反式-1,2-环己二醇和甲酸钠的结晶介稳区研究

采用激光测量装置在不同温度、不同搅拌速度下研究了反式-1,2-环己二醇在水和乙酸乙酯中的溶解和超溶解特性,亦测定了甲酸钠在水中不同温度下的溶解和超溶解特性,得到了反式-1,2-环己二醇和甲酸钠的结晶介稳区。反式-1,2-环己二醇在水中和乙酸乙酯中的溶解度、超溶解度和介稳区宽度丛均随温度的升高而增加,且反式-1,2-环己二醇在水中的溶解度、超溶解度和介稳区宽度ΔS远远大于其在乙酸乙酯中的溶解度、超溶解度和介稳区宽度ΔS;反式-1,2-环己二醇在水中的超溶解度和介稳区宽度△S均随搅拌速度的提高而减小。高速搅拌下反式-1,2-环己二醇在水中的介稳区宽度△θ为4℃左右,中速搅拌下为7℃左右;在乙酸乙酯中的介稳区宽度△θ为3℃左右。甲酸钠在水中的溶解度、超溶解度和介稳区宽度△S均随温度的升高而呈线性增加,介稳区宽度△θ在4～5℃之间。     

1，2-环己二醇溶解度的测定及关联

采用激光监视技术测定了1,2-环己二醇在乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙烯酸甲酯、丙烯酸乙酯、甲基丙基酮、乙酰乙酸乙酯和水中的溶解度,并用UNIFAC模型进行了关联,其溶解度预测值与实测值吻合良好.     

减压渣油在常压乙酸乙酯脱沥青溶解度研究

采用实验方法确定了减压渣油、乙酸乙酯的溶解度参数随温度的变化规律,关联出一个适用于低温下减压渣油在乙酸乙酯溶剂中的溶解公式,揭示了减压渣油在常压溶剂乙酸乙酯中的溶解度参数与萃取温度的规律,建立了萃取温度与摩尔分数之间关系,为进一步的减压渣油在常压溶剂脱沥青过程的研究提供了一定的数据基础。     

醋酸甲酯-甲醇-水体系的盐效应

在20℃的条件下研究了加入氯化钙对醋酸甲酯-甲醇-水体系产生的盐效应。实验结果表明,随着初始水相中氯化钙质量分数的增加,两相区逐渐扩大,醋酸甲酯在水相的溶解度和水在有机相中的溶解度均有所降低。在有机相中甲醇质量分数一定的条件下,随着初始水相中氯化钙质量分数的增加,甲醇在有机相和水相间的分配系数减小,甲醇的选择性系数而增大。这些结论表明,采用加盐萃取对醋酸甲酯和甲醇进行分离十分有利。对该含盐体系的液—液平衡数据采用Eisen-Joffe方程进行了关联,关联值与实验值的平均相对偏差为4 08%。     

Liquid-Liquid equilibria of heptane-methanol-toluene-calcium chloride and ethyl acetate-water-ethanol-calcium chloride quaternary systems

Liquid-liquid equilibria (LLE) data for the heptane-methanol-toluene-calcium chloride and ethyl acetate-water-ethanol-calcium chloride quaternary systems were measured under various salt concentrations at 298.15 K and the results obtained were correlated with a modification of Hàla's model. Distribution of the salt between the two liquid phases was found to be strongly influenced by the content of methanol or ethanol while the solubility of the salt in the heptane or ethyl acetate rich phase was very small. The two-liquid region, i.e. the miscibility gap was enlarged by adding the salt. Correlations of LLE data including the salt distribution for both the non-aqueous and aqueous quaternary systems were possible with reasonable accuracy.     

The separation of carbon nanotubes from chlorides

Carbon nanotubes (CNTs) were synthesized by molten chloride electrolysis, resulting in the suspension of CNTs in the molten chloride. After the chloride was cooled down to room temperature it was dissolved in water. As a result of this investigation, ethyl acetate was found to be the most efficient extracting agent, which was able to extract more than 90% of CNTs from the aqueous salt solution within 5 s. After additional seven washing cycles by water and evaporating the remaining ethyl acetate-water solution, pure CNTs were obtained, i.e. their separation from the chloride phase was complete.     

