Terephthaloyl chloride

Terephthaloyl chloride (TCL, 1,4-benzenedicarbonyl chloride) is the acyl chloride of terephthalic acid. It is a white solid. It is one of two precursors used to make Kevlar, the other being p-phenylenediamine. TCL is used as a key component in performance polymers and aramid fibers, where it imparts flame resistance, chemical resistance, temperature stability, light weight, and very high strength. TCL is also an effective water scavenger, used to stabilize isocyanates and urethane prepolymers.

Terephthaloyl chloride
Skeletal formula
Ball-and-stick model of the terephthaloyl chloride molecule
Names
Preferred IUPAC name
Benzene-1,4-dicarbonyl dichloride[1]
Other names
Terephthaloyl dichloride[1]
1,4-Benzenedicarbonyl chloride
Benzene-1,4-dicarbonyl chloride
Terephthalic acid dichloride
Terephthaloyl dichloride
p-Phthalyl chloride
TCL
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.002.572
UNII
  • InChI=1S/C8H4Cl2O2/c9-7(11)5-1-2-6(4-3-5)8(10)12/h1-4H checkY
    Key: LXEJRKJRKIFVNY-UHFFFAOYSA-N checkY
  • InChI=1/C8H4Cl2O2/c9-7(11)5-1-2-6(4-3-5)8(10)12/h1-4H
    Key: LXEJRKJRKIFVNY-UHFFFAOYAY
  • O=C(Cl)c1ccc(C(Cl)=O)cc1
Properties
C8H4Cl2O2
Molar mass 203.02 g/mol
Appearance white solid
Density 1.34 g/cm3
Melting point 81.5 to 83 °C (178.7 to 181.4 °F; 354.6 to 356.1 K)
Boiling point 265 °C (509 °F; 538 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

Preparation

Terephthalic acid dichloride is produced commercially by the reaction of 1,4-bis(trichloromethyl)benzene with terephthalic acid:[2]

C6H4(CCl3)2 + C6H4(CO2H)2 → 2 C6H4(COCl)2 + 2 HCl

It can also be obtained by chlorination of dimethyl terephthalate.[3]

Use

TCL is used for making various copolymers and aramid polymers such as Heracron, Twaron and Kevlar:

The reaction of 1,4-phenyl-diamine (para-phenylenediamine) with terephthaloyl chloride yielding Kevlar
The reaction of 1,4-phenyl-diamine (para-phenylenediamine) with terephthaloyl chloride yielding Kevlar

References
  1. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 797. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
  2. Pfoertner, Karl-Heinz (2000). "Photochemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_573.
  3. EP patent 0095698, Walter Böckmann, Friedrich Brühne, Karl-August Lipper, "Verfahren zur Herstellung von Terephthalsäure- und Isophthalsäuredichlorid", published 1983-12-07, assigned to Bayer AG
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