14benzenedicarboxylic

1,4-Benzenedicarboxylic acid, commonly called terephthalic acid, is an aromatic dicarboxylic acid with the formula C8H6O4. It consists of a benzene ring bearing carboxyl groups at the 1 and 4 positions, giving a para-disubstituted structure. The compound is typically a white crystalline solid with a high melting point and is practically insoluble in water. It can be converted to derivatives such as terephthaloyl chloride or various esters and is a precursor to several polymers.

Production and supply of terephthalic acid are predominantly industrial. It is mainly produced by catalytic air oxidation of para-xylene, followed by purification to remove byproducts and achieve high purity. Common catalysts include cobalt and manganese systems with bromine as a promoter. The refined product is crystallized and dried to meet polymer-grade specifications used in manufacturing.

Uses and applications center on polymer production. The most important application is as a monomer for polyesters, notably polyethylene terephthalate (PET), which is widely used in beverage bottles, fibers, and films. It is also employed in other polyester resins and in the production of polybutylene terephthalate (PBT) and certain unsaturated polyester resins. Beyond polymer chemistry, terephthalic acid derivatives serve in specialty coatings, plastics, and industrial chemicals.

Safety and handling notes indicate that terephthalic acid is of low acute toxicity, but the dust can irritate the eyes, skin, and respiratory tract. Appropriate personal protective equipment and standard laboratory or industrial hygiene practices should be followed. It reacts with strong bases to form soluble salts and can be converted to more reactive derivatives for further chemical processing.