Theoretical studies on the butene double bond isomerization catalyzed by 5-H of 1-ethyl-3-methyl-imidazolium fluoride

The isomerization of 1-butene to trans-2-butene catalyzed by 5-H proton of 1-ethyl-3-methyl-imidazolium fluoride (EMImF) has been studied with density functional theory of quantum chemistry. The equilibrium states geometries and transition state geometry are optimized at the levels of B3LYP/6-31G(d,p) and B3LYP/6-311++G(d,p), respectively. The apparent activation barrier of isomerization is about 208 kJ/mol theoretically. It indicates that the 5-H proton on the imidazole ring of EMImF has certain catalytic activity to the butene double bond isomerization, which is similar to that of the 4-H proton. According to the data of intrinsic coordinate path, it can be determined that the isomerization is an elementary course and the hydrogen exchange of butene with EMImF is synergetic.     

A DFT study on the double bond migration of butene catalyzed by ionic pair of 1-ethyl-3-methyl-imidazolium fluoride

The double bond migration of butene catalyzed by 1-ethyl-3-methyl-imidazolium fluoride (EmimF) has been studied using quantum chemical method. The geometries of reactant, transition state and product for the isomerization have been optimized by density functional theory (DFT) at the B3PW91/6-31G(d,p), 6-311++G(d,p) and aug-cc-PVDZ levels. The computed results show that the 4-H atom on imidazole ring of EmimF has a good catalytic activity to the double bond migration of butene and the catalytic reaction of 1-butene to 2-butene is a synergetic and elementary process. The apparent activation energy of isomerization is about 197 kJ/mol.     

Amine electrosynthesis from 1-ethyl-4-nitro-3-cyanopyrazole

Polarography and preparative electrolysis are used to show that the electrochemical behavior of 1-ethyl-4-nitro-3-cyanopyrazole (1) in acidic aqueous-alcoholic solutions resembles the behavior of nitrobenzene. By varying the parameters of the electroreduction (ER) of compound 1, one can obtain either 1-ethyl-4-amino-3-cyanopyrazole (2) or 1-ethyl-4-amino-3-cyano-5-chloropyrazole (3). Compound 2 is formed during the ER of compound 1 in the presence of a mediator (titanium(III)) at temperatures below 10°C. Compound 3 is produced by the direct reduction of compound 1 on a lead electrode (30% ethanol, 10% HCl). The yield of amine chlorohydrates 2 and 3 is 56 and 92%, respectively. The mediated ER of compound 1 at catholite temperatures higher than 10°C yields a mixture of compounds 2 and 3; the proportion of the latter increases with temperature to become the major product at 60°C. Compound 3 is formed due to the rearrangement of the hydroxylamine derivative produced by the ER of compound 1, followed by the substitution of chlorine for the hydroxy group.     

DFT法研究离子液中EMIM~ 催化丁烯双键异构反应机理(II)

用密度泛函理论(DFT)在B3LYP/6鄄31G(d,p)的计算水平上研究了离子液中1鄄乙基鄄3鄄甲基咪唑阳离子(EMIM )的4鄄H和5鄄H原子催化丁烯双键异构反应的可能途径,优化了反应体系的平衡态和过渡态的几何构型,分析了反应过程中键参数的变化,通过振动分析对平衡态和过渡态进行了验证.计算结果表明,离子液中的EMIM 首先通过4鄄H和5鄄H原子吸附丁烯,进而催化丁烯的双键异构反应,EMIM 的4鄄H和5鄄H催化1鄄丁烯异构为2鄄丁烯的正反应活化能分别为204.2和207.3kJ·mol-1,逆反应活化能约为220.9和223.8kJ·mol-1,反应为基元反应.     

DFT法研究离子液中EMIM+催化丁烯双键异构反应机理(II)

用密度泛函理论(DFT)在B3LYP/6-31G(d, p)的计算水平上研究了离子液中1-乙基-3-甲基咪唑阳离子(EMIM⁺)的4-H和5-H原子催化丁烯双键异构反应的可能途径，优化了反应体系的平衡态和过渡态的几何构型，分析了反应过程中键参数的变化，通过振动分析对平衡态和过渡态进行了验证. 计算结果表明, 离子液中的EMIM⁺首先通过4-H和5-H原子吸附丁烯, 进而催化丁烯的双键异构反应, EMIM⁺的4-H和5-H催化1-丁烯异构为2-丁烯的正反应活化能分别为204.2和207.3 kJ•mol^-1，逆反应活化能约为220.9和223.8 kJ•mol^-1， 反应为基元反应.     

