Wiktionary
n. (context organic compound English) 1,4-benzenedicarbonyl chloride, a monomer used in polymers and aramid fibres for flame and chemical resistance, stability, and strength.
Wikipedia
Terephthaloyl chloride (TCL, 1,4-benzenedicarbonyl chloride) is the acid chloride of terephthalic acid and is one of two monomers used to make Kevlar(R), the other being p-phenylenediamine. Its CAS reference number is 100-20-9 and its chemical formula is .
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.
TCL is a white crystalline solid at room temperature, soluble in common organic solvents. Its melting point is 81.5-83 °C, its boiling point is 265 °C. It is corrosive.
TCL is used for making various copolymers and aramid polymers such as Heracron, Twaron and Kevlar(R):