Volumetric behavior of the ternary system (methyl tert-butyl ether + methylbenzene + butan-1-ol) and its binary sub-system (methyl tert-butyl ether + butan-1-ol) within the temperature range (298.15 to 328.15) K

Values of the density and speed of sound were measured for the ternary system (methyl tert-butyl ether + methylbenzene + butan-1-ol) within the temperature range (298.15 to 328.15) K at atmospheric pressure by a vibrating-tube densimeter DSA 5000. Two binary sub-systems were studied and published previously while the binary sub-system (methyl tert-butyl ether + butan-1-ol) is a new study in this work. Excess molar volume, adiabatic compressibility, and isobaric thermal expansivity were calculated from the experimental values of density and speed of sound. The excess quantities were correlated using the Redlich–Kister equation. The experimental excess molar volumes were analyzed by means of both the Extended Real Associated Solution (ERAS) model and the Peng–Robinson equation of state. The novelty of this work is the qualitative prediction of ternary excess molar volumes for the system containing auto-associative compound and two compounds that can hetero-associate. The combination of the ERAS model and Peng–Robinson equation of state could help to qualitatively estimate the real behavior of the studied systems because the experimental results lie between these two predictions.     

Densities, viscosities, and ultrasonic velocity studies of binary mixtures of trichloromethane with methanol, ethanol, propan-1-ol, and butan-1-ol at T = (298.15 and 308.15) K

Densities, viscosities, and ultrasonic velocities of binary mixtures of trichloromethane with methanol, ethanol, propan-1-ol, and butan-1-ol have been measured over the entire range of composition, at (298.15 and 308.15) K and at atmospheric pressure. From the experimental values of density, viscosity, and ultrasonic velocity, the excess molar volumes (V^E), deviations in viscosity (Δη), and deviations in isentropic compressibility (Δκ_s) have been calculated. The excess molar volumes, deviations in viscosity and deviations in isentropic compressibility have been fitted to the Redlich-Kister polynomial equation. The Jouyban-Acree model is used to correlate the experimental values of density, viscosity, and ultrasonic velocity.     

The direct substitutions of 9H-xanthen-9-ol with indoles in a room temperature ionic liquid medium BmimBF4

A simple, atom economical, highly efficient and green protocol has been developed for the S_N1-type substitutions of 9H-xanthen-9-ol with indoles or other nucleophiles (such as diketone and pyrrole). This approach provides the substitution products in high or excellent yields in the BmimBF₄ media at room temperature.     

Inhibition effect of butan-1-ol on the corrosion behavior of austenitic stainless steel (Type 304) in dilute sulfuric acid

The electrochemical behavior of austenitic stainless steel (Type 304) in 3 M sulfuric acid with 3.5% recrystallized sodium chloride at specific concentrations of butan-1-ol was investigated with the aid of potentiodynamic polarization, open circuit measurement and weight loss technique. Butan-1-ol effectively inhibited the steel corrosion with a maximum inhibition efficiency of 78.7% from weight-loss analysis and 80.9% from potentiodynamic polarization test at highest concentration studied. Adsorption of the compound obeyed the Freundlich isotherm. Thermodynamic calculations reveal physiochemical interactions and spontaneous adsorption mechanism. Surface characterizations showed the absence of corrosion products and topographic modifications of the steel. Statistical analysis depicts the overwhelming influence and statistical significance of inhibitor concentration on the inhibition performance.     

N-Methylimidazolium perchlorate as a new ionic liquid for the synthesis of bis(pyrazol-5-ol)s under solvent-free conditions

N-Methylimidazolium perchlorate([MIm]ClO₄) was synthesized and some of its physico-chemical properties, such as density, surface tension were investigated. A thermo gravimetric analysis(TGA) and solvent performance were also studied. The results show that this ionic liquid is an excellent catalyst for the synthesis of 4,4'-(arylmethylene)bis(1H-pyrazol-5-ol) derivatives under solvent-free conditions. This method has the advantages of high yield, clean transformation, simple operation and short reaction time. The ionic liquid can be recycled without significant loss of activity.     

