DFT Studies on the Isomerization of Butene Double Bond Catalyzed by 1-Butyl-3-methyl-imidazolium in Ionic Liquid

The geometries of reactant, product and transition state of the title reaction have been optimized by using density functional theory (DFT) at the B3LYP/6-31G(d,p) and B3LYP/6- 311++G(d,p) levels. The variations of the bond parameters in the course of reaction were analyzed. The zero point energy corrections were performed by vibrational analysis. The equilibrium states and the transition state were verified according to the number of virtue frequency of geometry. The intrinsic reaction coordinates (IRC) were calculated from the transition state. The calculated results show that the double bond rearrangement of butene catalyzed by 1-butyl-3-methyl-imidazolium cation is a one-step reaction. The forward energy barrier of isomerization from 1-butene to 2- butene is about 193 kJ·mol-1 and the reverse energy barrier about 209 kJ·mol-1 at the B3LYP/6- 31G(d,p) level, which means that the reaction is easy to proceed at or above room temperature.

Microscopic structures of ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate in water probed by the relative chemical shift

The relative chemical shifts (△δ) △δwere put forward to investigate the microscopic structure of 1-ethyl-3-methyl-imidazolium tetrafluoroborate (EmimBF4) during the dilution process with water.The concentration-dependent △δ(C2)H-(C4)H,△δ(C2)H-(C5)H and △δ(C4)H-(C5)H were analyzed.The results reveal that the variations of the microscopic structures of three aromatic protons are inconsistent.The strength of the H-bond between water and three aromatic protons follows the order:(C2)H···O 】 (C4)H···O 】 (C5)H···O.The concentration-dependent △δ(C6)H-(C7)H and △δ(C6)H-(C8)H indicate the formation of the H-bonds of (Calkyl)H···O is impossible,and more water is located around (C6)H than around (C7)H or (C8)H.The concentration-dependent △δ(C2)H-(C4)H and △δ(C2)H-(C5)H both increase rapidly when xwater 】 0.9 or so,suggesting the ionic pairs of EmimBF4 are dissociated rapidly.The turning points of concentration-dependent △δ(C2)H-(C4)H and △δ(C2)H-(C5)H indicate that some physical properties of the EmimBF4/water mixtures also change at the corresponding concentration point.The microscopic structures of EmimBF4 in water could be clearly detected by the relative chemical shifts.

Nano-porous Composites Based on Liquid： Synthesis, Characterization, Esterification Heteropolyacid Functionalized Ionic and Catalytic Performance in

Fhnctionalized ionic liquid samples （bmim-PW12） were synthesized by 1-butyl-3-methyl- imidazolium bromide （bmimBr） and 12-phosphotungstic heteropolyacid （PW12）. The samples were annealed at 100-450 ℃ and were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, thermal gravity-DTG, brunauer emmett teller, and NHa-temperature programmed desorption. The results showed that the bmim-PW12 samples were crystal and maintained intact Keggin structure. The organic parts of those samples were partly decomposed at a temperature more than 350 ℃. The sample annealed at 400 ℃ exhibited nano-porous structure, strong acidity, and excellent catalytic activity on the esterification of n-butanol with acetic acid. The higher ester yield was obtained when the mass ratio of catalyst over the reactants amount was 5% for bmim-PW12 catalyst annealed at 400 ℃.

Synthesis and Characterization of [Cu（N-MeIm）4（BF4）2] in Ionic Liquid

A new transition metal complex, [Cu（N-MeIm）4（BF4）2]（N-MeIm=N-methylated imidazoles, BF4= tetrafluoroborate）, was synthesized via the solvothermal method in ionic liquid. The ionic liquid acts as thermal decomposition reaction medium, soft temple agent and ligand compound. The central Cu（Ⅱ） ion is coordinated by four N atoms from four N-methylated imidazole ligands, and the four N-methylated imidazole rings are perpendicular to each other. The crystal structure of [Cu（N-MeIm）4（BF4）2] was determined by single crystal X-ray diffraction. The results of thermogravimetry（TG） and Fourier transform infrared spectrometry（FTIR） analyses were in accordance with that of crystal structure. The complex showed strong ligand-based absorbance with maximum wavelength at 208 and 231 nm, which are attributed to π-π＊ transition of the N-methylated imidazole ligands.