Estimating the Melting Temperatures of Type V Deep Eutectic Solvents

The recently proposed category of type V deep eutectic solvents (DESs), composed only of non-ionic species, has attracted great interest in the literature. However, despite their importance in solvent design, measuring the solid–liquid equilibrium (SLE) diagrams of all possible type V DES precursor combinations is unfeasible. Therefore, a reliable computational tool must be found to estimate SLE phase diagrams and, thus, the melting points of type V DESs. In this work, a total of 134 different binary eutectic systems (1744 datapoints) were gathered from the literature, and the calculation capabilities and accuracy of three different models─COSMO-RS, UNIFAC of Dortmund, and Group and Group-Interaction Contribution method (GGIC)─were evaluated. UNIFAC and COSMO-RS were, by far, the best performing models, with average absolute deviations (AADs) of, respectively, 6.9 K for 94 systems and 7.4 K for 133 systems. Due to a lack of group interaction parameters, UNIFAC could only describe 94 systems, a severe disadvantage over COSMO-RS. Moreover, despite being able to describe all 134 systems, the GGIC model resulted in an AAD of 37 K. Finally, the effect of using the different parametrizations or multiple conformers in COSMO-RS predictions was also evaluated, and the validity of neglecting heat capacity terms when performing SLE calculations was verified.