10081. Xylene

Nomenclature

CAS number: 1330-20-7
Dimethylbenzene; xylol.
C8H10; mol wt 106.17.
C 90.50%, H 9.49%.

Description and 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.

Chemical structure

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.

Derivative

m-Xylene.

Nomenclature

CAS 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).

Derivative

o-Xylene.

Nomenclature

CAS 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.

Derivative

p-Xylene.

Nomenclature

CAS 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.

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.