1,4-Benzenedicarboxylic acid
[CAS# 100-21-0]

Identification

• Classification: Organic raw materials >> Carboxylic compounds and derivatives >> Cyclic carboxylic acid
• Name: 1,4-Benzenedicarboxylic acid
• Synonyms: NSC 36973; QTA; S-LOP; TA 33LP; TPA; TPA (terephthalic acid); WR 16262; p-Benzenedicarboxylic acidx
• Molecular Formula: C₈H₆O₄
• Molecular Weight: 166.13
• CAS Registry Number: 100-21-0
• EC Number: 202-830-0
• SMILES: C1=CC(=CC=C1C(=O)O)C(=O)O

Properties

• Solubility: Slightly soluble (3 g/L) (25 °C), Calc.^*
• Density: 1.51 g/cm^3**
• Melting point: 425 °C^***
• Flash point: 260 °C

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (©1994-2014 ACD/Labs)

^** ""International Chemical Safety Cards"" data were obtained from the National Institute for Occupational Safety and Health (US)

^*** Kajioka, Masahiko

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H302
Reproductive toxicity	Repr.	2	H361
Eye irritation	Eye Irrit.	2A	H319
Specific target organ toxicity - single exposure	STOT SE	3	H336

Discovery and Applications

1,4-Benzenedicarboxylic acid, also known as terephthalic acid, is an organic compound with the molecular formula C8H6O4. It was first discovered by French chemist Amédée Cailliot in the mid-19th century. Terephthalic acid is one of the three isomers of phthalic acid and is best known for its role in the production of polyethylene terephthalate (PET), a common plastic used for a variety of purposes.

1,4-Benzenedicarboxylic acid is a white crystalline powder that is slightly soluble in water but more soluble in alcohol and acetic acid. It has a melting point of 300°C and a boiling point of 402°C. The molecule consists of a benzene ring substituted with two carboxyl groups in the para position, which gives it a symmetrical structure.

The main application of 1,4-Benzenedicarboxylic acid is in the production of polyethylene terephthalate (PET). The polymerization of terephthalic acid with ethylene glycol produces PET, a versatile plastic. PET is widely used in the manufacture of beverage bottles, food containers, and synthetic fibers. Its properties, including high strength, chemical resistance, and recyclability, make it a material of choice across industries.

Terephthalic acid is a key ingredient in the production of polyester fibers. Polyester fibers derived from PET are widely used in the textile industry to make clothing, household goods, and industrial fabrics. These fibers are valued for their durability, resistance to shrinkage and stretch, and ease of care.

The compound is also used to produce high-performance engineering plastics. PET can be modified to produce engineering resins used in automotive parts, electrical components, and packaging materials. These resins have excellent mechanical properties, thermal stability, and abrasion and chemical resistance.

Terephthalic acid-based polymers are used in the film and packaging industry. PET films are used to package food, pharmaceuticals, and other consumer products. These films block moisture, oxygen, and other contaminants, extending the shelf life of the packaged products.

Terephthalic acid is used in scientific research and development. Researchers study the properties and potential applications of terephthalic acid and its derivatives to develop new materials with enhanced performance characteristics. This includes exploring its use in nanocomposites and advanced polymer blends.

While terephthalic acid is considered to have low toxicity, its production and use raise environmental concerns. The production of PET generates large amounts of plastic waste, causing pollution and environmental degradation. Efforts are underway to improve recycling technologies and develop biodegradable alternatives to reduce the environmental footprint of PET products.

References

Sergey A. Sapchenko, Danil N. Dybtsev, Denis G. Samsonenko and Vladimir P. Fedin. Synthesis, crystal structures, luminescent and thermal properties of two new metal-organic coordination polymers based on zinc(ii), New J. Chem., 2010, 34, 2445.