2-Aminophenol

2-Aminophenol
IUPAC name 2-Aminophenol
Other names 2-hydroxyaniline 2-amino-1-hydroxybenzene
Identifiers
CAS number	95-55-6 Y
ChemSpider	5596 Y
UNII	23RH73DZ65 Y
DrugBank	DB01726
KEGG	C01987 Y
ChEBI	CHEBI:18112 Y
ChEMBL	CHEMBL28319 Y
Jmol-3D images	Image 1 Image 2
SMILES Oc1ccccc1N c1ccc(c(c1)N)O
InChI InChI=1S/C6H7NO/c7-5-3-1-2-4-6(5)8/h1-4,8H,7H2 Y Key: CDAWCLOXVUBKRW-UHFFFAOYSA-N Y InChI=1/C6H7NO/c7-5-3-1-2-4-6(5)8/h1-4,8H,7H2 Key: CDAWCLOXVUBKRW-UHFFFAOYAP
Properties
Molecular formula	C6H7NO
Molar mass	109.13 g/mol
Appearance	White orthorhombic pyramidal needles
Density	1.328 g/cm³
Melting point	174 °C
Solubility in water	slightly soluble in cold water, soluble in hot water
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

2-Aminophenol is an organic compound with the formula C₆H₄(OH)NH₂. Along with its isomer 4-aminophenol, it is an amphoteric molecule and a reducing agent. It is a useful reagent for the synthesis of dyes and heterocyclic compounds.^[1] Reflecting its slight hydrophilic character, white powder is moderately soluble in alcohols and can be recrystallised from hot water.

Synthesis

2-Aminophenol (and its isomer, 4-aminophenol) is industrially synthesized by reducing the corresponding nitrophenol by hydrogen in the presence of various catalysts. The nitrophenols can also be reduced with iron.^[1]

Structure

The compound contains an internal hydrogen bond between the neighbouring amine and hydroxyl groups that partly co-ordinates with the same groups on a neighbouring molecule as well. As a result, 2-aminophenol has a rather high melting point compared to other molecules with a similar molecular mass such as methylphenol.^[2]

Applications

2-Aminophenol has a variety of uses. As a reducing agent, it is marketed under the names of Atomal and Ortol to develop black and white photographs.^[1] 2-Aminophenol is an intermediate in the synthesis of dyes. It is particularly useful in yielding tridentate ligands for metal-complex dyes when diazotized and coupled to a phenol, naphthol, or other aromatic or resonant dye species. Metal complex dyes using copper or chromium are commonly used for producing dull colors. Tridentate ligand dyes are particularly useful, since they are more stable than their bi- or mono-dentate counterparts.^[3][4]

Due to the adjacency of the amino and hydroxyl groups, 2-aminophenol readily forms heterocycles. These heterocycles, such as benzoxazoles, can be biologically active and useful in the pharmaceutical industry:^[1]

References

1. ^ ^{a b c d} Mitchell, S.C. & Waring, R.H. “Aminophenols.” In Ullmann’s Encyclopedia of Industrial Chemistry; 2002 Wiley-VCH, doi:10.1002/14356007.a02_099.
2. ^ Reference Handbook of Fine Chemicals, Acros Organics Publishers, Fisher Scientific UK, (2007), www.acros.com
3. ^ Grychtol, K.; Mennicke, W. “Metal-Complex Dyes.” In Ullmann’s Encyclopedia of Industrial Chemistry; 2002 Wiley-VCH, doi:10.1002/14356007.a16_299.
4. ^ Hunger, K.; Mischke, P.; Rieper, W.; Raue, R.; Kunde, K.; Engel, A. “Azo Dyes.” In Ullmann’s Encyclopedia of Industrial Chemistry 2002 Wiley-VCH, doi:10.1002/14356007.a03_245.