(i) Kolbe’s reaction : The fact that phenoxide ion is even more reactive than phenol towards incoming electrophiles is made use of in this reaction. Sodium phenoxide is reacted with CO2 followed by acid treatment to yield o-hydroxybenzoic acidas the major product.(ii) Reimer-Tiemann reaction : Treatment of phenol with chloroform in the presence of aqueous alkali introduces a CHO group at the ortho position. Acidification yields salicylaldehyde. (iii)Williamson synthesis : In this method, an alkyl halides is reacted with sodium alkoxide.
The reaction involves SN2 attack of an alkoxide ion on 1°RX. Better results are obtained when RX is primary.
(iv) Unsymmetrical ethers : Unsymmetrical ethers are organic compounds where the ethereal oxygen atom is attached to two different alkyl or aryl groups. e.g.,
C2H5−O−CH3, C6H5O−C2H5, etc.