Thermophysical properties of 1-methyl-3-methylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate

The density and surface tension of 1-methyl-3-methylimidazolium dimethylphosphate, [C₁mim](CH₃O)₂PO₂ and 1-ethyl-3-methylimidazolium diethylphosphate, [C₂mim](CH₃CH₂O)₂PO₂ ionic liquids have been measured over the temperature range from (283.15 to 338.15) K. The coefficients of thermal expansion were calculated from the experimental density results using an empirical correlation for T = (283.15 to 338.15) K. Molecular volume and standard entropies of these ILs were calculated from the experimental density values. The surface properties of ILs were investigated. The critical temperature and enthalpy of vapourization were also discussed.     

Anionic surfactant ionic liquids with 1-butyl-3-methyl-imidazolium cations: characterization and application

For the first time a series of anionic surfactant ionic liquids (SAILs) has been synthesized based on organic surfactant anions and 1-butyl-3-methyl-imidazolium cations. These compounds are more environmentally friendly and chemically tunable as compared to other common ionic liquids. A detailed investigation of physicochemical properties highlights potential applications from battery design to reaction control, and studies into aqueous aggregation behavior, as well as structuring in pure ILs, point to possible uses in electrochemistry.     

Carbon dioxide solubility in 1-ethyl-3-methylimidazolium trifluoromethanesulfonate

In this work, we present new solubility results for carbon dioxide in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate for temperatures ranging from (303.2 to 343.2) K and pressures up to 5.9 MPa using a thermogravimetric microbalance. Carbon dioxide solubilities were determined from absorption saturation (equilibrium) results at each fixed temperature and pressure. The buoyancy effect was accounted for in the evaluation of the carbon dioxide solubility. A highly accurate equation of state and a group contribution predictive method for carbon dioxide and for ionic liquids, respectively, were employed to determine the effect of buoyancy on carbon dioxide solubility. The solubility measurements are presented as a function of temperature and pressure. An extended Henry’s law equation was used to correlate the present experimental solubility values and the result was satisfactory.     

Thiophene separation from aliphatic hydrocarbons using the 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid

The ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate has been tested as solvent for the separation of thiophene from aliphatic hydrocarbons. Liquid–liquid equilibrium data have been determined for ternary systems containing the ionic liquid, thiophene and C₆, C₇, C₁₂ or C₁₆ alkanes at T = 298.15 K. The performance of the ionic liquid as solvent in such systems has been evaluated. The experimental data were correlated using the NRTL and UNIQUAC equations, and the binary interaction parameters have been reported. The phase diagrams for the ternary mixtures including both the experimental and calculated tie-lines have been presented.     

Electrodeposition of aluminum on magnesium alloy in aluminum chloride (AlCl3)–1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid and its corrosion behavior

A dense and adhesive Al layer was successfully electrodeposited on a Mg alloy in aluminum chloride–1-ethyl-3-methylimidazolium chloride ionic liquid. The corrosion resistance of the uncoated and Al-coated samples was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements in 3.5 wt% NaCl solution. It was confirmed that the protective Al layer significantly reduces the corrosion rate of the Mg alloy. However, the deposition potential was a crucial factor that governed the structure and therefore the protection capability of the Al layer.     

先锋褐煤在离子液体1-丁基-3-甲基咪唑三氟甲磺酸盐作用下热溶解聚及其产物分析

考察了先锋褐煤(XL)在高温稳定性很好的离子液体1-丁基-3-甲基咪唑三氟甲磺酸盐([Bmim]OTf)中的解聚性能,并对其在不同热溶条件下解聚所得热溶物和残煤进行了分析表征。结果表明,[Bmim]OTf对XL具有较好的解聚性能。在280℃,[Bmim]OTf/XL为3.5下解聚4h,[Bmim]OTf对XL的萃取率(以四氢呋喃可溶物计)为20.1%。四氢萘(THN)、H₂和催化剂ZnCl₂的加入可显著促进XL在[Bmim]OTf中的解聚,相比于XL在[Bmim]OTf作用下的萃取率,THN、H₂和催化剂ZnCl₂的加入使可溶物的收率分别提高到30.0%、36.9%和46.8%。产物分析结果表明,在[Bmim]OTf热溶解聚XL的过程中THN的加入使得XL经离子液体[Bmim]OTf解聚所得热溶物中氢键的数量明显增加;H₂和ZnCl₂的添加分别增加了产物中脂肪烃和芳烃的含量。     

