Isophthalic acid 121-91-5
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Isophthalic acid is an organic compound with the formula C 6 H 4 (CO 2 H) 2 . This colorless solid is an isomer of phthalic and terephthalic acids. These aromatic dicarboxylic acids are used as precursors (in the form of acid chlorides) for commercially important polymers such as the refractory material Nomex. Isophthalic acid is mixed with terephthalic acid to produce beverage bottle resin. High-performance polymer polybenzimidazole is produced from isophthalic acid.
| describe | Isophthalic acid is an organic compound with the chemical formula C 6 H 4 (CO 2 H) 2 . This colorless solid is an isomer of phthalic acid and terephthalic acid. These aromatic dicarboxylic acids are used as precursors (in the form of acid chlorides) of commercially important polymers, such as the refractory material Nomex. Isophthalic acid is mixed with terephthalic acid to produce beverage bottle resin. The high-performance polymer polybenzimidazole is produced from isophthalic acid. |
| chemical properties | Isophthalic acid is a white crystalline powder or needle-shaped crystal, which is an isomer of phthalic acid and terephthalic acid. Insoluble in cold water, soluble in oxygenated solvents and alcohol. It is flammable and finely dispersed particles can form explosive mixtures in the air.  Isophthalic acid (PIA) is mainly used in the production of PET bottles, but also in the production of alkyd resin, polyester resin, photosensitive materials, pharmaceutical intermediates, etc. One of the largest applications for PIA is in unsaturated polyester resins used in high-quality gelcoats. PIA's hardness, stain resistance and detergent resistance properties are ideal for polyester solid surface countertops and are an inexpensive alternative to acrylics. |
| use | Isophthalic acid is used as an intermediate for high-performance unsaturated polyesters, coating resins, high-solid paints, gel coats and polyethylene terephthalate modifiers for bottles. It can be used as a precursor for the refractory material nomex and for the preparation of high-performance polymer polybenzimidazole. It is also used as an input in the production of insulation materials. |
| use | Purified isophthalic acid (PIA) is mainly used as an intermediate for high-performance UPR, coating resins, high-solid paints, gel coats, and PET modifiers for bottles. Product data sheet |
| Prepare | By oxidizing m-xylene with oxygen, one billion kilograms of isophthalic acid can be produced annually. This process uses cobalt manganese catalyst. In the laboratory, chromic acid is used as an oxidizing agent. It can also be produced by melting potassium m-sulfobenzoate or potassium m-bromobenzoate with potassium formate (terephthalic acid is also formed in the latter case). Barium salt (hexahydrate) is very soluble (difference between phthalic acid and terephthalic acid). Gluconic acid, 5-methylisophthalic acid, is obtained by oxidation of mesitylene or by condensation of pyrrole racemic acid with barite water. |
| definition | ChEBI: A phthalic acid in which benzene is substituted with carboxyl groups at the 1 and 3 positions. One of three possible isomers of phthalic acid, the others being phthalic acid and terephthalic acid. |
| synthetic references | Journal of the American Chemical Society, 82, p. 1911, 1960 DOI: 10.1021/ja01493a020 |
| general instructions | White solid with slightly unpleasant odor. sink into the water. |
| air and water reaction | Dust forms explosive mixtures in air [USCG, 1999]. |
| reactive profile | Isophthalic acid is a carboxylic acid. Carboxylic acids will release hydrogen ions if a base that accepts them is present. They react in this way with all bases, including organic bases (such as amines) and inorganic bases. Their reaction with alkali is called "neutralization" and is accompanied by the release of large amounts of heat. Neutralization between acids and bases produces water and salt. Carboxylic acids with 6 or fewer carbon atoms are easily soluble or slightly soluble in water; those with more than 6 carbon atoms are slightly soluble in water. Soluble carboxylic acids dissociate to a certain extent in water to produce hydrogen ions. Therefore, the pH value of a carboxylic acid solution is less than 7.0. Many insoluble carboxylic acids react rapidly with aqueous solutions containing chemical bases and dissolve upon neutralization to form soluble salts. Carboxylic acids in aqueous solutions as well as liquid or molten carboxylic acids can react with reactive metals to form gaseous hydrogen and metal salts. In principle, this reaction also occurs for solid carboxylic acids, but the reaction is slow if the solid acid is kept dry. Even "insoluble" carboxylic acids can absorb enough water from the air and dissolve sufficiently in isophthalic acid to corrode or dissolve iron, steel and aluminum parts and containers. Like other acids, carboxylic acids react with cyanide salts to form gaseous hydrogen cyanide. For dry solid carboxylic acids, the reaction rate is slower. The insoluble carboxylic acid reacts with the cyanide solution, releasing gaseous hydrogen cyanide. Carboxylic acids react with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrogen compounds and sulfides to produce flammable and/or toxic gases and heat. Carboxylic acids, especially in aqueous solutions, also react with sulfites, nitrites, thiosulfates (forming H2S and SO3), dithionites (SO2), producing flammable and/or toxic gases and heat. They react with carbonates and bicarbonates to produce a harmless gas (carbon dioxide), but still produce heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidants and reduced by strong reducing agents. These reactions generate heat. A variety of products can be produced. Like other acids, carboxylic acids can initiate polymerization reactions; like other acids, they often catalyze chemical reactions (increase the rate of chemical reactions). |
| health hazard | Prolonged contact may cause mild to moderate irritation to eyes, skin and mucous membranes. May cause gastrointestinal irritation if ingested. |
| fire hazard | Fire Behavior: Dust forms explosive mixtures in air. |
| Flammability and explosiveness | non-flammable |
| Purification method | Acid crystallized from aqueous ethanol solution. [Berstein 9 IV 3292. ] |
| Isophthalic acid upstream and downstream product information |
| raw material | Acetic acid --> potassium permanganate --> m- xylene -->cobalt acetate-->1,3-dicyanobenzene -- > manganese acetate tetrahydrate --> methyl 3- bromobenzoate--> 3-Carboxybenzaldehyde |
| Preparation products | 1,3-dicyanobenzene --> 2-iodooxybenzoic acid --> dimethyl 5-sulfoisophthalate sodium --> 2,6-dicyano-4-nitroaniline- -> Dimethyl isophthalate --> 2,4,5-Trifluorobenzoic acid-- > 5-Amino-N-methylisophthalic acid --> 5-Nitroisophthalic acid-- > 5-Amino-2,4,6-triiodo-N-methylisophthalic acid --> Diethyl Isophthalate --> Polyester Fiber Color Modifier --> 5-Bromoisophthalic Acid Dimethyl dicarboxylate --> Biphenyl-3,4′,5-tricarboxylic acid --> cis-1,3-cyclohexanedicarboxylic acid |
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