Isophthalic acid

Isophthalic acid

Names
Preferred IUPAC name Benzene-1,3-dicarboxylic acid
Other names Isophthalic acid meta-Phthalic acid
Identifiers
CAS Number	121-91-5 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:30802 Y
ChemSpider	8182 Y
ECHA InfoCard	100.004.098
PubChem	8496
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
SMILES O=C(O)c1cccc(C(=O)O)c1
Properties
Chemical 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
Magnetic susceptibility (χ)	-84.64·10−6 cm3/mol
Hazards
EU classification (DSD)	not listed
Related compounds
Related carboxylic acids	Benzoic acid Phthalic acid (ortho) Terephthalic acid (para) Trimesic acid (benzene-1,3,5-tricarboxyllic acid)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
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.

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.

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 plastic bottles. The high-performance polymer polybenzimidazole is produced from isophthalic acid. Also, the acid is used as an important input to produce insulation materials.