Ethylbenzene `+Cl_(2)overset("Light")rarr`(main) compound is :

Options

A. `o-& p-` Chloroethylbenzene
B. `1-`Chloroethylbenzene
C. `2-`Chloroethylbenzene
D. `m-`Chloroethylbenzene

Explanation

To solve the problem of what the main compound formed when ethylbenzene reacts with chlorine in the presence of light, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants are ethylbenzene (C6H5C2H5) and chlorine gas (Cl2). Ethylbenzene consists of a benzene ring with an ethyl group attached.

2. **Understand the Reaction Type**: The reaction involves a free radical substitution mechanism. This is typical for alkanes and aromatic compounds when they react with halogens in the presence of light.

3. **Initiation Step**: In the presence of light, Cl2 undergoes homolytic cleavage to form two chlorine radicals (Cl•):
\[ Cl_2 \xrightarrow{light} 2Cl• \]

4. **Formation of Radicals**: The chlorine radical can abstract a hydrogen atom from the ethyl group of ethylbenzene, forming an ethyl radical (C2H5•) and hydrochloric acid (HCl):
\[ C_6H_5C_2H_5 + Cl• \rightarrow C_6H_5C_2H_4• + HCl \]

5. **Radical Stability**: The ethyl radical (C2H5•) can further react with another chlorine radical to form the main product. However, it is important to note that the benzyl radical (C6H5CH2•) can also be formed if the chlorine radical abstracts a hydrogen from the benzyl position:
\[ C_6H_5C_2H_4• + Cl• \rightarrow C_6H_5C_2H_4Cl \quad (1-chloroethylbenzene) \]
\[ C_6H_5CH_2• + Cl• \rightarrow C_6H_5CH_2Cl \quad (benzyl chloride) \]

6. **Product Distribution**: The major product is determined by the stability of the radicals formed. The benzyl radical is more stable than the ethyl radical due to resonance stabilization. Therefore, the major product will be 1-chloroethylbenzene (C6H5C2H4Cl).

7. **Final Products**: The two products formed are:
- Major product: 1-chloroethylbenzene (C6H5C2H4Cl)
- Minor product: Benzyl chloride (C6H5CH2Cl)

### Conclusion:
The main compound formed when ethylbenzene reacts with Cl2 in the presence of light is **1-chloroethylbenzene**.

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