Paraxylene
Description
Paraxylene (1.4-dimethylbenzene) is a colorless, flammable liquid that has a sweet odor. It is separated from the mixed xylene stream that results from the refining of petroleum.
Properties
| Parameter | Unit | Quantity / Description |
|---|
| Molecular weight | g/mol | 106.16 |
| Appearance and odor | | liquid, clear and sweet odor |
| pH | °C at 29°C | Not determined |
| Vapor pressure | mm Hg at 20°C | 6.4 mm Hg |
| Vapor density | (air = 1.2) kg/m3 | 1.23 |
| Boiling point | °C/°F | 139°C (282°F) |
| Melting point | °C/°F | 13°C (56°F) |
| Solubility in water | | Negligible, below 0.1% |
| Specific gravity | 20°C/4°C | 0.86 |
| CAS number | 106-42-3 |
| IUPAC name | 1,4-Dimethylbenzene |
Specifications
| Parameter | Unit | Quantity | Test Method UPON/ASTM |
|---|
| Purity | wt % | 99.7 min. | UOP 720 |
| Non-aromatic | wt % | 0.2 max. | UOP 720 |
| Ethylbenzene | wt % | 0.3 max. | UOP 720 |
| Meta-xylene | wt % | 0.3 max. | UOP 720 |
| Ortho-xylene | wt % | 0.1 max. | UOP 720 |
| Benzene and toluene | ppm, wt | 0.1 max. | UOP 720 |
| Distillation range | °C | 2.0°C max., including 138.4°C | ASTM D-850 |
| Relative density | 15.56/15.56°C | 0.865 - 0.867 | ASTM D-4052 |
| Bromine index | mg/100gm | 10 max. | ASTM D-1492 |
| Acid Wash Color | | 5 max. | ASTM D-848 |
| Color | Hazen, Pt/Co Scale | 5 max. | ASTM D-1209 |
| H2S + S02 | ppm, wt | Nil | ASTM D-853 |
| Halogen | ppm, wt | 0.2 max. | UOP 395 |
| Total sulfur | ppm, wt | 0.5 max. | ASTM D-4045 |
Note:
- ASTM : American Society for Testing and Materials.
Hazards and safety
OVERVIEW: Flammable. Causes eye and skin irritation. Can be harmful if high concentrations are inhaled. Harmful or fatal if liquid is aspirated into the lungs.
HMIS CODE: (Health: 2) (Flammability: 3) (Reactivity: 0)
NFPA CODE: (Health: 2) (Flammability: 3) (Reactivity: 0)
Applications
Mostly used in manufacturing of Terephthalic Acid (PTA) and dimethyle esters which are used in polyester manufacturing.
Storage and handling
Store in clearly labeled, tightly closed, containers in a cool, well ventilated place, away from strong oxidizing materials and heat and ignition sources. During transferring operations, use electrically ground and bond metal containers. To reduce potential health hazards, use sufficient dilution or local exhaust ventilation to control airborne contaminants and to maintain concentrations at the lowest practical level. Use hermetically sealed equipment, transfer xylene in enclosed systems, avoid processes associated with open evaporating surfaces, and provide sources of gas release with enclosures and local exhaust ventilation.