Study On The Structure-property Relationship Of Ammonium-type Ionic Liquids

Ionic liquid is the new media and "soft" functional materials, which developed under the framework of the green chemistry. Due to its unique physical and chemical properties and designability, it shows a wide range of applications prospect in the fields of clean production, organic synthesis, analysis of chemical and so on. In various ionic liquids, Ammonium-type ionic liquid is to be concerned as its cheap raw materials, convenient synthesis, and almost nontoxicity. At the present time, the structure research of Ammonium-type ionic liquid is still at the initial exploration stage, the rules of nature haven't been found completely, which occurred with the structure's changes. As the result, the further development and applications are restricted. The paper studies the internal structure of Ammonium-type ionic liquid at begining, and further extended to the synthesis reaction mechanism by combining Quantum Chemical Calculation, experiments and a collection of illustrative plates.Ammonium-type ionic liquids (including hydroxylammonium-type and amide-type ionic liquids) are synthesized in solvent-free condition firstly by one-step synthesis.The synthetic mechanism of hydroxylammonium-type and amide-type ionic liquids has been analyzed by spectra. The chemical and physical properties of hydroxylammonium-type and amide-type ionic liquids have been summarized.The microcosmic structure of Ammonium-type ionic liquids is studied furtherly by using Density Functional Theory (DFT) in Quantum Chemical. The study of internal interaction of anions and cations, anions and water molecules, cations and water molecules mainly divided into two aspects of no-water molecules and water molecules to be discussed. The study showed that in the system of no-water molecules, the stable structure of anions and cations formed basicly through the interaction of the hydrogen bond. With the Difference of imidazole-type ionic liquids, the hydrogen bonds formed by N atoms led to viscosity increase in Ammonium-type ionic liquids. In the system of water molecules, the water molecule can form strong hydrogen bonds with hydrophilic anion BF4-,the structure of BF4-…H2O and H2O…BF4-…H2O formed in the ionic liquids. In Ammonium-type ionic liquids, the cation also can form strong hydrogen bonds, the bond energy is between 30～100 kJ·mol-1. The synthesis reaction mechanism is studied based on the above research. The results showed that the synthetic reaction paths of Ammonium-type ionic liquids is R→IM→TS→P. In the synthesis reaction of hydroxylammonium-type ionic liquid, the reaction heating effect is-19.27 kJ·mol-1, the intermediate IM1 need to leap over 70.58 kJ·mol-1 energy barrier to reach transition state TS1.It is the control step of the whole process rate. In the synthesis reaction of amide-type ionic liquid, the path of IM2→TS2 is the control step, the heating effect is-17.56 kJ·mol-1.