||It has been suggested that Rodinal be merged into this article. (Discuss) Proposed since July 2014.|
|Jmol-3D images||Image 1
|Molar mass||109.126 g/mol|
|Appearance||colorless to reddish-yellow crystals|
|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
slightly soluble in toluene, diethyl ether, ethanol
negligible in benzene, chloroform
|Std enthalpy of
|EU classification||Carc. Cat. 2
Muta. Cat. 2
Repr. Cat. 3
|R-phrases||R20/21, R22, R40
R52, R54, R68
|S-phrases||S28, S36, S37
|Flash point||195 °C (cc)|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
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.
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
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:
- Metol, the N-methyl derivative of p-aminophenol. In 1891 it replaced p-aminophenol as a developing agent for black & white photography. It is worthy of note that the most common synthesis processes for these two similar molecules differ nonetheless strongly.
- CRC Handbook of Chemistry and Physics 65th Ed.
- Mitchell, S.C. & Waring, R.H. “Aminophenols.” In Ullmann’s Encyclopedia of Industrial Chemistry; 2002 Wiley-VCH, doi:10.1002/14356007.a02_099
- Ellis, Frank (2002). Paracetamol: a curriculum resource. Cambridge: Royal Society of Chemistry. ISBN 0-85404-375-6.
- 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.
- 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