Q136 / 200 · MHT CET - Medical 2026 (24 April Shift 1) · Chemistry
Chlorobenzene is formed by the reaction between benzene and chlorine in presence of $\text{AlCl}_3$. Which of the following species actually attacks the benzene ring in this reaction?
- A$\text{Cl}^-$
- B$\text{Cl}_2$
- Correct answerC$\text{Cl}^+$
- D$\text{AlCl}_4^-$
Solution
The reaction of benzene with chlorine in the presence of $\text{AlCl}_3$ is an electrophilic aromatic substitution.
The Lewis acid $\text{AlCl}_3$ reacts with $\text{Cl}_2$ to generate the chloronium ion, $\text{Cl}^+$, which acts as an electrophile.
$\text{Cl}_2 + \text{AlCl}_3 \rightarrow \text{Cl}^+ + \text{AlCl}_4^-$
The electrophile $\text{Cl}^+$ then attacks the electron-rich benzene ring to form a resonance-stabilized carbocation (sigma complex).
Thus, the species that actually attacks the benzene ring is $\text{Cl}^+$.
Answer: $\text{Cl}^+$
The Lewis acid $\text{AlCl}_3$ reacts with $\text{Cl}_2$ to generate the chloronium ion, $\text{Cl}^+$, which acts as an electrophile.
$\text{Cl}_2 + \text{AlCl}_3 \rightarrow \text{Cl}^+ + \text{AlCl}_4^-$
The electrophile $\text{Cl}^+$ then attacks the electron-rich benzene ring to form a resonance-stabilized carbocation (sigma complex).
Thus, the species that actually attacks the benzene ring is $\text{Cl}^+$.
Answer: $\text{Cl}^+$
Hence, the correct answer is option: 'C'.