Nitrophenols are a family of nitrated phenol

Phenol

Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

s with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 HOC₆H₄NO₂. Three isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

ic 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 aminosalicylic acid
  Aminosalicylic acid
  4-aminosalicylic acid, commonly known as PAS, is an antibiotic used to treat tuberculosis. This organic compound has been use since the 1940s for the treatment of inflammatory bowel diseases , where it has shown greater potency in ulcerative colitis and Crohn's disease. It is thought to act via...
  
  .
• p-Nitrophenol
  4-Nitrophenol
  4-Nitrophenol is a phenolic compound that has a nitro group at the opposite position of hydroxy group on the benzene ring.-Properties:...
  
   (1-hydroxy-4-nitrobenzene, CAS number: 100-02-7), yellow crystals (m.p. 114 °C). It is a precursor to the rice
  Rice
  Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
  
   herbicide fluorodifen and the pesticide parathion
  Parathion
  Parathion, also called parathion-ethyl or diethyl parathion, is an organophosphate compound. It is a potent insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, including humans. Its use is banned or restricted in many...
  
  .

The nitrophenols are produced industrially by the reaction of chlorides with sodium hydroxide at temperatures close to 200 °C.

The mononitrated phenols are often hydrogenated

Hydrogenation

Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...

 to the corresponding aminophenol

Aminophenol

4-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....

s that are also useful industrially.

Di- and trinitrophenols

2,4-Dinitrophenol

2,4-Dinitrophenol

2,4-Dinitrophenol , C6H4N2O5, is a cellular metabolic poison. It uncouples oxidative phosphorylation by carrying protons across the mitochondrial membrane, leading to a rapid consumption of energy without generation of ATP....

 (m.p. 83 °C) is a moderately strong acid (pK_a = 4.89). 2,4,6-trinitrophenol is better known as picric acid

Picric acid

Picric acid is the chemical compound formally called 2,4,6-trinitrophenol . This yellow crystalline solid is one of the most acidic phenols. Like other highly nitrated compounds such as TNT, picric acid is an explosive...

, 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.