Solvent Effect on the Kinetics of Arylsulfonation of Benzhydrazide with 3-Nitrobenzenesulfonyl Chloride in Aqueous-Organic Solutions

A comparative study is made of the solvent effect on the kinetics of arylsulfonation of benzhydrazide with 3-nitrobenzenesulfonyl chloride in aqueous-organic solutions (water-2-propanol, water-dioxane, water-tetrahydrofuran, and water-acetonitrile) at 298 K. The arylsulfonation product can be obtained in nearly theoretical yield at the initial reactant concentrations of 0.1 M in the water-dioxane, water-MeCN, and water-THF mixtures containing above 30 wt % water.     

Kinetic Characteristics of Back-Osmosis Separation of Aqueous-Organic Solutions

Back-osmosis separation of aqueous solutions of morpholine and hydroquinone on an industrial back-osmosis installation was studied in relation to the concentration and flow velocity of a solution in the intermembrane channel. The behavior of the main kinetic characteristics of separation as influensed by physical conditions of the separation process was analyzed and accounted for.     

Activity Coefficients of Ferrocenium Iodide in Aqueous-Organic Salt Solutions

Potentiometric titration at 298.2 was used to measure electrode potentials and to estimate standard EMFs and unified activity coefficients for ferrocenium iodide in aqueous-acetone and aqueousethanol solutions of various salt compositions.     

Electrochemical Amination of Chlorobenzene in Aqueous-Organic Solutions of Sulfuric Acid

Russian Journal of Electrochemistry - The process of electrochemical amination of chlorobenzene using hydroxylamine and the Ti(IV)/Ti(III) mediator system is studied in aqueous solutions of...     

Kinetics of the Volume and Surface Reactions in the Phase-Transfer Catalytic Aminolysis of 4-Nitrophenyl Acetate

It was shown that a distribution-type kinetic model can be used to describe the mechanism of the phase-transfer catalytic aminolysis of 4-nitrophenyl acetate with potassium glycinate in chlorobenzene with 18-crown-6 as catalyst. A quantitative assessment was made of the contributions from the reactions in the volume and at the interface in the solid/liquid system.     

(2,6-二溴-4-硝基苯)-3-(4-硝基苯)-三氮烯与银(Ⅰ) 的显色反应及其应用

研究了1-(2,6-二溴-4-硝基苯)-3-(4-硝基苯)-三氮烯(DBNPNPT)与Ag(Ⅰ)的显色反应。在Na2B4O7-NaOH缓冲溶液(pH=10.0)中和在Triton X-100存在下,试剂与Ag(Ⅰ)生成1∶1的配合物。该配合物在波长445 nm处有正吸收峰,在530 nm有负吸收峰,用双峰双波长法测得配合物的表观摩尔吸光系数为2.06×105L.mol-1.cm-1,符合比耳定律的范围为0~12μg/25mL。该法已用于回收定影液中银(Ⅰ)的测定,结果满意。     

Phase-Transfer Aminolysis of 4-Nitrophenyl Acetate with Amino Acid Salts in the System Liquid-Solid. Kinetics of the Reaction in the Organic Phase

In the phase-transfer system solid potassium aminoacetate-crown ether-chlorobenzene, the fraction of the nucleophile-catalyst complex trasferred to the organic phase does not exceed 1% of the amount of the solid phase. Nevertheless, the reactivity of the crown ether complex with potassium aminoacetate is sufficient to ensure the aminolysis to proceed in the organic phase at an appreciable rate.     

溴化轻稀土甘氨酸配合物的热分解动力学

溴化轻稀土甘氨酸配合物的热分解动力学;溴化轻稀土甘氨酸配合物; 热分解动力学     

生物转化L-脯氨酸生成反式-4-羟基-L-脯氨酸的定量分析方法

以芴甲氧羰酰氯(FMOC-Cl)为柱前衍生剂,四硼酸钠为缓冲溶液,建立了一种柱前衍生反相高效液相色谱(RP-HPLC)测定微生物转化L-脯氨酸生成反式-4-羟基-L-脯氨酸的定量分析方法。优化了衍生反应条件,当衍生反应体系中水和乙腈的比例为66∶34,p H值为9.9时衍生效果最佳。采用Agilent Extend C-18柱进行分离,以0.1%三氟乙酸水溶液和乙腈作为流动相,梯度洗脱,检测波长263 nm。L-脯氨酸和反式-4-羟基-L-脯氨酸均在0.01~5.00 mg/m L范围内线性关系良好,相关系数均大于0.999,检出限为5.00~7.00 ng/L,不同浓度下的平均回收率分别为98.9%~102%和97.9%~100%。该方法重现性好,精密度高,为定量分析微生物发酵液中的L-脯氨酸和反式-4-羟基-L-脯氨酸提供了有效方法。     

甘氨酸在N,N-二甲基甲酰胺水溶液中的体积性质

用Anton Paar型55精密数字密度计测定了甘氨酸在N,N-二甲基甲酰胺(DMF)水溶液中的密度,计算了甘氨酸的表观摩尔体积、极限偏摩尔体积、迁移偏摩尔体积和理论水化数,讨论了DMF的结构对甘氨酸迁移偏摩尔体积和理论水化数的影响。结果表明,甘氨酸在DMF水溶液中的迁移偏摩尔体积为正值,并且随着溶液浓度增大而增大。在DMF水溶液中的理论水化数比在纯水中的小,并且随着DMF浓度的增大而减小。把上述计算结果与在N,N-二甲基乙酰胺(DMA)水溶液中的实验结果进行了比较。     

