Uncertainties in Solubility Calculations

A Novel Technique To Predict the Solubility of Planar Molecules

“…In particular, the lower experimental values of the solubility should be regarded as “order of magnitude” estimations. Therefore, our degree of uncertainty in determining the solubility is not uncommon: different computational or phenomenological methodologies applied to different kind of systems, from salts to organic solids, can only predict critical solubility values within an error in the range 10–50%. − With this in mind, we can say that our theoretical method provides very good accuracy considering the computationally cheap character of the method. Using a single empirical parameter for the whole set of PAH molecules, and from the results of an umbrella-sampling molecular dynamics simulation with just two solute molecules in the solvent, we obtain a rather accurate prediction for a property that changes over 3 orders of magnitude.…”

“…Despite its simple definition, the accurate calculation of solubilities is a considerable challenge because the solubility depends exponentially on a free-energy difference. The challenge of predicting and accounting for solubilities of pairs of substances is also an experimental one, and recent efforts in collecting disperse and, in many instances, inaccurate data are being carried out by several groups and institutions. , Not surprisingly, uncertainties in theoretical predictions are typically large and can be as high as 50% and need to be handled with care, particularly for sparingly soluble substances, like large PAHs as clearly shown in the recent compilation of ref (see Figure 1 therein). The number of theoretical models aimed at predicting the solubility behavior of an organic solid in a solvent is not very large.…”