Terephthalic acid
An aromatic dicarboxylic acid used with ethylene glycol to make PET.
- Formula
- C8H6O4
- Functional group
- Two carboxylic acid groups
- Molar mass
- 166.13 g/mol
- Also known as
- benzene-1,4-dicarboxylic acid, TPA, PTA
Overview
Benzene-1,4-dicarboxylic acid
An aromatic dicarboxylic acid used with ethylene glycol to make PET.
Its two carboxylic acid groups allow it to link with diol molecules to build a polyester chain. Oxidation of p-xylene supplies this 1,4-disubstituted diacid. With butane-1,4-diol it instead forms PBT, showing how a shared aromatic feedstock can lead to different polyester repeat units.
Identifiers
- Formula
- C8H6O4
- Functional group
- Two carboxylic acid groups
- Molar mass
- 166.13 g/mol
- Also known as
- benzene-1,4-dicarboxylic acid, TPA, PTA
Chemical identifiers
- SMILES
- O=C(O)c1ccc(C(=O)O)cc1
- InChI
- InChI=1S/C8H6O4/c9-7(10)5-1-2-6(4-3-5)8(11)12/h1-4H,(H,9,10)(H,11,12)
- PubChem CID
- 7489
Properties
- Melting Point
- 427 °C (sealed tube)
- Sublimation
- greater than 572 °F at 760 mmHg (sublimes without melting) (NTP, 1992)
- Relative density (water = 1)
- Specific gravity = 1.522 at 25 °C
- Water solubility
- In water, 15 mg/L at 20 °C
Related compounds
- Dicarboxylic acids
An aromatic dicarboxylic acid used with ethylene glycol to make PET.
References
- Polyesters: manufacture and usesChemical Industry Education Centre, University of York
- Purified terephthalic acid: products and manufacturing, annual report 2023, page 94INEOS Quattro
- PubChem: Terephthalic acidNational Center for Biotechnology Information
Identity retrieved 2026-09-08; matched against the record's isomeric structure. Unspecified stereochemistry remains unspecified.
- Hazardous Substances Data Bank (HSDB): Terephthalic acid — melting pointHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7489#section=Melting-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Park CM, Sheehan RJ; Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2011). New York, NY: John Wiley & Sons; Phthalic Acids and Other Benzenepolycarboxylic Acids. Online Posting Date: Dec 4, 2000
- CAMEO Chemicals: Terephthalic acid — boiling pointCAMEO Chemicals
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7489#section=Boiling-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
- Hazardous Substances Data Bank (HSDB): Terephthalic acid — densityHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7489#section=Density. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Park CM, Sheehan RJ; Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2011). New York, NY: John Wiley & Sons; Phthalic Acids and Other Benzenepolycarboxylic Acids. Online Posting Date: Dec 4, 2000
- Hazardous Substances Data Bank (HSDB): Terephthalic acid — solubilityHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7489#section=Solubility. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 459