The development and determination of chemically distinct solute parameters for use in linear solvation energy relationships

Linear solvation energy relationships (LSERs) have been used to correlate hundreds of chemical systems. However, several of the solute parameters used in the LSERs do not model any one specific type of interaction, but rather are blends of multiple interactions. Thus, LSERs generated with these parameters cannot be rigorously interpreted to provide a complete understanding of the forces underlying solute-solvent interactions. In this work, the development of a new set of chemically distinct solute parameters based on Kovats retention indices on a variety of GC stationary phases is presented. The determination of the parameters does not utilize the same initial input estimates as to the values of the parameters which were used in previous studies and which were based on descriptors that reflected a blend of molecular properties. Using this new method, a set of parameters describing the dipolarity, polarizability, size, and hydrogen bond acidity of 53 compounds has been determined. The parameters are shown to be superior to older parameters in that they are chemically "purer" (i.e. are not blends of multiple interactions). The success of these new parameters in LSERs for the correlation of gas/water and water/octanol partitioning, and retention in gas chromatography is also presented.