Nitrophenol

Nitrophenols are compounds of the formula HOC₆H_5−x_x. The conjugate bases are called nitrophenolates. Nitrophenols are more acidic than phenol itself.

Mono-nitrophenols

with the formula HOC₆H₄NO₂. Three isomeric nitrophenols exist:

o-Nitrophenol, a yellow solid.
m-Nitrophenol, a yellow solid and precursor to the drug mesalazine. It can be prepared by nitration of aniline followed by replacement of the amino group via its diazonium derivative.
p-Nitrophenol, yellow solid is a precursor to the rice herbicide fluorodifen, the pesticide parathion, and the human analgesic paracetamol.

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

Di- and trinitrophenols

2,4-Dinitrophenol is a moderately strong acid.

[Image:2,4-Dinitrophenol.svg|frameless|center|upright=0.3|]

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

[Image:Pikrinsäure.svg|frameless|center|upright=0.4|]

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.