Reaction between phenol and alkaline chloroform or carbon tetrachloride to form salicylaldehyde and salicylic acid respectively.
In the Reimer-Tiemann reaction, the electrophile used is CCl2 (dichlorocarbene), an electron deficient species.
Salicylaldehyde can also be prepared by heating phenol with hexamethylenetetramine, glycerol and boric acid (Duff reaction).
An interesting reaction of salicylaldehyde is its oxidation with alkaline hydrogen peroxide to form 1, 2-dihydroxybenzene (Dakin reaction).