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61.
The inducing method for preparing Ag-micelle solution with the use of mixed solvent/nonsolvent, and the morphological characterization of the generated metal–micelles were investigated and reported in this paper. In this method, an Ag containing metal chelate polymer (MCP) raw solution was preprepared by dissolving poly(vinyl acetate) (PVAc)–silver nitrate (AgNO3) MCP in conc. formic acid, and a mixed solvent of HCOOH/H2O with specific water composition was then added to induce the micellization of the MCP chain. The critical water concentration (CWC) that was needed for inducing the formation of the Ag-micelles, and the water concentration at which the flocculation of the Ag-micelles occurred in micellar solution, were studied by measuring the transmittance of the dilute MCP solution; the results showed that a long-lasting MCP solution with stable micelles might be prepared by using a H2O/HCOOH solvent of specific weight ratio 1:1.2. The effect of the AgNO3 concentration on the morphology of the Ag-micelles was also investigated by transmission electron microscopy (TEM). At AgNO3 concentration below 0.5 wt%, the Ag-micelles displayed a variety of core-shell structure; but as the AgNO3 concentration was increased to 1.0–2.0 wt%, micelles that had Ag-solid embedded in the micellar core were observed. 相似文献
62.
Summary The net solvent effect for several solute-solvent pairs has been calculated by using the solvophobic approach for describing the liquid chromatographic process. For the same solutes and solvents the net solvent effect has been experimentally measured by using graphitized carbon black columns in GC and HPLC. A comparison between the measured and calculated values made in terms of normalized free energy changes, indicates that the solvophobic theory is fairly adequate for predicting the sequence of solvent strength and provides a comprehensive explanation of the various interactions occurring in reversed-phase LC. A critical discussion of the deviations of the theory from the experimental data is also presented.Presented at the 14th International Symposium on Chromatography London, September, 1982 相似文献
63.
Yasuyuki Takeda Chihiro Takagi 《Journal of inclusion phenomena and macrocyclic chemistry》1994,17(1):93-97
The theory is derived to determine the dimer-formation constant,K
2, of a crown ethermetal salt 111 complex in organic solvents of low dielectric constant by solvent extraction. The theoretical predictions are verified experimentally by extraction of sodium picrate (NaA) with 15-crown-5 (15C5) into carbon tetrachloride. All the experiments were conducted at 25°C. The logK
2 value of the Na(15C5)A complex in carbon tetrachloride has been determined to be 4.05±0.11. Moreover, the partition constant of the complex is calculated. 相似文献
64.
本文应用溶剂浮选吸光光度原理,拟定了微量铂的分析方案。用CTMAB作捕收剂,捕收〔Pt(SnC1_3)5〕~(3-)离子,浮选至有机溶剂乙酸乙酯中,在398nm处用1cm的比色皿测定吸光度,可以测定ppb级的铂。富集比为40,表观摩尔吸光系数为2.6×10~5,铂的回收率接近100%。 相似文献
65.
G. Papanastasiou A. Papoutsis M. Tsirtou I. Ziogas 《Journal of solution chemistry》1996,25(2):203-217
The kinetics of the reaction between sodium ethoxide and methyl iodide has been studied at 25°C in various cyclohexane-ethanol solvent mixtures with a cyclohexane content of 10 to 50% per volume. The determination of the rate constants att=0 were carried out by a new iterative method proposed in this investigation. The obtained results show that the reaction rate decreases with the increasing cyclohexane content. This behavior can be attributed to various solute-solvent interactions of electrostatic nature. On the other hand, the variation of ion and ion pairs rate constants with solvent composition permits the various solvation effects to be taken into account. 相似文献
66.
The performance of a PTV injector operated in the solvent venting mode with Tenax in the glass insert was evaluated with synthetic mixtures containing 5 to 50 ng of n-alkanes, ethyl esters, n-alcohols, and carboxylic acids. The influence of the sampled amount, the injected volume, and the nature of the solvent on accuracy and precision were studied. Coefficients of variation of relative (normalized) peak areas and absolute peak area ratios of each compound to the standard are of the order of 5 %. 相似文献
67.
