Question

What happens when Benzene reacts with Bromine water?

Answer 1

1. Benzene does not undergo Electrophilic Addition Reaction. Therefore, it does not react with Bromine water due to the presence of delocalized pi electrons.
2. Thus, Benzene does not decolorize Bromine water.
3. However, if the reaction occurs in presence of Lewis acid Ferric chloride (${\mathrm{FeBr}}_3$) and Aluminium chloride ( ${\mathrm{AlCl}}_3$) then, the bromination of Benzene will take place.
4. In presence of Lewis acid Bromine molecule (${\mathrm{Br}}_2$) get polarised and protonated to form ${\mathrm{Br}}^{+}$which acts as an Electrophile.
5. This reaction is an Electrophilic aromatic substitution reaction.

$$\begin{gathered} {\mathrm{C}}_6{\mathrm{H}}_6\left(\mathrm{l}\right)+\hspace{0.17em}{\mathrm{Br}}_2\left(\mathrm{l}\right)\stackrel{{\mathrm{FeBr}}_3}{\to }{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{Br}\left(\mathrm{l}\right)+\mathrm{HBr}\left(\mathrm{l}\right) \\ \mathrm{Benzene}\mathrm{Bromobenzene}\mathrm{Hydrogen}\mathrm{bromide} \end{gathered}$$