1Methyl4methylbenzene

1-Methyl-4-methylbenzene, also known by its common name p-xylene, is an organic compound with the chemical formula C8H10. It is one of three isomers of xylene, the others being o-xylene and m-xylene. In p-xylene, the two methyl groups are positioned opposite each other on the benzene ring, hence the "para" designation. It is a colorless liquid at room temperature with a sweet, aromatic odor.

p-Xylene is a significant industrial chemical. Its primary application is as a precursor in the production of terephthalic acid (TPA) and dimethyl terephthalate (DMT), which are then used to manufacture polyethylene terephthalate (PET) plastics. PET is widely used in the production of beverage bottles, food packaging, and synthetic fibers for textiles. The oxidation of p-xylene is the key step in this process.

Industrially, p-xylene is typically obtained from catalytic reforming of naphtha, a fraction of crude oil. It can also be produced through the disproportionation of toluene. Separation of the xylene isomers is often achieved through crystallization or selective adsorption processes due to their similar boiling points. Its flammability and potential health effects necessitate careful handling and storage.