Isophthalic acid

Isophthalic acid
Other names Benzene-1,3-dicarboxylic acid meta-Phthalic acid
Identifiers
CAS number	121-91-5 Y
PubChem	8496
ChemSpider	8182 Y
ChEBI	CHEBI:30802 Y
Jmol-3D images	Image 1
SMILES O=C(O)c1cccc(C(=O)O)c1
InChI InChI=1S/C8H6O4/c9-7(10)5-2-1-3-6(4-5)8(11)12/h1-4H,(H,9,10)(H,11,12) Y Key: QQVIHTHCMHWDBS-UHFFFAOYSA-N Y InChI=1/C8H6O4/c9-7(10)5-2-1-3-6(4-5)8(11)12/h1-4H,(H,9,10)(H,11,12) Key: QQVIHTHCMHWDBS-UHFFFAOYAY
Properties
Molecular formula	C6H4(COOH)2
Molar mass	166.14 g/mol
Appearance	White crystalline solid
Density	1.526 g/cm3, Solid
Solubility in water	Insoluble in water
Acidity (pKa)	3.46, 4.46[1]
Hazards
EU classification	not listed
Related compounds
Related carboxylic acids	Benzoic acid Phthalic acid (ortho) Terephthalic acid (para) Trimesic acid (benzene-1,3,5-tricarboxyllic acid)
Y acid (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.^[2]

Preparation

Isophthalic acid is produced on the billion kilogram/y scale by oxidizing meta-xylene using oxygen.^[2] 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.

References

1. ^ 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.
2. ^ ^{a b} 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

External links

• International Chemical Safety Card 0500