The Preparation And Physico-chemical Properties Of The Acetic Acid Ionic Liquid Series

Acetic acid ionic liquids have the ionic liquid inherent advantages. For example,low vapor pressure, chemical and thermal stability, amenable to diverse solutes, at al.According to the theory of acid-base proton, the acetate is alkaline, so the acetic acidionic liquids is a functional alkaline ionic liquids. Acetic acid ionic liquids with goodfunctionality have a wide range of applications in synthesis, electrochemical, tsuitaking the separation, and biological fields.Currently, study what the main [C₂mim]OAc and [C₄mim]OAc about acetic acidionic liquids. In the synthesis, home and abroad rarely been reported in acetic acidionic liquids of a series of imidazolium cation-based ionic liquid. First of all, wesynthesizes five kinds of bromide intermediate1-ethyl-3-methylimidazoliumbromide （[C₂mim]Br）、1-propyl-3-methylimidazolium bromide （[C₃mim]Br）、1-butyl-3-methylimidazolium bromide （[C₄mim]Br）、1-pentyl-3-methylimidazoliumbromide （[C₅mim]Br）、1-hexyl-3-methylimidazolium bromide （[C6mim]Br） byanion resin exchange method. Then, we synthesizes five kinds of acetic acid ionicliquids1-ethyl-3-methylimidazolium acetate （[C₂mim]OAc）、1-propyl-3-methylimidazolium acetate （[C₃mim]OAc）、1-butyl-3-methylimidazo-lium acetate （[C₄mim] OAc）、1-pentyl-3-methylimidazolium acetate（[C₅mim]OAc）、1-hexyl-3-methyl-imidazolium acetate （[C6mim] OAc） by usingbromide intermediate of the above synthesis.The five kinds of acetic acid ionicliquids were characterized by1HNMR，DSC.In the application about acetic acid ionic liquids, Due to the lack of physical andchemical properties hinders its further application to a certain extent hinders.Electrical conductivity and enthalpy of solution are two important properties of aceticacid ionic liquids in catalysis research in the field of electrochemistry, be extractedfrom the separation of important reference value. Electrical conductivity and enthalpyof solution rarely been reported in acetic acid ionic liquids, so electrical conductivityand the enthalpy of solution of the two physical and chemical properties be focused. But acetic acid ionic liquids have strong hydrogen bonds, water must consider theimpact on the physical and chemical properties. The standard addition method （SAM）were measured in the acetate ion conductivity of the liquid and the enthalpy ofsolution of two important physical and chemical properties, and have achieved goodresults.Electrical conductivity of five kinds of acetic acid ionic liquids were measuredby the standard addition method （SAM） at temperature ranging from288.15to338.15K with an interval of5K. The electrical Conductivity of the pure ionic liquidcan be obtained by linear fit. The two laws of acetic acid ionic liquids increase withtemperature and the number of cationic carbon can be obtained. Namely, electricalconductivity of acetic acid ionic liquids are increasing with temperature increases anddecreasing with increase of cationic carbon; electrical conductivity of acetic acidionic liquids are non-linear relationship by temperature increases.The Arrhenius and the Fulcher equations are two ways to estimate the law of theconductivity change of acetic acid ionic liquid with temperature at298.15K. In ionicliquid [C2mim]OAc example, the Arrhenius and the Fulcher equations are verified forestimates and experimental values. We have come to Estimates values of the Fulcherequation that is is very close to to experimental values.That Fulcher equation is moresuitable to study the relationship between temperature and electrical conductivity ofacetic acid ionic liquids.Determination of The molar enthalpies of solution of acetic acid series of ionicliquids.The molar enthalpies of solution, Δ_solH_m（wc）, of ionic liquid [C₄mim]OAcwith various amount of water and with various molalities were measured at（298.15±0.0005）K.According to Archer’s theory, the standard molar enthalpies ofsolution of [C₄mim]OAc with a known amounts of water, Δ_solH_mθ（wc）, wereobtained,and the standard molar enthalpy of solution, Δ_solH_mθ（pure IL[C₄mim]OAc）was also obtained.Other, The molar enthalpies of solution, Δ_solH_m, of ionic liquid[C2mim]OAc with various molalities were measured from288.15to308.15K with aninterval of5K. According to Archer’s theory, the standard molar enthalpies ofsolution of [C2mim]OAc were obtained.The hydration enthalpy of ionic liquid [C₄mim]OAc（-272.0kJ·mol-1） was estimated using the value of Δ_solH_m（pure ionic liquid） in terms of the followingthermodynamic cycle of ionic liquid [C₄mim]OAc. In comparison with-227.0kJ·mol^-1of hydration enthalpy of BF₄^-is the hydration of OAc-is stronger. Accordingto the molar enthalpies of solution of ionic liquids [C₂mim]OAc at differenttemperatures, molar heat capacity solCp,mθwas obtained by the molar enthalpies,ΔsolHm, to T-298.15for linear fit.