Thermodynamic properties of the mixtures of some ionic liquids with alcohols using a simple equation of state

In the present work, we have used a simple equation of state called the GMA EoS to calculate the density of three ionic liquid mixtures including 1-butyl-3-methylimidazolum hexafluorophosphate, [BMIM] [PF₆] + methanol, 1-butyl-3-methylimidazolum tetrafluoroborate, [BMIM] [BF₄] + methanol, and [BMIM] [BF₄] + ethanol at different temperatures, pressures, and compositions. The isothermal compressibility, excess molar volumes, and excess Gibbs molar energy of these mixtures have been computed using this equation of state. The values of statistical parameters show that the GMA EoS can predict these thermodynamic properties very well within the experimental errors. The results show that isothermal compressibility of ionic liquids is lower than alcohols and the effect of temperature and pressure on the isothermal compressibility of ionic liquids is lower than alcohols. The excess molar volumes and excess molar Gibbs energy for these ionic liquid mixtures with alcohols are all negative at various temperatures and pressures over the whole composition range. The results have been interpreted in terms of intermolecular interactions and structural factors of the ionic liquids and alcohols.     

Acoustical and excess properties of {1-hexanol + n-hexane, or n-octane, or n-decane} at (298.15, 303.15, and 308.15) K

Densities (ρ) and speeds of sound (u) for the binary mixtures of 1-hexanol with n-hexane, n-octane and n-decane have been measured over the entire composition range at 298.15, 303.15 and 308.15 K. The dynamic viscosities (η) for these systems have been measured at 298.15 K. From experimental data, excess molar volumes (V_m^E), molar isentropic compressibility (K_s,m), excess molar isentropic compressibility (K_s,m^E), deviation in speed of sound (u^D) from their ideal values (u^id) in an ideal mixture, and excess free volumes (V_f^E) have been calculated. The excess functions have also been correlated with the Redlich–Kister polynomial equation. The viscosity data have been analysed in terms of some semi-empirical equations. The theoretical values of speed of sound (u) and isentropic compressibility (κ_S) have also been estimated using the Prigogine–Flory–Patterson (PFP) theory with the van der Waals (vdW) potential energy model and the results have been compared with experimental values. The effect of chain-length of n-alkanes as well as the temperature on the excess properties has also been studied.     

Excess molar volumes and isentropic compressibilities of binary liquid mixtures containing n-alkanes at 298.15 K

Excess molar volumes (V ^E) and deviation in isentropic compressibilities (Δβ _s) have been investigated from the density ρ and speed of sound u measurements of six binary liquid mixtures containing n-alkanes over the entire range of composition at 298.15 K. Excess molar volume exhibits inversion in sign in one binary mixture, i.e., n-heptane + n-hexane. Remaining five binary mixtures, n-heptane + toluene, cyclohexane + n-heptane, cyclohexane + n-hexane, toluene + n-hexane and n-decane + n-hexane show negative excess molar volumes over the whole composition range. However, the large negative values of excess molar volume becomes domainant in toluene + n-hexane mixture. Deviation in isentropic compressibility is negative over the whole range of composition in the case of all the six binary mixtures. Existence of specific intermolecular interactions in the mixtures has been analyzed in terms of excess molar volume and deviation in isentropic compressibility.     

运用液体声学理论研究超临界二氧化碳的声特性

利用液体声学模型,根据美国国家标准局提供的二氧化碳声速、密度、摩尔体积和绝热压缩系数数据,计算了气态、液态和超临界态二氧化碳在不同温度和压力条件下的摩尔声速、摩尔压缩系数及Van der Waals 常数. 分析发现,在较宽的温度和压力范围内,液体中的声学模型能够很好地运用于超临界态二氧化碳的研究. 并在液体声学模型适用范围内,计算了超临界二氧化碳在不同温度及压力状态下的表面张力、粘度、自扩散系数,为超临界流体技术提供了参考数据,并分析了这些参量的变化规律. 关键词： 超临界二氧化碳 声速 摩尔声速 摩尔压缩系数     

运用液体声学理论研究超临界二氧化碳的声特性

利用液体声学模型，根据美国国家标准局提供的二氧化碳声速、密度、摩尔体积和绝热压缩系数数据，计算了气态、液态和超临界态二氧化碳在不同温度和压力条件下的摩尔声速、摩尔压缩系数及Van der Waals 常数. 分析发现，在较宽的温度和压力范围内，液体中的声学模型能够很好地运用于超临界态二氧化碳的研究. 并在液体声学模型适用范围内，计算了超临界二氧化碳在不同温度及压力状态下的表面张力、粘度、自扩散系数，为超临界流体技术提供了参考数据，并分析了这些参量的变化规律.     

Electrochemical reduction of benzoyl chloride to benzil in ionic liquid BMIMBF4

A new electrochemical procedure for the electrocatalytic dimerisation of benzoyl chloride in ionic liquid, 1‐butyl‐3‐methylimidazoliumtetrafluoborate, to benzil was investigated for the first time. The electrochemical behavior of benzoyl chlorides in BMIMBF₄ was studied by cyclic voltammetry with a reduction peak at ?1.2 V (vs Ag). The electrolysis experiments were carried out in an undivided cell under mild conditions without any toxic solvents, catalysts and supporting electrolytes, creating benzil at a moderate yield (51%). The results showed that the yields were strongly affected by various factors: temperature, working potential, electrode material. Moreover, the ionic liquid was successfully recycled for this reaction. Copyright © 2011 John Wiley & Sons, Ltd.     

