Xylenes are any one of three isomers of dimethylbenzene, or a combination thereof. All are colorless, flammable liquids composed of a central benzene ring with two methyl groups attached at substituents. They can be applied as precursor chemicals and solvents.

Xylenes are flammable petrochemical products that can be produced via catalytic reforming and coal carbonization during coke production and found in crude oil, gasoline, and aircraft fuel. Xylenes were first isolated from wood tar and named by the French chemist Auguste Cahours.

What Is Xylene?

Xylene, more appropriately called xylenes, refers to any single or combination of the three isomers of dimethylbenzene. The isomeric forms are designated as ortho- (o-), meta- (m-), and para- (p-), a reference to the carbon in the benzene ring to which the two methyl groups are attached.

• o-isomer: 1,2-dimethylbenzene
• m-isomer: 1,3-dimethylbenzene
• p-isomer: 1,4-dimethylbenzene

Xylenes are colorless and can be detected by odor at concentrations as low as 0.08 to 3.7 ppm in air and tasted in water at 0.53 to 1.8 ppm.

Refer to the Certificate of Analysis or the Safety Data Sheet for specific information about xylene density and safety hazards.

What Is Xylene Used For?

Industrial Uses

p-Xylene is a precursor to terephthalic acid and dimethyl terephthalate, used to make polyethylene terephthalate plastic bottles and polyester clothing.

Xylene can be used as a solvent and is a common component of ink, rubber, adhesives, and paint and varnish thinners. Xylenes may be used to clean steel, silicon wafers, and integrated circuits. Medical applications include use as a solvent of dental materials and ear wax.

Laboratory Uses

Xylene can be used with dry ice in baths, to remove oil from microscope objectives, and as a cleaning agent or mounting material in histology procedures.