Which is/are the correct order of electron density in aromatic ring ?

Options

A.
B.
C.
D.

Explanation

To determine the correct order of electron density in an aromatic ring, we need to analyze the effects of various substituents on the benzene ring. The substituents can either be electron-donating groups (EDGs) or electron-withdrawing groups (EWGs), which will affect the electron density in the ring.

### Step-by-Step Solution:

1. **Identify Electron-Drawing and Electron-Donating Groups**:
- Electron-donating groups (EDGs) increase the electron density in the aromatic ring. Examples include -NH2 (amino), -OH (hydroxyl), and -CH3 (methyl).
- Electron-withdrawing groups (EWGs) decrease the electron density in the aromatic ring. Examples include -NO2 (nitro), -CN (cyano), and -Cl (chlorine).

2. **Analyze the Effects of Substituents**:
- **For EDGs**:
- The -NH2 group donates its lone pair of electrons to the ring, increasing electron density.
- The -OH group also donates electrons but has a -I (inductive) effect due to the electronegativity of oxygen.
- The -CH3 group has a +I (inductive) effect, which slightly increases electron density.
- **For EWGs**:
- The -NO2 group is a strong EWG and pulls electron density away from the ring, significantly reducing electron density.
- The -CN group is also an EWG but is less strong than -NO2.
- The -Cl group has both -I and +M effects, but its -I effect is predominant, making it a weak EWG.

3. **Rank the Substituents Based on Their Effects**:
- The strongest EDG is -NH2, followed by -OH, and then -CH3.
- The strongest EWG is -NO2, followed by -CN, and then -Cl.

4. **Establish the Order of Electron Density**:
- The order of electron density from highest to lowest can be summarized as:
- **Highest**: -NH2 > -OH > -CH3 > Benzene > -Cl > -CN > -NO2 **Lowest**.

5. **Conclusion**:
- Based on the analysis, we can conclude that the correct order of electron density in the aromatic ring is:
- **Option B**: -NH2 > -OH > -Cl > Benzene > -CN > -NO2
- **Option C**: -CH3 > Benzene > -OH > -Cl > -CN > -NO2