4-Chlorophthalic anhydride has a melting point of around 99 °C. Like most acid anhydrides, it can hydrolyze in the presence of water.
4-chlorophthalic anhydride is an important monomer synthesis of polyimide and polyimide is considered to be the highest tolerance has been industrialized in the polymer and the shape and chemical stability of other materials can not like the outburst strength, wear resistance and extreme temperatures, excellent, has been widely used in aviation, aerospace, microelectronics and atom to the field of high technology. 4- of 4-chlorophthalic anhydride is mainly used in the synthesis of diphenyl ether dianhydride anhydride, two single and two double ether, thioether dianhydride anhydride two, two, and two amine polymerization ring was a series of polyimide engineering plastic with excellent performance. 4- of 4-chlorophthalic anhydride is not only the ideal raw material for the synthesis of various intermediates of polyimide, and can be used as a drug or pesticide.
A preparation method of 4-chlorophthalic anhydride uses monosodium phthalic acid as a raw material, uses water as a medium, uses a weak alkali solution as a pH regulator of a reaction system, and directly performs chlorination reaction with chlorine gas. The weak alkali solution is used as the pH regulator of the reaction system, which is beneficial to stabilizing the pH value of the reaction system, and can obtain high-yield 4-chlorophthalic acid monosodium coarse salt. The crude salt is desalted, dehydrated and closed to obtain a crude product of 4-chlorophthalic anhydride, which is purified by rectification to obtain high-purity 4-chlorophthalic anhydride.
