Electrochemical perfluoroalkoxylation of aromatic compounds

New approaches to the electrochemical synthesis of aryl perfluoroalkyl ethers based on a) the electrooxidation of perfluorocarboxylic acid on a consumable PbO₂ anode and b) the simultaneous anodic oxidation of the “aromatic compound-alkaline perfluoroalkoholate” system on a platinum electrode were proposed.     

Influence of Pu(IV) complex formation with 1,2-diaminocyclohexanetetraacetic acid on the reduction rate of quadrivalent plutonium

The behaviour of the complex ion formed by quadrivalent plutonium with 1,2-diaminecyclohexanetetraacetic acid (DCTA) in reductive media is studied.     

Thermal decomposition of 1-ethyl-5-iodotetrazole

The thermal decomposition of 1-ethyl-5-iodotetrazole in a melt and in solutions was studied using thermogravimetry, manometry, pyrolytic mass spectrometry, and IR spectroscopy. The kinetic and activation parameters of the process and the nature of the decomposition products were determined. The reaction mechanism is assumed to involve equilibrium tautomeric rearrangement of the tetrazole to azidoazomethine form followed by homolytic cleavage of the C-I bond.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1923–1926, November, 1994.The authors are grateful to O. A. Ivashkevich and P. N. Gaponic (Belarussian State University), who provided the samples of the tetrazole.     

Effect of change of phase resistances on the kinetics of mass transfer with a chemical reaction across spherical phase boundary in the interphase instability mode

The influence exerted by the concentration of the binder reagent on the ratio of phase resistances in mass exchange across a spherical phase boundary in the liquid-liquid system was studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1847–1852.Original Russian Text Copyright © 2004 by S. Ermakov, A. Ermakov, Stepanov.     

Crystal and Molecular Structure of the Nitramino Derivatives of Tetrazole and 1,2,4-Triazole. III. 5-Nitraminotetrazole Lithium Salt Monohydrate

The structure of 5-nitraminotetrazole lithium salt monohydrate was determined by X-ray diffraction analysis. Crystals are monoclinic, space group P2₁/c; a = 8.3789(5), b = 10.1872(6), c = 6.6709(5) ; = 106.63(1)°; V = 545.60(98) ³; Z = 4; _calc = 1.875 g/cm³. The anion has a planar nitrimine structure with a delocalized negative charge. Each lithium cation (c.n. 5) is bound to three anions and two hydration water molecules. Both oxygen atoms of the nitro groups and the N(3) atom of the tetrazole ring are involved in cation coordination. The geometrical characteristics of the anion are similar to those found for other monosalts of 5-nitraminotetrazole.     

Application of isotope dilution method for mass- and alpha-spectrometric determination of burn-up and uranium,plutonium and transplutonium element content in VVER-440 spent fuel

In this report the procedures and the methodology of our versions of alpha- and mass-spectrometric techniques for destructive analysis of VVER spent fuel are discussed. These techniques allow the determination of the content of americium and curium isotopes with relative error 3–5%, that of plutonium isotopes with error ≤1% and of uranium isotopes ?0.3–0.4%. They allow one to determine the fuel burn-up using¹⁴⁸Nd monitor with relative error not exceeding 2% at confidence level P=0.95. The investigation was directed at the increase of sensitivity of analysis to ensure that the amount of analysed material should be equivalent to ～1 mg of irradiated uranium at mean burn-up values. These techniques are based on the isotope dilution method.     

What do Positrons Say about the Structure and Properties of Fluids?

Applications of positron annihilation spectroscopy to fluid state physics and chemistry are discussed. Special attention is paid to problems of surface (interface) layer structure, molecular orientations in the layer, and the effects of freesurface curvature and age on surface tension. Positron investigations of the structure of liquid mixtures, including microheterogeneity studies, are considered.     

NMR studies of the interaction between tris-acetylacetonates of Fe(III), Cr(III) and diethyldichloride of Sn (IV)

Paramagnetic relaxation rate of CH₂ protons has been found to be higher than that of CH₃ protons of SnEt₂Cl₂ in the presence of tris-acetylacetonate of Cr(III) in chloroform at 298 K, which supports the specific interactions between these compounds. The revealed ligand exchange between Cr(AA)₃, Fe(AA)₃ and SnEt₂Cl₂ takes place with the equilibrium shifted to the side of initial reactants.

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, -CH₂ CH₃- SnEt₂Cl₂ - Cr(III) 298 K, . Cr(AA)₃, Fe(AA)₃ SnEt₂Cl₂, .

     

The compensation effect as a result of integration of theArrhenius equation

Summary It has been shown that joined segments of straight lines are observed upon plotting the logarithm of the rate constant against the reciprocal temperature, exhibiting sharp breaks at so-called critical temperatures indicating sudden changes in activation energy [3, 5–8]. If the integration of the differential form of theArrhenius equation from 0 toT K is taken into account, the compensation effect can easily be explained.

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Der Kompensationseffekt als Ergebnis der Integration derArrhenius-Gleichung

Zusammenfassung Wenn man den Logarithmus der Geschwindigkeitskonstante gegen die reziproke Temperatur aufträgt, erhält man aufeinanderfolgende Teilstücke von Geraden mit scharfen Knicks bei sogenannten kritischen Temperaturen, welche jeweils eine Änderung der Aktivierungsenergie anzeigen [3, 5–8]. Integration derArrhenius-Gleichung zwischen 0 undT K führt zu einer zwanglosen Erklärung des Kompensationseffekts.