Predicting logarithmic values of the subcooled liquid vapor pressure of halogenated persistent organic pollutants with QSPR: How different are chlorinated and brominated congeners?

Logarithmic values of the subcooled liquid vapor pressure (log PL) were estimated for 1436 polychlorinated and polybrominated congeners of benzenes, biphenyls, dibenzo-p-dioxins, dibenzofurans, diphenyl ethers and naphthalenes by employing the Quantitative Structure–Property Relationships (QSPR) approach. The QSPR model developed with GA–PLS technique was characterized by satisfactory goodness-of-fit, robustness and the external predictive performance (R2Y = 0.970, QCV2 = 0.970, QExt2 = 0.966, RMSEC = 0.21, RMSECV = 0.22 and RMSEP = 0.22). The externally validated model has been applied to predict subcooled liquid vapor pressure of uninvestigated halogenated persistent organic pollutants. Moreover, a simple arithmetic relationship between logarithmic values of subcooled liquid vapor pressures in pairs of chloro- and bromo-analogues has been found. This relationship can be used for estimating log PL of a brominated compound, whenever log PL of its chlorinated counterpart is known, without necessity of performing any time-consuming computations.