Reactions of Phenols

Phenols, like simple alcohols, will form an anion which will undergo an S_N2 reaction with alkyl halides (or alkyl groups with "good leaving groups") to give ethers. They will also react with activated carbonyl compounds to undergo acyl transfer reactions; thus aryl esters are readily formed by the reaction of phenols with acid halides or acid anhydrides. As with aryl amines, the ring of phenols is electron-rich and will rapidly react with Br₂ to give a tri-substituted product.

The last reaction shown above is a specific and unusual reaction of phenols, that is the direct reaction with CO₂ to give carboxylation at the ortho- postion. This reaction is called the Kolbe-Schmitt carboxylation, and is important since the product is salicylic acid, which is widely used in pharmaceuticals.

Another reaction which is highly specific for phenols is oxidation with Fremy's salt: potassium nitrosodisulfonate, to give the para-quinone as product.