The Entropy of Deep Eutectic Solvent Formation

The standard entropies S-298 degrees E of deep eutectic solvents (DESs), which are liquid binary mixtures of a hydrogen bond acceptor component and a hydrogen bod donor one, are calculated from their molecular volumes, derived from their densities or crystal structures. These values are compared with those of the components-pro-rated according to the DES composition-to obtain the standard entropies of DES formation Delta S-f. These quantities are positive, due to the increased number and kinds of hydrogen bonds present in the DESs relative to those in the components. The Delta S-f values are also compared with the freezing point depressions of the DESs Delta T-fus/K, but no general conclusions on their mutual relationship could be drawn.