Thermal decomposition mechanism of 1-ethyl-3-methylimidazolium bromide ionic liquid

In order to better understand the volatilization process for ionic liquids, the vapor evolved from heating the ionic liquid 1-ethyl-3-methylimidazolium bromide (EMIM(+)Br(-)) was analyzed via tunable vacuum ultraviolet photoionization time-of-flight mass spectrometry (VUV-PI-TOFMS) and thermogravimetric analysis mass spectrometry (TGA-MS). For this ionic liquid, the experimental results indicate that vaporization takes place via the evolution of alkyl bromides and alkylimidazoles, presumably through alkyl abstraction via an S(N)2 type mechanism, and that vaporization of intact ion pairs or the formation of carbenes is negligible. Activation enthalpies for the formation of the methyl and ethyl bromides were evaluated experimentally, ΔH(?)(CH(3)Br) = 116.1 ± 6.6 kJ/mol and ΔH(?)(CH(3)CH(2)Br) = 122.9 ± 7.2 kJ/mol, and the results are found to be in agreement with calculated values for the S(N)2 reactions. Comparisons of product photoionization efficiency (PIE) curves with literature data are in good agreement, and ab initio thermodynamics calculations are presented as further evidence for the proposed thermal decomposition mechanism. Estimates for the enthalpy of vaporization of EMIM(+)Br(-) and, by comparison, 1-butyl-3-methylimidazolium bromide (BMIM(+)Br(-)) from molecular dynamics calculations and their gas phase enthalpies of formation obtained by G4 calculations yield estimates for the ionic liquids' enthalpies of formation in the liquid phase: ΔH(vap)(298 K) (EMIM(+)Br(-)) = 168 ± 20 kJ/mol, ΔH(f,?gas)(298 K) (EMIM(+)Br(-)) = 38.4 ± 10 kJ/mol, ΔH(f,?liq)(298 K) (EMIM(+)Br(-)) = -130 ± 22 kJ/mol, ΔH(f,?gas)(298 K) (BMIM(+)Br(-)) = -5.6 ± 10 kJ/mol, and ΔH(f,?liq)(298 K) (BMIM(+)Br(-)) = -180 ± 20 kJ/mol.     

Thermodynamic investigations of 1-ethyl-3-methylimidazolium tetrafluoroborate and cycloalkanone mixtures

The densities, ρ, speeds of sound, u, and heat capacities, (C _P)_mix, for binary 1-ethyl-3-methylimidazolium tetrafluoroborate (1) + cyclopentanone or cyclohexanone (2) mixtures within temperature range (293.15–308.15 K) and excess molar enthalpies, H ^E, at 298.15 K have been measured over the entire composition range. The excess molar volumes, V ^E, excess isentropic compressibilities, \( \kappa_{\text{S}}^{\text{E}}, \) and excess heat capacities, \( C_{\text{P}}^{\text{E}}, \) have been computed from the experimental results. The V ^E, \( \kappa_{\text{S}}^{\text{E}} \) , H ^E, and \( C_{\text{P}}^{\text{E}} \) values have been calculated and compared with calculated values from Graph theory. It has been observed that V ^E, \( \kappa_{\text{S}}^{\text{E}} \) , H ^E, and \( C_{\text{P}}^{\text{E}} \) values were predicted by Graph theory compare well with their experimental values. The V ^E, \( \kappa_{\text{S}}^{\text{E}}, \) and H ^E thermodynamic properties have also been analyzed in terms of Prigogine–Flory–Patterson theory.     

