Its melting point is 191℃ (closed tube) and density (at 20/4℃) is 1.593g/cm3 When rapidly heated to 230, it will dehydrate and become intramolecular anhydride – phthalic anhydride, commonly known as PA. It is slightly soluble in water and ether, soluble in methanol and ethanol, but insoluble in chloroform and benzene.
It is used for producing dye, polyester resin, PET, medicine and plasticizer etc., where phthalic anhydride can replace OX. OX is the raw material for resin, fiber and medicine etc., is an important organic industrial product, and can serve as a gas chromatography reference substance as well as analytical reagent of some metals.
After dehydration OX can form PA, which is an important raw material in PU industry and its product therein can be used for producing PU heat insulating material, whose performance is better than polyether.