In which of the following reactions, phenol is not obtained ?

Options

A.
B.
C.
D.

Explanation

To determine in which of the following reactions phenol is not obtained, we will analyze each reaction step by step.

### Step-by-Step Solution:

1. **Identify the Reactions**: We need to analyze the given reactions to see if phenol is produced or not. The reactions involve different reagents and substrates.

2. **Reaction A**:
- **Reactants**: COOH (carboxylic acid) and NaOH with CaO.
- **Mechanism**:
- The CaO will react with COOH, leading to the formation of CaCO3 and the transfer of an H atom to the carbon.
- This results in the formation of phenol (C6H5OH).
- **Conclusion**: Phenol is produced in this reaction.

3. **Reaction B**:
- **Reactants**: An alkyl bromide (R-Br) with Mg (Grignard reagent) in the presence of H3O+.
- **Mechanism**:
- The Grignard reagent will react with H3O+, leading to the formation of a carbonium ion.
- The reaction will yield benzene (C6H6) and not phenol.
- **Conclusion**: Phenol is NOT produced in this reaction. This is a potential answer.

4. **Reaction C**:
- **Reactants**: NaOH with a carboxylic acid (COOH).
- **Mechanism**:
- The NaOH will react with the COOH, leading to a reduction process.
- This will yield phenol as a product.
- **Conclusion**: Phenol is produced in this reaction.

5. **Reaction D**:
- **Reactants**: Water (H2O) added to a compound containing a nitrogen atom (N).
- **Mechanism**:
- The H2O will dissociate into H+ and OH-.
- The H+ will attack the nitrogen, and the OH- will attack the carbon, leading to the formation of phenol.
- **Conclusion**: Phenol is produced in this reaction.

### Final Answer:
Based on the analysis, the reaction in which phenol is NOT obtained is **Reaction B**.