p-Xylene

p-Xylene

Names
Other names p-Xylol 1,4-Dimethylbenzene
Identifiers
CAS Registry Number	106-42-3 Y
ChEBI	CHEBI:27417 N
ChEMBL	ChEMBL31561 N
ChemSpider	7521 N
InChI InChI=1S/C8H10/c1-7-3-5-8(2)6-4-7/h3-6H,1-2H3 N Key: URLKBWYHVLBVBO-UHFFFAOYSA-N N InChI=1/C8H10/c1-7-3-5-8(2)6-4-7/h3-6H,1-2H3 Key: URLKBWYHVLBVBO-UHFFFAOYAE
Jmol-3D images	Image
KEGG	C06756 Y
PubChem	7809
RTECS number	ZE2625000
SMILES CC1=CC=C(C)C=C1
UNII	6WAC1O477V N
Properties
Molecular formula	C8H10
Molar mass	106.17 g·mol−1
Appearance	Colorless liquid Colorless crystalline solid
Density	0.861 g/mL
Melting point	13.2 °C (55.8 °F; 286.3 K)
Boiling point	138.35 °C (281.03 °F; 411.50 K)
Solubility in water	insoluble
Solubility in ethanol	very soluble
Solubility in diethyl ether	very soluble
Refractive index (nD)	1.49582
Viscosity	0.7385 cP at 0 °C 0.6475 cP at 20 °C
Dipole moment	0.07 D
Hazards
MSDS	External MSDS
Main hazards	Harmful or fatal if swallowed. Vapor harmful. Flammable liquid and vapor.
R-phrases	R10 R20 R21 R36 R38
S-phrases	S25
NFPA 704	3 2 0
Flash point	25 °C (77 °F; 298 K)
Explosive limits	1.1%-7.0%[1]
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 100 ppm (435 mg/m3)[1]
Related compounds
Related aromatic hydrocarbons	benzene toluene o-xylene m-xylene
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
N verify (what is: Y/N?)
Infobox references

p-Xylene is an aromatic hydrocarbon based on benzene with two methyl substituents with the chemical formula C₈H₁₀ or C₆H₄(CH₃)₂. The “p” stands for para, identifying the location of the methyl groups as across from one another. It is an isomer of xylene. Other isomers include o-xylene and m-xylene. The boiling point of p-xylene is 138.35 °C (281 °F) and the melting point is 13.2 °C (56 °F).^[2] p-Xylene is used on a large scale for the manufacture of terephthalic acid for polyester. Its polymer is known as parylene.

p-Xylene is produced by catalytic reforming of petroleum naphtha as part of the BTX aromatics (benzene, toluene and the xylene isomers) extracted from the catalytic reformate. The p-xylene is then separated out in a series of distillation, adsorption or crystallization and reaction processes from the m-xylene, o-xylene and ethylbenzene. Its melting point is the highest among this series of isomers, but simple crystallization does not allow easy purification due to the formation of eutectic mixtures. It is also highly flammable.

Nomenclature

p-Xylene is also called 1,4-dimethylbenzene, p-dimethylbenzene; p-xylol; 1,4-xylene; p-methyltoluene; para-sylene; chromar; scintillar; 4-methyltoluene; NSC 72419; 1,4-dimethyl-benzene.^[3]

Physical properties

p-Xylene is a colorless, flammable liquid that is insoluble in water with the chemical formula C₈H₁₀ or C₆H₄(CH₃)₂.^[2][4][5] p-Xylene has a boiling point of 138.35 °C (281 °F) and a melting point of 13.2 °C (56 °F). It has a specific gravity of 0.86. p-Xylene is flammable and has a flash point of 27°C (81 °F) or lower. The odor threshold of p-xylene is 0.62 parts per million (ppm).^[2]

Exposure to p-Xylene

Inhalation

Inhaling p-xylene can cause dizziness, headache, drowsiness, and nausea. If exposure through inhalation occurs, first aid includes fresh air, rest and possible medical attention. Through the use of ventilation or breathing protection, exposure to p-xylene through inhalation can be prevented.^[4]

Skin

Exposure of p-xylene through the skin can cause dry skin and redness. If skin exposure occurs, first aid includes rinsing and then washing the affected area with soap and water as well as removing any contaminated clothing and thoroughly cleaning and drying before reuse. Exposure can be prevented through the use of protective gloves.^[4]

Eyes

Exposure of p-xylene to eyes can cause redness and pain. If eyes are exposed, first aid includes rinsing of the eyes with water for several minutes, removal of contact lenses if applicable, and medical attention. Eye exposure can be prevented through the use of safety glasses or safety goggles.^[4]

Ingestion

Ingestion of p-xylene can result in a burning sensation, abdominal pain, dizziness, drowsiness, headache, and nausea. If p-xylene is ingested one's mouth should be rinsed and vomiting should NOT be induced. Further medical attention should be sought. Ingestion can be prevented by not eating, drinking, or smoking when working with p-xylene.^[4]

Short-term exposure

p-Xylene can cause issues with the central nervous system and if swallowed could cause chemical pneumonitis when breathed into the lungs.^[4]

Long-term exposure

Liquid p-xylene exposure to the skin over long periods of time can remove the fat from the skin. The substance may also have effects on the Central Nervous System. Exposure can enhance hearing loss caused by noise exposure. Animal tests suggest that this substance could cause damage to human development and reproductive systems.^[4]

Toxicity

Overexposure of p-xylene in humans can cause headache, fatigue, dizziness, listlessness, confusion, irritability, gastrointestinal disturbances including nausea and loss of appetite, flushing of the face, and a feeling of increased body heat. p-Xylene vapor exposure over the recommended exposure limit of 100 parts per million (ppm) can cause irritation to eye, nose, and throat and possible chest tightening and an abnormal gait.^[5]

References

External links

• MSDS