Kinetics of homogeneous dehydrogenation of formic acid in the presence of supramolecular rhodium(III) complex with P-functionalized calix[4]resorcine

The kinetics of homogeneous dehydrogenation of formic acid in the presence of supramolecular rhodium(III) complex with P-functionalized calix[4]resorcine were studied in dioxane, tetrahydrofuran, dimethylformamide, and binary formamide-dioxane mixtures (volume ratio 10: 90, 20: 80, 30: 70) over a wide temperature range (40?C90°C). The examined Rh(III) complex catalyzed the dehydrogenation process, and its catalytic activity was higher than that observed previously for rhodium complexes with non-macrocyclic phosphorus-containing ligands. The dehydrogenation rate constants were proportional to neither catalyst concentration nor dielectric constant of the medium, which is likely to be related to supramolecular nature of the Rh(III) complex. No micelle formation was observed in the examined systems.     

Arc-Assisted Synthesis of Germanium Nanocrystals in Argon

High Energy Chemistry - This paper presents results on the synthesis of germanium nanocrystals in electric arc discharge. During the synthesis, the surface of a germanium anode was heated to the...     

Thermodynamic characteristics of adsorption of some 1,3,4-oxadiazoles and 1,2,4,5-tetrazines from water-acetonitrile solutions on phenyl-bonded silica gel

Standard differential molar changes of the Gibbs energy, enthalpy, and entropy during adsorption in the Henry region of 17 derivatives of 1,3,4-oxadiazole and 1,2,4,5-tetrazine from water-acetonitrile solutions with acetonitrile concentrations of 20 to 80 vol % and a variation step of 5 vol % on silica gel with grafted phenyl groups at column temperatures of 313.15 to 333.15 K with at a step of 5 K are determined under dynamic conditions by high-performance liquid chromatography. The dependence of the thermodynamic characteristics of adsorption on the molecular structure of adsorbates is discussed. It is established that the absolute values of the changes in the Gibbs energy and enthalpy during adsorption as a whole increase with increasing Van der Waals surface area and volume of the adsorbate molecules, while the adsorption of most 1,3,4-oxadiazoles is characterized by a dependence close to isentropic. It is assumed that the determining role in the change of entropy during adsorption from solutions is played by the polarity of the adsorbate molecule and the conformational flexibility of its substituents.     

Simulation of the Carbon Synthesis Process in Atmospheric-Pressure Microwave Discharge in an Argon–Ethanol Gas Mixture

High Energy Chemistry - A self-consistent model has been formulated that describes microwave discharge in an argon/ethanol gas mixture. On the basis of this model, two-dimensional numerical...     

Laws of sorption of some aromatic heterocycles from solutions on nanoporous supercrosslinked polystyrene

Principles of the sorption of 5-tetrazole, 1,3,4-oxadiazole, and 1,2,4,5-tetrazine derivatives from solutions of various composition on nanoporous supercrosslinked polystyrene were studied by high performance liquid chromatography. The influence of the nature of heteroatom on the sorption of these heterocycles was demonstrated. The role of different types of intermolecular interactions in the sorption of the studied substances from solutions on nanoporous supercrosslinked polystyrene in quasi-normal phase and reverse phase liquid chromatography are discussed.     

Thermodynamic characteristics of the adsorption of 1,3,4-oxadiazoles and 1,2,4,5-tetrazines from methanol and water–methanol solutions onto hypercrosslinked polystyrene

Russian Journal of Physical Chemistry A - The thermodynamic characteristics of the adsorption of several 1,3,4-oxadiazoles and 1,2,4,5- tetrazines from methanol and water-methanol solutions onto...     

Regularities of the sorption of cycloalkenyl-substituted thiophenes and 2,2′-bithiophenes from water-acetonitrile solutions on hexadecyl silica gel under conditions of high-performance liquid chromatography

Regularities of the sorption of newly synthesized cycloalkenyl-substituted thiophenes and 2,2′-bithiophenes from water-acetonitrile solutions of different compositions on hexadecyl silica gel are investigated by high-performance liquid chromatography (HPLC). The retention factors and Henry constants of adsorption of these substances are determined. We discuss the effect of the molecular structure of the investigated heterocycles, and the nature and positions of the substituents, on the sorption. The equilibrium constants for the quasi-chemical reactions of sorption of the investigated compounds at the interface, and their solvation in a multicomponent bulk solution, are calculated using the Lanin-Nikitin equation. Based on the obtained results, we suggest that structural self-organization in the bulk solution and at the interface with the hydrophobic surface of hexadecyl silica gel plays an important part in the sorption of cycloalkenylsubstituted thiophenes and 2,2′-bithiophenes from multicomponent solutions.     

Effect of acoustic flows on the structure of a constricted glow discharge in argon

Numerical experiments on the effect of acoustic flows on the structure of a constricted glow discharge in argon have been performed in the hybrid approximation. The possibility of controlling the combustion regime of the glow discharge with an extended positive column at a high pressure by means of the formation of acoustic flows at the excitation of a standing acoustic wave has been demonstrated. In this case, the discharge transfers from the constricted combustion regime to the diffuse one and becomes stable.     

Degree of polymerization and polydispersity of cellulose obtained from cyclone fluff by the oxygen-soda method

The dependence of the degree of polymerization and the polydispersity of samples of cellulose isolated from cyclone fluff under the conditions of an oxygen-soda cook has been studied. It has been shown that the cellulose obtained from soda-oxygen digestion in the presence of copper sulfate and hexamethylenetetramine is more monodisperse and has a higher degree of polymerization. Films and fibers of the triacetylcellulose obtained from this cellulose possess the highest physicomechanical properties.     

Effect of Supramolecular and Morphological Structure on Cellulose Characteristics

The dependence of quality indicators of cotton cellulose obtained by an oxygen-alkaline digestion method, cellulose from the Bakai company, and wood cellulose on their supramolecular and morphological structure was studied by various physicochemical methods. The number of gel particles in cellulose solutions depends on their degree of polymerization; in solutions of their Na-CMC esters, on the content of the primary fiber wall of the starting cellulose