Question

In which of the following compounds, an electrophile prefers to attack the meta position?

• A. Phenol
• B. Chlorobenzene
• C. Nitrobenzene
• D. Aniline

Hint:

Common meta-directing groups: \[ -NO_2,\; -CHO,\; -COOH,\; -COR,\; -CN,\; -SO_3H \] Common ortho/para-directing groups: \[ -OH,\; -NH_2,\; -OR,\; -NHR,\; -Cl,\; -Br \]

Answer 1

The Correct Option is C

Concept: The position of electrophilic substitution depends on the directing effect of the substituent already present on the benzene ring.

• Electron-donating groups are generally ortho/para directing.

• Electron-withdrawing groups are generally meta directing.

Step 1: Examine the directing effects of the substituents. \[ \begin{aligned} \text{Phenol} &: -OH \rightarrow \text{Ortho/Para directing} \\ \text{Chlorobenzene} &: -Cl \rightarrow \text{Ortho/Para directing} \\ \text{Nitrobenzene} &: -NO_2 \rightarrow \text{Meta directing} \\ \text{Aniline} &: -NH_2 \rightarrow \text{Ortho/Para directing} \end{aligned} \]

Step 2: Identify the meta-directing group. The nitro group strongly withdraws electrons through both \(-I\) and \(-R\) effects. Therefore electrophilic substitution occurs predominantly at the meta position. \[\begin{aligned} \boxed{\text{Nitrobenzene}} \end{aligned}\] Hence, option \(\mathbf{(C)}\) is correct.