Phthalate Anhydride

Cas No: 85-44-9           
EINESC No: 201-607-5
Molecular weight: 148,1 g/mol  

Chemical Formula: C8H4O3
Chemical Structure:

Physical Properties

General Properties: White particles

Odor: Characteristic, strong

Intensity: 1.53 g/cm3 

Boiling point: 295   °C

Melting point: 131,6  °C

Flash point: 152 ° C

Vapor pressure: 0,0015 mmHg (20 °C)

Refraction index: –

Solubility (aqueous) 0.62 g/100 mL (20 °C)

General Properties

Phthalate anhydride is a colorless, crystalline solid. It is a bivalent carboxylic acid. It is raw material for many organic resins and chemically used esters. It is estimated that 3 billion tons of it was produced worldwide in 2000.


Phthalate anhydride had been produced via oxidation of concentrated sulphuric acid in presence of naphthalene mercury sulphate in early times. In today’s chemistry, it is produced by reaction of naphthalene and molecular oxygen, catalyzed by vanadium pentaoxide.


Phthalate anhydride’s main production purpose is phthalae ester production. Phthalate ester is acquired from reaction of phthalate anhydride and alcoholysis. These phthalate esters are raw materials for many  plastic productions such as DOP and DEHP.

It is also used in dyestuff production. Phthalate anhydrides are pioneers for many  dyestuff.

Certain medicines also contain phthalate anhydride.

Safety Measures and Toxic Values

Phthalate anhydride may cause irritation in airway and skin in short-term exposure. If it contacts with skin, it may cause permanent injuries.

In long-term exposure, it causes reproduction disfunctions. It also creates toxic effects for kidneys and liver. Therefore, people who work with it should follow safety instructions.