Thermal properties and crystalline structure of poly(10-undecene-1-ol)

Atactic and isotactic-rich poly(10-undecene-1-ol)s were synthesized by metallocene-catalyzed polymerization. The thermal properties and the crystalline structure of the poly(10-undecene-1-ol)s were characterized using Dynamic Scanning Calorimetry (DSC), Temperature-Modulated DSC (MDSC), Fourier Transform Infrared Spectroscopy (FTIR), and Wide-Angle X-ray Scattering (WAXS). It was found that the polymers crystallize primarily at their side chains, which is indicated by similar arrangement of both isotactic-rich and atactic polymers. The polymers form smectic layer structures independent on their tacticity, however, for the isotactic-rich polymers, higher crystallinities were observed than for the atactic polymers in terms of higher melting enthalpies.     

Monitor adsorption of acetone vapor to a room temperature ionic liquid 1-octyl-3-methylimidazolium bromide by a langasite crystal resonator

In this work, the responses of a Y-cut langasite crystal resonator (LCR) in liquid phases were investigated by an impedance analysis method. The resonant frequency (f_S) of the LCR decreases with increasing mass loading on the active surface of the resonator. The LCR can be operated at the resonant frequency that is down to about 60% of the fundamental frequency (f₀) under foreign mass loading. The frequency-mass coefficient of the Y-cut LCR is theoretically derived to be −1.282 × 10⁻⁶, which is supported by the experimental results. The resonant frequency of the LCR decreases linearly while its motional resistance (R_m) increases linearly with increasing (ρη)^1/2, where η and ρ are the viscosity and density of the liquid phase, respectively. The slopes of the plots of f_S versus (ρη)^1/2 and R_m versus (ρη)^1/2 are related to the region of (ρη)^1/2 because of the influence of surface roughness of the LCR. The changes in viscodensity of a room temperature ionic liquid (RTIL), 1-octyl-3-methylimidazolium bromide ([C₈MIM][Br]), were investigated in acetone vapor adsorption and ascending temperature processes by the LCR. The adsorption of acetone into [C₈MIM][Br] causes a significantly drop in viscosity of the [C₈MIM][Br] film, which induces an increase in f_S and a decrease in R_m for the RTIL modified LCR. When the thickness of [C₈MIM][Br] film is less than the decay distance of the thickness-shear wave, a mass effect model is observed in the early adsorption process. Based on the responses of the LCR, the viscodensity of the [C₈MIM][Br] film as well as the adsorbed amounts of acetone into film were monitored in real time during the adsorption or desorption processes.     

Vapor–liquid equilibrium,densities, and interfacial tensions for the system ethyl 1,1-dimethylethyl ether (ETBE) + propan-1-ol

Isobaric vapor–liquid equilibrium data at 50, 75, and 94 kPa have been determined for the binary system ETBE + propan-1-ol, in the temperature range 325–368 K. The measurements were made in a vapor–liquid equilibrium still with circulation of both phases. Mixing volumes have been also determined from density measurements at 298.15 K and 101.3 kPa and, at the same temperature and pressure, the dependence of interfacial tension on concentration has been measured using the pendant drop technique. According to experimental results, the mixture presents positive deviation from ideal behavior and azeotropy is present at 75 and 94 kPa. No azeotrope was detected at 50 kPa. The mixing volumes of the system are negative over the whole mole fraction range, and the interfacial tensions exhibit negative deviation from the linear behavior. The activity coefficients and boiling points of the solutions were well correlated with the mole fraction using the Wohl, Wilson, NRTL, UNIQUAC equations. Excess volume data and interfacial tensions were correlated using the Redlich–Kister model.     

