Which of the following compound gives p- cresol with p-methyl diazonium chloride :

Options

A. `H_2O`
B. `H_3PO_2`
C. HCOOH
D. `C_6H_5OH`

Answer

To solve the question of which compound gives p-cresol with p-methyl diazonium chloride, we need to analyze the reactions of p-methyl diazonium chloride with the given compounds. Let's go through the steps systematically.

### Step 1: Understand the structure of p-methyl diazonium chloride
The structure of p-methyl diazonium chloride can be represented as follows:
- A benzene ring (C6H5) with a methyl group (CH3) at the para position (relative to the diazonium group).
- The diazonium group is represented as -N≡N^+Cl^−.

### Step 2: Identify the target product
We need to produce p-cresol (para-cresol), which has the following structure:
- A benzene ring with a hydroxyl group (-OH) and a methyl group (CH3) at the para position.

### Step 3: Analyze the given options
The four options given are:
1. H2O (water)
2. H3PO2 (phosphorous acid)
3. H3O2 (hydroperoxyl)
4. C6H5OH (phenol)

### Step 4: Reaction of p-methyl diazonium chloride with each option
1. **With H2O**:
- The diazonium salt reacts with water, leading to the substitution of the diazonium group with a hydroxyl group (-OH), resulting in phenol. Since the methyl group is already present at the para position, this reaction will yield p-cresol.

2. **With H3PO2**:
- This reagent will reduce the diazonium salt to benzene, effectively removing the diazonium group and not producing any hydroxylated product.

3. **With H3O2**:
- This compound does not participate in a reaction that would yield p-cresol.

4. **With C6H5OH**:
- This would lead to electrophilic substitution, but it would not yield the desired p-cresol product.

### Step 5: Conclusion
The only compound that reacts with p-methyl diazonium chloride to produce p-cresol is **H2O**.

### Final Answer
The correct option is **A. H2O**.

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