Which acid can be oxidised by `H_2O_2` ?

Options

A. Malonic acid
B. Acetic acid
C. Oxalic acid
D. Propanoic acid

Answer

To determine which acid can be oxidized by hydrogen peroxide (H₂O₂), we need to analyze the structures of the given acids and identify if they contain a beta carbon. The presence of a beta carbon is essential because H₂O₂ oxidizes acids by adding a hydroxyl group (-OH) to the beta carbon.

### Step-by-Step Solution:

1. **Understanding the Role of H₂O₂**:
- H₂O₂ can oxidize acids by performing beta hydroxylation, which means it adds a hydroxyl group to the beta carbon of the acid.

2. **Analyzing the Options**:
- **Option A: Malonic Acid (CH₂(COOH)₂)**:
- Structure: HOOC-CH₂-COOH
- The carbon adjacent to the carbonyl (C=O) is the alpha carbon, and there are no beta carbons present.
- Conclusion: **Not oxidizable by H₂O₂**.

- **Option B: Acetic Acid (CH₃COOH)**:
- Structure: CH₃-COOH
- The carbon attached to the carbonyl is the alpha carbon, and there is no beta carbon present.
- Conclusion: **Not oxidizable by H₂O₂**.

- **Option C: Oxalic Acid (HOOC-COOH)**:
- Structure: HOOC-COOH
- There are no carbons between the two carboxylic groups; hence, there are no alpha or beta carbons.
- Conclusion: **Not oxidizable by H₂O₂**.

- **Option D: Propanoic Acid (CH₃CH₂COOH)**:
- Structure: CH₃-CH₂-COOH
- The carbon adjacent to the carbonyl is the alpha carbon (CH₂), and the next carbon (CH₃) is the beta carbon.
- Conclusion: **Oxidizable by H₂O₂**.

3. **Final Conclusion**:
- The only acid that can be oxidized by H₂O₂ due to the presence of a beta carbon is **Propanoic Acid**.

### Answer:
**D. Propanoic Acid**