Which of the following compounds has maximum electron density in ring ?

Options

A.
B.
C.
D.

Answer

To determine which of the given compounds has the maximum electron density in the ring, we need to analyze the electron-donating or withdrawing effects of substituents on each compound. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
Let's denote the compounds as follows:
1. Compound 1: Contains a nitrogen-oxygen double bond (N=O) with a positive charge.
2. Compound 2: Contains a phenolic structure (–OH) with a lone pair on oxygen.
3. Compound 3: Contains a negatively charged oxygen (–O^-) attached to a benzene ring.
4. Compound 4: Contains a carboxylate group (–COO^-) attached to a benzene ring.

### Step 2: Analyze Electron Density in Each Compound
1. **Compound 1**: The nitrogen-oxygen double bond (N=O) pulls electron density away from the benzene ring due to resonance. The positive charge on nitrogen also indicates a deficiency of electrons, leading to a decrease in electron density in the ring.

2. **Compound 2**: The –OH group (phenol) has a lone pair of electrons that can be donated into the benzene ring, increasing the electron density. This donation stabilizes the ring and enhances its electron density.

3. **Compound 3**: The negatively charged oxygen (–O^-) wants to stabilize itself by donating its electrons into the benzene ring. This results in a significant increase in electron density in the ring.

4. **Compound 4**: The carboxylate group (–COO^-) also pulls electron density away from the ring due to resonance and the electronegative nature of oxygen, leading to a decrease in electron density in the ring.

### Step 3: Compare the Electron Densities
- **Compound 1**: Decreased electron density (due to N=O and positive charge).
- **Compound 2**: Increased electron density (due to lone pair donation from –OH).
- **Compound 3**: Maximum increase in electron density (due to the negative charge on oxygen donating electrons).
- **Compound 4**: Decreased electron density (due to the –COO^- group pulling electrons).

### Conclusion
Based on the analysis, **Compound 3** has the maximum electron density in the ring due to the presence of a negatively charged oxygen that donates electrons into the benzene ring.

### Final Answer
**Compound 3** has the maximum electron density in the ring.

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