Том 476, № 1 (2017)
- Год: 2017
- Статей: 6
- URL: https://journals.rcsi.science/0012-5008/issue/view/9275
Chemistry
Synthesis of novel spirocyclopropylmalonates and barbiturates
Аннотация
Alkylidenemalonates have been subjected to dichlorocyclopropanation to produce novel spiro-gem-dichlorocyclopropylmalonates in quantitative yields. The latter have been reacted with urea in the presence of sodium ethoxide to produce the corresponding barbiturates in 80–95% yields. The cleavage of the spiro-gem-dichlorocyclopropylmalonate carbocycle with ethanol with the aid of aluminum chloride has led to ethyl ethers, while carbocycle expansion with isobutyraldehyde has afforded polysubstituted tetrahydrofurans. The prepared compounds have been structurally characterized in detail by 1H and 13C NMR spectroscopy.
Optimization of the chemical stage of pretreatment of technical polychlorobiphenyls for destruction
Аннотация
The reactions of commercial polychlorobiphenyl mixtures of Sovol and Trikhlorbifenil brands (Russia) with sodium methoxide were studied in dimethyl sulfoxide and methanol. It was shown for the first time that Sovol congeners are exhaustively converted, without formation of potentially toxic products, in the reaction with alkali metal alkoxide based on a monobasic aliphatic alcohol. This process is a stage of chemical pretreatment of polychlorobiphenyls subject to destruction for the subsequent microbiological mineralization of the new derivatives.
Short-lived 224Ra and 223Ra isotopes in the Anadyr River–Bering Sea system
Аннотация
The first results of activity measurement of short-lived radium isotopes dissolved in water in the Anadyr River–Bering Sea transit system are presented. The trends of the radionuclide behavior after passage through high-gradient river–coastal sea water mixing zone were identified and the exchange rate of the horizontal mixing was determined. The 224Ra/223Ra activity ratio was used to construct the “radium age” model, which served for estimating the residence time of brackish water in the Anadyr River estuary. The factors affecting this value were elucidated.
Quantum-chemical study of (Z)-6,8-di-tert-butyl-N-(4-methoxyphenyl)-3-((4-methoxyphenyl)imino)-3H-phenoxazine-2-amine complexation with cobalt bis(chelate)s
Аннотация
Computational modeling (DFT UB3LYP*/6-311++G(d,p)) of mixed-ligand complexes of cobalt bis(chelate)s with N,N-diphenyl-diiminophenoxazine has been performed. It has been shown that variation of the electron-withdrawing and bulky substituents in the diketonate and azomethine moieties has a significant impact on the stability of the resulting adducts and on the energy difference between their low-spin and high-spin states. The compounds capable of exhibiting valence tautomeric properties have been revealed.
Chemical Technology
Physicochemical efficiency of electroflotation of finely divided carbon nanomaterial from aqueous solutions containing surfactants
Аннотация
Electroflotation of finely divided carbon nanomaterials—carbon nanoflakes (CNFls)—from aqueous solutions with a wide pH range of 3.0 to 11.0 in the presence of surfactants of various types was studied experimentally. The efficiency indices were determined for the electroflotation of CNFls from CNFls–surfactant–Na2SO4 solutions in the presence of a coagulant (iron(III) chloride) and flocculants, which enabled one to find the optimal conditions for electroflotation of carbon nanomaterials.
The effect of phosphate group replacement by sulfate groups on the phase formation in the synthesis of hydroxyapatite
Аннотация
Sulfate-substituted hydroxyapatite materials with a degree of substitution of up to 20 mol % (Ca10(PO4)(6 – 0.06x)(SO4)0.09x(OH)2, x = 0, 0.1, 0.5, 1, 5, 10, and 20) were synthesized. For substitutions of 0, 0.1, 0.5, and 1 mol %, a single-phase material with the apatite structure is formed. On further increase in the concentration of SO42− groups up to 20 mol %, a second phase, CaSO4, is formed; the amount of this phase increases for higher degrees of substitution. The unit cell parameters of hydroxyapatite-based materials change slightly upon the replacement of phosphate groups by sulfate groups: the parameter a tends to increase, while c tends to decrease. The introduction of sulfate groups results in decreasing particle size.