 \xrightarrow{H\nu} 2 \text{Cl}• \]

**Hint:** Remember that initiation involves the formation of free radicals from stable molecules.

### Step 4: Chain Propagation
In the propagation steps, the chlorine radical reacts with ethane to form a new radical and hydrochloric acid (HCl). The reaction can be shown as:
\[ \text{C}_2\text{H}_6 + \text{Cl}• \rightarrow \text{C}_2\text{H}_5• + \text{HCl} \]
The ethyl radical (C2H5•) can then react with another chlorine molecule to form chloroethane (C2H5Cl) and regenerate the chlorine radical:
\[ \text{C}_2\text{H}_5• + \text{Cl}_2 \rightarrow \text{C}_2\text{H}_5\text{Cl} + \text{Cl}• \]

**Hint:** In propagation, radicals react to form new products and regenerate radicals.

### Step 5: Chain Termination
In the termination step, two radicals combine to form a stable product, effectively stopping the reaction. For example:
\[ \text{C}_2\text{H}_5• + \text{Cl}• \rightarrow \text{C}_2\text{H}_5\text{Cl} \]

**Hint:** Termination involves the combination of radicals to form stable molecules.

### Step 6: Conclusion
The overall process of chlorination of ethane is classified as a free radical substitution reaction. This is because the reaction involves the substitution of hydrogen atoms in ethane with chlorine atoms through a series of radical intermediates.

**Final Answer:** The chlorination of ethane is an example of a **free radical substitution reaction**.