테레프탈산

개요Terephthalic acid is the organic compound with formula C6H4(COOH)2. This colourless solid is a commodity chemical, used principally as a precursor to the polyester PET, used to make clothing and plastic bottles. Several million tones are produced annually. It is one of three isomeric phthalic acids.

역사Terephthalic acid came to prominence through the work of Winfield and Dickson in Britain around 1940. Earlier work by Carothers and coworkers in the United States established the feasibility of producing high molecular weight linear polyesters by reacting diacids with diols, but they used aliphatic diacids and diols. These made polyesters which were unsuitable to be spun into fibers. Winfield and Dickson found that symmetrical aromatic diacids yield high-melting, crystalline, and fiberforming materials; poly(ethylene terephthalate) (PET) has since become the largest volume synthetic fiber.

용도Terephthalic acid (TPA) is a benzenepolycarboxylic acid with potential anti-hemorrhagic properties. It is a high-tonnage chemical, widely used in the production of synthetic materials, notably polyester fibers (poly-(ethylene terephthalate)).

일반 설명White powder.

The major commercial route to terephthalic acid which is suitable for the direct preparation of poly(ethylene terephthalate) is from p-xylene: p-Xylene is obtained largely from petroleum sources, being a product of the fractionation of reformed naphthas. The oxidation is carried out in the liquid phase. Typically, air is passed into a solution of p-xylene in acetic acid at about 200 and 2 MPa (20 atmospheres) in the presence of a catalyst system containing cobalt and manganese salts and a source of bromide ions. The terephthalic acid produced contains only small amounts of impurities (mainly p-carboxybenzaldehyde), which are readily removed. The acid is dissolved in water at about 2500 e and 5 MPa (50 atmospheres) and treated with hydrogen (which converts the aldehyde to p-toluic acid). The solution is then cooled to 100 and pure terephthalic acid crystallizes.

생산 방법Terephthalic acid is produced by oxidation of p-xylene by oxygen in air: This reaction proceeds through a p-toluic acid intermediate which is then oxidized to terephthalic acid. In p-toluic acid, deactivation of the methyl by the electron withdrawing carboxylic acid group makes the methyl one tenth as reactive as xylene itself, making the second oxidation significantly more difficult . The commercial process utilizes acetic acid as solvent and a catalyst composed of cobalt and manganese salts, with a bromide promoter.