Disproportionation of 6,8-Dialkyl-3-thia-2,4,6,8-tetraazabicyclo[3,3,0]octan-7-one 3,3-Dioxides under Conditions of Acid Hydrolysis and Acetylation

Acid hydrolysis and acetylation of 6,8-dialkyl-3-thia-2,4,6,8-tetraazabicyclo[3,3,0]octan-7-one 3,3-dioxides have been studied. 6,8-Dialkyl-3-thia-2,4,6,8-tetraazabicyclo[3,3,0]octan-7-one 3,3-dioxides disproportionate to 4,4'-sulfonyldiiminobis(1,3-dialkylimidazolidin-2-ones) and sulfamide when treated with acid at pH 1 or with acetyl chloride. The kinetics of the disproportionation have been studied.     

Synthesis and structures of 5(3H)-oxotetrahydro-1H-imidazo[4,5-c][1,2,5]thiadiazole 2,2-dioxides

The reactions of sulfamides with 4,5-dihydroxyimidazolidin-2-ones were studied at ambient and high pressure. The previously unknown derivatives of 5(3H)-oxotetrahydro-1H-imidazo-[4,5-c][1,2,5]thiadiazole 2,2-dioxide, viz., sulfo analogs of tetrahydroimidazo[4,5-d]imidazole-2,5-(1H,3H) diones (glycolurils), were synthesized. The structures of some of these compounds were established by X-ray diffraction. The high-pressure reactions performed under conditions of solvent phase transitions afforded also N-(1,3-diethyl-5-hydroxy-2-oxoimidazolidin-4-yl)-N,N′-dialkylsulfamides. Among these compounds, a new conglomerate was found. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1711–1719, May, 2008.     

Procedures and findings of examination of air contamination by alpha-active plutonium aerosols: Primary and secondary products of Chernobyl accident

Atmospheric contamination pattern by Pu-radionuclides over a 30 km zone of the Chernobyl nuclear power plant in 1987–1988 has been examined. Aerosol samples were analyzed for isotopic composition by using gamma- and alpha-spectrometric, and radiochemcal methods. Preliminary analysis of isotopic and fractional composition of aerosols carried out earlier indicated that over the first few months after the Chernobyl accident the relative contribution of^238,239,240Pu to air contamination was lowered as compared with beta-active products. At present, however, alpha-active plutonium isotopes became the dominant radioactive contaminants of the atmosphere and the concentrations of^238,239,240Pu inhaled fractions turned out to be lower than the limiting permissible values based on the USSR radiation safety standards for radioactive contamination of the atmosphere for the limited part of population exposed to radionuclides. Neverheless, it is necessary to know even moderate levels of atmospheric contamination by Pu-radionuclides, since their long impacts on the personnel operating in the 30 km zone of the Chernobyl NPP and population residing in the adjavent regions have not been studied properly. So, the risks for population health of such impacts cannot be generally excluded from consideration.     

Reactions of nucleophilic substitution involving solid organic halogen compounds under shear deformation at high pressure

Under conditions of shear deformation and high pressures (SD+HP), reactions of nucleophilic substitution were studied: 1) the replacement of aliphatic halogen atom with alkaline metal halides (halo-substituted aliphatic carboxylic acids, 1-bromoadamantane); 2) the replacement of halogen atom in aromatic nucleus (halobenzoic acids, dihalobenzenes) with halogen of salt; 3) the replacement of aliphatic halogen with hydroxyl (hydrolysis in a solid phase); 4) the replacement of halogen with amino group under deformation of the samples of ammonium -halocarboxylates to give the corresponding amino acids. It was found that the exchange of the halogen atoms bonded with aliphatic carbon is most intensive in the mixtures of alkaline metal iodides with bromo-substituted acetic and propionic acids: the exchange reaction in these mixtures is observed even during grinding in the mortar. Unlike the liquid phase, under conditions of SD+HP exchange of the halogen atom of the aromatic nucleus with alkaline metal halides, proceeds successfully, and the reactivity of halides increases in the series Na < K < Rb < Cs. Under SD+HP, 1-Br-adamantane reacts with water to form 1-adamantanol. A high reactivity of the water adsorbed by the reagents is observed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1090–1095, June, 1995.     

Small motions and eigenoscillations of a “fluid–barotropic gas” hydrosystem

This paper deals the problem of small motions and eigenoscillations of the hydrodynamical system” ideal fluid–barotropic gas” with regard for gravitational and capillary forces. The spectrum structure and the basis property of eigenfunctions are studied. The variational principles for eigenvalues are presented. The theorems of strong solvability of an initial boundary-value problem and the inverse Lagrange’s theorem of stability of the hydrosystem are proved.     

Influence of deposition conditions on the antireflection properties of diamond-like carbon films for Si-based solar cells

The influence of deposition conditions on the antireflection properties of diamond-like carbon films for Si-based solar cells is studied theoretically. The values of the short-circuit current density for Si solar cells covered by diamond-like carbon films deposited at different concentrations of nitrogen in the gas mixture are calculated and compared with the associated values for uncovered solar cells. It is shown that the short-circuit current density increases with nitrogen concentration in the gas mixture because of a lower light absorption by the growing film. Optimum thicknesses of the diamond-like carbon films are calculated that provides a maximal increase in the output short-circuit current density of Si-based solar cells under both AM1.5 and AM0 conditions. Published in Russian in Zhurnal Tekhnicheskoĭ Fiziki, 2006, Vol. 76, No. 5, pp. 122–126. The article was translated by the authors.     

Synthesis of new 2H-benzimidazole 1,3-dioxide derivatives analogous to separase inhibitor (Sepin-1)

Russian Journal of Organic Chemistry - New biologically active 2H-benzimidazole 1,3-dioxide derivatives, analogs of Sepin-1, have been synthesized starting from benzofuroxan. Electrophilic...     

In Situ Radioisotopic Study of the Active Sites of Sulfide CoMo Catalysts and the Mechanism of Thiophene Hydrodesulfurization

The mechanism of thiophene hydrodesulfurization over sulfide catalysts for hydrotreating and the effect of the catalyst composition and feed on the number, distribution, and performance of active sites were studied using ³⁵S and ³H isotopes. Based on the results of radioisotopic study, a method for systematic testing–monitoring of sulfide Co(Ni)Mo catalysts for hydrotreating is developed. The method involves the evaluation of the fraction of the active phase surface occupied by SH groups and the ratio between the concentrations of the surface SH groups and coordinatively unsaturated sites including functioning vacancies. General conditions for the formation and functioning of active sites are formulated on the basis of the monitoring data. Criteria for evaluation of the catalyst performance under conditions of hydrodesulfurization of various kinds of crude are proposed. The results of the pilot tests of commercial catalysts suggest that the criteria proposed are suitable.