4-Aminophenol

4-Aminophenol

Skeletal formula of 4-aminophenol Space-filling model of the 4-aminophenol molecule
Names
IUPAC name 4-Aminophenol
Identifiers
CAS Number	123-30-8 Y
ChEBI	CHEBI:17602 Y
ChEMBL	ChEMBL1142 Y
ChemSpider	392 Y
Jmol 3D model	Interactive image Interactive image
KEGG	C02372 Y
MeSH	Aminophenols
PubChem	403
UNII	R7P8FRP05V Y
InChI InChI=1S/C6H7NO/c7-5-1-3-6(8)4-2-5/h1-4,8H,7H2 Y Key: PLIKAWJENQZMHA-UHFFFAOYSA-N Y InChI=1/C6H7NO/c7-5-1-3-6(8)4-2-5/h1-4,8H,7H2 Key: PLIKAWJENQZMHA-UHFFFAOYAD
SMILES Oc1ccc(N)cc1 c1cc(ccc1N)O
Properties
Chemical formula	C6H7NO
Molar mass	109.126 g/mol
Appearance	colorless to reddish-yellow crystals
Density	1.13 g/cm3
Melting point	187.5 °C (369.5 °F; 460.6 K)
Boiling point	284 °C (543 °F; 557 K)
Solubility in water	1.5 g/100 mL (25 °C)
Solubility	very soluble in dimethylsulfoxide soluble in acetonitrile ethyl acetate acetone slightly soluble in toluene, diethyl ether, ethanol negligible in benzene, chloroform
log P	0.04
Acidity (pKa)	10.30
Structure
Crystal structure	orthorhombic
Thermochemistry
Std enthalpy of formation (ΔfHo298)	-190.6 kJ/mol
Vapor pressure	{{{value}}}
Related compounds
Related aminophenols	2-Aminophenol 3-Aminophenol
Related compounds	Aniline Phenol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

4-Aminophenol (or para-aminophenol or p-aminophenol) is the organic compound with the formula H₂NC₆H₄OH. Typically available as a white powder, it is commonly used as a developer in black-and-white film, marketed under the name Rodinal.

Reflecting its slight hydrophilic character, the white powder is moderately soluble in alcohols and can be recrystallised from hot water. In the presence of base, it oxidizes readily. The N-methyl and N,N-dimethyl derivatives are of commercial value.

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

Preparation

From phenol

It is produced from phenol by nitration followed by reduction with iron. Alternatively, the partial hydrogenation of nitrobenzene affords phenylhydroxylamine, which rearranges primarily to 4-aminophenol:

C₆H₅NO₂ + 2 H₂ → C₆H₅NHOH + H₂O

C₆H₅NHOH → HOC₆H₄NH₂

From nitrobenzene

It can be produced from nitrobenzene by electrolytic conversion to phenylhydroxylamine, which spontaneously rearranges to 4-aminophenol.

Uses

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

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Amidation with the acid chloride of ATRA gives Fenretinide. Another drug AM404 can be made by acylating arachidonic acid.

See also

• Metol is the N-methyl derivative of p-aminophenol. In 1891 it replaced p-aminophenol as a developing agent for black & white photography.