Isophthalic acid

Isophthalic acid
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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Isophthalic acid is an organic compound with the formula C6H4(CO2H)2. This colorless solid is an isomer of phthalic acid and terephthalic acid. The main industrial uses of purified isophthalic acid (PIA) are for the production of polyethylene terephthalate (PET) resin and for the production of unsaturated polyester resin (UPR) and other types of coating resins.

Isophthalic acid is one of three isomers of benzenedicarboxylic acid, the others being phthalic acid and terephthalic acid.

Crystalline isophthalic acid is built up from molecules connected by hydrogen bonds, forming infinite chains.[2]

  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. ^ Derissen, JL (1974). "The crystal structure of isophthalic acid". Acta Crystallogr. B30 (6): 764–2765. doi:10.1107/S0567740872004844.