Which of the following will not undergo diazotisation?

Options

A. m-Toluidine
B. Aniline
C. p-Aminophenol
D. Benzylamine

Explanation

To determine which compound will not undergo diazotization, we need to analyze the given options based on the presence of an amino group (NH2) and the stability of the resulting diazonium ion. Diazotization typically requires the presence of a primary aromatic amine.

### Step-by-Step Solution:

1. **Identify the Compounds**:
We are given four compounds to analyze:
- Option 1: Toluene (C6H5CH3)
- Option 2: Aniline (C6H5NH2)
- Option 3: Para-aminophenol (C6H4(OH)(NH2))
- Option 4: Benzylamine (C6H5CH2NH2)

2. **Understanding Diazotization**:
Diazotization is a reaction where a primary aromatic amine reacts with nitrous acid (generated from sodium nitrite and hydrochloric acid) to form a diazonium salt. For this reaction to occur, the amine must be able to stabilize the positive charge on the nitrogen atom in the diazonium ion.

3. **Analyze Each Compound**:
- **Toluene**: This is not an amine, so it cannot undergo diazotization.
- **Aniline**: Contains a primary amine (NH2) directly attached to the aromatic ring, allowing for diazotization.
- **Para-aminophenol**: Also contains a primary amine (NH2) and an -OH group, which can stabilize the diazonium ion.
- **Benzylamine**: Contains a primary amine (NH2) attached to a benzyl group, which can also undergo diazotization.

4. **Conclusion**:
The compound that will **not** undergo diazotization is **Toluene (Option 1)**, as it does not contain an amino group.

### Final Answer:
**Toluene will not undergo diazotization.**