Nitrophenol

Nitrophenols are compounds of the formula HOC₆H_5−x(NO₂)_x. The conjugate bases are called nitrophenolates. Nitrophenols are more acidic than phenol itself.

Mono-nitrophenols

Mono-nitrophenols

2-Nitrophenol (o-)
3-Nitrophenol (m-)
4-Nitrophenol (p-)
Identifiers
Compounds o: o-nitrophenol (2-) m: m-nitrophenol (3-) p: p-nitrophenol (4-) p: p tautomer
CAS Number	o: 88-75-5 Y m: 554-84-7 Y p: 100-02-7 Y
3D model (JSmol)	o: Interactive image m: Interactive image p: Interactive image p: Interactive image
ChEBI	o: CHEBI:16260 m: CHEBI:34346 p: CHEBI:16836
ChEMBL	m: ChEMBL13888 p: ChEMBL14130
ChemSpider	p: 955
DrugBank	p: DB04417
KEGG	p: C00870
PubChem CID	o: 6947 m: 11137 p: 980
UNII	o: BD148E95KD Y m: T6P4T52V9W Y p: Y92ZL45L4R Y
InChI o: InChI=1S/C6H5NO3/c8-6-4-2-1-3-5(6)7(9)10/h1-4,8H Key: IQUPABOKLQSFBK-UHFFFAOYSA-N m: InChI=1S/C6H5NO3/c8-6-3-1-2-5(4-6)7(9)10/h1-4,8H Key: RTZZCYNQPHTPPL-UHFFFAOYSA-N p: InChI=1S/C6H5NO3/c8-6-3-1-5(2-4-6)7(9)10/h1-4,8H Key: BTJIUGUIPKRLHP-UHFFFAOYSA-N
SMILES o: Oc1ccccc1[N+]([O-])=O m: Oc1cccc(c1)[N+]([O-])=O p: c1cc(ccc1[N+](=O)[O-])O p: O=[N+]([O-])c1ccc(O)cc1
Properties
Chemical formula	C6H5NO3
Molar mass	139.110 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

with the formula HOC₆H₄NO₂. Three isomeric nitrophenols exist:

• o-Nitrophenol (2-nitrophenol; OH and NO₂ groups are neighboring; CAS number: 88-75-5), a yellow crystalline solid (m.p. 46 °C).
• m-Nitrophenol (3-nitrophenol, CAS number: 554-84-7), a yellow solid (m.p. 97 °C) and precursor to the drug mesalazine (5-aminosalicylic acid).
• p-Nitrophenol (4-nitrophenol, CAS number: 100-02-7), yellow crystals (m.p. 114 °C). It is a precursor to the rice herbicide fluorodifen, the pesticide parathion, and the human analgesic paracetamol (also known as acetaminophen).

The mononitrated phenols are often hydrogenated to the corresponding aminophenols that are also useful industrially.

Di- and trinitrophenols

2,4-dinitrophenol

picric acid

• 2,4-Dinitrophenol (m.p. 83 °C) is a moderately strong acid (pK_a = 4.89).

• 2,4,6-Trinitrophenol is better known as picric acid, which has a well-developed chemistry.

Safety

Nitrophenols are poisonous. Occasionally, nitrophenols contaminate the soil near former explosives or fabric factories and military plants, and current research is aimed at remediation.