|Molar mass||166.14 g/mol|
|Appearance||White crystalline solid|
|Density||1.526 g/cm3, Solid|
|Insoluble in water|
|Acidity (pKa)||3.46, 4.46|
|EU classification||not listed|
Related carboxylic acids
Phthalic acid (ortho)
Terephthalic acid (para)
Trimesic acid (benzene-1,3,5-tricarboxyllic acid)
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Isophthalic acid is an organic compound with the formula C6H4(CO2H)2. This colourless solid is an isomer of phthalic acid and terephthalic acid. These aromatic dicarboxylic acids are used as precursors (in form of acyl chlorides) to commercially important polymers, e.g. the fire-resistant material Nomex. Mixed with terephthalic acid, isophthalic acid is used in the production of resins for drink bottles. The high-performance polymer polybenzimidazole is produced from isophthalic acid.
Isophthalic acid is produced on the billion kilogram per year scale by oxidizing meta-xylene using oxygen. The process employs a cobalt-manganese catalyst. In the laboratory, chromic acid can be used as the oxidant. It also arises by fusing potassium meta-sulphobenzoate, or meta-brombenzoate with potassium formate (terephthalic acid is also formed in the last case).
The barium salt (as its hexahydrate) is very soluble (a distinction between phthalic and terephthalic acids). Uvitic acid, 5-methylisophthalic acid, is obtained by oxidizing mesitylene or by condensing pyroracemic acid with baryta water.
- Brown, H.C., et al., in Baude, E.A. and Nachod, F.C., Determination of Organic Structures by Physical Methods, Academic Press, New York, 1955.
- Richard J. Sheehan "Terephthalic Acid, Dimethyl Terephthalate, and Isophthalic Acid" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.doi:10.1002/14356007.a26_193