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.[5]

m-Xylene
Skeletal formula
Space-filling model
Names
Preferred IUPAC name
1,3-Xylene
Systematic IUPAC name
3-Methyltoluene
Other names
m-Xylene
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.252
KEGG
RTECS number
  • ZE2275000
UNII
Properties
C8H10
Molar mass 106.16 g/mol
Appearance Colorless liquid
Density 0.86 g/mL
Melting point −48 °C (−54 °F; 225 K)
Boiling point 139 °C (282 °F; 412 K)
insoluble
Solubility in ethanol miscible
Solubility in diethyl ether miscible
Vapor pressure 9 mmHg (20°C)[1]
-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[2]
Hazards
Main hazards Harmful or fatal if swallowed. Vapor harmful. Flammable liquid and vapor.
Safety data sheet See: data page
External MSDS
R-phrases (outdated) R10 R20 R21 R38
S-phrases (outdated) S25
NFPA 704 (fire diamond)
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
1
0
Flash point 27 °C (81 °F; 300 K) [3]
527 °C (981 °F; 800 K)[3]
Explosive limits 1.1%-7.0%[1]
100 ppm[3] (TWA), 150 ppm[3] (STEL)
Lethal dose or concentration (LD, LC):
2010 ppm (mouse, 24 hr)
8000 ppm (rat, 4 hr)[4]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 100 ppm (435 mg/m3)[1]
REL (Recommended)
 TWA 100 ppm (435 mg/m3) ST 150 ppm (655 mg/m3)[1]
IDLH (Immediate danger)
 900 ppm[1]
Related compounds
benzene
toluene
o-xylene
p-xylene
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
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.[6]

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.[7][5] 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.[5]

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See also

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0669". National Institute for Occupational Safety and Health (NIOSH).
  2. DeanHandb, Lange´s Handbook of chemistry, 15th edition,1999.
  3. "m-Xylene". International Chemical Safety Cards. IPCS/NIOSH. July 1, 2014. Archived from the original on December 5, 2017. Retrieved September 9, 2017.
  4. "Xylene (o-, m-, p-isomers)". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. Fabri, Jörg; Graeser, Ulrich; Simo, Thomas A. (2000). "Xylenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_433.
  6. 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
  7. Ashford's Dictionary of Industrial Chemicals, third edition, page 9692.
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