Phthalic anhydride is an organic compound with the formula C6H4(CO)2O. Phthalic anhydride (PA) is a colorless, toxic solid that dissolves in alcohol and carbon disulfide.

PA is slightly dissolved in hot water and hydrolyzed to phthalic acid. It is one of the first bivalent dicarboxylic acids, which has high commercial consumption and is comparable to acetic acid in terms of importance.

Phthalic anhydride is the main commercial form of phthalic acid.This chemical was the first dicarboxylic acid anhydride to be used commercially.

Boiling Point295 °C
Density1.53 g/cm3
Vapor pressure0.0015 mmHg (20 °C)
Flash point152 ºC
Storage temperatureroom temperature
Solubility in water0.62 g/100g (20-25 °C)
Appearancewhite flake


  • Synthesis of plasticizers, alkyd resins and unsaturated polyester resins
  • Production of softeners such as DIDP, DOP, BBP and DINP
  • Compositions of the main plasticizers for polyvinyl chloride resins
  • A monomer for synthetic resins such as glyptal, alkyd resins and polyester resins
  • Anthraquinone, phthalene, rhodamine, phthalocyanine precursor of fluorescein and xanthene dyes


Phthalic anhydride can be supplied in 25 kg bags.

Other names

  • Isobenzofuran-1
  • 3-dione
  • 2-Benzofuran-1

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