Question

In halogenation of arenes, the main function of using a lewis acids like $AlC{l}_{3}orFeB{r}_3$ is for the generation of :
(Here X is the halogen)

• A. $X$
• B. $X^{-}$
• C. $X^{+}$
• D. $\stackrel{\bullet }{X}$

Answer 1

The correct option is C $X^{+}$

Halogenation of benzene takes place in 3 steps:
1. Generation of an electrophile. $X^{+}$
2. Formation of an arenium ion (intermediate).
3.Removal of proton $\left(H^{+}\right)$ from the arenium ion.

1. Generation of an electrophile. $X^{+}$ :
The Lewis acid e.g. $AlC{l}_3$ combines with the attacking reagent to form an electrophile.
When halogen is chlorine $C{l}^{+}$ is generated: