Question

Halogenation of phenol in polar medium gives tri substituted product whereas in non polar solvent monosubstitution occur why

Answer 1

In phenol, the −OH group activates the benzene ring towards electrophilic substitution. But why is it that the electrophilic bromination of phenol gives trisubstitution (forming 2,4,6-tribromophenol) when aqueous bromine is used, but monosubstitution (either 2- or 4-bromophenol) when a CCl4 solution of bromine is used.

Answer 2

Answer:

activating effect of oxide group are greater than hydroxyl group

Explanation:

within aqueous medium the phenol ionizes to form oxido ion while in nonpolar solvent the phenol does not ionize and the activating effect of hydroxyl is less