Thermochemical Properties of Tunable Aryl Alkyl Ionic Liquids (TAAILs) based on Phenyl‐1<i>H</i>‐imidazoles

Abstract

Vaporization enthalpies of five different imidazolium based Tunable Aryl Alkyl Ionic Liquids (TAAILs) with a common bis(trifluoromethylsulfonyl)imide ([NTf 2 ]) anion were measured using a Quartz Crystalline Microbalance (QCM) and by Thermogravimetric Analysis (TGA). The counter anion and the alkyl chain of these imidazolium‐based ionic liquids with one N ‐aryl and one N ‐alkyl substituent were kept constant to study the influence of the ortho ‐ and para ‐substituted aryl moieties on the vaporization enthalpies of these ionic liquids. For comparison, enthalpies of vaporization measured at elevated temperatures were adjusted to the reference temperature 298 K. Structure‐property relations between TAAILs and similarly shaped corresponding 1‐(R‐phenyl)‐imidazoles were analyzed. An incremental approach to predict vaporization enthalpies of ionic liquids by group contributions was suggested. The procedure is based on vaporization enthalpy of a starting IL and group contributions well established from molecular compounds.