General properties Physical properties Colourless solid, partially miscible in the cold water, soluble in organic solvents. Differ in many ways to aliphatic alcohols. For example: Acidity Presence of activated ring Chemical properties The difficulty in substituting the -OH group is due to the stabilisation caused by the overlap of the p-orbital of the oxygen atom with the bonding in the ring. The situation is similar to that in chlorobenzene. Acid-base properties Phenol is a stronger acid than water whereas aliphatic alcohols are weaker. The polarity of the hydroxyl bond facilitates the loss of a proton and the formation of a phenoxide ion and the delocalisation in the phenoxide ion also stabilises it as compared with RO- or OH- ions. If electron-withdrawing groups (-Cl) are substituted into the benzene ring the polarity of the O-H bond is increased still further giving still stronger acids. Reaction with Sodium 2C6H5OH + 2Na 2C6H5O-Na+ + H2 Halogenation Both chlorine and bromine in aqueous halogenate phenol react so readily that the 2,4,6 -trihalogenated phenols are formed at room temp. They are white insoluble solids. 2,4,6 tribromophenol Nitration Dilute nitric acid reacts with phenol at room temp. to give a mixture of 2-nitro and 4-nitrophenol: