Phenol reacts with benzenediazonium cation at pH 7.5 to give

Options

A. Aniline
B. Chlorobenzene
C. Benzene
D. Azo dye

Answer

To solve the problem of what product is formed when phenol reacts with benzenediazonium cation at pH 7.5, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We have phenol (C6H5OH) and benzenediazonium cation (C6H5N2+).

2. **Understand the Reaction Type**:
- This reaction is known as a coupling reaction. In this case, the benzenediazonium cation will couple with phenol.

3. **Consider the Reaction Conditions**:
- The reaction is carried out at pH 7.5, which is slightly acidic. This pH is suitable for the reaction to proceed.

4. **Mechanism of the Reaction**:
- The benzenediazonium cation (C6H5N2+) will react with the phenolic hydroxyl group (–OH) of phenol. The nitrogen of the diazonium group is electrophilic and will attack the aromatic ring of phenol.

5. **Determine the Position of Substitution**:
- The hydroxyl group (–OH) on phenol is an activating group and directs electrophilic substitution to the ortho and para positions of the aromatic ring. In this case, the nitrogen from the diazonium cation will attach to the para position relative to the –OH group.

6. **Write the Product**:
- The product formed is para-hydroxyazobenzene (C6H4(OH)-N=N-C6H4). This compound consists of the phenolic part and the azobenzene part.

7. **Final Answer**:
- The product of the reaction between phenol and benzenediazonium cation at pH 7.5 is para-hydroxyazobenzene.