Kinetic Model of the PTC Aminolysis of 4-Nitrophenyl Acetate with Solid Potassium Glycinate

A mechanism of phase-transfer catalysis in a solid/liquid system was proposed during akinetic investigation of the aminolysis of 4-nitrophenyl acetate with solid potassium glycinate in chlorobenzene in the presence of 18-crown-6. The quantitative parameters were determined for all the stages of the catalytic cycle, including the distribution of the reagents between the phases and the chemical reactions that occur.     

Reaction of Amino Acid Salts with 4-Nitrophenyl Acetate under Solid-Liquid Phase Transfer Conditions

The reaction of amino acid salts with 4-nitrophenyl acetate in a system consisting of a solid phase and organic solvent with catalysis by crown ethers and quaternary onium salts may be carried out both on the phase separation surface and in the organic phase depending on the nature of the participants in the phase transfer catalysis reaction.     

1,3-二环基碳化二亚胺催化的阿魏酸对硝基苯酚酯一步合成法

1;3-二环基碳化二亚胺催化的阿魏酸对硝基苯酚酯一步合成法;酯化反应     

Palladium-Catalyzed Coupling of L-Proline Acid Chloride with Vinylstannanes

Vinylstannanes were found to undergo a palladium-catalyzed coupling with L-N-protected proline acid chloride to produce the corresponding N-protected α'-amino-α,β-unsaturated ketones in moderate to good yield.     

Kinetics of Silver Electrocrystallization in Nonaqueous Solutions

The effect of the solvent nature on the silver electroreduction and electrooxidation, including the initial electrocrystallization stage, is studied. Basic kinetic parameters of the process are determined. With increasing donor number of the solvent, which defines its capability for solvating cations, the rate constant of the electrochemical reaction decreases and the silver nucleation overvoltage increases. With increasing dipole moment of the solvent, which defines its adsorption properties, the surface energy of the silver nucleation decreases. The effect of the solvent on the silver electroreduction reveals itself through its solvation and adsorption properties.     

Kinetics of Ozone-Olefin Reactions in Aqueous Solutions

The kinetics of the reactions of ozone with 12 substituted olefins in aqueous solutions at 293 K are studied by the stopped-flow method. Second-order rate constants are determined for these reactions. The dependence of the reactivity of olefins in H₂O on their structure can be described by the Taft equation.     

Kinetics of Gold Dissolution in Thiosemicarbazide Solutions

The kinetics of gold dissolution in thiosemicarbazide solutions was studied relative to the ratio of ferric ion and thiosemicarbazide concentrations as well as pH. The composition of the complex formed was found to be [Au(NH₂)₂NHC=S₃]⁺. The rate constants for gold dissolution were determined at 278-298 K along with the stability, dissociation, and equilibrium constants at 288 K. The activation energy at 288 K was also found.     

沸石与酸性水溶液反应的动力学机制

利用连续搅拌筒反应器(CSTR)对天然沸石与酸性水溶液的反应动力学进行研究, 通过改变流速、 pH值等参数, 对反应速率进行计算和比较. 同时利用二次离子质谱(SIMS)、扫描电镜(SEM)对反应后的沸石表面进行分析研究. 实验结果表明, 沸石中的Si、Al、Na的释放速率在多数情况下不相同, 沸石的溶解为不一致溶解作用. 25 ℃、1.01×10⁵ Pa条件下, 硅的释放速率为：在pH=2.45溶液中反应时, -rSi=kS(aH+)1.25/ (aSi)0.60；在pH=3.26溶液中反应时, -rSi=kS(aH+)1.50/(aSi)0.25(S为矿物材料的表面积). SIMS研究显示, 天然沸石与酸性水溶液的反应中, 在沸石表面Si、Al、Na在100 nm的厚度范围内, 随着离表面距离的改变, 在近表面范围内Na、Al大量淋失, 有H⁺浸入. 此外, SEM分析结果显示, 天然沸石与纯水及酸性水溶液反应后, 表面形貌显著不同.     

L-脯氨酸催化合成1,4-二氢吡啶和1,8-二氧代十氢吖啶

含1,4-二氢吡啶和1,8-二氧代十氢吖啶分子片段的化合物具有扩张血管、抗菌和抗肿瘤等药理活性,因此,探讨和优化该类衍生物绿色合成方法成为药物合成领域的热点之一。基于有机小分子催化剂L-脯氨酸廉价易得、无毒无害和水溶性等特点,结合微波辐射技术快速高效等优势,以芳香醛、β-二酮 (乙酰乙酸乙酯/二甲基环己二酮)和乙酸铵为原料,乙醇为溶剂,催化剂用量20 mol/mol,微波功率300 W和80℃的条件下,通过成环缩合反应“一锅法”合成了目标化合物,收率达80%～93%。该方法具有条件温和、操作简单以及环境友好等优点。