Electrophilic aromatic substitution can be seen in which of the following cases ?

Options

A.
B.
C.
D.

Answer

To determine in which cases electrophilic aromatic substitution occurs, we will analyze each of the provided options step by step.

### Step 1: Understanding Electrophilic Aromatic Substitution
Electrophilic aromatic substitution (EAS) is a reaction where an electrophile replaces a hydrogen atom on an aromatic ring. This type of reaction typically requires the presence of an electrophile and a catalyst, often a Lewis acid.

### Step 2: Analyzing the Options
1. **Option A**: Friedel-Crafts Alkylation
- In this reaction, a benzene ring reacts with an alkyl halide in the presence of a Lewis acid (like AlCl₃). The alkyl group replaces a hydrogen atom on the benzene ring, forming a new alkyl-substituted aromatic compound.
- **Conclusion**: This is an example of electrophilic aromatic substitution.

2. **Option B**: Friedel-Crafts Acylation
- Similar to alkylation, this reaction involves the acylation of a benzene ring using an acyl halide and a Lewis acid. The acyl group replaces a hydrogen atom on the aromatic ring.
- **Conclusion**: This is also an example of electrophilic aromatic substitution.

3. **Option C**: Bromination of Aromatic Compounds
- In this case, an aromatic compound reacts with bromine (Br₂) in the presence of a halogen carrier (like FeBr₃). The bromine acts as an electrophile and substitutes a hydrogen atom on the aromatic ring.
- **Conclusion**: This is another example of electrophilic aromatic substitution.

4. **Option D**: Aliphatic Halogenation
- This reaction involves the substitution of hydrogen in an aliphatic compound (not aromatic) with bromine in the presence of light. This is a free radical mechanism and does not involve an aromatic ring.
- **Conclusion**: This is not an example of electrophilic aromatic substitution.

### Final Conclusion
Electrophilic aromatic substitution can be observed in **Options A, B, and C**. Option D does not involve aromatic compounds and is therefore excluded.

### Summary of the Solution
- **Options A, B, and C** are examples of electrophilic aromatic substitution.
- **Option D** is not an example of electrophilic aromatic substitution.