Strongest base is

Options

A. `CH_(2) = CH-CH_(2)-NH_(2)`
B. `CH -= C-CH_(2)-NH_(2)`
C. `CH_(3)CH_(2)CH_(2)NH_(2)`
D.

Answer

To determine the strongest base among the given options, we will analyze the basicity of each compound based on the presence of lone pairs and the hybridization of the atoms involved.

### Step-by-Step Solution:

1. **Understanding Basicity**:
- Basicity refers to the ability of a compound to donate a lone pair of electrons. According to Lewis theory, a base is a substance that can donate an electron pair.

2. **Analyzing the First Option**:
- The first compound is CH2=CH-CH2-H2 (an alkene).
- The nitrogen in this compound has a lone pair of electrons. However, the carbon atoms are sp² hybridized, which means they have 33.3% s-character.
- Higher s-character means higher electronegativity, which makes it harder for the lone pair to be donated since they are held more tightly.

3. **Analyzing the Second Option**:
- The second compound involves a triple bond (alkyne).
- The carbon atoms here are sp hybridized, which means they have 50% s-character.
- This increased s-character results in higher electronegativity, making it even more difficult for the nitrogen's lone pair to be donated compared to the first option.

4. **Analyzing the Third Option**:
- The third compound is CH3-CH2-CH2-NH2 (an amine).
- The nitrogen here has a lone pair of electrons, and all the carbon atoms are sp³ hybridized, which means they have only 25% s-character.
- Lower s-character leads to lower electronegativity, allowing the lone pair on nitrogen to be more freely available for donation, making this compound a stronger base.

5. **Analyzing the Fourth Option**:
- The fourth compound has a nitrogen with lone pairs involved in resonance (aromatic amine).
- The resonance delocalizes the lone pair, making it less available for donation. The lone pair is not localized, which decreases the basicity.

6. **Conclusion**:
- After analyzing all four options, we find that the third option (CH3-CH2-CH2-NH2) is the strongest base because the lone pair on nitrogen is more available for donation due to the lower s-character of the sp³ hybridized carbons.

### Final Answer:
The strongest base is **Option 3: CH3-CH2-CH2-NH2**.

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