Experimental and predicted physicochemical properties of monopropanolamine-based deep eutectic solvents

Abstract

In this work, the novel deep eutectic solvents (DESs) based on 3-amino-1-propanol (AP) as hydrogen bond donor (HBD) and tetrabutylammonium bromide (TBAB) or tetrabutylammonium chloride (TBAC) or tetraethylammonium chloride (TEAC) as hydrogen bond acceptors (HBAs) were synthesized with different molar ratios of 1: 4, 1: 6 and 1: 8 salt to AP. Fourier Transform Infrared Spectroscopy measurements were performed to provide an evidence of any chemical structure changes. Physical properties of the prepared DESs including densities, viscosities, refractive indices and sound velocities were measured within the temperature range of 293.15–333.15 K at the pressure of 0.1 MPa. They were analyzed in terms of estimating the effect of HBA to HBD molar ratio, anion and length of alkyl chain in a salt, and their temperature dependences were fitted by empirical equations. Thermal expansion coefficients and activation energies for viscous flow were obtained accordingly. Moreover, experimental values of density and refractive index were compared with predicted ones. For prediction of density, Rackett equation modified by Spencer and Danner and the mass connectivity index-based method were used, while refractive index was estimated by the atomic contribution method.