Question

Identify the major product formed in the following reaction. Chlorobenzene \( \xrightarrow[\text{Anhydrous FeCl}_{3}]{\text{Cl}_{2}} \) Product}

• A. o-dichlorobenzene
• B. m-dichlorobenzene
• C. 1,3,5-trichlorobenzene
• D. p-dichlorobenzene

Hint:

In most electrophilic substitutions of mono-substituted benzenes, the para-isomer is the major product due to minimal steric repulsion.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The reaction is electrophilic aromatic substitution (chlorination) of chlorobenzene.
Step 2: Key Formula or Approach:
The chlorine atom already present on the benzene ring is ortho and para directing due to the resonance effect (\( +R \)).
Step 3: Detailed Explanation:
When chlorobenzene reacts with chlorine in the presence of anhydrous \( FeCl_{3} \), the incoming electrophile \( Cl^{+} \) attacks the ortho and para positions.
The para-substituted product (p-dichlorobenzene) is the major product due to less steric hindrance at the para position compared to the ortho position.
Looking at the provided images:
- Image A shows 1,2-dichlorobenzene (ortho).
- The bottom left image shows 1,3-dichlorobenzene (meta).
- Image C shows 1,3,5-trichlorobenzene.
- The bottom right image shows 1,4-dichlorobenzene (para).
Therefore, the para product is the major one.
Step 4: Final Answer:
The major product is p-dichlorobenzene.