4-Substituted tetrahydro-3,6-pyridazinedione 3-hydrazones (2) (or their 3-hydrazino tautomers 3), useful intermediates in the synthesis of bicyclic pyridazine derivatives, were prepared in satisfactory yields in the reaction of the corresponding alkyl 3-substituted 3-cyanopropionates with hydrazine hydrate. 相似文献
The adsorption of metal ions at the stearic acid/electrolyte and nnonadccane-stearic acid mixture/electrolyte interface was investigated by means of the potentiometric titration, zeta potential and adsorption measurements. It was found that the studied colloidal suspensions exhibited an adsorption affinity towards multivalent metal ions. The adsorption of Ca2+, Cd2+ and Al3+ ions caused a strong decrease of surface charge density and zeta potential values in this systems. The adsorption reactions occur by way of cation exchange with protons from two surface carboxyl groups. Al high metal concentrations, in adsorption reactions there are involved also carboxyl groups from the subsurface layer. On the basis of the adsorption data, the cation surface complexation constants were calculated by Shindler's method. 相似文献
A few experiments testing technetium behavior at different conditions for complex matrixes (soils, sediments) were performed. It was confirmed that the incineration of samples soaked with ammonia can be done without technetium losses. Next, for the precipitation of iron(III) hydroxide at different pH levels, the degree of co-precipitation of technetium was studied. It can be helpful during purification of very matrix-rich and massive samples. Finally the technetium and rhenium fractionation during separation of technetium from the environmental samples was studied. This test clearly showed limitations for using Re as yield tracer during 99Tc analyses in case of mineral matrixes. 相似文献
Abstract A power law behaviour of dielectric loss versus frequency has been found in members of the 4,4′-di-n-alkyloxyazoxybenzene series. For each member the scaling of the data with respect to v/vmax is possible in the liquid-crystalline temperature range; this suggests a fractal-like geometry in nematic and smectic phases. The values of the scaling exponents, indicating a cooperativity of molecular reorientation around the short axes, exhibit an odd–even effect. 相似文献
The synthesis, mesomorphic and physical properties of 14 homologous series of laterally fluorinated 4?-alkyl-4-isothiocyanatoterphenyls were described. Influence of the number of fluorine atoms and their position in the terphenyl core on the phase transition temperatures, nematic range, dielectric and optic anisotropy as well as bulk viscosity were discussed. The compounds with the most optimal properties for formulation of nematic mixtures were selected, and mixture examples with low viscosity and medium or high birefringence were presented. 相似文献
A simple and sensitive thin-layer chromatography (TLC) method coupled with an image analysis technique was developed for the simultaneous quantitative determination of L-proline and L-lysine in dietary supplement with good precision and accuracy. Separation was performed on silica gel plates using ethanol‒toluene (2:3, V/V) as the mobile phase. The visualization of chromatograms was based on iodine–azide reaction; therefore, pre-chromatographic derivatization reaction of amino acids with phenyl isothiocyanate was performed. Digital images of TLC plate chromatograms were converted into peak chromatograms, and quantitative analysis was conducted using TLSee software.
Results of chemical kinetics modeling in methane subjected to the microwave plasma at atmospheric pressure are presented in this paper. The reaction mechanism is based on the methane oxidation model without reactions involving nitrogen and oxygen. For the numerical calculations 0D and 1D models were created. 0D model uses Calorimetric Bomb Reactor whereas 1D model is constructed either as Plug Flow Reactor or as a chain of Plug Flow Reactor and Calorimetric Bomb Reactor. Both models explain experimental results and show the most important reactions responsible for the methane conversion and production of H2, C2H2, C2H4 and C2H6 detected in the experiment. Main conclusion is that the chemical reactions in our experiment proceed by a thermal process and the products can be defined by considering thermodynamic equilibrium. Temperature characterizing the methane pyrolysis is 1,500–2,000 K, but plasma temperature is in the range of 4,000–5,700 K, which means that methane pyrolysis process is occurring outside the plasma region in the swirl gas flowing around the plasma. 相似文献
A novel, sensitive catalytic adsorptive stripping voltammetric procedure which can be used to determine trace amounts of germanium is described. The method is based on the interfacial accumulation of the complex formed by Ge(IV) and the product of the reduction of chloranilic acid on the hanging mercury drop electrode or the renewable silver amalgam film electrode, and its subsequent reduction from the adsorbed state followed by the catalytic action of the V(IV)·HEDTA complex. The presence of V(IV)·HEDTA greatly enhances the adsorptive stripping response of Ge. The reduction of the Ge(IV) in the presence of chloranilic acid and V(IV)·HEDTA was investigated in detail and the effects of pH, electrolyte composition, and instrumental parameters were studied. Under optimal conditions, the catalytic peak current of germanium exhibited good linearity for Ge(IV) concentrations in the range of 0.75–60 nM (for 60 s of accumulation at −0.1 V, r2 = 0.995) and a low limit of detection (LOD = 0.085 nM). The procedure was successfully applied to determine Ge in water samples.