Preparation of sulfuric acid ([3-(3-silicapropyl)sulfanyl]propyl)ester: A new and recyclable catalyst for the formylation and acetylation of alcohols under heterogeneous conditions

We describe a simple and efficient procedure for the preparation of sulfuric acid ([3-(3-silicapropyl)sulfanyl]propyl)ester (3) by the reaction of 3-(thio(propy-3-yl)silica)-propanol (2) and chlorosulfonic acid in chloroform. 3-(Thio(propy-3-yl)silica)-propanol was prepared by the reaction of 3-mercaptopropylsilica (MPS) with 3-chloropropanol in refluxing toluene. This solid sulfuric acid ([3-(3-silicapropyl)sulfanyl]propyl)ester is employed as a new catalyst for the formylation of alcohols with ethyl formate under mild and heterogeneous conditions at room temperature with good to excellent yields. Also, 3 can catalyze the acetylation of various alcohols by the reaction of alcohols with ethyl acetate under reflux conditions or with acetic anhydride at room temperature.     

Splitting of the liquid solution and the compositions of liquid phases in the water-<Emphasis Type="Italic">n</Emphasis>-propanol-<Emphasis Type="Italic">n</Emphasis>-propyl acetate system at 293.15, 303.15, and 313.15 K

New experimental data on solubility and liquid-liquid phase equilibrium in a water-n-propanol-n-propyl acetate system under polythermal conditions are presented. The results of modeling the liquid-liquid equilibrium using the UNIFAC model are given.     

离子液体反应萃取精馏合成乙酸乙酯

采用离子液体1-磺酸丁基-3-甲基咪唑硫酸氢盐([HSO₃bmim][HSO₄])和1-丁基-3-甲基咪唑双三氟甲磺酰亚胺盐([BMIM][Tf₂N])分别作为催化剂和萃取剂,对乙酸甲酯与乙醇合成乙酸乙酯和甲醇的反应萃取精馏(RED)过程进行了模拟计算。在反应动力学和汽液相平衡分析基础上建立了反应萃取精馏流程,研究了理论板数、回流比、持液量、进料位置、溶剂比(萃取剂进料与原料进料摩尔流量的比值)、催化剂进料流量等参数对反应萃取精馏过程的影响。在优化的操作条件下,甲醇纯度为0.9922,乙酸乙酯纯度为0.9905,乙酸甲酯转化率为0.9922。     

Fast and very slow reactions: phase transfer catalysis

The effect of phase transfer catalysts (PTC), such as tricaprylmethyl ammonium chloride (Aliquat-336), cetyl trimethyl ammonium bromide, etc. on the rate of alkaline hydrolysis of different formate and acetate esters was studied. In the case of formate esters extraction is accompanied by fast pseudo-first order reaction in diffusion film; for acetate esters the reaction is insufficiently fast to occur in the diffusion film.The values of the volumetric rate of extraction, R_Aa, and the specific rate of extraction, R_A, with or without PTC, were measured in a fully baffled mechanically agitated contactor and a constant interfacial area stirred cell, respectively. The alkaline hydrolysis reaction was carried out with aqueous solutions of sodium hydroxide or aqueous lime slurry and the effect of speed of agitation and PTC concentration on the rate of hydrolysis was studied. A remarkable increase in the value of R_A was realized in the presence of PTC and the enhancement factor for the formate ester hydrolysis reaction ranged from 20 to over 200.     

KINETICS OF ALKALINE HYDROLYSIS OF ISOAMYLACETATE

The theory of mass transfer accompanied by chemical reaction has been used to determine the kinetics of alkaline hydrolysis of isoamylacetate. The rate constant for the alkaline hydrolysis is around 9.52 cm³/(mole)(sec). This is much lower than the rate constant for alkaline hydrolysis of n-amyl acetate, which is about 85 cm³/(mole)(sec). The presence of an electrolyte like sodium chloride in the aqueous phase reduced the rate of extraction to some extent. The rates of extraction with sodium chloride in the aqueous phase and the corresponding rate constant values have been reported.     

BENZYL ALCOHOL FROM PHASE TRANSFER CATALYZED WEAKLY ALKALINE HYDROLYSIS OF BENZYL CHLORIDE

The chemical and mass transfer processes were formulated and explained for the system initially composed of BzCl/BzR₃”NCI, R'COONa, H₂O. The effects of the size of the alkyl group of benzyltrialkylammonium chloride, the pH of the aqueous phase, the concentration of the pH controlling agent, aqueous NaOH, the stirring speed, the reaction temperature, the amounts of the cocatalysts, sodium formate and sodium acetate, and the initial volume-ratio of benzyl chloride to water on the product distribution and the production rate of benzyl alcohol were investigated experimentally.

