2-Aminophenol

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2-Aminophenol
O-Aminophenol.svg
Space filling model of 2-aminophenol Ball-and-stick model of 2-aminophenol
Identifiers
CAS number 95-55-6 YesY
ChemSpider 5596 YesY
UNII 23RH73DZ65 YesY
DrugBank DB01726
KEGG C01987 YesY
ChEBI CHEBI:18112 YesY
ChEMBL CHEMBL28319 YesY
Jmol-3D images Image 1
Image 2
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
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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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 and structure[edit]

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]

The compound exhibits intra- and intermolecular hydrogen bond involving the neighbouring amine and hydroxyl groups. As a result, 2-aminophenol has a rather high melting point compared to other compounds with a similar molecular mass such as methylphenol.[2]

Applications[edit]

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 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 useful because they are more stable than their bi- or mono-dentate counterparts.[3][4]

2-aminophenol diaz coup.png 2-aminophenol coord.png

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]

2-aminophenol cyclization.png

References[edit]

  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.