Fluorine-containing heterocycles: XVI. Reactions of tetrafluorobenzoyl isothiocyanate with hydrazines and their derivatives

Fluorinated derivatives of 4H-1,3-benzothiazin-4-one, [1,2,4]triazolo[4,3-a]pyrimidine, [1,2,4]triazolo[3,4-b][1,3]benzazoles, and 1,5-dihydro-1,2,4-triazole-5-thione were synthesized by addition of hydrazines and their derivatives to tetrafluorobenzoyl isothiocyanate, followed by cyclization of intermediate thiosemicarbazides.     

Ambident Properties of 4-Substituted Thiosemicarbazides in Condensations with Fluoroacetic Acids

4-Substituted thiosemicarbazides react with di- and trifluoroacetic acids to give the corresponding 3-fluoroalkyl-4,5-dihydro-1,2,4-triazole-5(1H)-thiones. Condensation of 4,4-disubstituted thiosemicarbazides with trifluoroacetic acid leads to formation of 2-amino-5-trifluoromethyl-1,3,4-thiadiazoles.     

Synthesis and electrochemical properties of fullerene-containing C<Subscript>60</Subscript>-acceptor dyads with fluoronitrobenzene and fluoroquinoxaline moieties as substituents

Reactions of fullerene C₆₀ with 4-azido-3-fluoro-1-nitrobenzene and 7-azido-6-fluoroquinoxaline afforded earlier unknown cycloadducts (C₆₀-acceptor dyads), in which the electron affinities of the fullerene spheres are comparable with the affinity of nonmodified C₆₀.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 650–655, March, 2005.     

Fluoro-containing Heterocycles: VI. New Derivatives of 1,3,4-Thiadiazino[6,5,4-i,j]quinoline

A series of new tricyclic fluoroquinolones was prepared by replacing fluorine atoms in derivatives of 2-R-8-Y-7-oxo-9,10-difluoro-7H-1,3,4-thiadiazino[6,5,4-i,j]quinoline-6-carboxylic acids. In acids and esters containing a hydrogen atom in position 8 occurred replacement of F¹⁰ by amine rests, and in compounds with a fluorine in position 8 was substituted either F⁸or F¹⁰ and F⁸depending on the amine character.     

Equilibrium and Transport Characteristics of Perfluorinated Cation-Exchange Membranes Containing Carboxyl Groups

Equilibrium (the exchange capacity and moisture content) and transport (the ion transport numbers and the electrical conductance) properties of perfluorinated cation-exchange membranes containing carboxyl groups were studied as a function of pH and concentration of KCl solutions (10^–4–1 M). Dissociation constants of carboxyl groups, adsorption potentials of K⁺ ions, transport numbers and mobilities of counterions in the membranes, concentrations of fixed ions, co- and counterions, as well as the Donnan potentials were calculated.     

Determination of diagnostical markers of urolithiasis by capillary electrophoresis

Methods of the electrophoretic determination of the main markers of urolithiasis, i.e., inorganic cations, ammonium, potassium, sodium, magnesium, and calcium; inorganic anions, chloride, sulfate, and phosphate; and organic acid anions, urate, citrate and oxalate, and creatinine in 24-hour collection urine with spectrophotometric detection were developed. The detection limits of analytes ranged form 0.25–1.0 μg/mL. The precision and accuracy were 2–5% and 97–101.5%, respectively. In dependence on the analyte. The developed procedures were used in the analysis of 156 urine samples. Normal ranges were preliminarily determined on a group of healthy donors.     

Electrosurface characteristics of titanium dioxide in solutions of simple electrolytes: I. Effect of nature of counterions on adsorption and electrokinetic parameters of TiO<Subscript>2</Subscript>

The adsorption and electrokinetic characteristics of different titanium dioxide samples (produced by the Merck Co. and synthesized by the sol-gel method) are studied depending on the pH, background electrolyte concentration, and the nature of counterions (halide ions and Na⁺, K⁺, Ba²⁺, and La³⁺ metal ions). It is revealed that, in the presence of an indifferent electrolyte, the points of zero charge (PZC) for the synthesized TiO₂ sample and the Merck sample correspond to pH = 6.0 ± 0.1 and 5.0, respectively. It is found that the nature of halide ions has almost no influence on the magnitude of the TiO₂ surface charge σ₀ (in the region of its positive values) and the position of PZC. An increase in the specificity of cations with a rise in the charge causes PZC shift to the acidic region and enhances the absolute values of σ₀ at both negative and positive surface charges. It is established that the positions of PZC and isoelectric point in 10⁻² M solutions of the examined 1: 1 electrolytes nearly coincide with one another. The ζ potential is found to decline in the following series of counterions: Cl⁻, Br⁻, and I⁻ due to an increase in the degree of filling of the dense part of the electrical double layer.     

Effect of porous structure of activated carbon electrodes on characteristics of double-layer supercapacitors

Porous structure of electrode materials was studied and the role played by macroporous in electrodes of model double-layer supercapacitors was experimentally analyzed. It was shown that the excess macropore volume in electrodes has an adverse effect and, on the whole, reduces in a complicated way the specific electrochemical characteristics of these devices. This makes necessary to develop the optimal electrode structure as regards not only nanoporous, but also macroporous structure.