Which of the following statements is correct ?

Options

A. Aliphatic amines are stronger bases than ammonia
B. Aromatic amines are stronger bases than ammonia
C. The alkyl group in alkyl ammonium ion more stablizes the ion relative to the amine
D. The aryl group in aryl ammonium ion less stablizes the ion relative to the amine

Answer

To determine which statements are correct regarding the basicity of amines and their stability, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement A: Aliphatic amines are stronger bases than ammonia.**
- **Analysis:** Aliphatic amines, such as methylamine (CH3NH2), have an electron-donating alkyl group (methyl group). This electron-donating effect increases the electron density on the nitrogen atom, making it more capable of donating its lone pair of electrons. Therefore, aliphatic amines are indeed stronger bases than ammonia (NH3).
- **Conclusion:** This statement is **correct**.

2. **Statement B: Aromatic amines are stronger bases than ammonia.**
- **Analysis:** Aromatic amines, such as aniline (C6H5NH2), have their lone pair of electrons on the nitrogen atom involved in resonance with the aromatic ring. This resonance delocalizes the lone pair, making it less available for donation compared to ammonia, which does not have such resonance stabilization. Thus, aromatic amines are weaker bases than ammonia.
- **Conclusion:** This statement is **incorrect**.

3. **Statement C: Alkyl ammonium ions stabilize the ion relative to the amine.**
- **Analysis:** When an alkyl group replaces one of the hydrogen atoms in ammonium ions (e.g., CH3NH3+), the alkyl group donates electron density to the positively charged nitrogen, which stabilizes the ion. Therefore, alkyl ammonium ions are indeed more stable than their corresponding amines.
- **Conclusion:** This statement is **correct**.

4. **Statement D: Aryl groups in aryl ammonium ions less stabilize the ion relative to the amine.**
- **Analysis:** In aryl ammonium ions (e.g., C6H5NH3+), the presence of the aryl group (phenyl) leads to delocalization of the positive charge over the aromatic system. This delocalization reduces the stability of the ion compared to the amine, which does not have such resonance. Therefore, aryl groups do indeed lead to less stabilization of the ion.
- **Conclusion:** This statement is **correct**.

### Final Answer:
The correct statements are **A, C, and D**.

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