Which of the following reactions is given by only primary amines ?

Options

A. Reaction with HONO
B. Reaction with chloroform and alcoholic KOH
C. Reaction with acetyl chloride
D. Reaction with Grignard reagent.

Explanation

To determine which reaction is given by only primary amines, we will analyze the provided options step by step.

### Step 1: Understand the Reactions
We need to evaluate the reactions mentioned in the options and identify which ones are specific to primary amines.

### Step 2: Analyze Each Option
1. **Reaction with Nitrous Acid (HONO)**:
- Primary amines react with nitrous acid to form diazonium salts, which are unstable and can convert to alcohols.
- Secondary amines react with nitrous acid to form nitroso compounds.
- **Conclusion**: This reaction is not exclusive to primary amines.

2. **Reaction with Chloroform and Alcoholic KOH (Carbylamine Test)**:
- Primary amines react with chloroform and alcoholic KOH to form isocyanates, which is characteristic of primary amines.
- Secondary and tertiary amines do not undergo this reaction.
- **Conclusion**: This reaction is exclusive to primary amines.

3. **Reaction with Acetyl Chloride**:
- Both primary and secondary amines can react with acetyl chloride to form amides.
- Tertiary amines do not react with acetyl chloride.
- **Conclusion**: This reaction is not exclusive to primary amines.

4. **Reaction with Grignard Reagents**:
- Both primary and secondary amines can react with Grignard reagents to form alkanes.
- **Conclusion**: This reaction is not exclusive to primary amines.

### Step 3: Final Conclusion
Based on the analysis, the only reaction that is specific to primary amines is the reaction with chloroform and alcoholic KOH, known as the Carbylamine test.

### Answer
**The reaction that is given by only primary amines is the reaction with chloroform and alcoholic KOH (Option B).**

---