Linear solvation energy relationship parameters of some pure liquid organic compounds from solvatochromic investigations

The partitioning of an organic solute between an aqueous and an organic pha se is governed by the properties of the phase forming aqueous/organic syste m as well as by the properties of the solute. As organic solutes are often highly diluted in such systems the infinite dilution partition coefficient is of particular interest. Partition coefficients at infinite dilution are often described using quantitative structure-activity relationships (QSAR), e.g. the linear solvation energy relationship (LSER) method of Kamlet and coworkers. The LSER method requires five parameters for the characterizatio n of a solute j: a volume parameter nu (j), a polarity parameter pi (j), a parameter for the polarizability delta (j), and two parameters describing t he capability of the solute to undergo hydrogen bonding as a proton accepto r beta (j) (basicity parameter) and as a proton donor alpha (j) (acidity pa rameter). This contribution reports new experimental data for the polarity parameter pi (j) and the basicity parameter beta (j) of about 90 liquid org anic compounds. Such parameters can be used to predict thermodynamic proper ties such as the octanol-water partition coefficient or to develop methods for estimating such parameters. (C) 2001 Elsevier Science B.V. All rights r eserved.