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ESTIMATION OF WATER SOLUBILITY AND OCTANOL/WATER PARTITION COEFFICIENT OF HYDROPHOBIC DYES - PART I. RELATIONSHIP BETWEEN SOLUBILITY AND PARTITION COEFFICIENT
Citation:
Baughman, G. AND E. Weber. ESTIMATION OF WATER SOLUBILITY AND OCTANOL/WATER PARTITION COEFFICIENT OF HYDROPHOBIC DYES - PART I. RELATIONSHIP BETWEEN SOLUBILITY AND PARTITION COEFFICIENT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-91/295 (NTIS PB92124320).
Description:
Three regression approaches are examined for use in estimating water solubilities and octanol/water partition coefficients, two fundamental equilibrium constants that are widely used predicting the fate of organic chemicals in aquatic systems. pproaches examined are regression of solubility against partition coefficient, determination of the product of solubility and partition coefficient, and application from Yalkowsky and Valvani (J. Pharm. Sci. 69 (1980) 912). he regressions are based on data for water solubility, octanol/water partition coefficient, entrophy of fusion, and melting point of 20 disperse and solvent dyes. n this study, all three methods produced more reliable data on dyes than other equations available in the literature. oot-mean-square deviations are on the order of a factor of four to six for all three methods. actors such as purity, polymorphism, tautomerization, polarization and hydrogen bonding are suggested as factors precluding the development of highly reliable prediction relationships between solubility and partition coefficient of dyes. ources of error in both the data and methodologies are discussed. he study also provided information on entrophies of fusion, which ranges from 50.7 to 136 and averaged 78.8 J/mol K. nthraquinone dyes exhibited much lower entrophies of fusion than did azo dyes. hus, use of an average entropy in estimation is inappropriate for dyes and leads to more error than neglecting the change in heat capacity.