m-Xylene

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]

m-Xylene
Skeletal formula
Space-filling model
Names
Preferred IUPAC name
1,3-Xylene[1]
Systematic IUPAC name
1,3-Dimethylbenzene
Other names
m-Xylene,[1] meta-Xylol
Identifiers
3D model (JSmol)
605441
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.252
EC Number
  • 203-576-3
101390
KEGG
RTECS number
  • ZE2275000
UNII
UN number 1307
  • InChI=1S/C8H10/c1-7-4-3-5-8(2)6-7/h3-6H,1-2H3 Y
    Key: IVSZLXZYQVIEFR-UHFFFAOYSA-N Y
  • Cc1cccc(c1)C
  • CC1=CC(C)=CC=C1
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 °C
0.6200 cP at 20 °C
0.33-0.37 D[3]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
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)
1
3
0
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):
PEL (Permissible)
TWA 100 ppm (435 mg/m3)[2]
REL (Recommended)
TWA 100 ppm (435 mg/m3) ST 150 ppm (655 mg/m3)[2]
IDLH (Immediate danger)
900 ppm[2]
Safety data sheet (SDS) External MSDS
Related compounds
benzene
toluene
o-xylene
p-xylene
Supplementary data page
M-Xylene (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Production and use

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.

Toxicity and exposure

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]

See also

  • Tetrachloro-m-xylene

References

  1. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 139. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
  2. NIOSH Pocket Guide to Chemical Hazards. "#0669". National Institute for Occupational Safety and Health (NIOSH).
  3. DeanHandb, Lange´s Handbook of chemistry, 15th edition,1999.
  4. "m-Xylene". International Chemical Safety Cards. IPCS/NIOSH. July 1, 2014. Archived from the original on December 5, 2017. Retrieved September 9, 2017.
  5. "Xylene (o-, m-, p-isomers)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  6. Fabri, Jörg; Graeser, Ulrich; Simo, Thomas A. (2000). "Xylenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_433.
  7. EPA-454/R-93-048 Locating and estimating air emissions from sources of xylene Emission Inventory Branch Technical Support Division Office of Air Quality Planning and Standards U.S. Environmental Protection Agency March 1994
  8. Ashford's Dictionary of Industrial Chemicals, third edition, page 9692.
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