Which one of the following is the strongest base in aqueous solution ?

Options

A. Dimethylamine
B. Methylamine
C. Trimethylamine
D. Aniline

Answer

To determine which one of the following compounds is the strongest base in aqueous solution, we need to analyze the basicity of the given options: dimethyl amine, methyl amine, trimethyl amine, and aniline.

### Step-by-Step Solution:

1. **Understanding Basicity**:
Basicity refers to the ability of a compound to accept protons (H+ ions). The stronger the base, the more readily it can accept protons.

2. **Analyzing Dimethyl Amine**:
- Dimethyl amine has the structure (CH3)2NH.
- The nitrogen atom has a lone pair of electrons and is bonded to two methyl groups.
- The methyl groups exhibit a +I (inductive) effect, which increases the electron density on the nitrogen, enhancing its ability to accept protons.
- Therefore, dimethyl amine is a strong base.

3. **Analyzing Methyl Amine**:
- Methyl amine has the structure CH3NH2.
- It has only one methyl group, which means the +I effect is less pronounced compared to dimethyl amine.
- Thus, methyl amine is less basic than dimethyl amine.

4. **Analyzing Trimethyl Amine**:
- Trimethyl amine has the structure (CH3)3N.
- With three methyl groups, the +I effect is maximized, significantly increasing the electron density on the nitrogen.
- This makes trimethyl amine a stronger base than both dimethyl amine and methyl amine.

5. **Analyzing Aniline**:
- Aniline has the structure C6H5NH2.
- The nitrogen's lone pair can participate in resonance with the benzene ring, decreasing its availability to accept protons.
- Consequently, aniline is the least basic among the options provided.

6. **Conclusion**:
- Comparing all the analyzed compounds, trimethyl amine has the highest basicity due to the strong +I effect from the three methyl groups, making it the strongest base in aqueous solution.

### Final Answer:
**Trimethyl amine is the strongest base in aqueous solution.**

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