The experimental results show that the pH of the aqueous phase is the most important factor. With sodium formate as the cocatalyst it should be controlled within 7.2-7.7, while with sodium acetate it should be within 9.5-10. Under the suitable pH and 110°C and other suitable conditions, 95% yield of benzyl alcohol can be obtained within 3 hrs of reaction time.     

Determination and correlation solubility of 4-nitroimidazole in twelve pure solvents from 278.15 K to 323.15 K

In this paper, the solubility of 4-nitroimidazole in twelve pure solvents (toluene, benzene, 1,4-dioxane, acetonitrile, ethyl acetate, acetone, GBL, ethanol, methanol, n-butanol, DMF and NMP) were determined by using the laser monitoring system from 278.15 K to 323.15 K under 101.1 kPa, which are 0.00018-0.00070, 0.00021-0.00073, 0.00034-0.00092, 0.00038-0.00142, 0.00047-0.00120, 0.00126-0.00303, 0.00225-0.00517, 0.00310-0.00724, 0.00467-0.00982, 0.00453-0.01940, 0.01947-0.04652, and 0.04670-0.07452, respectively. At constant temperature, the mole fraction solubility of 4-nitroimidazole were increased as the following order: toluene < benzene < 1,4-dioxane < (ethyl acetate or acetonitrile) < acetone < GBL < ethanol < (methanol or nbutanol) < DMF < NMP, and the solubility of 4-nitroimidazole in (ethyl acetate, acetonitrile) and (methanol, n-butanol) had an intersection point at 297.55 K and 281.85 K, respectively. The solubility of 4-nitroimidazole could be increased with increasing temperature in twelve pure solvents. The ideal model, modified Apelblat equation, polynomial empirical equation, and λh equation were used to correlate the experimental values. The experimental solubility values were employed to calculate the standard dissolution enthalpy, standard dissolution entropy and Gibbs energy. The dissolution of 4-nitroimidazole could be an endothermic process in twelve pure solvents. The determination and fitting solubility of 4-nitroimidazole have important guiding significance for the purification and crystallization of its preparation process.     

Transport of hydrogen in poly(vinylidene chloride-ethyl acrylate)

The time-lag technique has been used to measure the diffusion, permeability and solubility coefficients of hydrogen in poly(vinylidene chloride—ethyl acrylate) containing 0.864 mole fraction of vinylidene chloride between 25° and 45°C. The low permeability of hydrogen in this material can be accounted for by the high activation energy of diffusion.     

Determination and correlation solubility of 4-nitroimidazole in twelve pure solvents from 278.15 K to 323.15 K

In this paper, the solubility of 4-nitroimidazole in twelve pure solvents (toluene, benzene, 1,4-dioxane, acetonitrile, ethyl acetate, acetone, GBL, ethanol, methanol, n-butanol, DMF and NMP) were determined by using the laser monitoring system from 278.15 K to 323.15 K under 101.1 kPa, which are 0.00018–0.00070, 0.00021–0.00073, 0.00034–0.00092, 0.00038–0.00142, 0.00047–0.00120, 0.00126–0.00303, 0.00225–0.00517, 0.00310–0.00724, 0.00467–0.00982, 0.00453–0.01940, 0.01947–0.04652, and 0.04670–0.07452, respectively. At constant temperature, the mole fraction solubility of 4-nitroimidazole were increased as the following order: toluene < benzene < 1,4-dioxane < (ethyl acetate or acetonitrile) < acetone < GBL < ethanol < (methanol or n-butanol) < DMF < NMP, and the solubility of 4-nitroimidazole in (ethyl acetate, acetonitrile) and (methanol, n-butanol) had an intersection point at 297.55 K and 281.85 K, respectively. The solubility of 4-nitroimidazole could be increased with increasing temperature in twelve pure solvents. The ideal model, modified Apelblat equation, polynomial empirical equation, and λh equation were used to correlate the experimental values. The experimental solubility values were employed to calculate the standard dissolution enthalpy, standard dissolution entropy and Gibbs energy. The dissolution of 4-nitroimidazole could be an endothermic process in twelve pure solvents. The determination and fitting solubility of 4-nitroimidazole have important guiding significance for the purification and crystallization of its preparation process.     

