By oxidation with` V_(2) O_(5)`, which one of the following gives phthalic acid ?

Options

A. naphthalene
B. Benzene
C. Mesitylene
D. Toluene

Explanation

To determine which compound gives phthalic acid upon oxidation with V2O5, let's analyze the options provided step by step.

### Step 1: Understand the Structure of Phthalic Acid
Phthalic acid is a dicarboxylic acid with the molecular formula C8H6O4. Its structure consists of two carboxylic acid groups (-COOH) attached to a benzene ring. The structural representation is:

```
O
||
C - C
| |
C - C
||
O
|
H
```

### Step 2: Analyze the Given Compounds
We need to evaluate the oxidation of each compound to see if it can yield phthalic acid.

1. **Naphthalene**:
- Naphthalene consists of two fused benzene rings. When oxidized with V2O5, it can form phthalic acid.
- Reaction:
\[ \text{Naphthalene} \xrightarrow{V2O5} \text{Phthalic Acid} \]

2. **Benzene**:
- Benzene does not contain any substituents that can be oxidized to form a dicarboxylic acid. Instead, it can lead to the formation of malic anhydride when oxidized.
- Reaction:
\[ \text{Benzene} \xrightarrow{V2O5} \text{Malic Anhydride} \]

3. **Mesitylene**:
- Mesitylene has three methyl groups. Upon oxidation, V2O5 will oxidize the methyl groups to form aldehydes, but not to phthalic acid.
- Reaction:
\[ \text{Mesitylene} \xrightarrow{V2O5} \text{Aldehydes} \]

4. **Toluene**:
- Toluene has one methyl group. Oxidation with V2O5 will convert the methyl group to benzaldehyde, not to phthalic acid.
- Reaction:
\[ \text{Toluene} \xrightarrow{V2O5} \text{Benzaldehyde} \]

### Step 3: Conclusion
From the analysis, only naphthalene can be oxidized by V2O5 to yield phthalic acid. Therefore, the correct answer is:

**Naphthalene gives phthalic acid upon oxidation with V2O5.**