It is a mixture of three structural isomers: ortho-xylene (o-xylene), meta-xylene (m-xylene), and para-xylene (p-xylene), each with distinct industrial applications. Classified as a Class 3 Flammable Liquid (UN number 1307), xylene is also labeled as a harmful substance due to its toxicological effects on the human body.
Basic Information
| Item | Details |
| Chemical Formula | (C8H10) (isomer mixture) |
| Молекулярная масса | 106.17 g/mol |
| Appearance | Colorless transparent liquid; sweet aromatic odor |
| Key Physical Properties | Melting point: -47.4°C (mixed isomers); boiling point: 138–144°C; density: 0.86–0.87 g/cm³ (20°C); volatile; insoluble in water, miscible with ethanol, ether, acetone, and most organic solvents |
| Purity Grades | Industrial grade (≥98.5% mixed isomers); high-purity grade (≥99.9% single isomer for chemical synthesis); solvent grade (for coatings and printing) |
| Production Method | Primarily derived from petroleum refining (catalytic reforming of naphtha) and coal tar distillation; single isomers are separated via fractional distillation or crystallization |
Main Applications
Химический синтез: Single isomers are critical raw materials:
p-xylene: Produces terephthalic acid (TPA) and purified terephthalic acid (PTA), core components of polyester fibers and plastic bottles.
o-xylene: Synthesizes phthalic anhydride, used in plasticizers, resins, and dyes.
m-xylene: Manufactures isophthalic acid, for alkyd resins and coatings.
Industrial Solvent: Mixed xylene is a universal solvent in paints, coatings, adhesives, printing inks, and rubber processing; it dissolves resins, pigments, and organic polymers effectively.
Petrochemical Industry: Blended into gasoline to improve octane number and combustion efficiency.
Laboratory & Medical: Used as a solvent for sample extraction, purification, and histology (tissue processing in pathology labs).