Thermolysis of 1-ethyl-3-nitro-1,2,4-triazole in the melt

Russian Journal of General Chemistry -     

二氰胺1-羟乙基-3-甲基咪唑离子液体的合成及对糖类化合物的溶解性能

根据离子液体结构-性能的关系,设计合成了一种新的低熔点、低黏度的功能化离子液体二氰胺1-羟乙基-3-甲基咪唑[Hemim][N(CN)2],并在298.2～353.2K的温度范围内测定了α-D-木糖、α-D-葡萄糖、D-果糖、蔗糖、D-乳糖、麦芽糖、棉子糖和木聚糖在该离子液体中的溶解度,计算了糖类化合物在离子液体中的标准溶解热力学参数.实验结果表明,除木聚糖外其他糖类化合物在[Hemim][N(CN)2]中均具有较高的溶解度,且其溶解度随着温度的升高显著增大.木聚糖属于多聚糖,溶解度较小,但温度效应非常明显.糖类化合物的溶解热力学参数SΔGo、TΔSSo和ΔHSo均为正值,且ΔHSoTΔSSo,说明溶解为焓控制过程.红外光谱结果表明,在溶解过程中木聚糖的氢键受到了一定程度的破坏,但它的结构并未发生明显的变化.     

Electrodeposition of Ni-Mg alloys from 1-butyl-3-methylimidazolium chloride/glycerin eutectic-based ionic liquid

Journal of Solid State Electrochemistry - The electrodeposition of Ni-Mg alloys in 1-butyl-3-methylimidazolium chloride/glycerin (BMIC/GL, 1:1 M ratio) eutectic-based ionic liquid...     

Electrodeposition of Al in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids: in situ STM and EQCM studies

In the present paper, the electrodeposition of Al on flame-annealed Au(111) and polycrystalline Au substrates in two air- and water-stable ionic liquids namely, 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py(1,4)]Tf(2)N, and 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide, [EMIm]Tf(2)N, has been investigated by in situ scanning tunneling microscopy (STM), electrochemical quartz crystal microbalance (EQCM), and cyclic voltammetry. The cyclic voltammogram of aluminum deposition and stripping on Au(111) in the upper phase of the biphasic mixture of AlCl(3)/[EMIm]Tf(2)N at room temperature (25 degrees C) shows that the electrodeposition process is completely reversible as also evidenced by in situ STM and EQCM studies. Additionally, a cathodic peak at an electrode potential of about 0.55 V vs Al/Al(III) is correlated to the aluminum UPD process that was evidenced by in situ STM. A surface alloying of Al with Au at the early stage of deposition occurs. It has been found that the Au(111) surface is subject to a restructuring/reconstruction in the upper phase of the biphasic mixture of AlCl(3)/[Py(1,4)]Tf(2)N at room temperature (25 degrees C) and that the deposition is not fully reversible. Furthermore, the underpotential deposition of Al in [Py(1,4)]Tf(2)N is not as clear as in [EMIm]Tf(2)N. The frequency shift in the EQCM experiments in [Py(1,4)]Tf(2)N shows a surprising result as an increase in frequency and a decrease in damping with bulk aluminum deposition at potentials more negative than -1.8 V was observed at room temperature. However, at 100 degrees C there is a frequency decrease with ongoing Al deposition. At -2.0 V vs Al/Al(III), a bulk aluminum deposition sets in.     

1-甲基-1-乙基-3-丁烯基环戊二烯基稀土二氯化物的 合成与表征

报道了1-甲基-1-乙基-3-丁烯基环戊二烯基稀土二氯化物的合成。用元素分析、质谱、红外光谱和核磁共振表征了这类配合物的组成为[C~5H~4C(CH~3)(C~2H~5)CH~2CH＝CH~2]LnCl~2·MgCl~2·THF[Ln=La(1),Nd(2),Sm(3),Gd(4)]。     

离子液体AlCl3/Et3NHCl中电沉积法制备金属铝

在AlCl3/Et3NHCl型离子液体中铝电极上通过恒电位电解沉积制备出金属铝. 测定了不同摩尔比的AlCl3/Et3NHCl离子液体在不同温度下的电导率, 考察了离子液体AlCl3/Et3NHCl摩尔比为2/1中Al电极上铝沉积的晶核成核过程, 以及恒电位电解沉积铝的工艺条件对电流效率和沉积铝表面形貌的影响. 结果表明, 不同比例AlCl3/Et3NHCl离子液体的电导率随温度升高而升高, 符合Arrhenius规律; 在Al电极上铝沉积的成核机理为三维瞬时成核过程; 恒电位电解沉积结果表明, 室温下在电位-2.4 V(vs Pt)和电解时间20 min条件下, 沉积铝的表面形貌比较平整致密,电流效率达73%, 沉积铝的纯度达96%(w).