What Is Xylene?
Xylene is a clear, colorless, aromatic oily liquid with the chemical formula C6H4(CH3)2 and a molecular weight of 106.17. It’s known as dimethylbenzene and is pronounced “xylin” in both the United Kingdom and the United States. Xylene has three isomers: ortho, meta, and para, distinguished by their unique CAS numbers: 95-47-6, 108-38-3, and 106-42-3, respectively.
Uses of Xylenes
Xylenes serve various industrial applications, primarily in isomerization to ortho and para isomers for use in plasticizers and pigments for plastics. The meta isomer is a key raw material for isophthalic acid, contributing to polyester resin production. Para-xylene is used for terephthalic acid and dimethyl terephthalate, essential in plastics and clothing fibers. Mixed xylenes, produced with ethylbenzene, find applications in paints and thinners. Due to regulatory considerations, especially concerning ethylbenzene, careful handling is advised.
Properties of Xylenes
The melting points of xylene isomers vary, with -25 °C (-13 °F) for ortho, -48 °C (-54.4 °F) for meta, and 13 °C (55.4 °F) for para. Their boiling points are similarly close: 144 °C (291.2 °F), 139 °C (282.2 °F), and 138 °C (280.4 °F), respectively. Xylene is practically insoluble in water but dissolves in ether and ethanol, showcasing its utility as a solvent in various industrial processes.
Other Information on Xylene
1. Manufacturing Process of Xylene
Xylene is produced by methylation of toluene and benzene. The composition of commercial or laboratory-grade xylene typically includes a significant portion of o-xylene, with m-xylene, p-xylene, and ethylbenzene also present. Advanced methods allow for adjusting isomer ratios to favor high-value p-xylene.
2. Reaction of Xylene
Xylene undergoes reactions involving both methyl groups and ring C-H bonds, leading to products used in various chemical processes, including the production of dicarboxylic acids, dinitriles, and compounds used in tear gas.
3. Legal Information and Handling Precautions
Under multiple laws and regulations, xylene is classified as a hazardous substance, requiring specific labeling and precautions during handling and storage. It is imperative to use protective gear and ensure proper ventilation when working with xylene to prevent health risks.