Activity Coefficients of Potassium Chloride in Water–Ethanol Mixtures

Activity coefficients of KCl were determined in water–ethanol solvents in the range 5–20% (w/w) ethanol, from experimental electromotive force (emf) data. The molalities varied from 0.1 mol-kg^–1 to near saturation and measurements were taken in the temperature range 25 to 45°C. The Pitzer model was used to describe the nonideal behavior of the electrolyte and the corresponding coefficients were determined for each solvent. The Pitzer–Simonson equations were also applied and found superior in the study of KCl in those nonaqueous solutions.     

D-甘露醇与D-山梨醇在氯化钠水溶液中的稀释焓

应用等温流动微量热法测定了298.15 K时互为旋光异构体的D-甘露醇与D-山梨醇在不同浓度的氯化钠水溶液中的稀释焓, 利用 McMillan-Mayer 理论计算了D-甘露醇与D-山梨醇在不同浓度的氯化钠水溶液中的焓对相互作用系数. 结果表明, D-甘露醇和D-山梨醇在氯化钠水溶液中的焓对相互作用系数h2均为正值, h2的值随着氯化钠浓度的增加皆逐渐增大, 但D-山梨醇的焓对相互作用系数h2增大的速率[dh2 /dm(NaCl)]比 D-甘露醇的要大. 根据两多元醇分子构象结构的差异， 溶质-溶质相互作用和溶质-溶剂相互作用对结果进行了解释.     

Surface Tension in Aqueous Dodecylethylaminocarbonyldimethylbenzylammonium Chloride

The surface tension of aqueous solutions of the cationic surfactant dodecylethylaminocarbonyldimethylbenzylammonium chloride is measured for the first time over a wide concentration range from 7.9×10^{- 7} to 3.9×10^{- 2} M at 20-35°C. The critical micelle concentration of DAEDMBAC as influenced by temperature is determined.     

Activity Coefficients of Sodium Chloride in Water–Ethanol Mixtures: A Comparative Study of Pitzer and Pitzer–Simonson Models

Activity coefficients of NaCl were determined in water–ethanol solvents, in the range 5–20% (w/w) ethanol, from emf data. The molalities varied from 0.1 mol-kg^-1 to near saturation and measurements were taken in the temperature range 25–50°C. The Pitzer model was used to describe the nonideal behavior of the electrolyte and the corresponding coefficients were determined for each solvent. The Pitzer–Simonson equations were also applied and a detailed study, involving the short- and long-range forces, was done in order to better understand the different results obtained with both models.     

In situ derivatization hollow fibre liquid-phase microextraction for the determination of biogenic amines in food samples

Hollow fibre liquid-phase microextraction with in situ derivatization using dansyl chloride has been successfully developed for the high-performance liquid chromatography-ultraviolet (HPLC-UV) determination of the biogenic amines (tryptamine, putrescine, cadaverine, histamine, tyramine, spermidine) in food samples. Parameters affecting the performance of the in situ derivatization process such as type of extraction solvent, temperature, extraction time, stirring speed and salt addition were studied and optimized. Under the optimized conditions (extraction solvent, dihexyl ether; acceptor phase, 0.1 M HCl; extraction time, 30 min; extraction temperature, 26 °C; without addition of salt), enrichment factors varying from 47 to 456 were achieved. Good linearity of the analytes was obtained over a concentration range of 0.1–5 μg mL⁻¹ (with correlation coefficients of 0.9901–0.9974). The limits of detection and quantification based on a signal-to-noise ratio of 3–10, ranged from 0.0075 to 0.030 μg mL⁻¹ and 0.03 to 0.10 μg mL⁻¹, respectively. The relative standard deviations based on the peak areas for six replicate analysis of water spiked with 0.5 μg mL⁻¹ of each biogenic amine were lower than 7.5%. The method was successfully applied to shrimp sauce and tomato ketchup samples, offering an interesting alternative to liquid–liquid extraction and solid phase extraction for the analysis of biogenic amines in food samples.     

