Data have been compiled from the published literature on the partition coefficients of solutes and vapors into anhydrous sulfolane. The logarithms of the water-to-sulfolane partition coefficients, log P, and gas-to-sulfolane partition coefficients, log K, were correlated with the Abraham solvation parameter model. The derived correlations described the observed log P and log K values for solutes dissolved in sulfolane to within average standard deviations of 0.14 log units or less. The log P correlation was extended to include the partition of ions by inclusion of a cation-solvent and an anion-solvent term.
Experimental data have been compiled from the published literature on the partition coefficients of solutes and vapors into o-xylene, m-xylene and p-xylene at 298 K. The logarithms of the water-to-xylene partition coefficients, log P, and gas-to-xylene partition coefficients, log K, were correlated with the Abraham solvation parameter model. The derived mathematical expressions described the observed log P and log K data for the three xylene isomers to within average deviations of 0.14 log units or less.
Key words and phrasesPartition coefficients, xylene solvents, Abraham model correlations ________________________________________________________________________ *To whom correspondence should be addressed. (E-mail: acree@unt.edu) 2
IntroductionLiquid-liquid extraction affords a convenient experimental means for separating synthesized organic materials from reaction solvent media, and for pre-concentrating chemicals in unknown liquid samples prior to quantitative analyses. Extraction methods are based on solute partitioning in a biphasic liquid system containing two or more solvents having limited mutual solubility. Molecular interactions between the dissolved solute(s) and surrounding extraction solvents determine the solute recovery factor and separation efficiency. Considerable attention has been given in recent years to developing methods for selecting the best biphasic partitioning system to achieve a desired chemical separation.In many previous studies [1-8], we have shown that two general linear free energy Abraham model correlations, equations 1 and 2, can be used to mathematically describe the transfer of neutral solutes from water to organic solvents and from the gas phase to organic solvents log P = c p + e p ·E + s p ·S + a p ·A + b p ·B + v p ·Vlog K = c k + e k ·E + s k ·S + a k ·A + bk·B + l k ·LThe dependent variables in eqns. 1 and 2 are the logarithm of the water-to-organic solvent partition coefficient, log P, and the logarithm of the gas-to-organic solvent partition coefficient, log K, for a series of solutes. The independent variables, or solute descriptors, are properties of the neutral solutes as follows: [9,10] E is the solute excess molar refraction in cm 3 mol -1 /10, S is the solute dipolarity/polarizability, A is the overall solute hydrogen bond acidity, B is the overall solute hydrogen bond basicity, V is McGowan's characteristic molecular volume in cm 3 mol -1 /100 and L is the logarithm of the gas to hexadecane partition coefficient measured at 298 K.
Gas-to-liquid and water-to-liquid partition coefficients have been compiled for more than 2800 different solute-solvent combinations. Solutes considered include acyclic monofunctional alkanols, dialkyl ethers, alkyl alkanoates and alkanones, as well difunctional alkoxyalcohols.Both sets of partition coefficients were analyzed using the Abraham solvation parameter model with fragment-specific equation coefficients. The derived equations correlated the experimental gas-to-alcohol and water-to-alcohol partition coefficient data to within 0.15 and 0.16 log units, respectively. The fragment-specific equation coefficients that have been calculated for the CH 3 , CH 2 , CH, C, OH, O, C(O)O and C=O fragment groups can be combined to yield expressions capable of predicting the partition coefficients of solutes in other anhydrous alkanol, dialkyl ether, alkyl alkanolate, alkanone and alkoxyalkanol solvents.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.