Which of the following on oxidation with alkaline `KMnO_(4)` follwed by acidification with dil. HCl gives terephthalic acid?

Options

A. a.`p`-Ethyl toluene
B. b.`p`-Xylene
C. c.`1, 3`-Diisopropyl benzene
D. d.`m`-Xylene

Explanation

To determine which of the given compounds yields terephthalic acid upon oxidation with alkaline KMnO4 followed by acidification with dilute HCl, we need to analyze each compound step by step.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- A: Paraethyl toluene
- B: Para-xylene
- C: 1,3-Diisopropylbenzene
- D: Meta-xylene

2. **Understand the Reaction**: The reaction involves oxidation using alkaline KMnO4, which will oxidize alkyl groups on the aromatic ring to carboxylic acid groups (–COOH). After oxidation, the solution is acidified with dilute HCl.

3. **Analyze Compound A (Paraethyl Toluene)**:
- Structure: CH3-C2H5 attached to a benzene ring.
- Upon oxidation, both the methyl (–CH3) and ethyl (–C2H5) groups will be oxidized to carboxylic acids.
- Result: The product will be terephthalic acid (1,4-benzenedicarboxylic acid).

4. **Analyze Compound B (Para-xylene)**:
- Structure: Two methyl groups (–CH3) at the para positions on a benzene ring.
- Upon oxidation, both methyl groups will be oxidized to carboxylic acids.
- Result: The product will also be terephthalic acid.

5. **Analyze Compound C (1,3-Diisopropylbenzene)**:
- Structure: Two isopropyl groups (–C3H7) at the 1 and 3 positions on a benzene ring.
- Upon oxidation, the isopropyl groups will be oxidized to carboxylic acids, but they will be at the meta positions.
- Result: The product will be isophthalic acid (1,3-benzenedicarboxylic acid), not terephthalic acid.

6. **Analyze Compound D (Meta-xylene)**:
- Structure: Two methyl groups (–CH3) at the meta positions on a benzene ring.
- Upon oxidation, the methyl groups will also be oxidized to carboxylic acids, but they will be at the meta positions.
- Result: The product will again be isophthalic acid, not terephthalic acid.

### Conclusion:
The compounds that yield terephthalic acid upon oxidation with alkaline KMnO4 followed by acidification with dilute HCl are:
- **Option A: Paraethyl toluene**
- **Option B: Para-xylene**

### Final Answer:
**A and B are the correct options.**

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