Electrochemical study and electrodeposition of copper in the hydrophobic tri-n-octylmethylammonium chloride ionic liquid media

The electrodeposition of metallic Copper in binary mixture ionic liquid/organic solvent (tri-n-octylmethylammonium chloride (TOMAC))/chloroform (CHCl₃) was investigated. The electrochemical behavior of Cu(II) in TOMAC/CHCl₃ at glassy carbon working electrode at room temperature was studied by cyclic voltammetry and spectroscopy impedance. The results from the cyclic voltammetry showed that the electrodeposition of metallic Cu in the binary mixture ionic liquid/organic solvent was an irreversible process and was controlled by the diffusion of Cu(II) on a glassy carbon working electrode. The average value of αn_α was found to be 0.23 at 25 °C and the diffusion coefficient (D₀) of Cu(II) was calculated to be 7.12 10^− 9 cm²/s at room temperature. The performance of TOMAC ionic liquid such as internal resistance has been investigated with electrochemical impedance spectroscopy (EIS). The scanning electron microscopy (SEM) micrographs was used to observe that the copper plating was moderately dense and contains fine crystallites with average sizes of about 1 μm at room temperature. Energy dispersive X-ray analysis (EDAX) profile showed that the obtained film was copper.     

Speeds of sound and isentropic compressibilities of (2-ethoxyethanol + ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol) binary mixtures at 298.15 K

The speed of sound (u) has been obtained at a frequency of 8.3 MHz in {CH₃CH₂OCH₂CH₂OH + HOCH₂CH₂(OCH₂CH₂)_nOH}for n = 0, 1, 2, and 3 over the whole composition range of studied binary liquid mixtures, at T = 298.15 K. The speed of sound values were combined with those of our previous results for densities and viscosities to obtain isentropic compressibility (κ_s), free volume (V_f), and intermolecular free length (L_f). From all these data excess isentropic compressibility (κ_s^E), excess free volume (V_f^E) and excess intermolecular free length (L_f^E) as well as the deviations of the speed of sound (Δu) were obtained. The results are interpreted in terms of molecular interactions occurring in the solutions.     

Poly(4-vinylpyridine) supported acidic ionic liquid: A novel solid catalyst for the efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones under ultrasonic irradiation

A novel poly(4-vinylpyridine) supported acidic ionic liquid catalyst was synthesized by the reaction of 4-vinylpyridine with 1,3-propanesultone, followed by the polymerization and the addition of the heteropolyacid. Due to the combination of polymer features and ionic liquid, it acted as a heterogeneous catalyst to effectively catalyze the cyclocondensation reaction of anthranilamide with aldehydes under ultrasonic irradiation and afforded the corresponding 2,3-dihydro-4(1H)-quinazolinones compounds in good to excellent yields. In addition, the catalyst could be easily recovered by the filtration and reused six times without significant loss of catalytic activity. More importantly, the use of ultrasonic irradiation can obviously accelerate the reaction.     

An equation of state and non-linear parameter from sound velocity measurements for liquid alkali metals

In the present paper, an equation of state has been obtained in case of liquid alkali metals like Na, K, Rb and Cs from sound velocity measurements. The theory developed gives very good agreement for both the sound velocity and the volume as a function of pressure at different temperatures in these liquid alkali metals. Further, the variation of non-linear parameter,B / A, as a function of pressure and temperature is also studied.     

一种测量液膜高度的方法

给出一种测量液膜高度的新方法,利用此方法测定液体表面张力系数时发现,计算液膜重量时,液膜厚度不能用金属丝直径代替,否则液体表面张力系数会出现负值。     

Isothermal compressibility and sound velocity of binary liquid systems: Application of hard sphere models

Sound velocity and density were measured in six binary liquid mixtures namely,n-heptane+toluene (I);n-heptane+n-hexane (II); toluene+n-hexane (III); cyclohexane+n-heptane (IV); cyclohexane+n-hexane (V), andn-decane+n-hexane (VI) at 298.15 K. The experimental isothermal compressibility has been evaluated from measured values of density and sound velocity. The isothermal compressibility of these mixtures has been calculated theoretically using different models for the hard sphere equation of state and also using Flory’s statistical theory. The computed values of isothermal compressibility were also compared with the experimentally evaluated values. A satisfactory agreement has been observed.     

Volumetric, acoustic and spectroscopic studies for binary mixtures of ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) with alkoxyalkanols at T = (288.15 to 318.15) K

Densities and speeds of sound have been measured for the binary mixtures of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF₆] with ethylene glycol monoethyl ether (EGMEE), diethylene glycol monoethyl ether (Di-EGMEE), triethylene glycol monoethyl ether (Tri-EGMEE) over the whole composition range at atmospheric pressure. Experimental densities have been used to estimate excess molar volumes, V^E. Changes in isentropic compressibility, Δκ_s have been estimated by using experimental speed of sound and density values. Excess properties were fitted to the Redlich-Kister polynomial equation to obtain the binary coefficients and the standard errors. The molecular scale interactions between ionic liquid and alkoxyalkanols have been investigated through ¹H NMR spectroscopy. NMR chemical shifts for hydroxyl group of alkoxyalkanols and their deviations show hydrogen bonding interactions of varying strengths between ionic liquid and alkoxyalkanol in their binary mixtures.