Study On Pysicochemical Properties And Semi-Empirical Estimation Of Ionic Liquids Exafluoride Antimonite

Since the discovery of ionic liquids,its chemical and physical properties are excellent and unique,which has aroused great interest among many chemists.Ionic liquids can be used as solvents for for separation because their polarity is controllable.In addition,ionic liquid has great catalytic and extraction capabilities,and has been widely concerned and applied in many fields such as medical solubilization.It can be seen that,ionic liquids,as a new solvent,have shown great potential in green reagents and renewable sustainable development of energy.Two series of limidazolium-based ionic liquids including N-methylimidazolium hexafluoride antimonite and N-ethylimidazolium hexafluoride antimonite were designed and synthesized by the two-step synthesis method and these products were characterized by ~1H NMR and ESI-MS.After the characterization,the density,surface tension,refractive index and conductivity of the hydrophobic ILs were measured in the temperature range of(293.15 to 343.15±0.05)K with an interval of 5 K.And then,the volume and surface properties of these two kinds of ionic liquids were estimated by semi empirical estimation based on the experimental data.The molecular volume of the ILs was calculated respectively.The relationship between the molecular volume of the ILs and the change of the number of carbon atoms in the cationic alkyl chain was discussed.Based on the Classer theory,the standard entropy S~0(298 K)of the six ILs were calculated,and the contribution value of each methylene to S~0(298 K)were also analyzed with the linear change of the number of carbon atoms in the cationic alkyl chain.The value of the lattice energy of the ILs were calculated by the experimental data,and the values of the lattice energy were calculated.As for the problem of the melting state of the ionic liquid under room temperature,the lattice energy of the ILs with the minimum inorganic molten salt,and explain that why the the ionic liquid at normal temperature is melting were compared.According to the Kabo empirical equation and the theory of Rebelo empirical equation,the values of the vaporization enthalpy of the ILs were calculated,Based on the theory of molar surface Gibbs’s free energy,the traditional E?tv?s equation were improved,and the new E?tv?s one was obtained.And it has clearer physical meaning:the intercept of the new equation represents the molar surface entropy,the slope represents the molar surface enthalpy.In addition,based on the refractive index and the surface tension,the mole surface Gibbs free energy values are estimated.The results show that the estimated values are in accordance with the corresponding experimental ones.The thermal expansion coefficient,α,of two kinds of ILs were calculated.Based on the gap model theory.The data results were the same as the corresponding experimental values at the order of magnitude.And the theory was extended and the concept of Gibbs free energy on the surface of the mole surface were introduced,and then it was found that the value is a kind of constant of the ionic liquid.Finally,the concept of solubility parameter was introduced.This parameter is used to estimate the polarity of ionic liquids.According to the calculated polarity,the hydrophilic or hydrophobicity of ionic liquids can be judged.The results judged by this method are the same as that of inference.