Chemistry:O-Xylene

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o-Xylene
Skeletal formula
Space-filling model
Names
Preferred IUPAC name
1,2-Xylene[1]
Systematic IUPAC name
1,2-Dimethylbenzene[1]
Other names
o-Xylene,[1] o-Xylol
Identifiers
3D model (JSmol)
1815558
ChEBI
ChEMBL
ChemSpider
DrugBank
EC Number
  • 202-422-2
67796
KEGG
RTECS number
  • ZE2450000
UNII
UN number 1307
Properties
C8H10
Molar mass 106.168 g·mol−1
Appearance Colorless liquid
Density 0.88 g/ml
Melting point −24 °C (−11 °F; 249 K)
Boiling point 144.4 °C (291.9 °F; 417.5 K)
0.02% (20°C)[2]
Solubility in ethanol very soluble
Solubility in diethyl ether very soluble
Vapor pressure 7 mmHg (20°C)[2]
-77.78·10−6 cm3/mol
1.50545
Viscosity 1.1049 cP at 0 °C
0.8102 cP at 20 °C
Structure
0.64 D[3]
Hazards
Main hazards Mildly toxic
Safety data sheet External MSDS
GHS pictograms GHS02: FlammableGHS07: HarmfulGHS08: Health hazard
GHS Signal word Danger
H225, H226, H304, H305, H312, H315, H319, H332, H335, H412
P210, P233, P240, P241, P242, P243, P261, P264, P271, P273, P280, P301+310, P302+352, P303+361+353, P304+312, P304+340, P305+351+338, P312, P321, P322, P331, P332+313, P337+313, P362, P363
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 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
3
2
0
Flash point 32 °C (90 °F; 305 K)
463 °C (865 °F; 736 K)[4]
Explosive limits 0.9%-6.7%[2]
100 ppm[4] (TWA), 150 ppm[4] (STEL)
Lethal dose or concentration (LD, LC):
4300 mg/kg (rats, orally)[5]
6125 ppm (rat, 12 hr)
6125 ppm (human, 12 hr)[6]
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]
Related compounds
m-xylene
p-xylene
toluene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Tracking categories (test):

o-Xylene (ortho-xylene) is an aromatic hydrocarbon with the formula C6H4(CH3)2, with two methyl substituents bonded to adjacent carbon atoms of a benzene ring (the ortho configuration). It is a constitutional isomer of m-xylene and p-xylene, the mixture being called xylene or xylenes. o-Xylene is a colourless slightly oily flammable liquid.[7]

Production and use

Petroleum contains about one weight percent xylenes. Most o-xylene is produced by cracking petroleum, which affords a distribution of aromatic compounds, including xylene isomers. m-Xylene is isomerized to o-xylene. Net production was approximately 500,000 tons in the year 2000.

o-Xylene is largely used in the production of phthalic anhydride, which is a precursor to many materials, drugs, and other chemicals.[7] Related to their easy oxidation, the methyl groups are susceptible to halogenation. When treated with elemental bromine, these groups are brominated, yielding xylylene dibromide:[8]

C6H4(CH3)2 + 2 Br2 → C6H4(CH2Br)2 + 2 HBr

Toxicity and exposure

Xylenes are not acutely toxic, for example the -1">50 (rat, oral) is 4300 mg/kg. Effects vary with animal and xylene isomer. Concerns with xylenes focus on narcotic effects.[7]

References

  1. 1.0 1.1 1.2 Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 121, 139, 653. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4. 
  2. 2.0 2.1 2.2 2.3 2.4 2.5 NIOSH Pocket Guide to Chemical Hazards. "#0668". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0668.html. 
  3. Rudolph, H.D.; Walzer, K.; Krutzik, Irmhild (1973). "Microwave spectrum, barrier for methyl rotation, methyl conformation, and dipole moment of ortho-xylene". Journal of Molecular Spectroscopy 47 (2): 314. doi:10.1016/0022-2852(73)90016-7. Bibcode1973JMoSp..47..314R. 
  4. 4.0 4.1 4.2 "o-Xylene". International Chemical Safety Cards. ICSC/NIOSH. July 1, 2014. https://www.cdc.gov/niosh/ipcsneng/neng0084.html. 
  5. O-xylene toxicity
  6. "Xylene (o-, m-, p-isomers)". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/idlh/95476.html. 
  7. 7.0 7.1 7.2 Fabri, Jörg; Graeser, Ulrich; Simo, Thomas A. (2000). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_433. 
  8. Emily F. M. Stephenson (1954). "o-Xylylene Dibromide". Organic Syntheses 34: 100. doi:10.15227/orgsyn.034.0100.