Phenol

"Phenols and their ethers are ubiquitous in nature; some derivatives have medicinal and herbicidal applications, whereas others are important industrial materials. (...) phenols are stronger acids because of the neighboring aromatic ring."

"When a benzene ring bears enough strongly electron-withdrawing substituents, nucleophilic addition to give an intermediate anion with delocalized charge becomes feasible, followed by elimination of the leaving group (nucleophilic aromatic ipso substitution). Phenols result when the nucleophile is hydroxide ion, arenamines (anilines) when it is ammonia, and alkoxyarenes when alkoxides are employed. Very strong bases are capable of eliminating HX from haloarenes to form the reactive intermediate benzynes, which are subject to nucleophilic attack to give substitution products. Phenols may also be prepared by decomposition of arenediazonium salts in water and by Pd-catalyzed hydroxylations of haloarenes."