Hansen Solubility Parameters
Formal steps in the solution process: Removing a solvent molecule from solution costs energy, the heat of vaporisation = Hvap and leaves an empty space, the molar volume = Vm
Hvap/Vm = Cohesive Energy Density (CED) is a characteristic solvent property. Hansen solubility parameters (HSP) divide Cohesive Energy Density into 3 important intermolecular forces.
- Dispersion (D), the nonpolar interactions
- Polarity (P), the permanent dipole molecular interactions
- Hydrogen bonding (H), electron interchange molecular interactions
The parameters describe a 3 dimensional space (HSP space) with defined positions for every solvent and substrate. If a substrate S is good soluble in a solvent their HSPs are very similar and they are close neighbours in the HSP space. Good solvents (green) have low distance to the substrate S and bad solvents (red) have high distance. Relative solubilities of the substrate in different solvents can be ranked according to the solvent/substrate distance in the HSP space.
HSP basics and applications are explained on the homepage of Dr. Charles Hansen (left). The power of HSP has been made available via an eBook, software and dataset package in cooperation with Prof. Steven Abbott (middle) and Dr. Hiroshi Yamamoto (right).