SYNTHESIS AND PROPERTIES OF SULFONATED POLY（ARYLENE ETHER） CONTAINING TRIPHENYL METHANE MOIETIES FROM ISOCYNATE MASKED BISPHENOL

A novel sulfonated poly（arylene ether） containing triphenylmethane moieties was synthesized by the sulfonation of a designed parent polymer using chlorosulfonic acid as sulfonation agent. The sulfonation took place at the para position of the pendant phenyl rings because of the specially designed parent polymer. The position and degree of sulfonation were characterized by ^1H-NMR and elemental analysis. The sulfonated polymers are highly soluble in common organic solvents, such as dimethylsulfoxide, N,N＇-dimethylacetamide, dimethylformamide, ethylene glycol monomethyl ether, and can be readily cast into tough and smooth films from solutions. The films showed good thermal and hydrolysis stabilities. Moreover, Fenton＇s reagent test revealed that the films exhibited superior stability to oxidation. The proton conductivities of the films were comparable with Nation 117 under same conditions. The membrane electrode assembly （MEA） prepared with the asmade film （706 EW, 100 μm dry thickness） shows better cell performance than Nation 115-MEA in the whole current density range.     

Effect of pressure on retention factors in HPLC using a non-porous stationary phase

Summary Pressure and temperature have significant influence on retention in HPLC. This study investigates the effect of pressure and temperature on the retention behavior of aromatic hydrocarbons (toluene, ethyl benzene, butyl benzene, pentyl benzene) and polar, acidic and basic samples (phenol, acetophenone, N,N-dimethyl aniline, benzophenone) on a reversed phase column. The effect has been studied on non-porous, tetradecyl (C₁₄) coated silica particles. We found that the adsorption-induced decrease of the partial molar volume of the solutes investigated was between ΔV _m =5–15 cm³ mol⁻¹. The increment of the decrease of the partial molar volume due to the addition of one CH₂ group, for the homologous series of the aromatic hydrocarbons is approximately ΔV _CH2 =2.3 cm³mol⁻¹. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001.     

Evaluation of behaviour of linear monoamines CH3-(CH2)n−1-NH2 (n=1-6) in ion chromatography

This paper reports the results on a study of ion chromatography (IC) behaviour on strong cationic exchange column of CH₃-(CH₂)_n−1-NH₂ (n=1-6) type linear monoamines. The eluents were mixtures of HCl-NaCl, HNO₃-NaNO₃, HClO₄-NaClO₄, H₂SO₄-Na₂SO₄, HClO₄-NaClO₄-CH₃CN. Amines were revealed with an amperometric detector. The influence of different counter-ions on retention factors, k′, is discussed. Relationships between k′ and pE (E=sum of Na⁺ and H⁺ concentrations), and length of alkylic chain, and sensitivity coefficient S, are reported and discussed. The addition of acetonitrile (ACN) in the eluent was also taken into account. Suitable considerations are derived from these data. An example of monoamines separation is given.     

Effect of solvent on glass transition temperature in chemically modified polyvinyl chloride (PVC)

Polyvinylchloride has been chemically modified with sodium benzene thiolate at different temperatures, in solvents promoting the formation of polymer gels, in solvents favoring light polymer interactions and in the absence of solvent, that is, in the melt. From the¹³C-NMR results it is shown that the substitution reactions on PVC, in all media and temperatures studied, are stereospecific and the nature of substituted chlorines the same.The glass transition temperature of modified polymers has been studied by differential scanning calorimetry. The glass transition temperature of the modified polymers in the absence of solvent decreases linearly with degree of substitution. When the reaction is carried out in solvents containing carbonyl groups, such as diethyl malonate, cyclohexanone and 2-butanone, the evolution of the glass transition up to about 25% substitution does not follow the above behavior. At higher levels of substitution the evolution ofT _g is similar to that in the melt. For the ether-containing solvents, such as tetrahydrofurane and dioxane, the evolution lies between the two previous curves.When the reactions of PVC with sodium benzene thiolate are carried out in cyclohexanone at different temperatures, between 15–90°C, the evolution of the glass transition temperature with conversion is different for each temperature, and if the reaction temperature increases, the slope of the initial part moves to that in the absence of solvent.These results are related to the formation of PVC gels or interactions. As the nature and percentage of substituted chlorine for a given chemical composition are the same in all the solvents and conditions studied, we propose that Cl-atoms of isotactic and/or heterotactic configurations are implied in the formation of PVC gels or interactions.     

可调移动重叠分离图法用于高效液相色谱多台阶梯度分离条件优化的研究

计算机辅助高效液相色谱（HPLC）分离条件优化可以低成本、快速地得到优化的分离条,因而已较为广泛地用于复杂样品的分离分析。基于移动重叠分离图方法,又发展了一种新型的多台阶梯度分离条件的优化方法可调移动重叠分离图法。该方法通过预测不同流动相条件下各组分的保留时间、峰宽和分离度,绘制出对于样品中各组分的重叠分离区域图。在对当前台阶流动相组成进行优化的同时,考虑其对后面一到两个台阶上流出组分保留的影响,实时地重新绘制对于后面台阶上流出组分的重叠分离区域图。通过观察当前台阶流动相条件对当前台阶和后面台阶上流出组分分离的影响,综合考虑样品中所有组分的分离情况,找到更接近全局最优的分离条件。通过扫描的方法对优化得到的分离条件进行微调,能够进一步提高分离效果。采用文献数据对可调移动重叠分离图法的应用加以说明,在二元流动相体系下,证明了该方法在HPLC方法建立方面的优越性。     

