Physical properties of phenol

Physical properties of Phenols

•    Phenols are colourless liquids or crystalline solids but become coloured due to slow oxidation with air.

•    Due to the presence of strong intermolecular hydrogen bonding, phenols have a higher boiling point than the corresponding hydrocarbon or aryl halides.

•    Due to their ability to form hydrogen bonds with water, phenols are moderately soluble in H₂O.

•   The phenols are acidic in nature and stronger acids than alcohols. This is due to the fact that the sp² hybridised carbon of phenol to which −OH is attached, is highly electronegative which causes a decrease in electron density on oxygen. This Increases the polarity of O−H bond and results in an increase in ionisatlon of phenols than that of alcohols.

Moreover, the phenoxide ion so produced is stabilised by the delocalization of charge in phenol.

Note:  The presence of electron withdrawing group like NO² group, increases the acidic strength whereas the electron donating groups  like an alkyl group decreases the acidic strength. Therefore, the acidic strength order is