p-Aminophenol

p-Aminophenol (also known as 4-aminophenol or para-aminophenol) is an organic compound with the formula C6H7NO. It appears as a white powder and is moderately soluble in alcohols and water[8]. p-Aminophenol is primarily used as an intermediate in the synthesis of dyes (notably azo dyes), pigments, and pharmaceuticals—including analgesics such as paracetamol (acetaminophen)[6][8]. It also serves as a developer in black-and-white photographic processing under trade names like Rodinal[8]. In hair dye formulations, it acts as a color precursor for permanent hair coloring[6][4]. Mechanistically, p-aminophenol can form covalent bonds with sulfhydryl (-SH) groups on hemoglobin and transfer electrons to oxygen to create methemoglobin. This oxidation of hemoglobin interferes with normal oxygen transport and can result in methemoglobinemia at high exposures[2][5]. Additionally, its cytotoxicity has been attributed to inhibition of tissue respiration (oxidative phosphorylation), particularly affecting renal epithelial cells through accumulation via organic cation transporters[5].

Brand names

Rodinal

Other names

4-aminophenolpara-aminophenolp-hydroxyaniline4-hydroxyanilinephenol 4-amino-phenol4-amino-phenol-4-amino-paranol