S. Filipek J. Rzeszotarska M. K. Kalinowski 《Monatshefte für Chemie / Chemical Monthly》1994,125(8-9):801-809
Summary The stability constants,K
sof monensin complexes with Li+, Na+, K+ and Cs+ ions were studied by a competitive polarographic method using the Tl+/Tl(Hg) redox couple as a sensitive electrochemical probe. TheK
svalues are strongly influenced by the solvents (acetonitrile, propionitrile, acetone, N,N-dimethylformamide, N-methyl pyrolidinone, N,N-dimethylacetamide, dimethylsulfoxide, N,N-diethylformamide and N,N-diethylacetamide were used in experiments) and vary inversely with the Gutmann donicity scale. Molecular mechanics computations revealed the probable structures of the complexes.
Polarographische Untersuchung von Tl+-, Li+-, Na+- und Cs+-Komplexen mit Monesin-Anion in dipolaren aprotischen Lösungsmitteln
Zusammenfassung Es wurden die StabilitätskonstantenK svon Monesin-Komplexen mit Li+-, Ma+- und Cs+-Ionen mittels einer competitiven polarographischen Methode unter Verwendung der Tl+/Tl(Hg)-Redoxelektrode als sensitiver elektrochemischer Sonde bestimmt. DieK s-Werte werden stark vom Lösungsmittel (Acetonitril, Propionitril, Aceton, N,N-Dimethylformamid, N-Methylpyrrolidinon, N,N-Dimethylacetamid, Dimethylsulfoxid, N,N-Diethylformamid und N,N-Diethylacetamid) beeinflußt, wobei sie invers zurGutmann schen Donizitätsskala variieren. Die wahrscheinliche Struktur der Komplexe wurde mittels molekularmechanischer Berechnungen ermittelt.相似文献
68.
Natalini B Marinozzi M Sardella R Macchiarulo A Pellicciari R 《Journal of chromatography. A》2004,1033(2):363-367
The chromatographic resolution of enantiomeric amino acids is accomplished on a reversed phase column using aqueous mobile phase containing the chiral reagent N,N-dimethyl-S-phenylalanine-Cu(II). The separation is a result of the whole interaction between the diastereomeric complex surface and the mixed stationary phase realized by the dynamic coating of the RP-18 carbon chains layer. The elution order seems to be related to the different water coordination capability on copper ion in the formation of the mixed ternary complexes. 相似文献
69.
Nitro aromatic compound can be obtained in high yields via nitration of aromatic compound with wet carbon-based solid acid and NaNO_3 under solvent free oxidation at room temperature. 相似文献
70.
Effect of 1,10-phenanthroline on the extraction and separation of lithium(I), sodium(I) and potassium(I) with thenoyltrifluoroacetone 总被引:1,自引:0,他引:1
The extraction of Li+ with thenoyltrifluoroacetone (Htta) in the presence of 1,10-phenanthroline (phen) has been studied in various organic solvents. The remarkable enhancement of the extraction of Li+, that is a synergistic effect, was observed by the addition of phen, and the high extractability of Li+ was attained in toluene, benzene, chlorobenzene and o-dichlorobenzene. The extraction equilibrium of Li+, Na+ and K+ (denoted as M+) in the presence or absence of phen in chlorobenzene and the adduct formation reaction in the organic phase were studied in detail. The adduct of Li+ was Li(tta)(phen) in the wide concentration range of phen in the organic phase, while in Na+ and K+ M(tta)(phen)2 also exists in the high concentration region. The maximum value of the separation factor between Li+ and Na+ was observed in the present system and was larger than that in the Htta-trioctylphosphine oxide (TOPO)-benzene system reported previously. 相似文献