What Is Aminophenol?
Aminophenol is an organic compound where one hydrogen atom on the benzene ring of phenol is replaced by an amino group. It exists in three isomers: o-aminophenol (ortho-aminophenol), m-aminophenol (meta-aminophenol), and p-aminophenol (para-aminophenol), all solid at room temperature. The ortho form is white or pale yellow and needle-like, the meta form is white, and the para form is colorless platelet crystals, which gradually oxidize in air and turn brown.
The molecular weight of aminophenol is 109.13, with densities of 1.328 g/cm3 for ortho, 1.276 g/cm3 for meta, and 1.13 g/cm3 for para. Water solubility varies among the isomers: 2.0 x 103 mg/L for ortho, 26 g/L for meta, and 16 g/L for para.
Uses of Aminophenol
All three isomers of aminophenol are important building blocks in synthetic organic chemistry. Specific uses include the synthesis of acetaminophen from p-aminophenol, heterocycle synthesis from o-aminophenol, and 3-(diethylamino)phenol from m-aminophenol, an intermediate in fluorescent dye synthesis. o-aminophenols are used by photographic developers, while m-aminophenols find applications as dyes, thermosensitive dyes, agrochemicals, and aramid fiber materials. p-aminophenols are used as antioxidants for rubber, oxidative dyes for fur, and also as a photographic developer like o-aminophenol.
Principle of Aminophenol
1. Production Method of Aminophenol
o-aminophenol and p-aminophenol can be produced by reducing a mixture of o-nitrophenol and p-nitrophenol, obtained from the nitration of phenol. The synthesis of m-aminophenol requires a different route, such as melting 3-aminobenzene sulfonic acid with sodium hydroxide or substituting resorcinol with ammonium hydroxide.
2. Properties and Chemical Reactions of Aminophenol
o-Aminophenol forms intra- and intermolecular hydrogen bonds. Its amino groups can be diazotized for dye synthesis, and diazotized o-aminophenol compounds are useful as tridentate ligands to form metal complexes.
Types of Aminophenol
Aminophenols are available as reagent products for research and development, as well as oxidative