Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures of Polyaromatic Hydrocarbons

The vaporization enthalpies and liquid vapor pressures from T ) 298.15 K to T ) 510 K of a series of polyaromatic hydrocarbons have been measured by correlation-gas chromatography. The vaporization enthalpies measured in kJ ·mol include: biphenylene (66.4 ( 1.7), fluorene (72.4 ( 1.7), 1-methylfluorene (77.2 ( 3.6), 2-phenylindene (84.3 ( 0.7), 1-, 2-, 9-methylanthracene (87.0 ( 1.0, 84.5 ( 2.7, 88.1 ( 1.0, respectively), 1-methylphenanthrene (84.5 ( 1.4), 4H-cyclopenta(def)phenanthrene (83.4 ( 0.7), pyrene (92.4 ( 1.1), 9,10dimethylanthracene (94.5 ( 0.2), 2-ethylanthracene (91.4 ( 1.1), 2,3-benzofluorene (97.5 ( 3.9), 1,2benzanthracene (105.8 ( 1.9), 2,3-benzanthracene (106.2 ( 3.7), triphenylene (106.1 ( 3.9), p-terphenyl-d14 (99.5 ( 4.4), triphenylmethane (93.2 ( 2.2), benzo[a]pyrene (117.8 ( 1.0), benzo[e]pyrene (118.2 ( 0.3), benzo[k]fluoranthene (117.4 ( 1.1), 3,4-benzofluoranthene (116.8 ( 1.6), benzo[ghi]perylene (128.9 ( 1.5), and p-quaterphenyl (136.1 ( 1.6). Vaporization enthalpy comparisons are made with available literature values by means of a thermochemical cycle, and agreement is within the combined experimental uncertainties. Vapor pressures are compared with available experimental literature values at elevated temperatures. Good agreement is found for most compounds. Comparisons with subcooled vapor pressures at T ) 298.15 K obtained using other protocols are also made, and agreement generally is quite good.