Explain which compound is the weaker base.
`CH_(2) = CH - CH = CH - CH_(2)^(-)" or " CH_(2) = CH - CH_(2)^(-)`

Answer

To determine which compound is the weaker base between `CH₂=CH-CH=CH-CH₂⁻` (Compound 1) and `CH₂=CH-CH₂⁻` (Compound 2), we will analyze the stability of their conjugate bases. The stability of a conjugate base is a key factor in determining the strength of the corresponding acid and the basicity of the compound.

### Step-by-Step Solution:

1. **Identify the Structures**:
- Compound 1: `CH₂=CH-CH=CH-CH₂⁻`
- Compound 2: `CH₂=CH-CH₂⁻`

2. **Determine the Conjugate Bases**:
- The conjugate base of Compound 1 is formed by removing a proton (H⁺) from the terminal CH₂ group, resulting in `CH₂=CH-CH=CH-CH₂⁻`.
- The conjugate base of Compound 2 is formed by removing a proton from the CH₂ group adjacent to the double bond, resulting in `CH₂=CH-CH₂⁻`.

3. **Analyze Resonance Stability**:
- **Compound 1**: The negative charge in Compound 1 can be delocalized over a longer chain due to the presence of two double bonds. This allows for resonance stabilization over five carbons.
- **Compound 2**: The negative charge in Compound 2 can only be delocalized over three carbons due to the presence of a single double bond. This limits its resonance stabilization.

4. **Compare Resonance**:
- Compound 1 has more resonance structures available, which means it can distribute the negative charge more effectively. This results in greater stability for the conjugate base.
- Compound 2 has fewer resonance structures, leading to less stability for its conjugate base.

5. **Conclusion on Basicity**:
- Since Compound 1 has a more stable conjugate base due to greater resonance, it is more acidic. Therefore, its corresponding compound is less basic.
- Conversely, Compound 2, with a less stable conjugate base, is more basic.

6. **Final Answer**:
- The weaker base is **Compound 1** (`CH₂=CH-CH=CH-CH₂⁻`) because it has a more stable conjugate base.