Aromatic hydrocarbons, heats vaporization

White, C. M., Prediction of the Boiling Point, Heat of Vaporization, and Vapor Pressure at Various Temperatures for Polycyclic Aromatic Hydrocarbons. J. Chem. Eng. Data, 1986 31, 198-203. 

White, C.M. 1986. Prediction of boiling point, heat of vaporization, and vapor pressure at various temperatures for polycyclic aromatic hydrocarbons. /. Chem. Eng. Data 31 198-203. 

The Hydrocarbon Oils. These oils are the most common and least expensive. They are composed of paraffinic, naphthenic, and aromatic hydrocarbons and provide excellent sealing qualities. When these oils are properly distilled, they can exhibit low vapor pressures (10 4 to 10 6 torr). However, they oxidize quickly when heated, have a tendency to form sludge and tars, and are likely to foam if pumping against atmospheric pressure (as opposed to a vacuum). 

The vapor pressure of the super-cooled liquid is shown to be significantly higher than that of the solid, which would be expected. Melting points are usually available in the literature, however, values for the entropy of fusion, AAf are not as common. Molar heats of vaporization, AH are more likely to be listed, for example, values for this parameter have been compiled for a number of chlorinated aromatic compounds and for aromatic hydrocarbons. For many compounds it has been shown that the entropy of fusion approximates 56 J mol K , and AS/R = 6.79. ... 

Features Compat. with dimethyl silicone fluids, aliphatic and aromatic hydrocarbon soivs. good heat stability high amine-alkyl content Properties Colorless to straw, clear to hazy liq. m.w. 31,000 sp.gr. 1.00 dens. 8.0 Ib/gal vise. 6600 cSt amine no. 54 flash pt. (PMCC) > 300 F Toxicology Alkaline material prevent contact with skin, eyes avoid breathing vapors... 

The aromatic content of hydrocarbon mixture is estimated from the determination of aniline point.Aromatic hydrocarbons have the lowest and paraffins the highest aniline points. Cycloparaffins and olefins are between the two. Aniline point increases as the molecular weight increases. A mixture of specific aniline and solvent is heated at a controlled rate until it forms one phase. The mixture is then cooled and the temperature at which the miscible liquid separates into two phases is determined. Four methods are discussed in the standard suitable for transparent, non-transparent, easily vaporizing, and measured in small quantities. 

Heats of sublimation are usually difficult to measure for high-melting compounds because of their low vapor pressures. One can calculate heats of sublimation with rather good accuracy for aromatic hydrocarbons in general, but fullerene has a volume/surface ratio that is markedly different from that found with essentially all other aromatic hydrocarbons (except other fuUerenes), so that the refiabihty of this calculation is less certain here than usual. 

When coal is destmctively distilled—heated in the absence of oxygen so that it decomposes and vaporizes—its sheetlike molecules break up, and the fiagments include the aromatic hydrocarbons and their derivatives. 

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