m-Xylene
Names Preferred IUPAC name Systematic IUPAC name Other names Identifiers 605441 ChEBI ChEMBL ChemSpider ECHA InfoCard 100.003.252 EC Number 101390 KEGG RTECS number UNII UN number 1307 Properties C8H10 Molar mass 106.16 g/mol Appearance Colorless liquid Odor Aromatic in high concentrations Density 0.86 g/mL Melting point −48 °C (−54 °F; 225 K) Boiling point 139 °C (282 °F; 412 K) does not react with water Solubility in ethanol miscible Solubility in diethyl ether miscible Vapor pressure 9 mmHg (20 °C)[2] −76.56·10−6 cm3/mol 1.49722 Viscosity 0.8059 cP at 0 °C0.6200 cP at 20 °C 0.33-0.37 D[3] Hazards Occupational safety and health (OHS/OSH): Harmful if swallowed. Vapor harmful. Flammable liquid and vapor. GHS labelling: Danger H226, H302, H304, H312, H315, H318, H332 P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P301+P310, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P322, P331, P332+P313, P362, P363, P370+P378, P403+P235, P405, P501 NFPA 704 (fire diamond) Flash point 27 °C (81 °F; 300 K)[4] 527 °C (981 °F; 800 K)[4] Explosive limits 1.1%-7.0%[2] 100 ppm[4] (TWA), 150 ppm[4] (STEL) Lethal dose or concentration (LD, LC): 2010 ppm (mouse, 24 hr)8000 ppm (rat, 4 hr)[5] NIOSH (US health exposure limits): TWA 100 ppm (435 mg/m3)[2] TWA 100 ppm (435 mg/m3) ST 150 ppm (655 mg/m3)[2] 900 ppm[2] Safety data sheet (SDS) External MSDS Related compounds benzenetolueneo-xylenep-xylene Supplementary data page M-Xylene (data page)
m-Xylene (meta-xylene) is an aromatic hydrocarbon. It is one of the three isomers of dimethylbenzene known collectively as xylenes. The m- stands for meta-, indicating that the two methyl groups in m-xylene occupy positions 1 and 3 on a benzene ring. It is in the positions of the two methyl groups, their arene substitution pattern, that it differs from the other isomers, o-xylene and p-xylene. All have the same chemical formula C6H4(CH3)2. All xylene isomers are colorless and highly flammable.[6]
Petroleum contains about 1 weight percent xylenes.[7] The meta isomer can be isolated from a mix of xylenes by the partial sulfonation (to which other isomers are less prone) followed by removal of unsulfonated oils and steam distillation of the sulfonated product.
The major use of meta-xylene is in the production of isophthalic acid, which is used as a copolymerizing monomer to alter the properties of polyethylene terephthalate. The conversion m-xylene to isophthalic acid entails catalytic oxidation. meta-Xylene is also used as a raw material in the manufacture of 2,4- and 2,6-xylidine as well as a range of smaller-volume chemicals.[8][6] Ammoxidation gives isophthalonitrile.
Xylenes are not acutely toxic, for example the LD50 (rat, oral) is 4300 mg/kg. Effects vary with animal and xylene isomer. Concerns with xylenes focus on narcotic effects.[6]
- Tetrachloro-m-xylene