Question

The purpose of using $AlC{l}_3$ in the below reaction is:
$C_6{H}_6+C{l}_2\stackrel{Anhyd.AlC{l}_3}{\to }\text{chlorobenzene}+HCl$

• A. To make halogen a stronger base
• B. To make halogen a stronger nucleophile
• C. To make halogen a stronger electrophile
• D. None of the above

Answer 1

The correct option is C To make halogen a stronger electrophile

The lewis acid anhyd. $AlC{l}_3$ acts as a catalyst in the reaction. It forms an anionic complex with $C{l}^{-}$ from $C{l}_2$ to form $AlC{l}_4^{-}$ and gives stronger electrophile $\left(C{l}^{+}\right)$. This $C{l}^{+}$ attacks on benzene as an electrophile and forms chlorobenzene and $H^{+}$. $AlC{l}_4^{-}$ combines with $H^{+}$ to form HCl and $AlC{l}_3$ is recovered back.