How will you prepare phenol (i) From chloro benzene (ii) From benzene sulphonic acid?

Explanation

(i) From halo arenes (Dows process):
When Chlorobenzene is hydrolysed with `6-8%` of NaOH at 300 bar and 633 K in a closed vessel, sodium phenoxide is formed which on treatment with dilute HCl gives phenol.

(ii) From benzene sulphonic acid:
Benzene is sulphonated with oleum and the benzene sulphonic acid so formed is heated with motlen NaOH at 623 K gives sodium phenoxide which on acidification gives phenol.