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 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:30802 ;
ChemSpider	8182 ;
ECHA InfoCard	100.004.098
PubChem CID	8496;
UNII	X35216H9FJ ;
CompTox Dashboard (EPA)	DTXSID3021485 ;
	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) Key: QQVIHTHCMHWDBS-UHFFFAOYSA-N ; 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	C8H6O4
Molar mass	166.132 g·mol−1
Appearance	White crystalline solid
Density	1.526 g/cm3, Solid
Solubility in water	Insoluble
Acidity (pKa)	3.46, 4.46
Magnetic susceptibility (χ)	−84.64·10−6 cm3/mol
Related compounds
Related carboxylic acids	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). verify (what is ?) Infobox references

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.