title: Models for liquid-liquid partition in the system dimethyl sulfoxide-organic solvent and their use for estimating descriptors for organic compounds.
abstract: Partition coefficients for varied compounds were determined for the organic solvent-dimethyl sulfoxide biphasic partition system where the organic solvent is n-heptane or isopentyl ether. These partition coefficient databases are analyzed using the solvation parameter model facilitating a quantitative comparison of the dimethyl sulfoxide-based partition systems with other totally organic partition systems. Dimethyl sulfoxide is a moderately cohesive solvent, reasonably dipolar/polarizable and strongly hydrogen-bond basic. Although generally considered to be non-hydrogen-bond acidic, analysis of the partition coefficient database strongly supports reclassification as a weak hydrogen-bond acid in agreement with recent literature. The system constants for the n-heptane-dimethyl sulfoxide biphasic system provide an explanation of the mechanism for the selective isolation of polycyclic aromatic compounds from mixtures containing low-polarity hydrocarbons based on the capability of the polar interactions (dipolarity/polarizability and hydrogen-bonding) to overcome the opposing cohesive forces in dimethyl sulfoxide that are absent for the interactions with hydrocarbons of low polarity. In addition, dimethyl sulfoxide-organic solvent systems afford a complementary approach to other totally organic biphasic partition systems for descriptor measurements of compounds virtually insoluble in water.
authors.affiliation: Department of Chemistry, Wayne State University, Detroit, MI 48202, USA.
authors.forename: Thushara
authors.initials: T
authors.lastname: Karunasekara
authors.forename: Colin F
authors.initials: CF
authors.lastname: Poole
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D016000:Cluster Analysis; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D006536:Heptanes / Q000737:chemistry; D016014:Linear Models; D008956:Models, Chemical; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification
chemical_list: D006536:Heptanes; D011084:Polycyclic Aromatic Hydrocarbons; C028618:n-heptane; D004121:Dimethyl Sulfoxide