Interaction energy, hydrogen bonds

Hansen [137-139], and later van Krevelen [114] proposed the generalization of the solubility parameter concept to attempt to include the effects of strong dipole interactions and hydrogen bonding interactions. It was proposed that the cohesive energy density be written as the sum of three terms, viz. 

Dispersion forces, dipole Interactions, and hydrogen bonds all are significantly weaker than covalent Intramolecular bonds. For example, the average C—C bond energy Is 345 kJ/mol, whereas dispersion forces are just 0.1 to 5 kJ/mol for small alkanes such as propane. Dipolar Interactions between polar molecules such as ace-tone range between 5 and 20 kJ/mol, and hydrogen bonds range between 5 and 50 kJ/mol. 

In the Born equation, the ion solvent interaction energy is determined only by one physical parameter of the solvent, i.e., the dielectric constant. However, since actual ion-solvent interactions include specific interactions such as the charge-transfer interaction or hydrogen bonds, it is natural to think that the Born equation should be insufficient. It is well known that the difference in the behavior of an ion in different solvents is not often elucidated in terms of the dielectric constant. 

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