On Plate Resolution of Three-Component Mixture of Cationic Surfactants with Mixed Aqueous-Organic Eluents Containing Formate Ion

Abstract

The chromatography of three long chain aliphatic quaternary ammonium halides (cationic surfactants) was performed on kieselguhr layers using different solvent systems. The mutual separation of dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), and hexadecyltrimethylammonium chloride (HTAC) was achieved with the solvent system methanol: 10% aqueous sodium formate (30:70, v/v) on kieselguhr layer. The effect of nature of alkane chain length of alcohols on the mobility of DTAB, TTAB, and HTAC and also the effect of formate ion substituted by acetate ion and benzoate ion of sodium acetate and sodium benzoate respectively on the mobility of these surfactants were studied. The effect of the nature of different adsorbents (kieselguhr, silica gel, and alumina) on the mobility of DTAB, TTAB, and HTAC was also studied. The interference of metal cations as impurities on the resolution of mixture of DTAB, TTAB, and HTAC was also examined. The limits of detection of DTAB, TTAB, and HTAC estimated were 3.3, 3.1, and 2.8 µg/zone respectively. The developed method was utilized to separate these surfactants from different spiked water samples.     

EFFECT OF DISSOLVED INORGANIC SALTS ON THE VAPOR-LIQUID EQUILIBRIA AND ENTHALPY OF MIXING OF THE METHANOL-ETHYL ACETATE SYSTEM

The effect of three inorganic chloride salts, namely, sodium chloride, calcium chloride and zinc chloride on the vapor-liquid equilibria (VLE) and heat of mixing (h.o.m) of the methanol-ethyl acetate system has been investigated under the atmospheric conditions of 760 ± 3 mm Hg pressure. In the experimentation for VLE a Smith and Bonner type equilibrium still was used while in h.o.m. determination a calorimeter connected to a microprocessor-based control unit (MIPROC) which displays digitally the heat of mixing values in calories was employed. All the three salts dissolved to various concentration levels in the solvent mixture brought about a decrease in the azeotropic composition (expressed in terms of mole fraction of methanol) from 0.75 to values like 0.50, 0.37 and 0.18 depending upon the salt added and its concentration level. The salts sodium chloride and calcium chloride which are more soluble in methanol have been found to salt-in that component but with a peculiarity in that, in methanol-rich region the salting-in effect was substantial while in the methanol-lean region it is only marginal. The addition of salt zinc chloride which is more soluble in ethyl acetate results in an anomalous behaviour.

As for the salt effect on h.o.m., the addition of calcium chloride brought about a significant enhancement in the h.o.m values while the salts sodium chloride and zinc chloride (which could be added only to about 5% by weight concentration due to the experimental difficulties) entailed a decrease and lateral shift respectively in the h.o.m. values.

The VLE and h.o.m data which were found to be thermodynamically consistent have been correlated respectively by NRTL, Wilson and by a model similar to the Scatchard series type equation.     

黏度法研究两性聚丙烯酰胺的水溶性

利用水溶液聚合合成了不同组成的两性聚丙烯酰胺(AM/MADQUAT/NaAMPS),对其溶液黏度受NaCl溶液浓度的影响进行了研究。结果表明,净电荷含量较大的两性聚丙烯酰胺溶液,在低NaCl浓度下特性黏度大、溶解性好;而净电荷含量较小的两性聚丙烯酰胺溶液(特别是带有高电荷密度时),在较高的NaCl浓度下,聚合物溶液特性黏度大、溶解性好,反聚电解质效应明显。     

1-氨丙基-3-甲基咪唑溴盐水溶液的汽液相平衡

1-氨丙基-3-甲基咪唑溴盐([APMIm][Br])是一种对CO₂有良好吸收性能的功能型离子液体,在工业中可采用水溶液来实现高效能的吸收和解吸循环过程,因此对其水溶液特性的研究至关重要。对[APMIm][Br]水溶液在中低温度下的汽液相平衡进行了测量,获得可靠的实验数据,从而揭示其水溶液特性。实验温度范围为278.15～348.15 K,[APMIm][Br]在水溶液中质量分数分别为10.0%、20.3%、29.5%、40.0%、57.5%、75.3%、84.0%、88.9%、90.9%。考虑了低温下离子液体分子在水溶液中的强缔合特性,采用带缔合惰化因子的离子液体水溶液活度模型对实验数据进行了拟合,实验值与计算结果符合很好,平均相对误差为2.15%。     

1,2-环己二醇在溶剂中的溶解度

1 INTRODUCTION The solubility of solid in liquids is an excellent tool to investigate solute-solvent intermolecular forces in the liquid state. In this work the solubility of trans-1,2-cyclohexanediol in some polar solvents (wa- ter, methyl acetate, acetic ester, propyl acetate, butyl acetate, methyl acrylate, and ethyl acrylate) was mea- sured at temperatures ranging from about 300 K to 330 K, using a modification of the experimental tech- nique of laser monitoring observation system. So…