Based on the LDL concept, Hildebrand solubility parameters (HSPs) were introduced as an useful extension for practical applications . Based on regular solution theory, the HSPs are presented by single numerical values in order to estimate the solubility of specific components in various solvents. In more detail, HSPs are calculated from the square root of the cohesive energy densities and compared for both components in a mixture. Good solubility is usually given if both HSPs are nearly comparable. Although this simple approach relies on a lot of approximations such as the regular ordering of the components on a lattice and the strict consideration of aprotic and apolar compounds , it has already gained its merits in various contexts 17 and specifically for pharmaceutical applications . This is even more surprising, as all electrostatic and dipolar interactions are ignored 20 . Despite the fact that simple approaches are attractive to estimate the solubilities, it has to be noted that real solutions reveal a plethora of complex interactions leading to ideal and non-ideal effects. Hence, it is highly questionable if a single number provides reliable estimates for good solubilities. Nevertheless, Hildebrand solubility parameters are still frequently used today as a first approach to identify suitable solvents in various combinations . In addition, many computer studies have already provided HSP values from DFT calculations, since experimental values for certain substances are usually difficult to determine .