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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.
The physical properties of the isomers of xylene differ slightly. The melting point ranges from −47.87 °C (−54.17 °F) (m-xylene) to 13.26 °C (55.87 °F) (p-xylene)—as usual, the para isomer's melting point is much higher because it packs more readily in the crystal structure. The boiling point for each isomer is around 140 °C (284 °F).
Critical point: 617 K (344 °C), 3500 kPa Std enthalpy change ... for p-Xylene/carbon tetrachloride [6] P = 760 mm Hg BP Temp. °C % by mole carbon tetrachloride
Boiling point (°C) K b (°C⋅kg/mol) Freezing point (°C) K f (°C⋅kg/mol) Data source; Aniline: 184.3 3.69 ... Xylene: 140.0 [32] See also. Freezing-point ...
This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture.
Likewise, the para-xylene consumption showed unprecedented growth in 2010, growing by 2,800,000 tons, a full ten percent growth from 2009. [ 1 ] Toluene is also a valuable petrochemical for use as a solvent and intermediate in chemical manufacturing processes and as a high octane gasoline component.
Parylene was discovered in 1947 by Michael Szwarc as one of the thermal decomposition products of para-xylene H 3 C − C 6 H 4 − CH 3 above 1000 °C. Szwarc identified para-xylylene as the precursor by observing that reaction with iodine yielded para-xylylene di-iodide as the only product. The reaction yield was only a few percent. [1] [2]
Although the specifics vary depending on the compound, in simple disubstituted arenes, the three isomers tend to have rather similar boiling points. However, the para isomer usually has the highest melting point, and the lowest solubility in a given solvent, of the three isomers. [1]