4-nitrophenol

4-Nitrophenol (also known as p-nitrophenol) is an organic compound with the formula C₆H₅NO₃. It is a pale yellow solid that is soluble in water. It is one of the isomers of nitrophenol, the others being 2-nitrophenol and 3-nitrophenol.

Structure and Properties

4-Nitrophenol consists of a phenol group (a benzene ring with a hydroxyl group) with a nitro group (NO₂) in the para position. This arrangement gives it distinct chemical properties, including its acidic nature and its ability to participate in various chemical reactions.

Physical Properties

• Molecular formula: C₆H₅NO₃
• Molar mass: 139.11 g/mol
• Appearance: Pale yellow crystalline solid
• Melting point: 113-114 °C
• Boiling point: 279 °C
• Solubility in water: 11.6 g/L at 20 °C

Chemical Properties

4-Nitrophenol is a weak acid with a pKa of 7.15. It can undergo nitration, reduction, and other typical reactions of phenols and nitro compounds. The nitro group is an electron-withdrawing group, which affects the reactivity of the phenol group.

Synthesis

4-Nitrophenol can be synthesized by the nitration of phenol using a mixture of nitric acid and sulfuric acid. The reaction is typically carried out at low temperatures to favor the formation of the para isomer over the ortho isomer.

Applications

4-Nitrophenol is used in the synthesis of pharmaceuticals, dyes, and pesticides. It is also used as a pH indicator and as a precursor in the synthesis of paracetamol (acetaminophen).

Toxicity and Safety

4-Nitrophenol is considered toxic and can cause irritation to the skin, eyes, and respiratory tract. It is harmful if swallowed and can affect the central nervous system. Proper safety precautions should be taken when handling this compound.

Environmental Impact

4-Nitrophenol can be released into the environment through industrial processes and the degradation of pesticides. It is considered a pollutant and can be harmful to aquatic life.

Also see

• Nitrophenol
• Phenol
• Paracetamol
• Nitrobenzene