Title: Xylene
CAS Registry Number: 1330-20-7
CAS Name: Dimethylbenzene
Additional Names: xylol
Molecular Formula: C8H10
Molecular Weight: 106.17
Percent Composition: C 90.50%, H 9.49%
Literature References: First isolated from a crude wood distillate: Cahours, Compt. Rend. 30, 319 (1850). Obtained from coal tar: Fittig, Ann. 153, 265 (1870). The xylene of commerce is a mixture of the three isomers o-, m- and p-xylene, the m-isomer predominating. Manuf from pseudocumene: Seubold, US 2960545 (1960 to Union Oil); by catalytic isomerization of a hydrocarbon fraction: Berger, US 3078318 (1963 to Universal Oil Prod.). Separation of isomers by clathration: Schaeffer, US 3029300 (1962 to Union Oil). Use as clearing agent: K. Kubota, J. Polym. Sci. 5, 1179 (1967); J. B. Matthews, J. Clin. Pathol. 34, 103 (1981). Toxicity data: H. F. Smyth et al., Am. Ind. Hyg. Assoc. J. 23, 95 (1962). Series of articles on toxicity: Environ. Health Perspect. 101, Suppl. 6, 115-149 (1993). Review of toxicology and human exposure: Toxicological Profile for Xylene (PB95-264404, 1995) 298 pp; of mfg processes and properties: W. J. Cannella in Kirk-Othmer Encyclopedia of Chemical Technology Suppl. (Wiley-Interscience, New York, 4th ed., 1998) pp 831-863.
Properties: Mobile, flammable liquid; d ~0.86; bp 137-140°. Flash pt 29°C. Practically insol in water. Miscible with abs alcohol, ether, and many other organic liquids.
Boiling point: bp 137-140°
Flash point: Flash pt 29°C
Density: d ~0.86
Derivative Type: m-Xylene
CAS Registry Number: 108-38-3
Properties: Colorless liquid; d415 0.8684; mp -47.4°; bp 139.3°; nD20 1.4973. Flash pt, closed cup: 81°F (27°C). Insol in water. Miscible with alcohol, ether, and many other organic solvents. LD50 orally in rats: 7.71 ml/kg (Smyth).
Melting point: mp -47.4°
Boiling point: bp 139.3°
Flash point: Flash pt, closed cup: 81°F (27°C)
Index of refraction: nD20 1.4973
Density: d415 0.8684
Toxicity data: LD50 orally in rats: 7.71 ml/kg (Smyth)
Derivative Type: o-Xylene
CAS Registry Number: 95-47-6
Properties: Colorless liquid; d420 0.8801; mp -25°; bp 144°; nD20 1.5058. Flash pt, closed cup: 90°F (32°C). Insol in water. Miscible with alc, ether.
Melting point: mp -25°
Boiling point: bp 144°
Flash point: Flash pt, closed cup: 90°F (32°C)
Index of refraction: nD20 1.5058
Density: d420 0.8801
Derivative Type: p-Xylene
CAS Registry Number: 106-42-3
Properties: Colorless plates or prisms at low temp; d420 0.86104; mp 13-14°; bp 137-138°; nD20 1.49575: Thorne et al., Ind. Eng. Chem. Anal. Ed. 17, 481 (1945). Flash pt, closed cup: 81°F (27°C). Insol in water. Sol in alcohol, ether, organic solvents.
Melting point: mp 13-14°
Boiling point: bp 137-138°
Flash point: Flash pt, closed cup: 81°F (27°C)
Index of refraction: nD20 1.49575: Thorne et al., Ind. Eng. Chem. Anal. Ed. 17, 481 (1945)
Density: d420 0.86104
CAUTION: Potential symptoms of acute overexposure by inhalation to m-, o-, or p-isomers are flushing and reddening of the face, a feeling of increased heat due to dilation of superficial blood vessels, disturbed vision, dizziness, tremors, salivation, cardiac stress, drowsiness, incoordination and staggering gait, CNS depression, confusion, coma. Symptoms of chronic inhalation exposure may include respiratory irritation, CNS excitation followed by CNS depression, paresthesia, tremors, apprehension, impaired memory, weakness, nervous irritation, vertigo, headache, anorexia, nausea, flatulence, anemia, mucosal hemorrhage. Overexposure by ingestion may cause severe GI distress. Aspiration into lungs may cause chemical pneumonitis, pulmonary edema, hemorrhage. Direct contact may cause eye irritation, conjuctivitis, corneal burns; skin irritation and dermatitis due to defatting action. See Patty's Industrial Hygiene and Toxicology vol. 2B, G. D. Clayton, F. E. Clayton, Eds. (Wiley-Interscience, New York, 4th ed., 1994) p 1332-1339; NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) pp 334-337.
Use: As solvent; raw material for production of benzoic acid, phthalic anhydride, isophthalic and terephthalic acids as well as their dimethyl esters used in the manufacture of polyester fibers; manuf dyes and other organics; sterilizing catgut; with Canada balsam as oil-immersion in microscopy; clearing agent in microscope technique.
Xylenol Xylenol Blue Xylidine Xylometazoline Xylose

The xylene isomers

A xylene (from Greek ξύλο, xylo, "wood") is an aromatic hydrocarbon consisting of a benzene ring with two methyl substituents. The three isomeric xylenes each have a molecular formula of C8H10, though the more informative semi-structural formula
C6H4(CH3)2 is also used commonly. The xylenes are major petrochemicals, produced by catalytic reforming and also by coal carbonisation in the manufacture of coke fuel. Representing about 0.5–1% of crude oil (depending on the source), xylenes are found in small quantities in gasoline and airplane fuels. Xylenes are mainly produced as part of the BTX aromatics (benzene, toluene and xylenes) extracted from the product of catalytic reforming known as "reformate". The mixture is a slightly greasy, colourless liquid commonly encountered as a solvent. It was named in 1851, having been discovered as a constituent of wood tar. Several million tons are produced annually.[1] In 2011, a global consortium began construction of one of the world’s largest xylene plants in Singapore.[2]