Hydrogen bond basicity defined

The hydrogen-bond donor and acceptor properties of a packing are another dimension of column selectivity. They are independent of the silanol ion-exchange activity described above, and affect the selectivity of a packing in a separate way. We have measured these properties by the relative retention between butylparaben, a hydrogen-bond donor, and dipropylphthalate. The same property, or at least a very similar property, has been called hydrogen bond basicity by Snyder.In our case, it has been defined as follows ... 

The parameters a and p indicate the capacity of a solvent to donate or accept a hydrogen bond from a solute, i.e., the solvent s hydrogen bond acidity or basicity. % is intended to reflect van der Waals-type solute-solvent interactions (dipolar, dispersion, exchange-repulsion, etc.). Equation (43) was subsequently expanded to include a term representing the need to create a cavity for the solute (and thus to interrupt solvent-solvent interactions).188 For this purpose was used the Hildebrand solubility parameter, 5, which is defined as the square root of the solvent s energy of vaporization per unit volume.189 Thus Eq. (43) becomes,190... 

Term defining hydrogen bonding at a basic site... 

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