4-Aminophenol

4-Aminophenol

Names
Preferred IUPAC name 4-Aminophenol
Other names p-Aminophenol (no longer recommended[1])
Identifiers
CAS Number	123-30-8
3D model (Jmol)	Interactive image Interactive image
ChEBI	CHEBI:17602
ChEMBL	ChEMBL1142
ChemSpider	392
ECHA InfoCard	100.004.198
KEGG	C02372
MeSH	Aminophenols
PubChem	403
UNII	R7P8FRP05V
InChI InChI=1S/C6H7NO/c7-5-1-3-6(8)4-2-5/h1-4,8H,7H2 Key: PLIKAWJENQZMHA-UHFFFAOYSA-N 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/cm^3
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 (ΔfH^o298)	-190.6 kJ/mol
Hazards
EU classification (DSD)	Carc. Cat. 2 Muta. Cat. 2 Repr. Cat. 3 Toxic (T)
R-phrases	R20/21, R22, R40 R52, R54, R68
S-phrases	S28, S36, S37 S60, S61
NFPA 704	1 2 0
Flash point	195 °C (383 °F; 468 K) (cc)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	671 mg/kg
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).
verify (what is  ?)
Infobox references

4-Aminophenol (or para-aminophenol or p-aminophenol) is the organic compound with the formula H₂NC₆H₄OH. Typically available as a white powder,^[2] it was commonly used as a developer for 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:^[3]

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.^[4]

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:^[5][6][7]

1. Parapropamol (4-HO-Ph-NHCOEt).
2. Amidation with the acid chloride of ATRA gives Fenretinide.
3. AM404 is made by acylating arachidonic acid.

See also

• Metol is the N-methyl derivative of p-aminophenol.

References

1. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 690. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
2. CRC Handbook of Chemistry and Physics 65th Ed.
3. Mitchell, S.C. & Waring, R.H. "Aminophenols." In Ullmann’s Encyclopedia of Industrial Chemistry; 2002 Wiley-VCH, doi:10.1002/14356007.a02_099
4. Polat, K.; Aksu, M.L.; Pekel, A.T. (2002), "Electroreduction of nitrobenzene to p-aminophenol using voltammetric and semipilot scale preparative electrolysis techniques", Journal of Applied Electrochemistry, Kluwer Academic Publishers, 32: 217–223, doi:10.1023/A:1014725116051
5. Ellis, Frank (2002). Paracetamol: a curriculum resource. Cambridge: Royal Society of Chemistry. ISBN 0-85404-375-6.
6. Anthony S. Travis (2007). "Manufacture and uses of the anilines: A vast array of processes and products". In Zvi Rappoport. The chemistry of Anilines Part 1. Wiley. p. 764. ISBN 978-0-470-87171-3.
7. Elmar Friderichs; Thomas Christoph; Helmut Buschmann (2005), "Analgesics and Antipyretics", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a02_269.pub2