Nitrophenol

p-Nitrophenol

Nitrophenols consist of a phenol molecule with one or more nitro-groups attached to the aromatic ring. The term is most often used to describe singly nitrated phenols.

Mono-nitrophenols

with the formula HOC₆H₄NO₂. Three isomeric nitrophenols exist:

• o-Nitrophenol (1-hydroxy-2-nitrobenzene; OH and NO₂ groups are neighboring; CAS number: 88-75-5), a yellow crystalline solid (m.p. 46 °C).
• m-Nitrophenol (1-hydroxy-3-nitrobenzene, CAS number: 554-84-7), a yellow solid (m.p. 97 °C) and precursor to the drug mesalazine (5-aminosalicylic acid).
• p-Nitrophenol (1-hydroxy-4-nitrobenzene, CAS number: 100-02-7), yellow crystals (m.p. 114 °C). It is a precursor to the rice herbicide fluorodifen and the pesticide parathion.

The mononitrated phenols are often hydrogenated to the corresponding aminophenols that are also useful industrially.^[1]

Di- and trinitrophenols

2,4-dinitrophenol

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.^[2][3] Occasionally, nitrophenols contaminate the soil near former explosives or fabric factories and military plants, and current research is aimed at remediation.

References

1. ↑ Gerald Booth "Nitro Compounds, Aromatic" in "Ullmann's Encyclopedia of Industrial Chemistry" 2007; Wiley-VCH, Weinheim. doi:10.1002/14356007.a17_411
2. ↑ Nitrophenol
3. ↑ Dinitrophenol

External links

• Fact sheet at atsdr.cdc.gov