4-Aminophenol

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4-Aminophenol
Skeletal formula of 4-aminophenol
Space-filling model of the 4-aminophenol molecule
Names
Preferred IUPAC name
4-Aminophenol[1]
Other names
  • p-Aminophenol
  • para-Aminophenol
Identifiers
3D model (
JSmol
)
385836
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.004.198 Edit this at Wikidata
EC Number
  • 204-616-2
2926
KEGG
MeSH Aminophenols
UNII
UN number 2512
  • InChI=1S/C6H7NO/c7-5-1-3-6(8)4-2-5/h1-4,8H,7H2 checkY
    Key: PLIKAWJENQZMHA-UHFFFAOYSA-N checkY
  • InChI=1/C6H7NO/c7-5-1-3-6(8)4-2-5/h1-4,8H,7H2
    Key: PLIKAWJENQZMHA-UHFFFAOYAD
  • Oc1ccc(N)cc1
  • c1cc(ccc1N)O
Properties
C6H7NO
Molar mass 109.128 g·mol−1
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)
1.5 g/100 mL
Solubility
log P 0.04
Acidity (pKa)
  • 5.48 (amino; H2O)
  • 10.30 (phenol; H2O)[2]
Structure
orthorhombic
Thermochemistry
Std enthalpy of
formation
(ΔfH⦵298)
 -190.6 kJ/mol
Hazards
GHS labelling:
GHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Warning
H302, H332, H341, H410
P201, P202, P261, P264, P270, P271, P273, P281, P301+P312, P304+P312, P304+P340, P308+P313, P312, P330, P391, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Flash point 195 °C (383 °F; 468 K) (cc)
Lethal dose or concentration (LD, LC):
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).
checkY verify (what is checkY☒N ?)

4-Aminophenol (or para-aminophenol or p-aminophenol) is an

black-and-white film, marketed under the name Rodinal
.

Reflecting its slightly hydrophilic character, the white powder is moderately soluble in alcohols and can be

N-methylaminophenol and N,N-dimethylaminophenol
are of commercial value.

The compound is one of three

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 (Bamberger rearrangement).[4]

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.[5]

From 4-nitrophenol

4-nitrophenol can be reduced through a variety of methods, to yield 4-aminophenol. One method involves hydrogenation over a Raney Nickel catalyst. A second method involves selective reduction of the nitro group by Tin(II) Chloride in anhydrous ethanol or ethyl ethanoate. [6][7]

Uses

4-Aminophenol is a building block used in organic chemistry. Prominently, it is the final intermediate in the industrial synthesis of paracetamol. Treating 4-aminophenol with acetic anhydride gives paracetamol:[8][9][10]

It is a precursor to amodiaquine, mesalazine, AM404, parapropamol, B-86810 & B-87836 (c.f. WO 2001042204 ).

4-Aminophenol converts readily to the

diazonium salt.[11]

References

  1. ISBN 978-0-85404-182-4
    .
  2. ISBN 978-1498754286
    .
  3. ^ CRC Handbook of Chemistry and Physics 65th Ed.
  4. doi:10.1002/14356007.a02_099
  5. S2CID 54499902
  6. ^ US2998450A, Godfrey, Wilbert & De, Angelis John, "Process of preparing nu-acetyl-p-amino phenol", issued 1961-08-29 
  7. ISSN 0040-4039
    .
  8. ISBN 0-85404-375-6
    .
  9. ISBN 978-0-470-87171-3
    .
  10. ISBN 978-3527306732
    .
  11. doi:10.15227/orgsyn.015.0039
    .
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