Experimental Determination Of Physicochemical Properties Of Pyridiniumium Ioinc Liquids And Its Predoction By Empirical Methods

Ionic liquids (ILs) have been attracted much attention from both industrial and academic communities for the nature of the liquid soft materials as the "Green solvents" The pyridinium-based ILs have a promising prospect, since they exhibit high heat capacities, high thermal stability and low cost compared with the imidazolium-based ILs. The pyridinium-based ILs have been widely applied to the environmental science and material science. The ILs with N(CN)2- anion have been widely used in the engineering technology, photothermal and photoelectric material. It is important to design, synthesis and application of the novel ionic liquids for the basic physicochemical data of ILs In recent years, there has been a developing trend toward estimation of the physicochemical properties for ILs by semiempirical methods. Walden product, W, is the important parameter to viscosity and conductivity. It is one of the frontier topics in academic communities whether W is a feature physical parameter for ILs? Based on above issues, the main work in this dissertation are as follows:Three novel N-alkyl-pyridinium dicyanamide ionic liquids [Cnpy][DCA](n=3,5,6) and [Cpy][DCA](n=2,4) were prepared by the metathesis method and characterized by 1H NMR spectroscopy, 13C NMR spectroscopy, differential scanning calorimetry (DSC), FT-IR spectroscopy and High Performance Liquid Chromatography (HPLC).The density, surface tension, refractive index, conductivity and kinematic viscosity were measured in the temperature range of 298.15 K to 338.15 K with an interval of 5 K. Since [Cnpy][DCA](n=2-6) can strongly form hydrogen bonds with water, which is considered an impurity, the standard addition method (SAM) was applied in these measurements.Based on the experiment values, the volumetric and surface properties have been discussed. The contribution of the molecular volume, standard molar entropy and lattice energy per methylene (-CH2-) on alkyl chain of [Cnpy][DCA](n=2-6) were calculated. Then the changes of the molecular volume, speed of sound, energy of surface formation, molar refraction, polarization coefficient and parachor with the temperature have been discussed. According to the interstice model, the thermal expansion coefficients of ILs were calculated and in comparison with experimental values.As a new concept-ionic parachor was put forward and regarded as an independent descriptor of parachor for ionic liquids. In order to expand the data of ionic parachor, the experiment values of parachor for [Cpy][DCA](n=2-6) were calculated and the ionic parachor of anion, [DCA] as a reference ion was obtained in terms of the extrathermodynamic assumption, and then the ionic parachor, P+, of all corresponding pyridinium cations, [Cnpy]+, were obtained. Using the cationic parachor of [Cnpy]+(n= 2-6) and [Cnmim]+(n=2-6), the values of ionic parachor for 10 kinds of anions were obtained. Then the data table of ionic parachor was established by the experimental and literature data of parachor with the reference ion [DCA]. By using the ionic parachor, the values of parachor for 47 ionic liquids were obtained, which are more closed to their experiment values than the values of parachor obtained by Rowley et al. The values of surface tension for 52 ionic liquids and the values of refractive index for 22 ionic liquids were predicted using the estimated values of parachor within their experimental expanded uncertainty at 0.95 confidence level of ±0.3 mJ·m-2 and ±0.0003, respectively.The dynamic viscosity, molar volume and molar conductivity. A, were calculated. The dynamic viscosity, conductivity and molar conductivity values were fitted by Vogel-Tammann-Fulcher (VTF), the relationship between these values and temperature was discussed, respectively. The changes of the values of the activation energy for electrical conduction and the activation energy for viscous flow with the increasing number of carbons in the alkyl chain of [Cnpy][DCA](n=2-6) were discussed, respectively.In order to illustrate the Walden product is the feature physical parameter for ILs, a new theory-ion exchange transition model was put forward and a series of Walden product, W, for [Cnpy][DCA](n=2-6) and 23 other different kinds of ILs were calculated. The results showed that different ionic liquids have the different Walden product, W, which is the feature physical parameter for ILs.