Pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride, hereinafter referred to as homo-anhydride) is a chemical raw material that plays a certain role in the chemical industry. The appearance of pyromellitic dianhydride is white powder or needle crystal, the molecular formula is C10H2O6, the melting point is 284~286 ° C, the boiling point is 397-400 ° C, and the relative density is 1.680. Soluble at room temperature in dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, N-methylpyrrolidone, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, etc., insoluble in chloroform, ether, The n-hexane and benzene are easily hydrolyzed to meta-tetracarboxylic acid when exposed to air, and the pyromellitic dianhydride has four carboxyl groups in the molecule. They are all symmetrical, and chemical reactions such as esterification, acid chloride, hydrogenation, amidation, imidization, and cyanation can occur.

     Application of pyromellitic dianhydride

     The anhydrides and their derivatives have important and wide-ranging uses, and in particular, the anhydrides are one of the main monomers for the production of polyimides. Polyimide can exhibit various properties in high temperature environment. It is the widest temperature used in organic polymer materials, high dimensional stability, radiation resistance, mechanical properties, electrical properties and corrosion resistance. A new type of engineering material. It can be made into films, laminates, fibers, adhesives, wire enamels, and cast parts. Etc. is called "universal plastic." With the increasing demand for polyimide materials in the market, as one of the main monomers, the research on the preparation method of the homo-anhydride is increasingly attracting the attention of researchers at home and abroad.