有机溶剂对镧和钇ICP光谱信号的增敏机理研究

本文考察了有机溶剂（乙酸丁酯）及有机试剂（PMBP）引入ICP－AES对稀土元素镧和钇光谱信号的影响。实验结果表明，有机溶剂的引入明显增大了待测物的传质效率，从而导致分析灵敏度的改善。与水相相比，有机相的引入对ICP激发温度未产生明显影响，但使线对强度比（LogI^ /I)增强，有利于待测物的电离。     

Solvent release upon ion association from entropy data

The translational entropy loss on the association of two ions to form an ion pair or 11 complex is overcompensated by a rotational entropy gain, an electrostatic entropy gain, and an entropy gain due to solvent release from translational immobilization. The first three effects can be calculated, leaving the fourth as a difference from the experimental entropy change on association. The ratio of the solvent release entropy gain to the entropy change on melting of the solvent indicates the number of solvent molecules released on the association. A similar value is obtained from data for the volume change on association.Presented as a poster at the 10th International Conference on Non-Aqueous Solvents (ICNAS) at Leuven, Belgium, August 1986, and at the 24th International Congress on Coordination Chemistry (ICCC) at Athens, Greece, August 1986.     

Solubility of benzil in binary alkane + dibutyl ether solvent mixtures. Comparison of predictive expressions derived from the nearly ideal binary solvent model

Experimental solubilities are reported for benzil dissolved in six binary mixtures containing dibutyl ether with hexane, heptane, octane, cyclohexane, methylcyclohexane, and 2,2,4-trimethylpentane at 25°C. Results of these measurements are compared to the predictions of equations developed previously for solubility in systems of nonspecific interactions. The most successful equation in terms of goodness of fit involved a volume fraction average of the excess Gibbs energies relative to the Flory-Huggins model, and predicted the experimental solubilities in the six systems studied to within an overall average absolute deviation of 3.4% and with a maximum deviation of 6.0%.     

The configurational dependence of binding free energies: A Poisson–Boltzmann study of Neuraminidase inhibitors

The linear finite difference Poisson-Boltzmann (FDPB) equation is applied to the calculation of the electrostatic binding free energies of a group of inhibitors to the Neuraminidase enzyme. An ensemble of enzyme-inhibitor complex conformations was generated using Monte Carlo simulations and the electrostatic binding free energies of subtly different configurations of the enzyme-inhibitor complexes were calculated. It was seen that the binding free energies calculated using FDPB depend strongly on the configuration of the complex taken from the ensemble. This configurational dependence was investigated in detail in the electrostatic hydration free energies of the inhibitors. Differences in hydration energies of up to 7 kcal mol^–1 were obtained for root mean square (RMS) structural deviations of only 0.5 Å. To verify the result, the grid size and parameter dependence of the calculated hydration free energies were systematically investigated. This showed that the absolute hydration free energies calculated using the FDPB equation were very sensitive to the values of key parameters, but that the configurational dependence of the free energies was independent of the parameters chosen. Thus just as molecular mechanics energies are very sensitive to configuration, and single-structure values are not typically used to score binding free energies, single FDPB energies should be treated with the same caution.     

ICP-MS法快速测定丙烯腈/乙腈中的铁、铜

采用带八级杆碰撞/反应池(ORS)的电感耦合等离子体质谱法(ICP-MS),直接测定丙烯腈或乙腈产品中的Fe、Cu,标准加入法定量.结果表明,方法的线性范围宽,线性相关系数均大于0.999.2种元素的相对标准偏差均低于5%,加标回收率在90%~110%.该方法简便、快速、准确.     

Copolymerization of ethylene and 1-butene with highly active Ticl4/THF/Mgcl2, Ticl4/THF/Mgcl2/SiO2, and TiCl3.1/3AlCl3 catalysts

Highly active catalysts for copolymerization have been prepared by the precipitation of MgCl₂/ToCl₄ complex with or without high surface area silica. Copolymerization of ethylene and 1-butene has been tested by using the prepared catalysts at various concentrations of 1-butene. The catalytic activities are 20–80 kg/g Ti h. The rate of copolymerization is strongly affected by the addition of 1-butene. The decay rate of copolymerization is first order with respect to time. Analyses of copolymers with solvent extraction, DSC, IR, XRD, and NMR were performed. Ethylene reactivity ratio (k₁₁) for TiCl₄/MgCl₂/THF catalyst is calculated to be about 26 by NMR spectrum. © 1994 John Wiley & Sons, Inc.     

VOCl_3/Et_3Al_2Cl_3/CCl_4溶剂体系催化乙烯丙烯共聚

本文以VOCl_3/Et_3Al_2Cl_3为催化剂,在CCl_4溶剂中进行乙烯共聚反应。在聚合过程中,发生一异常的颜色突变现象。颜色突变后,体系催化聚合生成分子量很低的产物。从聚合物的结构表征及机理探讨表明:颜色突变后,体系产生了新的活性中心,催化机理发生了转变——由配位机理转变为阳离子机理。     

Computerized optimization of gradient elution conditions with ternary solvent mobile phases in RPLC

Summary In this work, an optimization procedure for gradient RPLC separation, using ternary mobile phases, is described. This procedure requires eight preliminary experiments in gradient elution mode to predict the retention surface for each solute over the whole triangular space. This is followed by computerized calculations to determine the best ternary gradient elution profile with respect to both selectivity and analysis time. The efficiency of this procedure from the point of view of rapidity and of accuracy, is illustrated for the specific separation of twelve phenyl urea herbicides.     

NMR Study of the Stoichiometry, Stability, and Ligand Interchange of Silver Ion-Hexathia-18-crown-6 Complex in Binary Dimethyl Sulfoxide Solvent Mixtures at 300 K

Proton NMR was used to study the complexation reaction between silver ion and hexathia-18-crown-6 in a number of binary mixed solvents of dimethyl sulfoxide with acetonitrile and methanol. Formation constants for the resulting 1:1 complexes in different solvent mixtures were determined by computer fitting of the chemical shift-mole ratio data. The influence of solvent composition on the stability of the resulting complex is discussed. The exchange kinetics of Ag⁺-hexathia-18-crown-6 in 70-30 wt.% dimethyl sulfoxide-acetonitrile and 75-25 wt.% dimethyl sulfoxide-methanol were studied by proton NMR line-shape analysis. In both solvent mixtures, the exchange of thiacrown ether between the free and complexed sites was found to proceed via a dissociative pathway. The exchange rates and the activation parameters E _a, H , S, and G for the ligand exchange were determined and the influence of solvent properties on these parameters discussed.     

Linear free energy relationship of the energy of the CTTS transition of Halide ions with the solvatochromic parameter α

A linear free energy relationship was found betweenv _max, the energy of the absorption maximum of chloride, bromide, or iodide ion in various solvents, and the solvatochromic parameter which is a measure of the hydrogen bond donor ability of the solvent. The relationships are: for chloride,v _max=6.99+50.16 kK; for bromide,v _max=5.52+45.20 kK; for iodide,v _max=5.02+40.33 kK. The correlation ofv _max for iodide ion with gave a larger correlation coefficient and smaller standard deviation than a correlation with the E _T (30) parameter of Dimroth. From the values ofv _max for iodide ion and the solvated electron in liquid ammonia at 25°C, these correlations indicate a preliminary value of 0.00 for the parameter of liquid ammonia. This had not been reported before and is lower than expected from a general knowledge of the physical and chemical properties of liquid ammonia but is consistent with a more detailed consideration and recent gas phase measurements of hydrogen bond donor strength.