Effect of Hydrogen Bond Donor on the Physical Properties of Benzyltriethylammonium Chloride Based Deep Eutectic Solvents and Their Usage in 2-Ethyl-Hexyl Acetate Synthesis as a Catalyst

Abstract

Deep eutectic solvents (DES) containing benzyl triethylammonium chloride (BTEAC) as a hydrogen bond acceptor (HBA) and p-toluene sulfonic acid (PTSA), citric acid (CA), and oxalic acid (OX) as a hydrogen bond donor (HBD) were formed at their respective eutectic points. The physical properties such as pH, ionic conductivity, viscosity, density, and refractive index were measured between 293 and 333 K. Viscosity values as low as 0.21 Pa·s and conductivity values as high as 8 mS/cm were achieved, where the pH values of each DES proved to be extremely low. The effect of HBD on the physical properties was investigated and was found to be very significant. Also, the catalytic application of BTEAC based DES in the esterification reaction of the acetic acid with 2-ethyl-hexanol was studied, and the activation energy was obtained using initial reaction rates. The results showed that very high initial reaction rates and low activation energy can be achieved when catalyzed by DES which was formed using BTEAC and PTSA.