Phthalic Anhydride

Cas Number


Other Names

Isobenzofuran-1,3-dione, Phthalic anhydride

The formula



Phthalic anhydride is the organic compound. It is the anhydride of phthalic acid. The chemical is a principal commercial form of phthalic acid. It was the first anhydride of a dicarboxylic acid to be used commercially. This colourless solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2000, the worldwide production volume was estimated to be about 3 million tonnes per year.

Physical and Chemical Properties
Appearance white Flakes
Odor Choking odor
Boiling Point 295 °C
Flash point 152 °C
Melting Point 131 °C
Specific Gravity 1.53@20°C
Vapor Pressure 0.0002 @ 20°C
Vapor Density 6.6
Solubility 0.62 g/100g reacts slowly in water
Purity > 95%

1. Phthalate plasticizers

2. Polyester fibers

3. Alkyd resins, polyester resins

4. Paints

5. Pharmaceutical products

6. Rubber industry