Isophthalic acid

Chemical compound From Wikipedia, the free encyclopedia

Isophthalic acid is an organic compound with the formula C6H4(CO2H)2. It is a white solid that is very poorly soluble in water (0.012 g/100 mL at room temperature). The main industrial uses of purified isophthalic acid (PIA) are as a comonomer in the production of polyethylene terephthalate (PET) resin and for the production of unsaturated polyester resin (UPR) and other types of coating resins.[2]

Quick facts Names, Identifiers ...
Isophthalic acid
Skeletal formula
Skeletal formula
Ball-and-stick model of the isophthalic acid molecule
Names
Preferred IUPAC name
Benzene-1,3-dicarboxylic acid
Other names
Isophthalic acid
meta-Phthalic acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.004.098 Edit this at Wikidata
UNII
  • InChI=1S/C8H6O4/c9-7(10)5-2-1-3-6(4-5)8(11)12/h1-4H,(H,9,10)(H,11,12) checkY
    Key: QQVIHTHCMHWDBS-UHFFFAOYSA-N checkY
  • 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
  • O=C(O)c1cccc(C(=O)O)c1
Properties
C8H6O4
Molar mass 166.132 g·mol−1
Appearance White crystalline solid
Density 1.526 g/cm3, Solid
Insoluble
Acidity (pKa) 3.46, 4.46[1]
−84.64·10−6 cm3/mol
Related compounds
Benzoic acid
Phthalic acid (ortho)
Terephthalic acid (para)
Trimesic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure

Isophthalic acid is one of three isomeric benzenedicarboxylic acids, the others are phthalic acid and terephthalic acid. Crystalline isophthalic acid is built up from molecules connected by hydrogen bonds, forming infinite chains.[3]

Preparation

Isophthalic acid is produced by oxidizing meta-xylene using oxygen:

C6H4(CH3)2 + 3O2 → C6H4(CO2H)2 + 2 H2O

The approach is comparable to some routes to terephthalic acid.[2]

The barium salt, as its hexahydrate, is very soluble in water (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

External links

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