The ultraviolet (UV) absorption spectra, aqueous solubility, and distribution coefficients for partitioning between octanol (111875) and water were determined for phthalate esters. The compounds studied were dimethyl-phthalate (131113), diethyl-phthalate (84662), diisopropyl-phthalate (605458), dipropyl-phthalate (131168), diisobutyl-phthalate (84695), dibutyl-phthalate (84742), dipentyl-phthalate (131180), diallyl-phthalate (131179), butyl-benzyl-phthalate (85687), and diethylhexyl-phthalate (117817). The aqueous solubilities and distribution coefficients were determined at 20 degrees-C using gas chromatography or UV spectrophotometry. UV spectra were obtained in aqueous or octanol solutions using 1 centimeter cells in a UV visible spectrophotometer. The UV absorption spectra of aqueous solutions of the compounds coincided within experimental error. The absorption maxima occurred at wavelengths of 198.5, 229.5, 275.5, and 281 nanometers. The corresponding molar absorptivities were 4.54, 3.90, 3.14, and 3.1. The logarithms of the aqueous solubility data were correlated with the logarithms of the octanol and water distribution coefficients for all compounds except dipentyl-phthalate. A linear regression equation was obtained. The UV absorption maximum at 198.5 nanometers has not been previously reported.
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