4-Aminophenol

4-Aminophenol (or para-aminophenol or p-aminophenol) is an organic compound with the formula H₂NC₆H₄OH. It is a metabolite of acetaminophen which the body converts to N-arachidonoylphenolamine and this compound is responsible for all or part of acetaminophen's analgesic action and anticonvulsant effects..

Commercially available as a white powder, it is commonly used as a developer for black-and-white film, marketed under the name Rodinal.

Reflecting its slightly hydrophilic character, the white powder is moderately soluble in alcohols and can be recrystallized from hot water. In the presence of a base, it oxidizes readily. The methylated derivatives N-methylaminophenol and N,N-dimethylaminophenol are of commercial value.

The compound is one of three isomeric aminophenols, the other two being 2-aminophenol and 3-aminophenol.

4-Aminophenol can be prepared by several routes. One route is hydrogenation of 4-nitrophenol over Raney nickel.

The nitrophenol can also be reduced by iron or by stannous chloride.

4-Aminophenol can be produced by reduction of nitrobenzene via the intermediate phenylhydroxylamine, which spontaneously rearranges to 4-aminophenol.

4-Aminophenol is a building block used in organic chemistry. Prominently, it is the final intermediate in the industrial synthesis of paracetamol. Treating 4-aminophenol with acetic anhydride gives paracetamol: