A density model for screening hydrogen bond donors to improve the efficiency of hydrophobic deep eutectic solvents

Abstract

There are a few model studies on screening hydrogen bond donors (HBDs) to form hydrophobic deep eutectic solvents (HDESs). We propose a density model to screen HBDs for improving the extraction efficiency of HDES systems for the extraction of metal and organic compounds. In this model, HBDs are selected based on their density based on 15 different HDES systems available in the literature. The extraction efficiency increased with the decrease in HBD density, which proved the reliability of the density model. The so-established density model can screen suitable or narrow down HBDs based only on their density compared with the COSMO-RS model, which requires more information about the atoms of pure compounds. Significantly, this model can provide a convenient method to select suitable or narrow down the selection of HBD reagents. Furthermore, there are five correlations among the physicochemical properties (such as density, refractive index, boiling point, melting point, and viscosity) of HBDs, which are greatly beneficial to deepen the importance of understanding the physicochemical properties of HBDs for screening or narrowing down HBDs for improving the extraction efficiency of HDES systems.