Sulfur makes the difference: synthesis and mesomorphic properties of novel thioether-functionalized imidazolium ionic liquid crystals

Novel thioether-linked imidazolium ionic liquid crystals were synthesized starting from methyl 2-mercaptoacetate. The mesomorphic properties were determined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. All mesogens displayed smectic A mesophase geometries with strongly interdigitated bilayer structures. Comparison of the thioether-linked imidazolium salts with the corresponding amine- and amide-linked imidazolium salts as well as simple N-alkyl-imidazolium salts showed that both mesophase width and stability increased with increasing softness of the linking unit, thus indicating the beneficial effect of sulfur. Additionally, an increase of the length of the linking unit decreased the interdigitation of the alkyl chains.     

新型1-烷基-2,3-二甲基咪唑六氟磷酸盐离子液体/过氧化氢酶电极电化学性能研究与应用

合成了5种新型1-烷基-2,3-二甲基咪唑六氟磷酸盐类离子液体,并以离子液体为介质制备空白电极及过氧化氢酶电极.采用循环伏安法研究电极电化学行为,结果表明离子液体有优良的电化学性质.离子液体空白电极的基体峰电流都在数nA范围内,电化学窗口大于4 V;不同离子液体酶电极的电化学行为存在明显差异.在5种离子液体中,仅有1-戊基-2,3-二甲基咪唑六氟磷酸盐能很好地保持酶活,呈现灵敏的电化学响应.此外,该酶电极还具有良好的稳定性,4 ℃保存30 天后,电化学性质没有明显变化.在0.1 mol/L的H3PO4缓冲溶液(pH 7.0)中,该酶电极还原峰电流随溶液中H2O2浓度的增加而增大.当H2O2浓度在3.17×10-6～12.4×10-6 mol/L之间,酶电极的还原峰电流符合线性关系,其检出限为1.1×10-6 mol/L.方法已用于环境水中痕量H2O2的测定.     

Physical and electrochemical properties of 1-alkyl-3-methylimidazolium tetrafluoroborate for electrolyte

Three kinds of ionic liquids, 1-alkyl-3-methylimidazolium tetrafluoroborate (n=2–4), were prepared and fundamental properties of ionic liquids and those mixed with industrially used organic solvents (PC, GBL and AN) were investigated compared to solid salts, TEMABF₄. It was found that degree of ionization of the ionic liquids were almost same as that of TEMABF₄ from the conductivity measurement in diluted system of PC. The ionic liquids and the organic solvents intermingle with each other. Some enhancement in conductivity was observed compared to TEMABF₄.     

Thermochemical properties of 1-butyl-3-methylimidazolium nitrate

Heat capacity for 1-butyl-3-methylimidazolium nitrate [C₄mim][NO₃] in the temperature range (5–370) K has been measured by adiabatic calorimetry. Temperatures and enthalpies of its phase transitions have been determined. Thermodynamic functions have been calculated for the crystalline and the liquid states. Phase transition temperatures for set of nitrate salts have been compared. Enthalpy of combustion and enthalpy of formation for crystalline [C₄mim][NO₃] have been determined using a static-bomb isoperibol combustion calorimeter. A correlation scheme for the estimation of C_p of ionic liquids has been developed.     

Selective water sorbents for multiple applications, 1. CaCl2 confined in mesopores of silica gel: Sorption properties

This paper presents sorption properties of a selective water sorbent based on mesoporous KSKG silica gel as a host matrix and calcium chloride as a hygroscopic salt. Sorption isobars, isochores and isotherms at T=20–150°C and vapor partial pressures of 8–133 mbar clearly showed two types of water sorption: 1) the formation of solid crystal hydrates at low amounts N of sorbed water, and 2) vapor absorption mainly by the salt solution at higher N. Sorption properties of CaCl₂ crystal hydrates were found to change strongly due to their impregnation into mesoporous silica gel, whereas the solution confinement to the mesopores did not change its water sorption properties with respect to the bulk solution. Isosteric sorption heat was measured to depend on water sorption and to change from 62.5 kJ/mol for solid hydrates to 42.2–45.6 kJ/mol for solution.     

