1. From Haloarenes
When Haloarenes are treated with Sodium hydroxide at 623 Kelvin and 300 ATM pressure to whip sodium phenoxide which on further acidification gives phenol as a product.
2. From Benzene or Benzenesulphonic Acid
When benzeen react with (Oleum H2S2O8) to form benzeen sulfonic Acid which on further react with molten NaOH gives sodium phenoxide which on further acidification gives phenol as a product.
3. From Aniline or Diazonium Salt
When primary aromatic arene react with nitrous acid to give diazonium salt which on further hydrolysis by warm water give phenol as a product.
4. From Cumene
When Cumene oxidized with air to give hydro peroxide which on further acidic hydrolysis gives phenol and acetone as a product.