What Is P-Xylene (CAS 106-42-3)?
P-xylene (para-xylene, PX, 1,4-dimethylbenzene, CAS 106-42-3, molecular formula C8H10) is a colorless, flammable aromatic liquid with a characteristic sweet odor. It is one of the three xylene isomers and is the most valuable of them commercially: more than 90% of p-xylene is consumed as the feedstock for purified terephthalic acid (PTA), which is then polymerized into polyethylene terephthalate (PET) for bottles, polyester fibers and films.
Key Specifications
| Item | Typical Value |
|---|---|
| Purity | 99.8% min (typical) |
| Appearance | Clear, colorless liquid |
| Boiling point | 138.4 C |
| Melting point | 13.3 C |
| Flash point | 25 C (closed cup) |
| Density (20 C) | 0.861 g/cm3 |
| UN number | 1307, Class 3, PG III |
Confirm the certificate of analysis (COA) for purity, para-xylene content, non-aromatic impurities and color before shipment.
Main Applications
PTA production: oxidation of p-xylene to terephthalic acid, the main monomer of PET.
PET downstream: bottles, food containers, polyester staple and filament fibers, films and engineering resins.
Solvent use: smaller volumes as a solvent in printing inks, paints and cleaning agents.
Buying P-Xylene in Bulk
When sourcing p-xylene in bulk, buy directly from manufacturers or specialized exporters who can provide: consistent 99.8%+ purity with COA and SDS; stable monthly supply volume; flexible packaging (ISO tanks for bulk shipping, IBC totes of about 1,000 L, and steel drums); and experience with international export documentation. Because p-xylene freezes at about 13 C, bulk storage and ISO tank transport above this temperature are required, and insulated or heated tanks are standard in cold climates. Ask the supplier about typical lead time, incoterms and port of loading before ordering.
Safety and Transport
P-xylene is a flammable liquid (GHS Flam. Liq. 3, H226) and is harmful if inhaled (H332); vapors may cause dizziness and irritation of the eyes and airways, and aspiration of the liquid can cause chemical pneumonia. Handle with adequate ventilation, grounded equipment and PPE (chemical-resistant gloves, safety goggles). Transport it as UN 1307, Class 3. Store in cool, ventilated areas away from ignition sources and strong oxidizers.
Frequently Asked Questions
Q: What is p-xylene mainly used for?
Over 90% goes to purified terephthalic acid (PTA) for PET bottles, polyester fiber and film.
Q: What purity should bulk p-xylene have?
Bulk p-xylene is typically supplied at 99.8% minimum purity, and the certificate of analysis should confirm para-xylene content, non-aromatic impurities and color before shipment.
Q: What is the difference between p-xylene and the other xylene isomers?
The three xylene isomers differ in the position of the two methyl groups on the benzene ring: p-xylene is 1,4-dimethylbenzene (para), o-xylene is 1,2-dimethylbenzene (ortho) and m-xylene is 1,3-dimethylbenzene (meta); p-xylene is the most valuable because over 90% of it is used for PTA production.
Q: What are the key specifications of p-xylene?
Typical specifications are purity 99.8% min, boiling point 138.4 C, melting point 13.3 C, flash point 25 C (closed cup) and density 0.861 g/cm3 at 20 C, with transport as UN 1307, Class 3, packing group III.
Q: How is p-xylene converted into PET?
P-xylene is oxidized to purified terephthalic acid (PTA), which is then polymerized with monoethylene glycol to produce PET for bottles, food containers, polyester staple and filament fibers, films and engineering resins.
Q: What should a buyer confirm before ordering p-xylene in bulk?
Confirm the COA and SDS, stable monthly supply volume, packaging (ISO tanks for bulk, 1,000 L IBC totes or steel drums), heated-tank capability for cold climates, lead time, incoterms and port of loading.