General methods of preparation of phenols are described below:

Preparation of phenol From benzene sulphonic acid:

Preparation of phenol From haloarenes:

Preparation of phenol From diazonium salt:

Commercial Preparation:

Phenol is prepared commercially by the cumene-phenol process in which cumene (isopropylbenzene) is oxidised to cumene hydroperoxide which on treating with dilute acid yields phenol and acetones.