Measurement of Octanol−Air Partition Coefficients for Polycyclic Aromatic Hydrocarbons and Polychlorinated Naphthalenes

Abstract

Measurements of the octanol−air partition coefficient, K OA, are reported for 4 polycyclic aromatic hydrocarbons (PAHs) and 24 polychlorinated naphthalenes (PCNs) as a function of temperature over the range (0 to 50) °C. Results for PAHs are within a factor of 1.5 to 2 of values calculated as the ratio of the octanol−water and air−water partition coefficients. The enthalpies of transfer from octanol to air, H, for fluorene, phananthrene and pyrene are (82.9, 75.5, and 76.3) kJ/mol, respectively. Except for fluorene, these are within the range of reported values of the enthalpy of vaporization, Δ vap H . There is also good agreement between H and the temperature coefficient for vegetation-atmosphere partitioning ( Q D ). Correlations of log K OA against log vapor pressure ( p o ) are compared with previous results for polychlorinated biphenyls (PCBs). Values of log K OA for PCNs show a stepwise change and increase by more than 3 orders of magnitude from the 2-Cl to 6-Cl homologue groups.