A rational synthetic approach for producing quaternary ammonium halides and physical properties of the room temperature ionic liquids obtained by this way

Abstract

In the present paper the rational strategy for the high-yield solvent free synthesis of alkylammonium halides which consists in the nucleophilic addition of alkylaminoethanols to 2-chloroethanol was described. The proposed strategy was used to synthesize hydroxyl-functionalized solid ionic compounds such as dimethyl (or methyl) di-(tri)(2-hydroxyethyl) ammonium chloride and tetra-(2-hydroxyethyl) ammonium chloride, as well as novel room temperature ionic liquids (RTILs) such as dimethyl (IL-4) and methyl mono-(di-)(2-hydroxyethyl) (2-hydroxyethoxy)ethyl chloride (IL-5) all of which were characterized by FT-IR, 1H and 13C NMR. For the newly obtained RTILs, density (ρ) and viscosity (η) were obtained at temperatures from T = (283.15 to 353.15) K while the refractive index (nD) was measured from T = (283.15 to 343.15) K. The data on ρ and nD were used for calculation of the RTILs’ fractional free volumes (FFV), molar refraction, and pseudo-activation energy of viscous flow. In addition, NH3 absorption capacity of the obtained ILs was estimated gravimetrically. It was shown that this property correlates with the IL's FFV and increases by two times for IL-5 which exhibits an additional hydroxyl group compared to IL-4.