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Vol 475, No 2 (2017)
- Year: 2017
- Articles: 9
- URL: https://journal-vniispk.ru/0012-5008/issue/view/9271
Chemistry
Dependence of the properties of fluorine-containing poly(phenylquinoxaline) on the method of its preparation
Abstract
A method of synthesis of new fluorine-containing tetraamine, 2,2-bis[4-(3,4-diaminophenoxy) phenyl]hexafluoropropane, has been developed; the tetraamine has been used as the initial compound for preparing poly(phenylquinoxaline)s in both supercritical carbon dioxide and solution. Thermal characteristics of fluorine-containing poly(phenylquinoxaline)s have been studied. There is a bimodal particle size distribution at the used polymer concentration (Cpol = 0.1 wt %) according to dynamic laser light scattering data.
159-163
New coordination polymers of silver(I) based on dodecahydro-closo-dodecaborate anion: Synthesis and structure
Abstract
It has been demonstrated that the reaction of Cat[Ag[B12H12]] or [Ag2[B12H12]] with chelating ligands L (L = bipy, phen) leads to the selective formation of stable [(Ag2(L)2[B12H12]]n 1D polymers irrespective of the nature of cation (Cat) in the starting reagent, the ratio of the reaction components, and the solvent used. The structures of [Ag2(bipy)2[B12H12]]n · 2CH3CN and [Ag2(phen)2[B12H12]]n · DMF have been determined by X-ray crystallography. It has been demonstrated that the [B12H12]2− anion in polymer chains acts as a bridging ligand coordinated to silver atoms through edges or through an edge and a vertex of the icosahedron. The Ag–B(H) and Ag–H(B) distances are within 2.638(3)–3.074(3) and 1.90–2.80 Å, respectively. These complexes are the first examples of 1D coordination polymers based on the [B12H12]2− anion and azaheterocyclic ligands L.
164-167
Computational modeling of mixed-ligand cobalt diketonate complexes with pyrene-4,5,9,10-tetraimine
Abstract
Quantum-chemical modeling (DFT UB3LYP*/6-311++G(d,p)) of binuclear mixed-ligand cobalt diketonate complexes with pyrene-4,5,9,10-tetraimine has been performed. Equilibrium geometries and stabilization energies of all the electromeric forms of the studied adducts have been calculated, and the exchange spin coupling constants have been evaluated. Compounds capable of undergoing one- or two-step valence tautomeric rearrangements accompanied by a change in magnetic properties have been revealed by varying the substituents in the bis(chelate) moiety.
168-172
Symmetric cage structures of isomers of nonstoichiometric lower molybdenum oxides
Abstract
Molybdenum dioxide (Mo2) synthesized through thermal decomposition of the [MoO2(i-C3H7NHO)2] complex and containing a nanosized fraction has been studied by MALDI-TOF. The composition of clusters of lower nonstoichiometric molybdenum oxide cations in the gas phase has been determined, and theoretical calculations of the thermodynamic stability and structure of the isomers of the most symmetric structures have been performed. Molecular orbitals of the cationic and neutral clusters Mo5O8 and Mo5O9 have been examined, and the aromaticity of the Mo-Mo bonds in metallacycles has been demonstrated.
173-178
Disproportionation of manganese(II) (1-hydroxyethylidene) diphosphonate in reaction with 2-aminoethanol
Abstract
Reaction of poorly soluble manganese(II) bis(1-hydroxyethylidene)diphosphonate tetrahydrate Mn(H3L)2 · 4H2O with 2-aminoethanol H2NCH2CH2OH in an aqueous solution on heating to 70–80°C causes the initial formation of soluble tris(2-hydroxyethanaminium) manganese(II) bis(1-hydroxyethylidene) diphosphonate Mn(H3L)2 · 3H2NCH2CH2OH · 4H2O, which next disproportionates into poorly soluble 2-hydroxyethanaminium manganese(II) (1-hydroxyethylidene)diphosphonate MnH2L · H2NCH2CH2OH and metal-cation-free coordination polymer of (1-hydroxyethylidene)diphosphonic acid with 2-aminoethanol. Poorly soluble MnH2L · H2NCH2CH2OH can be readily converted into the soluble form by treatment with 2-aminoethanol or 2-amino-2-(hydroxymethyl)propane-1,3-diol H2NC(CH2OH)3.
179-183
Chemical Technology
Lignin conversion to hydrogen-containing gas under the action of microwave radiation
Abstract
The paper describes the carbon dioxide reforming of lignin in the presence of Ni-, Fe, and Ni/Fe-containing active components formed directly on the surface under microwave irradiation. The deposition of 0.1 wt % iron acetylacetonate on the lignin surface results in a sharp increase in the microwave absorption capacity at a 0.5 kW power and induces lignin conversion to hydrogen-containing gas with a degree of hydrogen recovery reaching 90 %. The maximum lignin conversion (65%) is attained in 10 min under microwave irradiation. It was shown for the first time that deposition of metals (Fe and Ni) on lignin can provide for targeted change of the selectivity of reforming to synthesis gas and the process can thus be classified as a plasma catalytic one. Using the obtained results, it is possible to minimize the amount of catalyst and to propose an efficient route for hydrogen and synthesis gas production from lignin waste.
184-187
Computer-aided modeling of the chemical process of drying of a moving dense multilayer mass of phosphorite pellets
Abstract
Mathematical and computer models were developed for the chemical process of drying of a moving dense multilayer mass of phosphorite pellets in a travelling grate machine. These models take into account the intensity of the internal moisture transfer in a pellet and the overmoisturization of individual horizons in the heated bed of pellets, which enables one to determine the technological parameters of the drying mode. The adequacy of the developed mathematical model was tested by comparing the calculated values of the moisture content and temperature of pellets, the characteristics of the heat-transfer gas, and the intensity of the moisture transfer in pellets while drying in a moving dense bed with the results of industrial tests. Numerous computational experiments were performed to determine the relative degree of drying, the moisture content, the pellet drying intensity, and the moisture content of the heat-transfer gas at various characteristics of moist pellets and the operating technological parameters of the travelling grate machine.
188-191
Modeling of carbonaceous feedstock pyrolysis in a countercurrent tubular reactor
Abstract
A mathematical model of carbonaceous feedstock pyrolysis in a countercurrent tubular reactor was proposed. It was shown that the pyrolysis in a tubular reactor in which porous carbonaceous feedstock is heated in a countercurrent flow of a heated gas can be highly efficient.
192-195
Development of composition and study of properties of a new high-efficiency silicon-containing protective conversion coating on zinc-plated surfaces
Abstract
The composition was developed for a new high-efficiency silicon-containing protective conversion coating for application to zinc-plated surfaces. It was proven experimentally and theoretically that this new environmentally safe coating is comparable in corrosion resistance and protective power to environmentally hazardous chromate coatings; however, unlike the latter, the former is efficient at high temperatures (to 150°C). For extra protection of a material being coated, it was proposed to additionally apply a new, nontoxic (hazard class 4) organic film based on gallic acid esters.
196-199