Terephthaloyl chloride

Terephthaloyl chloride (TCL, 1,4-benzenedicarbonyl chloride) is the acyl chloride of terephthalic acid. It is a white solid at room temperature. 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
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
CAS Number	100-20-9 Y
3D model (JSmol)	Interactive image
ChemSpider	7207 Y
ECHA InfoCard	100.002.572
PubChem CID	7488
UNII	G247CO9608 N
CompTox Dashboard (EPA)	DTXSID7026653
InChI InChI=1S/C8H4Cl2O2/c9-7(11)5-1-2-6(4-3-5)8(10)12/h1-4H Y Key: LXEJRKJRKIFVNY-UHFFFAOYSA-N Y InChI=1/C8H4Cl2O2/c9-7(11)5-1-2-6(4-3-5)8(10)12/h1-4H Key: LXEJRKJRKIFVNY-UHFFFAOYAY
SMILES O=C(Cl)c1ccc(C(Cl)=O)cc1
Properties
Chemical formula	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 YN ?) 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