4-Nitrophenol

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4-Nitrophenol
IUPAC name 4-nitrophenol
Other names p-nitrophenol
4-hydroxynitrobenzene
PNP
Identifiers
CAS number [100-02-7]
SMILES
ChemSpider ID 955
Properties
Molecular formula C6H5NO3
Molar mass 139.11
Appearance colorless or yellow pillars
Melting point

113–114 °C

Boiling point

279 °C

Solubility in water 10 g/L (15 °C)
11.6 g/L (20 °C)
16 g/L (25 °C)
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

4-Nitrophenol (also called p-nitrophenol or 4-hydroxynitrobenzene) is a phenolic compound that has a nitro group at the opposite position of hydroxy group on the benzene ring. Its molecular formula is C6H5NO3 and CAS registry number is 100-02-7.

Contents

Properties

4-Nitrophenol shows two polymorphs in crystalline state. The alpha-form is colorless pillars, unstable at room temperature, and stable toward sunlight. The beta-form is yellow pillars, stable at room temperature, and gradually turns red upon irradiation of sunlight. Usually 4-nitrophenol is existing as a mixture of these two forms.

In solution, 4-nitrophenol has a dissociation constant (pKa) of 7.08 at 22 °C. Solution of 4-nitrophenol alone appears colorless or pale yellow, whereas its phenolic salts tend to develop a bright yellow color. This color-changing property makes this compound useful as a pH indicator.

Uses

It is believed that aerobic decomposition of 4-nitrophenol in an environment is not very good. Bioaccumulation of this compound is considered to rarely occur. Mainly, 4-nitrophenol is used as the precursor for the preparation of phenetidine and acetophenetidine, indicator, and raw material of fungicides.

In the peptide synthesis, carboxylate ester derivatives of 4-nitrophenol may served as activated components for a constraction of an amide moieties.

Toxicity

4-Nitrophenol irritates eyes, skin, and respiratory tract; and may cause the inflammation of those parts. It makes delayed interaction with blood and forms methaemoglobin that is responsible for methemoglobinemia, which may cause cyanosis, confusion, and unconsciousness. When ingested, one will get abdominal pain and vomiting. Prolonged contact with skin may cause allergic response. Genotoxicity and carcinogenicity of 4-nitrophenol are not known. LD50: mouse, p.o. 282 mg/kg; rat, p.o. 202 mg/kg.

See also

Wikipedia content modification information:

  • This page was last modified on 28 August 2008, at 21:41.

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