Diethylamine-based ionic liquids: quantum chemical calculations and experiment

Abstract

The structural and energetic characteristics of the compounds formed by the reaction of diethylamine (DEA) with protic acids (sulfuric (H₂SO₄), methanesulfonic (MsOH), trifluoromethanesulfonic (TfOH), and para-toluenesulfonic (TsOH)) were examined using quantum chemical computations (B3LYP-GD3/6-31++G(d,p)). The strength of the hydrogen bonds in the ion pairs formed was quantitatively estimated by the QTAIM theory and NBO analysis. The results of the quantum chemical computations and the obtained thermal (phase transition and decomposition temperatures) and physicochemical (viscosity and conductivity) characteristics indicate that the reactions of DEA with the acids afford salts. The salts with the melting points higher than 100 °C are formed in the case of DEA/OTf(OTs), while protic ionic liquids are produced in the case of DEA/OMs(HSO₄).