Which one of the following gives imine formation with carbonyl compounds

Options

A. `C_6H_5-NH-C_6H_5`
B. `NH_4Cl`
C. `R_3N`
D. `C_6H_5NH_2`

Answer

To determine which of the given options can form an imine with carbonyl compounds, we need to understand the conditions necessary for imine formation. Here is a step-by-step solution:

### Step 1: Understanding Imine Formation
Imine formation occurs when a carbonyl compound (either an aldehyde or a ketone) reacts with a primary amine. The reaction involves the nucleophilic attack of the amine on the carbonyl carbon, followed by the elimination of water.

### Step 2: Identifying the Reactants
We need to identify the type of amines provided in the options. The key point is that only primary amines (RNH2) can form imines with carbonyl compounds.

### Step 3: Analyzing the Options
1. **Option 1: A secondary amine (R2NH)** - This cannot form an imine because it does not have a hydrogen atom attached to the nitrogen that can be lost as water.

2. **Option 2: NH4Cl** - This is ammonium chloride, which is not an amine and cannot participate in imine formation.

3. **Option 3: A tertiary amine (R3N)** - This cannot form an imine since it lacks a hydrogen atom on the nitrogen to be eliminated.

4. **Option 4: C6H5NH2 (aniline)** - This is a primary amine and can react with carbonyl compounds to form an imine.

### Step 4: Conclusion
Based on the analysis, the only option that can give imine formation with carbonyl compounds is **Option 4: C6H5NH2**.

### Final Answer
**The correct answer is Option 4: C6H5NH2 (aniline).**

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