Decarboxylation of which of the following acid gives benzoic acid –

Options

A. Phthalic acid
B. Anthranilic acid
C. Phenylacetic acid
D. Malic acid

Answer

To determine which acid undergoes decarboxylation to yield benzoic acid, we need to analyze the options provided.

### Step-by-Step Solution:

1. **Understanding Decarboxylation**:
- Decarboxylation is the process of removing a carboxyl group (-COOH) from a carboxylic acid, which results in the release of carbon dioxide (CO2). The general reaction can be represented as:
\[ RCOOH \rightarrow R + CO2 \]
- Here, R represents the remaining part of the molecule after the carboxyl group is removed.

2. **Analyzing the First Option - Phthalic Acid**:
- Phthalic acid has the structure:
\[ C6H4(COOH)2 \]
- Upon heating and decarboxylation, one of the carboxyl groups is removed, leading to the formation of benzoic acid:
\[ C6H4(COOH) + heat \rightarrow C6H5COOH + CO2 \]
- Thus, phthalic acid does yield benzoic acid upon decarboxylation.

3. **Analyzing the Second Option - Anthranilic Acid**:
- Anthranilic acid has the structure:
\[ C6H4(COOH)(NH2) \]
- When decarboxylated, the carboxyl group is removed, but the product formed is not benzoic acid:
\[ C6H4(NH2) + CO2 \]
- The product is an amino-substituted benzene, specifically aniline, not benzoic acid.

4. **Analyzing the Third Option - Phenylacetic Acid**:
- Phenylacetic acid has the structure:
\[ C6H5CH2COOH \]
- Upon decarboxylation, it forms benzyl alcohol, not benzoic acid:
\[ C6H5CH2 + CO2 \]
- Therefore, this option does not yield benzoic acid either.

5. **Conclusion**:
- The only acid that gives benzoic acid upon decarboxylation is **phthalic acid**.

### Final Answer:
The decarboxylation of phthalic acid gives benzoic acid.

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