Second virial coefficients of polar haloalkanes - 2002

The 1975 investigation of the second virial coefficients of polar haloalkanes [AIChE J. 21 (1975) 827] demonstrated an apparent difference between polar haloalkanes and non-hydrogen bonding fluids such as ketones and ethers that had been examined earlier [AIChE J. 20 (1974) 263]. The difference was in the dependence of the polar contribution to B (second virial coefficient) on it, (reduced dipole moment). However, the 1975 observation was based on data for only three polar haloalkanes. The large number of new measurements that have been made since 1990 on chlorofluoroalkanes and, especially, the environmentally-benign hydrofluoroalkanes has made it possible to re-examine the B of polar haloalkanes. This re-examination has included the correlation of Weber [Int. J. Thermophys. 15 (1994) 46 1], which differs both in the non-polar terms and in the dependence of the polar contribution to B on mu(r). A brief examination of three non-polar compounds (Ar, n-butane, n-octane) has helped clarify the strengths and weaknesses of three non-polar correlations (Pitzer-Curl, Tsonopoulos, Weber). A definitive study of the polar contribution to B may require an improvement of the non-polar B correlation. The two different approaches to the B of polar haloalkanes (Tsonopoulos, Weber) were investigated primarily for haloalkanes with mu(r) > 100, and the conclusion was that the two approaches are roughly equivalent, with Weber possibly having an advantage when mu(r) < 50, but not for chloroalkanes. The 1975 recommendation for the dependence of the polar contribution to B on mu(r) was confirmed by the new data. A more definitive conclusion on this dependence may be realized by using molecular modeling techniques. (C) 2003 Elsevier B.V All rights reserved.