p-Xylene (CAS 106-42-3)

p-Xylene, also known as para-xylene, is an aromatic hydrocarbon compound distinguished by the presence of two methyl groups attached at the para positions on a benzene ring. This structural arrangement imparts symmetrical properties to p-xylene, making it one of the isomers of dimethylbenzene. The compound is a colorless, flammable liquid that is primarily used in the chemical industry as a precursor to terephthalic acid and dimethyl terephthalate, both of which are key intermediates in the manufacture of polyethylene terephthalate (PET) polymers used in fibers and plastic bottles. The chemical mechanisms of p-xylene in these processes involve catalytic oxidation where the methyl groups are converted into carboxyl groups, forming the terephthalic acid. In research, p-xylene′s nonpolar characteristics make it an excellent solvent for the synthesis and isolation of organic compounds, particularly those that are sensitive to polar solvents. Additionally, its stability and relatively inert nature allow it to be used in various experimental settings to study reaction kinetics and mechanisms without interfering with the process. p-Xylene is also used in the calibration of chromatographic equipment due to its well-defined boiling point and clear, sharp peaks in analysis profiles. Furthermore, it has been utilized in materials science research, especially in studies related to the behavior of organic compounds under high thermal and oxidative conditions, due to its robustness and representative structure as an aromatic hydrocarbon.