Methods of Preparation of Phenols Preparation and Properties

Methods of Preparation of Phenols Preparation and Properties

Laboratory Methods :

→ From Benzene Diazonium SaIt : An aqueous solution of benzene diazonium salt on boiling gives phenol.

Methods of Preparation of Phenols Preparation and Properties 1

→ From Haloarenes : When chiorobenzene is heated or fused with NaOH at 623 K and 320 atmospheric pressure then sodium phenoxide is obtained. Phenol is obtained by acidification of sodium phenoxide.

Methods of Preparation of Phenols Preparation and Properties 2

→ From Benzenesulphonlc Acid : Benzene is suiphonated with oleum then benzene suiphonic acid is obtained. On heating it with sodium hydroxide, sodium phenoxide forms. Acidification of the sodium salt gives phenol.

Methods of Preparation of Phenols Preparation and Properties 3

→ From Salicylic AcId : On heating salicylic acid with soda lime (NaOH + CaO), sodium phenoxide forms. On acidic hydrolysis it forms phenol.

Methods of Preparation of Phenols Preparation and Properties 4

→ From Grignard Reagent : Phenyl magnesium bromide reacts with O2 in the presence of light. The product thus obtained on hydrolysis gives phenol.

Methods of Preparation of Phenols Preparation and Properties 5

Commercial Preparation :

→ From Cumene : Phenol is prepared commercially from cumene. Isopropyl benzene is known as cumene. In the presence of air cumene is oxidised to cumene hydro peroxide. On reaction with dii. acid it converts into phenol and acetone. Acetone is obtained as byproduct in this reaction, which is an important reagent for industrial purpose.

Methods of Preparation of Phenols Preparation and Properties 6

→ From Coaltar : Middle oil fraction is obtained by fractional distillation of coaltar. It contains mainly phenol and napthalene etc., When this fraction reacts with NaOH, sodium phenoxide forms, which is dicomposed by CO2 and phenol is obtained.

Methods of Preparation of Phenols Preparation and Properties 10

→ By Oxidation of Benzene It is modern method for the preparation of phenol. When mixture of benzene and air are passed over hot vanadium pentaoxide (V2O5) at 583 K, phenol is formed.

Methods of Preparation of Phenols Preparation and Properties 7

→ Rasching’s Process : In this process firstly chiorobenzene is prepared from benzene, then it reacts with red hot silica and steam to give phenol.

Methods of Preparation of Phenols Preparation and Properties 8

→ Dow’s Process : Chiorobenzene prepared from Rasching’s process is hydrolysed with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) solution at about 623 K under 300 atmospheres and in the presence of CuCl2 to form phenol.

Methods of Preparation of Phenols Preparation and Properties 9

Chemistry Notes

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