ИСТИНА

The enthalpy of solution of ionic liquids were measured in water at 298.15 K by calorimeter 6755 Parr Instrument Company. The enthalpies of [C2MIm][OAc] and [C4MIm][OAc] formation in the liquid state at 298.15 K were determined by Hess law on the basis of the experimental data and [С2MIm]+, [С4MIm]+(aq) [3] and ][OAc](aq) [4] enthalpies of formation. The gas phase enthalpies of formation of [C2MIm][OAc] and [C4MIm][OAc] were calculated assuming the existence of these ionic liquids in the vapor in the form of ion pairs. The conformational analysis was performed by considering the possible structures of the [C2MIm]+ and [C4MIm]+ cations and taking into account the different arrangement of the [OAc]– anion around them. The B3LYP-D3(BJ)/def2-TZVPP method was used to optimize the geometry and calculate the oscillation frequencies.