The effect of the solvents on the specific intramolecular C-H...N interactions studied by1H NMR spectroscopy

The analysis of the effect of the solvents on the proton chemical shifts in¹H NMR spectra of 2-vinyloxypyridine indicates that the C—H...N interaction of weak intramolecular hydrogen bond type hinders the formation of intermolecular hydrogen C—H...X and C-H... bonds. The protonating solvents reduce the intramolecular C—H...N interaction due to association with the N atom of the pyridine cycle.Translated fromIzvestiya Akademii Nauk. Seriya Khimieheskaya, No. S, pp. 1202–1204, May, 1996.     

Influence of quaternary onium salts,crown ethers and cryptands on olefin epoxidations promoted by HOCl/ClO− in the Presence of Mn(III)-tetrakis(2,6-dichlorophenyl)porphyrin chloride

Reaction rates of alkene epoxidations, promoted by aqueous NaOCl and catalyzed by Mn(III)-tetrakis(2,6-dichlorophenyl)porphyrin chloride1 (P) in the presence of a lipophilic axial ligand (L) (e.g.N-hexylimidazole) and carried out under H₂O/CH₂Cl₂ two phase conditions at 0°C, are strongly enhanced by lowering the pH of the aqueous phase from 12.7 to 9.5. Under these conditions, a further relevant increase in the reaction rates can be achieved by adding phase-transfer catalysts (PT), e.g. quaternary ammonium salt 3, lipophilic crown ether4 or cryptand5, provided that the amount of L is very small (L/P=1 for very reactive alkenes, e.g. cyclooctene, and 10 for poorly reactive ones, e.g. 1-dodecene). In the case of cyclooctene epoxidation, the use of 0.006–0.03 mol. equiv. of PT completes the reaction in 1–10 min., the initial rates being up to 600 turnovers/min. with (2.2.2,C₁₀) cryptand. In the absence of the axial ligand, the quaternary ammonium salt3 and cryptand5 show an inhibitory effect. Such an effect is due to the formation of the poorly reactive Mn(P)CI species, by Cl– extraction to the organic phase. However, dibenzo crown ether 4 does not show this effect. In the presence of 4, and with L/P =1, the 1-dodecene epoxidation reaches 94% in 1 min. The unique behavior of crown ethers can be explained by their ineffectiveness in extracting alkali chlorides, providing a very low concentration of Cl– in the organic phase and thus avoiding the Mn(III)-porphyrin deactivation.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

Six‐coordinate Co2+ with imidazole,NH3, and H2O ligands: Approaching spin crossover

Octahedral, six‐coordinate Co²⁺ can exist in two spin states: S = 3/2 and S = 1/2. The difference in energy between high spin (S = 3/2) and low spin (S = 1/2) is dependent on both the ligand mix and coordination stereochemistry. B3LYP calculations on combinations of neutral imidazole, NH₃, and H₂O ligands show that low‐spin isomers are stabilized by axial H₂O ligands and in structures that also include trans pairs of equatorial NH₃ and protonated imidazole ligands, spin crossover structures are predicted from spin state energy differences. Occupied Co d orbitals from the DFT calculations provide a means of estimating effective ligand strength for homoleptic and mixed ligand combinations. These calculations suggest that in a labile biological system, a spin crossover environment can be created. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Structure and dynamics of liquid water with different long-range interaction truncation and temperature control methods in molecular dynamics simulations

We have used molecular dynamics simulations to study the physical properties of modified TIP3P water model included in the CHARMM program, using four different methods-the Ewald summation technique, and three different spherical truncation methods-for the treatment of the long-range interactions. Both the structure and dynamics of the liquid water model were affected by the methods used to truncate the long-range interactions. For some of the methods artificial structuring of the model liquid was observed around the cutoff radius. The model liquid properties were also affected by the commonly applied temperature control methods. Four different methods for controlling the temperature of the system were studied, and the effects of these methods on the bulk properties for liquid water were analyzed. The system size was also found to change the dynamics of the model liquid water. Two control simulations with the SPC/E water model were carried out. The self-diffusion coefficient (D), the radial distribution function (g(OO)), the distance dependent Kirkwood G-factor [G(k)(r)] and the intermolecular potential energy (E(pot)) were determined from the different trajectories and compared with the experimental data.     

Influence of a water vapor admixture in the carrier gas on capacity coefficients of polar organic compounds

The influence of a water vapor admixture in helium, nitrogen, and carbon dioxide on capacity coefficients of C₃−C₅ alcohols and pyridine during chromatography process in capillary columns with polar (PEG-20M) and nonpolar (SE-30) stationary phases was studied. The introduction of a water admixture into the carrier gas, increases the capacity coefficient of polar organic compounds on the capillary column with PEG-20M and has almost no effect on this value in the case of SE-30. The change in retention of polar organic compounds on the capillary column with the PEG-20M polar phase occurs due to a change in the properties of the stationary phase when it adsorbs water from the mobile phase. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2258–2261, November, 1998.