Photoionization and Dissociation Study of 2-Methyl-2-propen-1-ol: Experimental and Theoretical Insights

The photoionization and dissociation of 2-methyl-2-propen-1-ol (MPO) have been investigated by using molecular beam experimental apparatus with tunable vacuum ultravioletsynchrotron radiation in the photon energy region of 8.0-15.5 eV. The photoionization efficiency (PIE) curves for molecule ion and fragment ions: C₄H₈O⁺、C₄H₇O⁺、C₃H₅O⁺、C₄H₇⁺、C₄H₆⁺、C₄H₅⁺、C₂H₄O⁺、C₂H₃O⁺、C₃H₆⁺、C₃H₅⁺、C₃H₃⁺、CH₃O⁺、CHO⁺ have been measured, and the ionization energy (IE) and the appearance energies (AEs) of the fragment ions have been obtained. The stable species and the first order saddle points have been calculated on the CCSD(T)/cc-pvTZ//B3LYP/6-31+G(d,p) level. With combination of theoretical and experimental results, the dissociative photoionization pathways of 2-methyl-2-propen-1-ol are proposed. Hydrogen migrations within the molecule are the dominant processes in most of the fragmentation pathways of MPO.     

An in situ STM study on the long-range surface restructuring of Au(1 1 1) in a non-chloroaluminumated ionic liquid

We report an in situ STM study of a potential-dependent long-range surface restructuring of Au(1 1 1) electrode in neat 1-butyl-3-methylimidazolium tetrafluoroborates (BMIBF₄) ionic liquid. Au(1 1 1) undergoes a significant long-range surface restructuring upon cathodic excursion to −1.0 V vs. Pt quasi-reference. The restructuring involves the formation of tiny pits, which then develops into a stable worm-like network with an average width of the network grids 2 nm. Electrochemical annealing occurs at the cathodic limit with the presence of a reduction product of cation BMI⁺. A smooth surface is recovered with the appearance of the typical (√3 × 22) reconstruction of Au(1 1 1). The surface restructuring is reestablished upon anodic excursion to −1.3 V after the adsorbed reduction product is oxidized. The long-range surface restructuring phenomenon is tentatively explained as a result of partial charge transfer to the weakly adsorbed BMI⁺, which reduces the metal–metal cohesive energy. In addition, the synergetic effect of the counter anion BF₄⁻ may also be involved. The results provide a knowledge of Au(1 1 1) electrode behavior in the neat ionic liquid and are beneficial to understanding in situ STM results involving surface morphological changes in such a media.     

Synthesis of 1,2-azidoalcohols from epoxides using a task-specific protic ionic liquid: 1-hydrogen-3-methylimidazolium azide

A task-specific ionic liquid as an environmentally eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. In order to use protic ionic liquids (PIL), we decided to synthesize 1,2-azidoalcohols via a ring opening reaction of epoxides with 1-hydrogen-3-methylimidazolium azide ([Hmim]N₃), which actually acts as a solvent, a reagent and an activator of the epoxide ring. The reaction was carried out in short times (50–70 min) at 70 °C to give 1,2-azidoalcohol in 80–94% isolated yields.     

Volumetric properties of (1-propoxypropan-2-ol + water) mixtures between (283 and 303) K: The effect of branching on alkoxyalcohols

