Effect of mechanical activation on the thermal stability of polytetrafluoroethylene powder

It was found that processing in a planetary activator leading to amorphization of the structure of polytetrafluoroethylene powder was not accompanied by a noticeable decrease in its thermal stability. It was established that the temperature at the onset of melting drops slightly, the melting rate increases, and the enthalpy of the endoeffect declines noticeably heating.     

Laboratory of Analytical Ecotoxicology at the Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences

The history of the establishment and development, functions, and advances of the Laboratory of Analytical Ecotoxicology at the Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences were considered.     

Parametric X-ray radiation from powders

Parametric X-ray Radiation (PXR) produced in powders has been observed for the first time. PXR spectra were measured under observation angles of 150° and 180° during the interaction of relativistic 7 MeV electrons with a tungsten powder. All the PXR peaks that theoretically can be produced in the studied energy region were registered. The performed absolute comparison of the experiment with the PXR kinematical theory from randomly oriented crystallites showed a good accordance.     

Statistical quality control of PCDD/PCDF analysis using a total measuring data set

 A random error and accuracy estimation approach for polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) analysis is presented based on statistical treatment of all the data set registered in a run or in a bunch of uniform runs. Received: 18 August 1998 / Accepted: 21 October 1998     

Synthesis and structural investigations of N(1-methyl-2-carbomethoxyindolyl-3-sulfonyl)-N′-hetarylureas

We have carried out synthetic and physicochemical investigations of N-(1-methyl-2-carbomethoxyindolyl-3-sulfonyl)-N-hetarylureas which are a new generation of potential herbicides and plant growth regulators.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 359–368, March, 1994.     

Tetrazole derivatives. 27. Structures of the products of autotransformation of the 1-(1-methyl-5-tetrazolyl)-3,5-diphenylverdazyl radical

It was established by mass spectrometry that one of the products of the spontaneous transformation of the 1-(1-methyl-5-tetrazolyl)-3,5-diphenylverdazyl radical has the 1,3-diphenyl-5-(1-methyl-5-tetrazolylamino)-1,2,4-triazole structure. The latter undergoes oxidation to give an N-oxide derivative involving the N₄ atom of the triazole.See [1] for Communication 26.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1560–1562, November, 1981.     

Synthesis of N-Isobutylanilines Substituted in the Benzene Ring and Their Reactivity in Arenesulfonylation

Secondary aliphatic-aromatic amines were synthesized by hydrogenative amination of aliphatic aldehydes with aromatic amines. The kinetics of arylsulfonation of the resulting alkylarylamines with benzenesulfonyl chloride and its monosubstituted derivatives in 2-propanol at 298 K were studied. The activation parameters of the reaction of ring-substituted N-isobutylanilines with 3-nitrobenzenesulfonyl chloride were determined.     

Purines,pyrimidines, and condensed systems based on them

The action of various oxidizing agents on 7- and 9-aminotheophyllines and also on 1-methyl-9-aminoxanthine was studied. 7-Aminotheophyllines are oxidized by almost all the oxidizing agents to 6,8-dimethylpyrimido[4,5-e]-as-triazine-5, 7(6H,8H)-dione (40–90%). 1-Methyl-9-aminoxanthine and 9-aminotheophylline are oxidized with greater difficulty. The best results are obtained with hydrogen peroxide, which transforms these amines with yields of –40% into the antibiotics rheumycin and fervenulin, respectively. Under certain conditions the action of bromine and nitric acid leads to the bromination and nitration of the N-aminoxanthines at position 8. A series of the physicochemical characteristics of the N-aminoxanthines were investigated. The factors which affect their behavior toward oxidizing agents and electrophiles are discussed.For Communication 5, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 95–102, January, 1989.     

Reactions of copper(II) polyfluorinated Β-diketonates and Β-ketoesterates with hydrazines

It has been shown that pyrazoles (hydroxypyrazoles) are formed upon reaction of fluorine-containing copper -diketonates (-ketoesterates) with hydrazines and their hydrochlorides. A preparative method has been developed for the synthesis of fluorinated pyrazoles and hydroxypyrazoles via treatment of fluorine-containing -diketonate and -ketoesterate copper compounds with hydrazines. The molecular structure of 1-phenyl-3-octafluorobutyl-5-hydroxypyrazole has been established based on x-ray structural analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 640–645, March, 1990.     

Mass spectra and structure of halo-substituted 2- and 4-aminopyrimidines

The mass spectra of methyl- and halo-substituted 2- and 4-aminopyrimidines at an ionizing electron energy of 70 eV were studied. It is shown that the molecular ion of the investigated compounds corresponds primarily to the imine form. This structure determines the principal direction of disintegration, which proceeds through the formation of pseudomolecular ions with an imidazole or pyrazole structure, depending on the position of the amino group in the pyrimidine ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1689–1693, December, 1973.