title: Thermochemical properties and phase behavior of halogenated polycyclic aromatic hydrocarbons.
abstract: Knowledge of vapor pressure of organic pollutants is essential in predicting their fate and transport in the environment. In the present study, the vapor pressures of 12 halogenated polycyclic aromatic compounds (PACs), 9-chlorofluorene, 2,7-dichlorofluorene, 2-bromofluorene, 9-bromofluorene, 2,7-dibromofluorene, 2-bromoanthracene, 9-chlorophenanthrene, 9-bromophenanthrene, 9,10-dibromophenanthrene, 1-chloropyrene, 7-bromobenz[a]anthracene, and 6,12-dibromochrysene, were measured using the Knudsen effusion method over the temperature range of 301 to 464 K. Enthalpies and entropies of sublimation of these compounds were determined via application of the Clausius-Clapeyron equation. The data were also compared with earlier published literature values to study the influence of halogen substitution on vapor pressure of PACs. As expected, the halogen substitution decreases vapor pressure compared with parent compounds but does not necessarily increase the enthalpy of sublimation. Furthermore, the decrease of vapor pressure also depends on the substitution position and the substituted halogen, and the di-substitution of chlorine and/or bromine decreases the vapor pressure compared with single halogen-substituted polycyclic aromatic hydrocarbons. In addition, the enthalpy of fusion and melting temperature of these 12 PACs were determined using differential scanning calorimetry and melting point analysis.
authors.affiliation: School of Engineering, Brown University, Providence, Rhode Island, USA. jinxia_fu@brown.edu
authors.forename: Jinxia
authors.initials: J
authors.lastname: Fu
authors.forename: Eric M
authors.initials: EM
authors.lastname: Suuberg
mesh_terms: D001551:Benz(a)Anthracenes / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D004785:Environmental Pollutants / Q000737:chemistry*; D054879:Halogenation; D044367:Phase Transition; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D055548:Vapor Pressure
chemical_list: D001551:Benz(a)Anthracenes; D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; C038901:7-bromobenzanthracene; C040345:1-chloropyrene