Estimating the aqueous solubilities of individual chlorinated n-alkanes (C10-C12) from measurements of chlorinated alkane mixtures

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Environmental Toxicology and Chemistry





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Water solubilities of several chlorinated n-alkanes, with carbon chain lengths ranging from C10 to C12, were determined from simple synthetic mixtures because few of these compounds are available in pure form. The apparent solubilities (S'(w)) of several chlorinated n-decanes in the mixture were determined using the generator column technique. To assess the effect of the mixture on S'(w), the aqueous solubility and activity coefficient (γ(org)) of a reference compound, 1,10-dichlorodecane, were determined as a function of its mole fraction in the same synthetic mixture. The mixture exhibited a cosolute effect on the solubility of dichlorodecane, with apparent solubilities decreasing linearly with decreasing mole fraction. The results were used to correct the apparent solubilities of tetra- and pentachlorodecanes determined from the synthetic mixture, thereby providing estimates of the true subcooled-liquid aqueous solubilities of these compounds. The solubilities of polychlorinated decane, undecane, and dodecane congeners were also estimated using subcooled-liquid vapor pressures and Henry's law constants determined from previous experiments. The two methods yielded comparable estimates, within a factor of 1.5, of the true solubilities of polychlorinated decanes. Water solubilities for selected chlorinated n-alkane congeners among the three carbon chain lengths ranged from 22.4 to 975 μg/L and showed a trend of increasing solubility with increasing degree of chlorination to chlorine number five. The data, providing some of the first physical properties of individual isomers of C10 to C12 polychlorinated n-alkanes, may be useful in assessing the environmental behavior of chlorinated paraffins in general.