Novel amino acids based ionic liquids analogues: Acidic and basic amino acids

Deep eutectic solvents (DES) are one of the immerging promising industrial green solvents that are gaining considerable attention. These novel liquids have been synthesized from a variety of quaternary ammonium and phosphonium salts in combination with one or more complexing agents. Amino acids may act as good hydrogen bond donors and hence can be used as the complexing agent in the synthesis of type III DES. In this work a variety of ammonium quaternary salts have been investigated in forming amino acids-based DESs by combining with acidic or basic amino acids. Five of the common basic and acidic amino acids were used for this purpose. Three amino acids (glutamic acid, aspartic acid and arginine) were successful in forming DESs with the salt tetrabutylammonium chloride. The successful molar ratios of these DESs were characterized by measuring their melting point, density, viscosity, surface tension, refractive index, and conductivity in the temperature range 303.15-353.15 K. The presented novel data for these DESs can be utilized for customizing these solvents for probable chemical or industrial applications.