氯化亚铜催化3-氯-1-丁烯异构为1-氯-2-丁烯研究

采用一价铜盐为催化剂、二甲基甲酰胺为溶剂,在均相体系中催化3-氯-1-丁烯异构化生成1-氯-2-丁烯.考察了溶剂、反应温度、催化剂种类和加入量对反应的影响,研究发现反应温度和催化剂的加入量对异构化反应有较大影响.在最优条件3-氯-1-丁烯1 mL,二甲基甲酰胺9 mL,CuCl 0.10 g,60℃反应5 h,产物和原料的浓度比为3.88 mmol L-1.采用在线红外光谱对反应过程进行监测,检测到有红外吸收峰在反应过程中先增加后减少的变化过程,提出了可能的反应机理.     

Volumetric Study of the Interaction Between Chloride Salts and Polyvinylpyrrolidone in Aqueous Solution

We are interested in polyvinylpyrrolidone as an analog for the D-state proteins. In a volumetric study, the interactions between polyvinylpyrrolidone (PVP) and sodium-, potassium-, calcium-, and tetrabutylammonium chloride at 35°C in a series of aqueous PVP solutions over a concentration range of PVP up to 20 wt.% was performed. The volumes of transfer at infinite dilution _tr V ₂ ⁰ from water to the PVP solutions were determined for the salts; their decreasing order showed a parallel relation to the Hoffmeister series. The _tr V ₂ ⁰ data were analyzed by applying the McMillan–Mayer method to obtain the volumetric interaction coefficients between the ions and the polymer unit.     

Thermodynamic studies of binary methanol and ethanol solutions of 1-dodecanol and 1-tetradecanol at 25°C

The osmotic coefficients of binary methanol and ethanol solutions of 1-dodecanol and 1-tetradecanol wer measured at 25°C up to 8 mol-kg^–1 in methanol and 5.5 mol-kg^–1 in ethanol. The activity coefficients of the solute were calculated from Bjerrum's relation. From the osmotic and activity coeficients the excess Gibbs energies of solution as well as the respective partial molar functions of solute and solvent and the virial pair interaction coefficients for the excess Gibbs energies were calculated. In addition, the difference in the Gibbs energy of solvation for the solvent in solution relative to the pure solvent was calculated, as well as the partial molar volumes and excess partial molar volumes of solutes at infinite dilution, and the coefficients of pairwise contributions to the excess volume were determined. The thermodynamic parameters obtained are discussed on the basis of solute-solvent and solute-solute interactions.     

The Thermal Diffusion of Hydrogen Chloride in Water–Monoatomic Alcohol Mixtures at 298 K

Standard entropies of the thermal diffusion transference of HCl, entropies of the moving H⁺ and Cl⁻ ions, and Soret coefficients of this electrolyte at 298 K were obtained from a thermoelectrochemical investigation of HCl in water + alcohol solvent systems. The thermoelectric powers of the silver/silver chloride and para-benzoquinone/hydroquinone thermocells have been measured. Effects of the mixed solvent composition and the nature of an alcohol on the thermal diffusion characteristics were discussed using the theories of De Bethune and Agar.     

二甲基烯丙基对甲基苄基氯化铵的合成与表征

以对甲基氯化苄与二甲基烯丙基胺为原料合成了二甲基烯丙基对甲基苄基氯化铵,考查了光照、氮气保护、避光、温度、原料配比、反应时间和不同溶剂等因素对反应的影响,通过四苯硼钠的定量分析确立了最佳反应条件,并对产物的结构进行了表征.     

Ionic interactions in aqueous electrolyte-polyelectrolyte mixtures: Comparisons with mixtures of sodium chloride and the model electrolyte benzyltrimethyl-ammonium chloride at 25°C

Osmotic coefficients for aqueous mixtures of sodium chloride with benzyltrimethylammonium chloride, BzMe₃NCl, obtained by the gravimetric isopiestic vapor pressure comparison method are interpreted with the McKay-Perring transform, with the Scatchard neutral electrolyte treatment, and with the Pitzer ion-component equations. Molal ionic and mean ionic activity coefficients for Na⁺ and Cl^– ions and for NaCl, respectively, in these mixtures at unit total ionic strength also were determined with an electrochemical cell. The excess free energy chenges G^ex on mixing NaCl with BzMe₃NCl were estimated and employed to gain an insight into the relative importance of like and unlike cation-cation interactions.     

