Preparation of Phenols:
Incorporation
Phenol groups can be incorporated in an aromatic ring via sulfonation of the aromatic ring followed through melting the product with sodium hydroxide to transform the sulfonic acid group to a phenol.
Figure: Synthesis of a phenol via sulfonation.
The reaction conditions are ruthless and just only alkyl-substituted phenols can be prepared via this method. A much more common method of synthesizing phenols is to hydrolyze a diazonium salt, prepared from an aniline group (NH2).
Figure: Synthesis of a phenol via a diazonium salt.