Which of the following on heating does not form an anhydride ?

Options

A. Oxalic acid
B. Succinic acid
C. Glutaric acid
D. Maleic acid

Explanation

To determine which of the given acids does not form an anhydride upon heating, we will analyze each acid one by one: oxalic acid, succinic acid, glutaric acid, and malic acid.

### Step 1: Analyze Oxalic Acid
- **Structure**: Oxalic acid has the formula HOOC-COOH.
- **Heating Reaction**: When oxalic acid is heated, it decomposes to form formic acid (HCOOH) and carbon dioxide (CO2).
- **Conclusion**: Oxalic acid does not form an anhydride upon heating.

### Step 2: Analyze Succinic Acid
- **Structure**: Succinic acid has the formula HOOC-CH2-CH2-COOH.
- **Heating Reaction**: When succinic acid is heated, it forms succinic anhydride.
- **Conclusion**: Succinic acid does form an anhydride upon heating.

### Step 3: Analyze Glutaric Acid
- **Structure**: Glutaric acid has the formula HOOC-CH2-CH2-CH2-COOH.
- **Heating Reaction**: When glutaric acid is heated, it forms glutaric anhydride.
- **Conclusion**: Glutaric acid does form an anhydride upon heating.

### Step 4: Analyze Malic Acid
- **Structure**: Malic acid has the formula HOOC-CHOH-CH=CH2.
- **Heating Reaction**: When malic acid is heated, it forms malic anhydride.
- **Conclusion**: Malic acid does form an anhydride upon heating.

### Final Conclusion
Based on the analysis:
- **Oxalic acid** does not form an anhydride upon heating.
- **Succinic acid**, **glutaric acid**, and **malic acid** all form anhydrides upon heating.

Thus, the correct answer is **oxalic acid**.

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