Chlorophenols and alkylphenols: A review and correlation of environmentally relevant properties and fate in an evaluative environment

Abstract

A review is presented of the physical-chemical properties of the chlorophenols and alkyl phenols, including acid dissociation constant, aqueous solubility, vapour pressure, octanol-water partition coefficient, Henry's law constant or air-water partition coefficient, bioconcentration factor and sorption partition coefficient. Graphical, rather than numerical correlations are presented of these properties, using additive LeBas molar volume as a molecular descriptor. Fairly reliable quantitative structure-property relationships are shown to exist which can be used for predictive purposes. The fates of selected chemicals in an evaluative environment are also described, including the estimated effect of pH on environmental partitioning. In general, the phenols tend to be primarily associated with soils and water and have persistencies controlled by degradation rates in these media. They are not subject to appreciable evaporation because of their low air-water partition coefficients. As pH increases, the tendency of dissociation increases, especially for phenols of relatively low pK, such as pentachlorophenol. The net effect is to enhance transport from air to soil and water, to reduce partitioning from water to sediment and to cause a slight overall reduction in persistence. There is little effect on fate in soil. The overall effect of pH change is quite complex and requires careful scrutiny of multimedia model results. It is recommended that the dependence of organic carbon-water, lipid-water, and octanol-water partitioning on pH and the presence of cations other than H + be more thoroughly investigated and the degradation rates of these compounds in soil and water be determined, especially at high concentrations.