Which of following gives positive carbylamine test ?

Options

A.
B.
C.
D.

Answer

To determine which of the following compounds gives a positive carbylamine test, we can follow these steps:

### Step 1: Understand the Carbylamine Test
The carbylamine test is a chemical reaction that is used to identify primary amines. In this test, a primary amine reacts with chloroform (CHCl3) in the presence of alcoholic potassium hydroxide (KOH) to form an isocyanide (or carbylamine), which is characterized by a strong and unpleasant odor.

### Step 2: Identify the Structure of Compounds
We need to analyze the structures of the compounds provided in the question. The compounds should be evaluated to see if they contain a primary amine group (RNH2).

### Step 3: Analyze Each Compound
1. **First Compound (NH2-R)**: This compound has a primary amine (NH2) group. Therefore, it will give a positive carbylamine test.

2. **Second Compound (R2NH)**: This is a secondary amine. Secondary amines do not give a positive carbylamine test, so this compound will not react.

3. **Third Compound (C=O-NH2)**: This is a primary amide. Amides do not give a carbylamine test, so this compound will not react.

4. **Fourth Compound (Aniline)**: Aniline is a primary aromatic amine (C6H5NH2). It will also give a positive carbylamine test.

### Step 4: Conclusion
Based on the analysis:
- The first compound (primary amine) and the fourth compound (aniline) will give a positive carbylamine test.
- The second compound (secondary amine) and the third compound (amide) will not give a positive test.

Thus, the answer is that the compounds that give a positive carbylamine test are the first compound and the fourth compound (aniline).

### Final Answer:
The compounds that give a positive carbylamine test are the first compound and aniline (the fourth compound).

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