Novel acid tuned deep eutectic solvents based on protonated L-proline

The paper presents new types of deep eutectic solvents (DESs) based on L-proline protonated using three different acids (hydrochloric, sulfuric and phosphoric)and playing the role of a hydrogen bond acceptor (HBA). Glucose and xylitol were used as hydrogen bond donors (HBD). A series of deep eutectic solvents with various mole ratios were obtained for the systems L-proline: glucose and L-proline: xylitol. Density, melting point, pH and viscosity of the synthesized DESs were determined along with the effect of water content, mole fraction of the HBA in DES and temperature on properties of the DESs. A wide range of densities (1343-1606 kg/m(3)), viscosities at 20 degrees C (699.6-48,590 mPa.s) and pH of 0.1 M DES solutions (1.578-2.456) make the obtained deep eutectic solvents potentially applicable in numerous technological processes, extractions as well as in analytical techniques, including microextraction. Components of these DESs are of natural origin and non-toxic, thus environmentally friendly and suitable for food as well as pharmaceutical industry. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

The paper introduces new types of deep eutectic solvents based on L-proline protonated using different acids, suitable for various technological processes and analytical techniques. These solvents have diverse properties and are applicable in the food and pharmaceutical industry.