Give 3 methods to distinguish primary amine from secondary and tertiary.

Answer

To distinguish primary amines from secondary and tertiary amines, we can use the following three methods:

### Method 1: Isocyanide Test
1. **Principle**: Primary amines react with carbonyl compounds to form isocyanides (also known as carbylamines), while secondary and tertiary amines do not undergo this reaction.
2. **Procedure**:
- Take a sample of the amine in an alcoholic solution of potassium hydroxide (KOH).
- Add chloroform (trichloromethane) to the mixture.
- Heat the mixture gently.
3. **Observation**:
- If a colored isocyanide (carbylamine) is formed, it indicates the presence of a primary amine.
- No reaction or color change indicates the presence of secondary or tertiary amines.

### Method 2: Hinsberg Test
1. **Principle**: The Hinsberg test differentiates between primary, secondary, and tertiary amines based on their reaction with benzenesulfonyl chloride.
2. **Procedure**:
- Dissolve the amine in water and add benzenesulfonyl chloride.
- The mixture is then treated with a base (like NaOH).
3. **Observation**:
- Primary amines form a sulfonamide that is soluble in base and insoluble in acid.
- Secondary amines form a sulfonamide that is insoluble in both acid and base.
- Tertiary amines do not react and remain unchanged.

### Method 3: Nitrous Acid Test
1. **Principle**: Primary amines react with nitrous acid (NaNO2 + HCl) to form diazonium salts, while secondary amines form N-nitrosamines, and tertiary amines do not react.
2. **Procedure**:
- Prepare a solution of the amine and add a mixture of sodium nitrite (NaNO2) and hydrochloric acid (HCl).
3. **Observation**:
- If a diazonium salt is formed (indicated by the formation of a colored solution), it confirms the presence of a primary amine.
- Secondary amines will produce a different product (N-nitrosamines), while tertiary amines will not react.

### Summary
- **Isocyanide Test**: Primary amines form isocyanides.
- **Hinsberg Test**: Differentiates based on solubility of sulfonamides.
- **Nitrous Acid Test**: Primary amines form diazonium salts.