o-Xylene

o-Xylene
Skeletal formula	Space-filling model
Names
	Preferred IUPAC name 1,2-Xylene
	Systematic IUPAC name 1,2-Dimethylbenzene
	Other names o-Xylene, o-Xylol
Identifiers
CAS Number	95-47-6 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	1815558
ChEBI	CHEBI:28063 ;
ChEMBL	ChEMBL45005 ;
ChemSpider	6967 ;
DrugBank	DB03029 ;
ECHA InfoCard	100.002.203
EC Number	202-422-2;
Gmelin Reference	67796
KEGG	C07212 ;
PubChem CID	7237;
RTECS number	ZE2450000;
UNII	Z2474E14QP ;
UN number	1307
CompTox Dashboard (EPA)	DTXSID3021807 ;
	InChI InChI=1S/C8H10/c1-7-5-3-4-6-8(7)2/h3-6H,1-2H3 Key: CTQNGGLPUBDAKN-UHFFFAOYSA-N ; InChI=1/C8H10/c1-7-5-3-4-6-8(7)2/h3-6H,1-2H3 Key: CTQNGGLPUBDAKN-UHFFFAOYAE;
	SMILES CC1=C(C)C=CC=C1;
Properties
Chemical formula	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)
Solubility in water	0.02% (20°C)
Solubility in ethanol	very soluble
Solubility in diethyl ether	very soluble
Vapor pressure	7 mmHg (20°C)
Magnetic susceptibility (χ)	-77.78·10−6 cm3/mol
Refractive index (nD)	1.50545
Viscosity	1.1049 cP at 0 °C; 0.8102 cP at 20 °C
Structure
Dipole moment	0.64 D
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Mildly toxic
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H226, H304, H305, H312, H315, H319, H332, H335, H412
Precautionary statements	P210, P233, P240, P241, P242, P243, P261, P264, P271, P273, P280, P301 P310, P302 P352, P303 P361 P353, P304 P312, P304 P340, P305 P351 P338, P312, P321, P322, P331, P332 P313, P337 P313, P362, P363, P370 P378, P403 P233, P403 P235, P405, P501
NFPA 704 (fire diamond)	2 3 0
Flash point	32 °C (90 °F; 305 K)
Autoignition; temperature	463 °C (865 °F; 736 K)
Explosive limits	0.9%-6.7%
Threshold limit value (TLV)	100 ppm (TWA), 150 ppm (STEL)
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	4300 mg/kg (rats, orally)
LCLo (lowest published)	6125 ppm (rat, 12 hr); 6125 ppm (human, 12 hr)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 100 ppm (435 mg/m3)
REL (Recommended)	TWA 100 ppm (435 mg/m3) ST 150 ppm (655 mg/m3)
IDLH (Immediate danger)	900 ppm
Safety data sheet (SDS)	External MSDS
Related compounds
Related aromatic hydrocarbons	m-xylene; p-xylene; toluene
Supplementary data page
	O-Xylene (data page)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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 LD₅₀ (rat, oral) is 4300 mg/kg. Effects vary with animal and xylene isomer. Concerns with xylenes focus on narcotic effects.^[7]

References

^ ^a ^b ^c 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.
^ ^a ^b ^c ^d ^e ^f NIOSH Pocket Guide to Chemical Hazards. "#0668". National Institute for Occupational Safety and Health (NIOSH).
^ 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. Bibcode:1973JMoSp..47..314R. doi:10.1016/0022-2852(73)90016-7.
^ ^a ^b ^c "o-Xylene". International Chemical Safety Cards. ICSC/NIOSH. July 1, 2014.
^ O-xylene toxicity
^ "Xylene (o-, m-, p-isomers)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b ^c Fabri, Jörg; Graeser, Ulrich; Simo, Thomas A. (2000). "Xylenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_433. ISBN 978-3527306732.
^ Emily F. M. Stephenson (1954). "o-Xylylene Dibromide". Organic Syntheses. 34: 100. doi:10.15227/orgsyn.034.0100.

[iupac2013-1] 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.

[PGCH-2] ^ ^a ^b ^c ^d ^e ^f NIOSH Pocket Guide to Chemical Hazards. "#0668". National Institute for Occupational Safety and Health (NIOSH).

[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. Bibcode:1973JMoSp..47..314R. doi:10.1016/0022-2852(73)90016-7.

[ICSC-4] "o-Xylene". International Chemical Safety Cards. ICSC/NIOSH. July 1, 2014.

[5] O-xylene toxicity

[6] "Xylene (o-, m-, p-isomers)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).

[Ullmann-7] Fabri, Jörg; Graeser, Ulrich; Simo, Thomas A. (2000). "Xylenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_433. ISBN 978-3527306732.

[8] Emily F. M. Stephenson (1954). "o-Xylylene Dibromide". Organic Syntheses. 34: 100. doi:10.15227/orgsyn.034.0100.

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