Experimental and Computational Study of the Properties of Imidazole Compounds with Branched and Cycloalkyl Substituents

Abstract

N-functionalized imidazole compounds with linear alkyl groups have been widely utilized precursors for imidazolium ionic liquids (ILs) while the effects of branched and cycloalkyl substituents on properties of imidazole compounds have not been studied; however, such compounds are just as synthetically accessible as those with linear alkyl groups. In this work, two fundamental properties, density and viscosity, of selected N-functionalized imidazoles bearing iso-propyl, iso-butyl, sec-butyl methylcyclopropyl, cyclopentyl, and methylcyclohexyl groups have been measured in the temperature range of 293.15–353.15 K for the guidance of molecular design for future applications. A linear and parabolic model were used for temperature-density correlation while temperature dependence of viscosity was summarized using the Andrade Equation and the Vogel-Fulcher-Tammann equation. In addition to experimental data, density, viscosity, vapor pressure and vaporization of enthalpies of target imidazole compounds were predicted using COSMOtherm calculations and compared with experimental data. It was found that the calculated densities were quite close to the experimental data, while viscosity data, obtained from COSMOtherm, underestimated experimental measurements and a scaling factor provided agreement with experiments. Predictions of vapor pressure were relatively reliable at low temperature, although the difference between experiment and prediction tended to expand with increasing temperature. Variances of vaporization enthalpies were small upon temperature change and a maximum error of ~12.3% was observed for all compounds studied.

Calculated Physicochemical Properties of Glycerol-Derived Solvents to Drive Plastic Waste Recycling

“…Thus, optimized structures for iodine-containing compounds were obtained using the def2-TZVP basis set on the iodine atom, and the TZVP basis set for all other atoms. Single-point energy calculations were then performed with the BP86 functional together with the TZVP basis set and the COSMO-RS solvation , model to obtain the necessary COSMO files following previous studies that had predicted the physical properties of liquid-phase compounds. ,, Similarly, for iodine-containing molecules, single-point energy calculations were carried out using the BP86 functional and the def2-TZVP basis set defined for the iodine atom (TZVP basis set defined for all other atoms) together with the COSMO-RS solvation model. Finally, we performed COSMO calculations in the COSMOtherm software package (BIOVIA COSMOtherm, Release 2020) at the TZVP level.…”

Properties of Imidazolium Ionic Liquids with Glycerol-Derived Functional Groups

“…Nevertheless, the vast majority of research efforts have simply focused on imidazolium cations with linear alkyl groups, while other types of functional groups are much less frequently considered. Furthermore, the influence of even the most simple branched groups (e.g., isopropyl) on fundamental thermophysical and transport properties such as density, viscosity, and vaporization enthalpy has only been considered for a handful of neutral imidazole compounds and imidazolium ILs. , …”

“…Nevertheless, the vast majority of research efforts have simply focused on imidazolium cations with linear alkyl groups, 25 while other types of functional groups are much less frequently considered. Furthermore, the influence of even the most simple branched groups (e.g., isopropyl) on fundamental thermophysical and transport properties such as density, viscosity, and vaporization enthalpy has only been considered for a handful of neutral imidazole compounds 26 and imidazolium ILs. 27,28 The source(s) of precursors and total number of synthetic steps for IL synthesis should also be carefully considered so as to avoid energy-intensive processes which will weaken the overall economic and environmental benefits of the industrialization of ILs.…”