Which of the following compound is the strongest base?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds is the strongest base, we need to analyze the structures of the compounds and their ability to donate a lone pair of electrons. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
Assume we have four compounds labeled A, B, C, and D. We will analyze compounds B, C, and D, as compound A is not considered in the initial analysis.

### Step 2: Analyze Compound B
- **Structure**: Compound B has a lone pair on a nitrogen atom.
- **Resonance Effect**: The lone pair can participate in resonance with the surrounding structure, which decreases its availability for donation.
- **Conclusion**: The ability of the lone pair to be donated is reduced due to resonance, making B a weaker base.

### Step 3: Analyze Compound C
- **Structure**: Compound C also has a lone pair on a nitrogen atom.
- **Resonance Effect**: The lone pair participates in resonance, but only in one part of the ring, which means it is somewhat available for donation.
- **Comparison**: Since the lone pair is less involved in resonance compared to compound B, compound C is a stronger base than B.

### Step 4: Analyze Compound D
- **Structure**: Compound D has a lone pair on a nitrogen atom, but it is involved in resonance with a carbonyl group (C=O).
- **Resonance Effect**: The lone pair is somewhat involved in resonance, but not as extensively as in compound B.
- **Comparison**: The lone pair is less available for donation compared to compound C, making D weaker than C but potentially stronger than B.

### Step 5: Compare All Compounds
- **B**: Weak base due to extensive resonance involvement.
- **C**: Stronger base than B due to lesser resonance involvement.
- **D**: Weaker than C but possibly stronger than B due to limited resonance.

### Step 6: Determine the Strongest Base
- Based on the analysis, compound C is the strongest base among the three compounds analyzed (B, C, and D) because it has a lone pair that is less involved in resonance compared to B and D.

### Final Answer:
**The strongest base among the given compounds is Compound C.**

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