Para-xylene
 |
|
 Space-filling model
|
|
| Names | |
|---|---|
|
Preferred IUPAC name
1,4-Xylene
|
|
|
Systematic IUPAC name
1,4-Dimethylbenzene
|
|
| Other names
p-Xylene
|
|
| Identifiers | |
106-42-3 
|
|
| 3D model (Jmol) | Interactive image |
| ChEBI |
CHEBI:27417 
|
| ChEMBL |
ChEMBL31561
|
| ChemSpider |
7521
|
| ECHA InfoCard | 100.003.088 |
| KEGG |
C06756
|
| PubChem | 7809 |
| RTECS number | ZE2625000 |
| UNII |
6WAC1O477V
|
|
|
|
|
| Properties | |
| C8H10 | |
| Molar mass | 106.17 g·mol−1 |
| Appearance | Colorless liquid |
| Odor | Aromatic |
| 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) |
| Insoluble | |
| Solubility in ethanol | Very soluble |
| Solubility in diethyl ether | Very soluble |
| Vapor pressure | 9 mmHg (20°C) |
| -76.78·10−6 cm3/mol | |
|
Refractive index (nD)
|
1.49582 |
| Viscosity | 0.7385 cP at 0 °C 0.6475 cP at 20 °C |
| 0.00 D | |
| Hazards | |
| Main hazards | Harmful or fatal if swallowed. Vapor harmful. Flammable liquid and vapor. |
| Safety data sheet |
See: data page External MSDS |
| R-phrases | R10 R20 R21 R36 R38 |
| S-phrases | S25 |
| NFPA 704 | |
| Flash point | 27 °C (81 °F; 300 K) |
| 528 °C (982 °F; 801 K) | |
| Explosive limits | 1.1%-7.0% |
| 100 ppm (TWA), 150 ppm (STEL) | |
| Lethal dose or concentration (LD, LC): | |
|
LC50 (median concentration)
|
4550 ppm (rat, 4 hr) |
|
LCLo (lowest published)
|
3401 ppm (mouse) |
| US health exposure limits (NIOSH): | |
|
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 |
| Related compounds | |
|
Related aromatic
hydrocarbons |
benzene toluene o-xylene m-xylene |
| Supplementary data page | |
|
Refractive index (n), Dielectric constant (εr), etc. |
|
|
Thermodynamic
data |
Phase behaviour solid–liquid–gas |
| UV, IR, NMR, MS | |
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
|
 (what is ?) |
|
| Infobox references | |
p-Xylene is an aromatic hydrocarbon. It is one of the three isomers of dimethylbenzene known collectively as xylenes. The p- stands for para-, indicating that the two methyl groups in p-xylene occupy the diametrically opposite substituent positions 1 and 4, as illustrated here in the schematic representation. It is in the positions of the two methyl groups, their arene substitution pattern, that it differs from the other isomers, o-xylene and m-xylene. Each of the three isomers has two methyl substituents attached to the benzene ring; ignoring the substitution patterns they therefore all have the same chemical formula C6H4(CH3)2. Like all xylene isomers, p-xylene is dangerously flammable.
For historical reasons, various sources refer to p-xylene as any of: 1,4-dimethylbenzene, p-dimethylbenzene; p-xylol; 1,4-xylene; p-methyltoluene; para-sylene; chromar; scintillar; 4-methyltoluene; NSC 72419; or 1,4-dimethyl-benzene. According to convenience, the chemical formula may be represented as C8H10 or C6H4(CH3)2.
p-Xylene is a colorless, flammable liquid practically insoluble in water. The boiling point is 138.35 °C (281 °F) and the melting point 13.2 °C (56 °F). Its specific gravity is 0.86.
p-Xylene is highly flammable, with a flash point of 27°C.
The odor threshold of p-xylene is 0.62 parts per million (ppm).
The production of p-xylene is industrially significant world-wide, with annual demand estimated at 37 million tons in 2014, and still on the increase.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.
...
Wikipedia