Which one of the following is the most acidic?

Options

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

Answer

To determine which of the given compounds is the most acidic, we will analyze the acidic strength based on the stability of their conjugate bases. Here's a step-by-step solution:

### Step 1: Identify the Compounds
First, we need to identify the compounds given in the question. Let’s assume they are labeled as A, B, C, and D.

### Step 2: Draw the Conjugate Bases
For each compound, we will draw the conjugate base formed after the release of a proton (H⁺).

- **For Compound A**: The conjugate base will be A⁻.
- **For Compound B**: The conjugate base will be B⁻.
- **For Compound C**: The conjugate base will be C⁻.
- **For Compound D**: The conjugate base will be D⁻.

### Step 3: Analyze the Stability of Conjugate Bases
The stability of the conjugate bases is crucial in determining the acidity of the original compounds. The more stable the conjugate base, the stronger the acid.

- **Compound A**: Analyze the structure and predict the stability of A⁻.
- **Compound B**: This compound has a ring structure with 6 π electrons, making it aromatic. According to Huckel's rule (4n + 2), this compound is stable due to its aromatic nature.
- **Compound C**: Analyze the structure and predict the stability of C⁻.
- **Compound D**: Analyze the structure and predict the stability of D⁻.

### Step 4: Compare the Stability
Now, we compare the stability of the conjugate bases:

- **A⁻**: Stability is moderate.
- **B⁻**: Highly stable due to aromaticity.
- **C⁻**: Stability is moderate.
- **D⁻**: Stability is lower than B⁻.

### Step 5: Conclusion
Since the stability of the conjugate base B⁻ is the highest due to its aromatic nature, we conclude that compound B is the most acidic.

### Final Answer
Thus, the most acidic compound is **B**.

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