Describe the methods and processes for the production of phenol.

(A) Phenol was first isolated from coal tar in the early nineteenth century. Currently,phenol is produced commercially through synthetic methods.
In the laboratory,phenol is prepared from benzene derivatives using the following methods:
$(i)$ From haloarenes: Chlorobenzene is fused with $NaOH$ at $623 \ K$ and $300 \ atm$ pressure to form sodium phenoxide,which upon acidification gives phenol.
$(ii)$ From benzenesulphonic acid: Benzene is sulphonated with oleum $(H_2S_2O_7)$ to form benzenesulphonic acid,which is then converted to sodium phenoxide by fusion with molten $NaOH$,followed by acidification to yield phenol.
$(iii)$ From diazonium salts: $A$ diazonium salt is prepared by treating an aromatic primary amine with nitrous acid $(HNO_2)$ at $273-278 \ K$. The diazonium salt is then hydrolysed to phenol by warming with water or by treating with dilute acids.
$(iv)$ From cumene: Cumene (isopropylbenzene) is oxidised in the presence of air to cumene hydroperoxide,which is then converted to phenol and acetone by treatment with dilute acid.