Definition of Koppel-Palm solvent parameters

1. Parameters to measure separately the ability of a solvent to enter into non-specific solvent-solute interactions (permittivity and refractive index nD) and specific solvent-solute interaction (solvent basicity or nucleophilicity B and solvent acidity or electrophilicity E) as contributing to overall solvent polarity. KOPPEL and PALM (1972).