Accurate density values are reported for aqueous binary mixtures of 1-propoxypropan-2-ol (1-PP-2-ol) over the whole composition range and temperatures between (283 and 303) K at intervals of 5 K. Excess molar volumes of the mixture, , apparent molar volumes of 1-PP-2-ol, V_φ,2, as well as excess partial molar volumes, , of both components were obtained over the entire composition and temperature ranges. Thermal expansibility effects on this (amphiphile + water) mixture are analysed in terms of excess molar isobaric expansions, , of the mixture and from the temperature dependence of limiting excess partial molar isobaric expansions, , for both chemical substances in the mixture. An analytical method based on Redlich−Kister fitting equations for as a function of the mole fraction has been used to obtain limiting excess partial molar volumes, . The excess properties are referred to a thermodynamically defined ideal liquid mixture. Interesting insights into the mixing process are gained from the visual impact of plots showing the composition and temperature dependence of different excess molar thermodynamic properties. The choice of 1-PP-2-ol was specially meant to highlight the role of branching in the alcohol versus alkoxy moieties. The present thermodynamic data are compared with that for isomeric 2-butoxyethanols, which are structural isomers of 1-PP-2-ol, and for 2-isopropoxyethanol. From this comparison an extended insight is gained into the role of branching and chain length on the mixing process and particularly in changes of local H-bond patterns of hydration water.     

Use of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate in countercurrent chromatography

Room temperature ionic liquids (RTIL) are molten salts that are liquids at room temperature. Their liquid state makes them possible candidates as solvents in countercurrent chromatography (CCC), which uses solvents as both the mobile and stationary phases. The study focuses on 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF₆), an easy to synthesize and purify RTIL whose melting point is –8°C. It is shown that BMIM PF₆ behaves like a solvent of significant polarity (comparable with that of ethanol). The ternary phase diagram water–acetonitrile–BMIM PF₆ is given, because it was necessary to add acetonitrile to reduce the ionic liquid viscosity. The 40:20:40% w/w water–acetonitrile–BMIM PF₆ biphasic liquid system was found to be appropriate as a biphasic liquid system for CCC. Different aromatic solutes, including bases, acids, and neutral compounds, were injected into the CCC column to estimate their distribution constants between the ionic liquid-rich phase and the aqueous phase. The resulting K_il/w constants were compared with the corresponding literature octanol–water partition coefficients, K_o/w. The important drawbacks in the use of RTIL in CCC are clearly pointed out: high viscosity producing pressure build-up, UV absorbance limiting the use of the convenient UV detector, and non-volatility precluding the use of the evaporative light-scattering detector for continuous detection.     

Selective extraction/isolation of hemoglobin with ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate (BtmsimPF6)

Ionic liquid was for the first time employed for selective isolation of heme-protein species. Direct extraction of hemoglobin into ionic liquid without using any concomitant reagent or extractant was carried out. Hemoglobin at the level of 100 ng μL⁻¹ could readily be quantitatively extracted into ionic liquid (IL) 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate (BtmsimPF₆) in the absence of any co-existing extractants/additives at pH 7, at the same time; however, the other protein species do not interfere and remain in the aqueous phase. A back extraction efficiency of ca. 80% for 20 ng μL⁻¹ hemoglobin in ionic liquid phase was achieved with sodium dodecyl sulfate (SDS) solution as stripping reagent. ⁵⁷Fe Mossbauer spectra and circular dichroism (CD) spectra indicated that the penta-coordinated ferrous atom in hemoglobin provide a vacant or free coordinating position, which could be occupied by the cationic Btmsim⁺ moiety. The interaction/coordination reaction between the iron atom in the heme group of hemoglobin and the cationic ionic liquid moiety furnishes the driving force for facilitating fast transfer of hemoglobin into BtmsimPF₆. The present system was applied for selective isolation of heme-protein, i.e., hemoglobin from human whole blood without any pretreatment, giving rise to satisfactory results.     

Liquid–liquid equilibrium of (1H,1H,7H-perfluoroheptan-1-ol + perfluoroalkane) binary mixtures

This work presents new liquid–liquid equilibrium data for mixtures of 1H,1H,7H-perfluoroheptan-1-ol and linear perfluoroalkanes from C₆ to C₉. Data were measured at atmospheric pressure by turbidimetry and at pressures up to 5 MPa using a laser light scattering technique. The coexistence curves have been fitted to renormalization group extended-scaling expressions with the critical temperature and molar fraction obtained from the fit.