Conductivity of Sodium Chloride in Water + 1,4-Dioxane Mixtures at Temperatures from 5 to 35°C I. Dilute Solutions

The molar and single-ion conductivities of dilute solutions of sodium chloride (C<0.01 mol-dm^–3) in binary mixtures of 1,4-dioxane with water were measured covering a broad solvent composition range at temperatures from 5 to 35°C. Accurate viscosity and permittivity data were determined for the organic solvent system. Evaluation of the limiting molar conductivity , ionic conductivities. ₊ , and _– , and the association constant K _A is based on the chemical model of electrolyte solutions, including short-range forces.     

Thermodynamics of Cadmium Chloride in 2-Butanone + Water Mixtures (5, 10, and 15 Mass%) from Electromotive Force Measurements

The emf (electromotive force) of the cell: CdHg_x (two phase) | CdCl₂ (m) | AgCl | Ag in 2-butanone + water mixtures (containing 5, 10, and 15 mass% 2-butanone) was measured at varying temperature (293.15, 298.15, 303.15, 308.15, and 313.15 K) and in the CdCl₂ molality range from 0.002 to 0.02 mol-kg^–1. At each temperature the standard emf of the cell (E_m^o) was determined using potentiometric data and literature values for the stability constants of chlorocadmium complexes. The E_m^o values were used to calculate the standard thermodynamic quantities for the cell reaction, the stoichiometric mean molal activity coefficients of CdCl₂, and the thermodynamic functions for CdCl₂ transfer from water to 2-butanone + water mixtures. The transfer process is a forced one and results in an entropy decrease. The transfer functions were compared to those obtained for the same electrolyte in acetone + water mixtures, as well as to those for HBr in ketone + water mixtures. Medium effects upon CdCl₂ were calculated and discussed for the examined mixtures (2-butanone + water).     

Activity coefficients for the system NaCl+Na2SO4+H2O at various temperatures. Application of Pitzer's equations

The mean activity coefficients of NaCl in the system NaCl+Na₂SO₄+H₂O at various compositions were determined in the temperature range 5–45°C from the emf of potentiometric cells. By processing the results using Pitzer's equations the mixing parameters describing the non-ideal behavior of electrolytes were calculated. The temperature coefficients of the mixing parameters were determined and found not to be significant. The mixing parameters and temperature coefficients calculated for the binary mixture can be used to describe the behavior of multicomponent systems containing NaCl and Na₂SO₄, and eventually sea water.     

Osmotic and activity coefficients of monomethyl-, dimethyl-, and trimethylammonium chlorides at 25°C

The osmotic and activity coefficients of monomethyl-, dimethyl-, and trimethylammonium chlorides in aqueous solution have been determined at 25°C by the gravimetric isopiestic method. The measurements extend from 0.1 molal (m) to 20, 17, and 15 mol-kg^–1, respectively, for the three salts. In the region below 2m, the osmotic coefficients decrease in the order NH₄Cl>MeH₃NCl>Me₂H₂NCl>Me₃HNCl>Me₄NCl, and above 3m the order is reversed. The intermediate members of the series have identical osmotic coefficients at the crossover molality of 3.0. It is suggested that the behavior at low molalities reflects primarily ion-dipole interactions, decreasing as the cation size increases, whereas hydrophobic (structure-making) interactions, increasing in importance with the number of non-polar methyl substituents, are predominant in concentrated solutions of these salts.     

