Terephthalic Acid

A summary of the most common chemical descriptors (InChI Key and SMILES codes) for Terephthalic Acid are summarized together with 3D and 2D structures and relevant physico-chemical properties.

What is the Terephthalic Acid?

The molecule Terephthalic Acid presents a molecular formula of C₈H₆O₄ and its IUPAC name is terephthalic acid.

Terephthalic acid (TPA) is an organic compound with the formula C6H4(CO2H)2. It is a white solid that is a precursor to many important chemicals, especially polyesters. It is produced on a large scale as a relatively inexpensive raw material for the production of polyethylene terephthalate (PET), a polyester used as a polymer resin in the production of synthetic fibers and containers for beverages, foods, and other consumer products. .

TPA is produced by the catalytic oxidation of p-xylene or dimethyl terephthalate: .

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

TPA can also be prepared by the catalytic reduction of terephthaloyl chloride with hydrogen:.

C6H4(COCl)2 + 2 H2 → C6H4(CO2H)2 + 2 HCl.

The main use of TPA is in the production of PET. In this process, TPA is reacted with ethylene glycol to give diethylene glycol, which is then reacted with further TPA to give the polyester. .

2 C6H4(CO2H)2 + 2 HOCH2CH2OH → 2 HOCH2CH2OOCCH2CH2OOC6H4(CO2H)2.

This polyester can be further processed to give the final product..

TPA is also used as an intermediate in the production of alkyd resins, which are used as coatings and in the manufacture of inks and adhesives. It is also used in the production of dyes, pigments, and pharmaceuticals..

3D structure

Cartesian coordinates

Geometry of Terephthalic Acid in x, y and z coordinates (Å units) to copy/paste elsewhere. Generated with Open Babel software.

2D drawing

Molecule descriptors

Other names (synonyms)

IUPAC nomenclature provides a standardized method for naming chemical compounds. Although this system is widely used in chemistry, many chemical compounds have also other names commonly used in different contexts. These synonyms can come from a variety of sources and are used for a variety of purposes.

One common source of synonyms for chemical compounds is the common or trivial names, assigned on the basis of appearance, properties, or origin of the molecule.

Another source of synonyms are historical or obsolete names employed in the past, however replaced nowadays by more modern or standardized names.

In addition to common and historical names, chemical compounds may also have synonyms that are specific to a particular field or industry.

Reference codes for other databases

• CAS number (Chemical Abstracts Service Registry Number) is a unique identifier is assigned to every chemical compound indexed in the CAS database.
• Beilstein: The Beilstein database is a comprehensive source of information on organic chemistry, including information on chemical structures, properties, and reactions. The Beilstein database assigns unique identifiers which can be used to identify compounds in scientific literature and other sources.
• ChEBI (Chemical Entities of Biological Interest): ChEBI is a database of small chemical molecules that are of interest in the field of biology.
• PubChem CID (Compound Identifier): PubChem is a database of chemical compounds that is maintained by the National Institutes of Health (NIH).
• RTECS number (Registry of Toxic Effects of Chemical Substances): The RTECS is a database of information on the toxic effects of chemicals, including information on their structures and properties.
• ChEMBL (Compound Bioactivity Data): ChEMBL is a database of bioactivity data for small molecules, including information on their properties and structures.
• CompTox Dashboard (Environmental Protection Agency): The CompTox Dashboard is a database of information on the toxicology and environmental effects of chemicals.

Physico-Chemical properties

LogP and topological polar surface area (TPSA) values were estimated using Open Babel software.

The n-octanol/water partition coeficient (K_ow) data is applied in toxicology and drug research. K_ow values are used, to guess the environmental fate of persistent organic pollutants. High partition coefficients values, tend to accumulate in the fatty tissue of organisms. Molecules with a log(K_ow) (or LogP) greater than 5 are considered to bioaccumulate.

TPSA values are the sum of the surface area over all polar atoms or molecules, mainly oxygen and nitrogen, also including hydrogen atoms.

In medicinal chemistry, TPSA is used to assess the ability of a drug to permeabilise cells.

For molecules to penetrate the blood-brain barrier (and act on receptors in the central nervous system), TPSA values below 90 Ų are required. Thus, molecules with a polar surface area greater than 140 Ų tend to be poorly permeable to cell membranes.