Quantitative Description of Thermal Properties of Alkylammonium Hydrogen Sulfates Based on Quantum Chemical Data

Abstract

How can the microstructure of an ionic liquid influence its properties? To answer this question, we used quantitative structure–property relationship (QSPR) models with quantum chemical descriptors derived from density functional theory calculations to correlate the decomposition and melting temperatures of alkylammonium hydrogen sulfate protic ionic liquids (PILs). These descriptors characterize the properties of the electronic structure of single cations and cation–anion pairs of the PILs and describe the interionic interactions. We thoroughly analyzed the calculated descriptors, as well as those previously obtained for some alkylammonium hydrogen sulfates. The QSPR models developed through multiple regression analysis show very good performance, with a coefficient of determination close to one, which provides a precise fit to the experimental data set. This information is valuable in guiding the synthesis of new alkylammonium hydrogen sulfates.