Overview of acidic deep eutectic solvents on synthesis, properties and applications

This review divides the acidic deep eutectic solvents (ADES) into Brønsted and Lewis DES according to their diversity of acidic character. The hydrogen bond donors and halide salts for formulating an ADES are classified, the synthesis methods are described, and the physicochemical properties including freezing point, acidity, density, viscosity and conductivity are presented. Furthermore, the applications of Brønsted acidic deep eutectic solvents (BADES) and Lewis acidic deep eutectic solvents (LADES) are overviewed, respectively, covering the fields in dissolution, extraction, organic reaction and metal electrodeposition. It is expected that the ADES has great potential to replace the pollutional mineral acid, expensive and unstable solid acid, and costly ionic liquid in many acid-employed chemical processes, thus meeting the demands of green chemistry. In this review, the components and synthesis methods of acidic deep eutectic solvent (ADES) are described and discussed, and the important physicochemical prpoperties are summarized and presented. In addition, the applications of ADES in various fields are introduced, and the further outlooks are also proposed. [Display omitted]