p-Xylene
Critical Chemical Intermediate: This compound serves as the principal precursor for terephthalic acid (PTA), dimethyl terephthalate (DMT), and polyethylene terephthalate (PET) manufacturing, forming the foundation of polyester polymer production.
Solvent Versatility: Its effectiveness as a solvation medium supports applications across pharmaceutical synthesis, fragrance compounding, and printing ink formulations.
Industrial-Scale Synthesis: Production via catalytic toluene disproportionation and xylene isomerization enables economically viable manufacturing at commercial volumes.
Physicochemical Stability: The material maintains structural integrity under standard processing conditions, with minimal aqueous solubility ensuring consistent performance in diverse industrial applications.
Paraxylene represents a fundamental organic chemical intermediate, principally employed as the primary precursor for terephthalic acid (PTA), dimethyl terephthalate (DMT), and polyethylene terephthalate (PET) synthesis—the essential building block for polyester manufacturing. Additionally, it functions as an industrial solvent and raw material for pharmaceutical compounds, fragrance ingredients, printing ink formulations, and related chemical products.
Parameters
Melting point | 12-13 °C (lit.) |
Boiling point | 138 °C (lit.) |
density | 0.861 g/mL at 20 °C (lit.) |
vapor density | 3.7 (vs air) |
vapor pressure | 9 mm Hg ( 20 °C) |
refractive index | n20/D 1.495(lit.) |
Fp | 77 °F |
storage temp. | Store at +5°C to +30°C. |
solubility | water: soluble0.2g/L |
form | Liquid |
pka | >15 (Christensen et al., 1975) |
color | Colorless |
Relative polarity | 0.074 |
Odor | Like benzene; characteristic aromatic. |
Odor Threshold | 0.058ppm |
explosive limit | 1.1-7%(V) |
Water Solubility | Miscible with alcohol, ether, acetone, benzene and chloroform. Immiscible with water. |
λmax | λ: 294 nm Amax: 1.00 |
Merck | 14,10081 |
BRN | 1901563 |
Henry's Law Constant | 16.1 at 45.00 °C, 18.6 at 50.00 °C, 20.3 at 55.00 °C, 23.4 at 60.00 °C, 30.5 at 70.00 °C (static headspace-GC, Park et al., 2004) |
Exposure limits | TLV-TWA100 ppm (～434 mg/m3) (ACGIH, MSHA, and OSHA); STEL 150 ppm (～651 mg/m3) (ACGIH); ceiling 200 ppm/ 10 min (NIOSH); IDLH 1000 ppm (NIOSH). |
Dielectric constant | 2.6（20℃） |
Stability: | Stable. Incompatible with oxidizing agents. Hygroscopic. Flammable. |
InChIKey | URLKBWYHVLBVBO-UHFFFAOYSA-N |
LogP | 3.16 at 20℃ |
Surface tension | 28.11mN/m at 298.15K |
CAS DataBase Reference | 106-42-3(CAS DataBase Reference) |
EPA Substance Registry System | p-Xylene (106-42-3) |
Safety Information
Hazard Codes | Xn,T,F |
Risk Statements | 10-20/21-38-39/23/24/25-23/24/25-11 |
Safety Statements | 25-45-36/37-16-7 |
RIDADR | UN 1307 3/PG 3 |
OEB | A |
OEL | TWA: 100 ppm (435 mg/m3), STEL: 150 ppm (655 mg/m3) |
WGK Germany | 2 |
RTECS | ZE2625000 |
Autoignition Temperature | 984 °F |
TSCA | Yes |
HazardClass | 3 |
PackingGroup | III |
HS Code | 29024300 |
Hazardous Substances Data | 106-42-3(Hazardous Substances Data) |
Toxicity | LD50 orally in Rabbit: 3910 mg/kg |
Globally, China maintains the dominant position in both production capacity and consumption volume for paraxylene. While traditional production relied on petroleum-derived aromatics from naphtha catalytic reforming, contemporary industrial practice has shifted toward optimized aromatics conversion technologies. Modern manufacturing predominantly utilizes toluene and C9 aromatic fractions as feedstocks, implementing integrated processes including toluene disproportionation, transalkylation, xylene isomerization, toluene-methanol alkylation, and selective adsorption separation to achieve industrial-scale paraxylene production.
