Aniline and methyl amine can be differentiated by

Options

A. Reaction with chlorofrm and aqueous solution of `KOH`
B. Diazotisation followed by coupling with phenol
C. reaction with `HNO_2`
D. None of these

Explanation

To differentiate between aniline and methyl amine, we can follow these steps:

### Step 1: Understand the Structures
- **Aniline** (C6H5NH2) is an aromatic amine, where the amino group (-NH2) is directly attached to a benzene ring.
- **Methyl amine** (CH3NH2) is an aliphatic amine, where the amino group is attached to a methyl group.

**Hint:** Recognize the difference between aromatic and aliphatic amines based on their structures.

### Step 2: Perform a Reaction with Sodium Nitrite
- When aniline is treated with sodium nitrite (NaNO2) and hydrochloric acid (HCl) at low temperatures (0-5°C), it undergoes diazotization to form a diazonium salt (C6H5N2+Cl-).
- Methyl amine does not undergo diazotization under the same conditions.

**Hint:** Recall that diazotization is a reaction specific to aromatic amines.

### Step 3: React with Phenol
- The diazonium salt formed from aniline can react with phenol in a mild alkaline medium to form an azo dye through a coupling reaction.
- Methyl amine, however, does not undergo this reaction with phenol because it does not form a stable diazonium salt.

**Hint:** Azo dye formation is a key indicator of the presence of an aromatic amine.

### Step 4: Conclusion
- The differentiation can be established based on the ability of aniline to form a diazonium salt and subsequently react with phenol to produce an azo dye, while methyl amine cannot.

**Final Answer:** Aniline and methyl amine can be differentiated by the reaction of aniline with sodium nitrite followed by coupling with phenol, which results in the formation of an azo dye.