Phenol is so strongly activated that bromination and chlorination lead readily to polysubstitution. The reaction affords 2- and 4-substituted derivatives. The regiochemistry of halogenation changes in strongly acidic solutions where predominates. Phenol reacts with dilute nitric acid at room temperature to give a mixture of 2-nitrophenol and 4-nitrophenol while with concentrated nitric acid, additional nitro groups are introduced, e.g. to give 2,4,6-trinitrophenol. Friedel Crafts alkylations of phenol and its derivatives often proceed without catalysts. Alkylating agents include alkyl halides, alkenes, and ketones. Thus, adamantyl-1-bromide, dicyclopentadiene), and cyclohexanones give respectively 4-adamantylphenol, a bis(2-hydroxyphenyl) derivative, and a 4-cyclohexylphenols. Alcohols and hydroperoxides alkylate phenols in the presence of solid acid catalysts (e.g. certain zeolite). Cresols and cumyl phenols can be produced in that way.
Phenol is so strongly activated that bromination and chlorination lead readily to polysubstitution. The reaction affords 2- and 4-substituted derivatives. The regiochemistry of halogenation changes in strongly acidic solutions where predominates. Phenol reacts with dilute nitric acid at room temperature to give a mixture of 2-nitrophenol and 4-nitrophenol while with concentrated nitric acid, additional nitro groups are introduced, e.g. to give 2,4,6-trinitrophenol Friedel Crafts alkylations of phenol and its derivatives often proceed without catalysts. Alkylating agents include alkyl halides, alkenes, and ketones. Thus, adamantyl-1-bromide, dicyclopentadiene), and cyclohexanones give respectively 4-adamantylphenol, a bis(2-hydroxyphenyl) derivative, and a 4-cyclohexylphenols. Alcohols and hydroperoxides alkylate phenols in the presence of solid acid catalysts (e.g. certain zeolite). Cresols and cumyl phenols can be produced in that way.