Peculiar properties of sodium lodide in alcohols,acetone, and alcohol-water mixtures at lower temperatures

The enthalpies of solution of sodium iodide in methanol, ethanol and acetone and in mixtures of methanol and ethanol with water were measured over wide ranges of electrolyte concentration and temperature. Standard enthalpies of solution, transfer enthalpies of NaI from alcohols to alcohol-water mixtures, and temperature coefficients of enthalpies of solution have been calculated. Thermodyanmic characteristics of solution and solvation of the Na⁺ and I^– ions in acetone and ethanol were determined at 243–298 K. It is noted that at lower temperatures the disruption of solvent structure by ions is a local effect. The presence of negative solvation of the Na⁺ and I^– ions in alcohol-water mixtures at lower temperatures is demonstrated.     

An Accurate Equation for the Electrolytic Conductivity of Potassium Chloride Solutions

An empirical equation has been developed to model the electrolytic conductivity of potassium chloride (KCl) solutions over the temperature range 0 to 55 °C (ITS-90) and molality concentrations from 0 to 5 mol⋅kg⁻¹ (H₂O). The National Institute of Standards and Technology (NIST) Demal values are treated as the defining data and selected historical data provided further data. Changes in the definition of the ohm, liter and temperature scales have been identified and the historical data were converted to modern units. The accuracy of the equation is estimated to be equal to 0.03% as suggested by NIST as the accuracy of these data.     

Electroreduction of Yttrium Trifluoride in Molten Potassium Chloride

Electroreduction of Y³⁺ in molten KCl–YF₃ is studied at 1053 to 1123 K using a voltammetry method. The discharge of Y³⁺ to the metal with the attachment of all three electrons proceeds in a single stage (Y³⁺ + 3e Y), in the range of mixed kinetics. The diffusion coefficients, activation energy, and transfer coefficients are determined.     

Electrochemical assessment of water|ionic liquid biphasic systems towards cesium extraction from nuclear waste

A room temperature ionic liquid (IL) composed of a quaternary alkylphosphonium (trihexyltetradecylphosphonium, P₆₆₆₁₄⁺) and tetrakis(pentafluorophenyl)borate anion (TB⁻) was employed within a water|P₆₆₆₁₄TB (w|P₆₆₆₁₄TB or w|IL) biphasic system to evaluate cesium ion extraction in comparison to that with a traditional water|organic solvent (w|o) combination. ¹³⁷Cs is a major contributor to the radioactivity of spent nuclear fuel as it leaves the reactor, and its extraction efficiency is therefore of considerable importance. The extraction was facilitated by the ligand octyl(phenyl)-N,N′-diisobutylcarbamoylphosphine oxide (CMPO) used in TRans-Uranium EXtraction processes and investigated through well established liquid|liquid electrochemistry. This study gave access to the metal ion to ligand (1:n) stoichiometry and overall complexation constant, β, of the interfacial complexation reaction which were determined to be 1:3 and 1.6 × 10¹¹ at the w|P₆₆₆₁₄TB interface while the study at w|o elicited an n equal to 1 with β equal to 86.5. Through a straightforward relationship, these complexation constant values were converted to distribution coefficients, δ_α, with the ligand concentrations studied for comparison to other studies present in the literature; the w|o and w|IL systems gave δ_α of 2 and 8.2 × 10⁷, respectively, indicating a higher overall extraction efficiency for the latter. For the w|o system, the metal ion-ligand stoichiometries were confirmed through isotopic distribution analysis of mass spectra obtained by the direct injection of an emulsified water–organic solvent mixture into an electron spray ionization mass spectrometer.     

酸化蒙脱土/氯化锌催化叔丁醚和叔丁酯的合成

以酸化蒙脱土/氯化锌作为催化剂,二碳酸二叔丁酯与一系列酚、醇和羧酸类化合物在120 ℃封管条件下反应,合成了叔丁醚和叔丁酯类衍生物,方法简单,经济可靠,环境友好,后处理方便,收率为61%~75%,产物结构经¹H NMR,ESI-MS确证。 探讨了溶剂、温度、金属离子等因素对反应收率的影响,并提出了可能的反应机理。 为今后该类化合物的合成提供了一种新的方法。