Partitioning of active agents between polar and nonpolar phases has a key role in the early stage of drug and drug-carrier design in the pharmaceuticals industry, as well as for separation of products in biosynthesis. In the present paper, the group-contribution Universal Quasi-Chemical Functional-Group Activity Coefficient (UNIFAC) and the a priori Conductor-like Screening Model for Real Solvents (COSMO-RS) models are applied to predict micelle/water partition coefficients. The models allow predictions based only on the molecular structure. The practical implementation of the models is examined by studying several homologous series of organic solutes in aqueous solutions of non-ionic (polyethoxy alcohols) and ionic surfactants (sodium dodecyl sulfate (SDS)). Good quantitative agreement with experimental data from the literature has been achieved. Factors that seem to be important in the calculation and to influence the prediction results are discussed. Among these are interfacial contribution and conformation analysis. Compared to UNIFAC, the COSMO-RS method opens up new perspectives, because ionic components, steric isomers, and inorganics can be modeled.

Solid–liquid equilibria (SLE) of the l-menthol/thymol eutectic system were studied in detail using a combination of differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). The existence of two cocrystals with stoichiometric ratios 1:3 and 3:2 for l-menthol:thymol was monitored by performing XRD on samples of different compositions. Moreover, the existence of two solid solution regions of l-menthol in thymol and l-menthol in the 1:3 cocrystal was observed. The nonrandom two-liquid (NRTL) and two-suffix Margules models were applied to model the measured SLE data. The two eutectic points of the system were determined at T e1 cal = 271.7 K, x thymol,e1 cal = 0.48 and T e2 cal = 273.1 K, x thymol,e2 cal = 0.33. The complex character of the obtained phase diagram of the system shows that not all deep eutectic systems can be assumed to be of a simple eutectic type with immiscible solid phases. For the accurate determination of the SLE of eutectic systems, a combination of several experimental techniques and thermodynamic modeling is needed.

This work is encouraged by the growing interest and recent success of quantum mechanics-based methods in modeling of thermodynamic properties in the field of chemical engineering and life sciences. Among those, the COSMO-RS model has become one of the most popular methods to predict phase equilibria in complex bio-related systems. Recently, we have shown that the quality of predictions of n-octanol/water and micelle/water partition coefficients is improved when the weighted mixtures of conformers are used to represent molecules, thereby demanding that the conformation analysis is performed for each component of the system. In this paper, different methods for performing the conformational search are evaluated. Micelle/water partition coefficients of solutes from different homologous series in aqueous solutions of Triton X100 as well as the n-octanol/ water partitioning of three common drugs (aminopinicillanic acid, ampicillin, and penicillin G) are calculated and compared with experimental data. Conformational analysis is made by the HyperChem program for the molecules placed in vacuum as well as by using the molecular dynamics simulation in a solvent medium (n-octanol and water). It is demonstrated that molecular dynamics simulation is a promising tool to conduct conformational analysis. Along with the possibility of providing the conformers for large surfactant and pharmaceutical molecules, the method accounts for the solvent in a realistic manner. The results for micelle/water partition coefficients illustrate that n-octanol is a reasonable approximation for the "micelle-like" medium in molecular dynamics (MD) simulations. Predicted n-octanol/water partition coefficients of three penicillins are in a good agreement with literature data and values calculated by a common quantitative structure-activity relationship (QSAR).

This paper presents an extensive study on the feasibility of ionic liquids (IL) for the extractive distillation of propene-propane mixtures. A new experimental method for express screening of non-volatile entrainers was elaborated. A series of ILs and their mixtures were screened at ambient temperature and low pressures. The screening results show that every tested IL turns a low boiler propene into a high boiler and the alkene-to-alkane separation factor can be as low as 0.28. The solubility and separation efficiency can be tuned by adjusting the chemical structures of the ions forming the IL. It was found that shortening of the alkyl substituents of the imidazolium ions leads to a decrease in capacity and to an increase in the separation factor. Interestingly, ILs containing nitrile functionalities in either the cation or the anion showed, in our experiments, enhanced separation ability combined with still good capacities. From our thermodynamic measurements, [EMIM] [[B(CN) 4 ] was proved to be the most promising candidate. Binary mixtures of ILs were also tested and resulted in separation factors and capacities between the values for the individual ILs. For the most promising candidates, also autoclave measurements at elevated temperatures and pressures were carried out. These experiments indicate that the separation ability decreases with growing temperature and loading. In general, our study definitely proves the high potential of ILs to act as entrainers in the extractive distillation of propenepropane mixtures or for the separation of any other low-boiling alkene-alkane mixture.