Benzoic acid can prepared by reacting phenyl magnesium bromide with

Options

A. N, N - dimethylformamide
B. carbon dioxide
C. formaldehyde
D. ethyl chloroformate

Answer

To prepare benzoic acid using phenyl magnesium bromide (PhMgBr), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Grignard Reagent**:
- Phenyl magnesium bromide (PhMgBr) is a Grignard reagent. It is formed by reacting bromobenzene with magnesium in dry ether.

2. **Understand the Reactivity of Grignard Reagents**:
- Grignard reagents act as nucleophiles due to the presence of a carbon atom with a partial negative charge (Cδ-). They can attack electrophilic centers.

3. **Choose the Electrophile**:
- To synthesize benzoic acid (C6H5COOH), we need an electrophile that can provide the carboxylic acid functional group (COOH). Carbon dioxide (CO2) is a suitable electrophile for this purpose.

4. **Reaction of PhMgBr with CO2**:
- When phenyl magnesium bromide reacts with carbon dioxide, the nucleophilic carbon from PhMgBr attacks the electrophilic carbon of CO2.
- The reaction can be represented as:
\[ \text{PhMgBr} + \text{CO}_2 \rightarrow \text{PhC(=O)O}^- \text{MgBr}^+ \]

5. **Hydrolysis**:
- The product formed after the reaction with CO2 is a magnesium salt of benzoic acid (PhC(=O)O^- MgBr^+).
- Upon hydrolysis (adding water), this salt will convert to benzoic acid:
\[ \text{PhC(=O)O}^- \text{MgBr}^+ + \text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_5\text{COOH} + \text{Mg(OH)Br} \]

6. **Final Product**:
- The final product of this reaction is benzoic acid (C6H5COOH).

### Conclusion:
Thus, benzoic acid can be prepared by reacting phenyl magnesium bromide with carbon dioxide (CO2).