Effect of the cation structure on the thiophene distribution between the ionic liquid with NTf2 anion and the hydrocarbon rich phases: A QSPR study

Abstract

In the present study, the effect of different cation structures has been investigated on the thiophene distribution between the ionic liquids containing NTf2 anion and hydrocarbon phases in the ternary systems utilizing quantitative structure-property relationship (QSPR). The role of cation structure was investigated in the presence of constant anion (i.e., NTf2) and different hydrocarbon solvents using three different datasets with 311 experimental data points. The first and second datasets contains {([different cations][NTf2]/thiophene/n-heptane or Toluene}, respectively. The third dataset contains {([different cations][NTf2]/thiophene/different hydrocarbons}. The results demonstrated that the effects of cation structures can vary by changing the involved hydrocarbons in the ternary systems. It was found that “G3u” as a directional WHIM descriptor can take into account the effect of cation structure on the thiophene distribution. “G3u” reflects the relevant molecular 3D information considering symmetry of structure. Therefore, it was tried to propose a predictive QSPR model with two molecular descriptors from the hydrocarbon structure (i.e., “Pol”) and cation structure (i.e., “G3u”) along with the thiophene mole fraction in the hydrocarbon rich-phase (i.e., X2) to estimate the thiophene mole fraction in the IL rich-phase (i.e., Y2 variable). The statistical results of internal and external validations confirmed the validity of the developed QSPR model.