paraxyleen

Para-xylene, or p-xylene, is an aromatic hydrocarbon and one of the three xylene isomers. It features a benzene ring with two methyl groups in the para (1,4-) positions. Its formula is C8H10. It is a colorless, flammable liquid with limited water solubility.

Industrial p-xylene is produced from petroleum-derived streams as part of the xylene fraction. Major routes include catalytic reforming to yield toluene and xylenes, followed by toluene disproportionation and xylene isomerization to enrich the p-xylene fraction. Separation from other isomers uses fractional distillation and selective adsorption.

Para-xylene is the principal feedstock for terephthalic acid production, via oxidation. Terephthalic acid is the monomer for polyethylene terephthalate (PET), used in bottles, fibers, and packaging. p-Xylene is also employed as a solvent in some industrial processes.

p-Xylene has a boiling point around 138 C. It is nonpolar and largely immiscible with water, with moderate vapor pressure. It is flammable and can cause dizziness or irritation on exposure; proper handling and ventilation are required.

Environmental and safety notes: spills should be contained to minimize soil and water contamination. Waste streams are treated to reduce emissions. Occupational exposure limits apply; use personal protective equipment and standard fire controls appropriate for volatile aromatic hydrocarbons.