Oxidation of Iron and Nickel with 3,5-Di-<Emphasis Type="Italic">tert</Emphasis>-butyl-1,2-benzoquinone in Coordinating Solvents

The final products of oxidation of iron and nickel with 3,5-di-tert-butyl-1,2-benzoquinone in DMSO were identified, and the formal-kinetics relationships of the process were elucidated. The apparent equilibrium constants, enthalpies, and entropies of adsorption of the reactants on the metal surfaces and the rate constants and activation energies of the reactions were determined.     

Oxidation of Group II Metals with 3,5-Di-tert-butyl-1,2-benzoquinone

Kinetic regularities of zinc and cadmium oxidation in systems comprising 3,5-di-tert-butyl-1,2-benzoquinone and dimethylformamide or dimethyl sulfoxide are studied. Thermodynamic parameters of oxidant and ligand adsorption on metal surface are estimated. The oxidation of Group II metals (Be, Ca, Mg, Zn, Cd) with 3,5-di-tert-butyl-1,2-benzoquinone gives metal bis-o-semiquinolates. In the presence of excess metal in the medium of coordinating solvents, diradical products convert to the corresponding catecholate derivatives. It is shown that the dependence of the rates of metal reactions with 3,5-di-tert-butyl-1,2-benzoquinone on the donor number of solvent passes through a maximum. With less active metals, the maximum shifts to more basic ligands.     

Problems of solubility of hydrolysis lignin

Interaction of hydrolysis lignin with polyacrylonitrile in water-dimethyl sulfoxide solution in the presence of an activator was studied, and the properties of the products were examined.     

Oxidation of Magnesium with Dicarbonyl(cyclopentadienyl)iron(II) Chloride in Dimethylformamide

Oxidation of magnesium with dicarbonyl(cyclopentadienyl)iron(II) chloride in dimethylformamide gives rise to ⁵-C₅H₅Fe(CO)₂MgCl. Kinetic regularities of the process were determined. Thermodynamic parameters of adsorption of the reagents on the metal surface were calculated.     

Oxidation of Magnesium with Cyclopentadiene in Tetrahydrofuran Solution,Catalyzed by Chlorides of Group IV-VI Transition Metals

Chlorides of Ti(IV), V(III), Nb(V), and Mo(VI), in contrast to Cr(III) and Zr(IV) chlorides, catalyze oxidation of magnesium with cyclopentadiene to magnesium cyclopentadienide. The kinetic features of the process were revealed, and the composition and yield of reaction products were determined. Certain details of the reaction mechanism were discussed.     

Synthesis of magnesium dicyclopentadienide catalyzed by titanium and vanadium derivatives

Synthesis of magnesium dicyclopentadienide from metal and cyclopentadiene in THF is effectively catalyzed by the derivatives of vanadium and titanium. The kinetics of the synthesis, as well as thermodynamic parameters of reagents adsorption on the magnesium surface, have been determined. The process catalyzed by titanium derivatives is accompanied by the quantitative hydrogenation of cyclopentadiene to cyclopentene whereas the catalysis by vanadium derivatives leads to hydrogen gas evolution. A number of reaction intermediates including Cp₂TiCl, Cp₂TiH₂MgCl, Cp₂Ti(cyclo‐C₅H₇) and Cp₂V, were identified by the electron spin resonance method. The equilibrium constants, enthalpies and entropies of adsorption of metal halides on the magnesium surface were calculated. Copyright © 2001 John Wiley & Sons, Ltd.     

Specific features of the photolytic transformations of the polynuclear quinone-aliphatic hydrocarbon systems

Dependence of the quantum yield of decomposition of quinone on the intensity of the absorbed irradiation in the compositions of 1,2-naphthoquinone, 9,10-phenanthrenequinone, and 4-nitro-9,10-phenathrenequinone with nonane has the extremal character.     

Determining the phase composition of yttrium oxide nanopowders by means of luminescence

The possibility of developing a luminescence technique for phase composition analysis is demonstrated via the example of bi-phase yttria nanopowders doped with neodymium ions. The deviation from X-ray diffraction reference values is ±2%. It is found that the results depend on the inhomogeneity of the crystalline phase distribution within a sample’s bulk, rather than on the luminescence scattering by powder nanoparticles. A luminescence coefficient that determines the phase inhomogeneity in nanopowders is introduced.     

Fabrication and properties of neodymium-activated yttrium oxide optical ceramics

About new technology of production of transparent ceramics including laser synthesis of nanopowders, their magnetic pulsed compaction and vacuum sintering is reported. The results of investigations of the synthesized samples of transparent ceramics made from neodymium-activated yttrium oxide are presented. It has been shown that in a 1.1 mm thickness sample with optical loss coefficient α_1.07μm = 0.03 cm^?1 laser generation at λ _g ～ 1.08 μm with a slope efficiency of 15% at laser diode pumping at a wavelength of 807 nm has been obtained.     

Features of photolytic transformations of di-<Emphasis Type="Italic">o</Emphasis>-quinones containing sulfide fragments

Quantum yields and products of photolytic transformation of bis(2,5-di-tert-butylcyclohexadiene-1,5-dion-3,4-yl)sulfide and 1,4,7,10-tetra-tert-butyl-5,6,11,12-tetrathia-dibenzo-cyclooctene-2,3,8,9-tetraone dissolved in saturated hydrocarbon at the action of irradiation with wavelength 436 and 313 nm, respectively. Possible mechanism of these photo reactions is proposed.