Voprosy khimii i khimicheskoi tekhnologii (Issues of Chemistry and Chemical Technology)

4-14

Authors: I.Yu. Yermolenko, M.V. Ved', A.V. Karakurkchi, N.D. Sakhnenko, Z.I. Kolupayeva

The kinetic parameters of electrochemical behavior of tungsten at the deposition of Fe-W and Fe-Mo-W alloys were determined using linear voltammetry and analyzing polarization relationships. In the presence of citrate ions the cathode process was shown to proceed with the participation of [FeHCitWO4]– clusters. An optimal concentration ratio of the components in electrolyte required for the Fe-W alloy deposition was defined as c(Fe3+):c(Сit3–):c(WO42–) = 1:1.5:0.3. The deviation from this ratio by an increase in the concentration of tungstate ions results in the formation of dimer forms W2O72– and [FeW2O7HCit]– clusters; as a result the concentration of electrode active particles [FeWO4HCit]– diminishes and the cathode process is inhibited. A peculiar feature of the formation of electrolytic alloy Fe-Mo-W is a competitive reduction of molybdates and tungstates. Based on the analysis of the kinetic parameters and characteristic criteria of electrochemical reactions, we proposed the mechanism for the co-deposition of alloy containing iron with molybdenum and tungsten; this mechanism is a sequence of coupled reactions of irreversible reduction of intermediates with slow charge transfer stage and previous chemical step of the ligands release. The data of X-ray phase analysis show that the binary alloys Fe-W are solid solutions of tungsten in iron and ternary alloys Fe-Mo-W are X-ray amorphous.

21-29

Authors: O.S. Lebed, N.V. Panasiuk, N.V. Kutsik-Savchenko, A.V. Prosyanik

The reaction path of the interaction between aminoethylene-1,2-dicarboxylic acid derivatives and amines critically depends on the structure of the enamines and the reaction conditions. Thus, aminofumarate forms amides of Z-2-amino-3-methoxycarbonylacrylic acid in absolute methanol; diamides of aminofumaric acid are formed in the presence of MeONa. N-alkylaminofumarates and N-tret-butylaminomaleate give 1,3-dialkylaminopyrrole-2,5-diones regardless of the reaction conditions, whereas N,N-dialkylaminomaleates are inert in these reactions. Amides of Z-2-amino-3-methoxycarbonylacrylic acid in absolute MeOH in the presence of MeONa generate diamides, whereas they form 1,3-dialkylaminopyrrole-2,5-diones in aqueous MeOH. In order to explain the experimental patterns, the quantum-chemical study of amidation reactions was performed in the PBE/def2-TZVPP approximation with the analysis of the wave functions obtained within the framework of NBO. Amidation of the deactivated β-ester group can be achieved theoretically as a result of increasing the energy of the unshared electron pair (NEP) of the nucleophile resulted from deprotonation and/or a decrease in energy of the antibonding molecular orbital π*β-C=О by removing conjugate with the amino group. Possible mechanisms of the amidation of Z-2-amino-3-carboxyacrylic acid esters are discussed under the conditions of basic catalysis by the generation of alkyl amide anions or intermediate formation of ethers of iminosuccinic, 2-amino-2-methylaminosuccinic and 2-amino-2-methoxysuccinic acids. Based on the analysis of the experimental and calculated data, the mechanism of the amidation of amides of Z-2-amino-3-methoxycarbonylacrylic acid has been developed which takes into consideration the formation of the intermediate amides of 2-amino-2-methoxy-3-methoxycarbonylpropionic acid. The exclusive formation from hem-methoxyamines of aminofumaric acid is explained by the combined effect of statistical and kinetic factors. The inertness of N,N-dimethylaminomaleate is probably due to the inability of the formation of intermediate, 2- (N,N-dimethylamino)-2-methoxysuccinic acid ester, due to the shielding the α-carbon atom by bulk Me2N- and MeO2C-groups.

36-41

Authors: А.S. Marshalek, R.T. Prokop, I.B. Sobechko, Yu.I. Horak, V.M. Dibrivnyi

The combustion enthalpies (СH0) of 5-(3-nitrophenyl)- furyl-2 oxime (FO), 5-(3-nitrophenyl)- furyl 2-carboxylic acid (FA) and β-(5-(3-nitrophenyl) -furyl-2-propenoic acid (FPA) have determined using bomb calorimeter, these values being equal to -5413.9±5.3, -4861.1±7.3 and -5970.6±6.8 kJ mol-1, respectively. The formation enthalpies of the studied compounds in solid state have been calculated (-58.0±5.3, -431.3±6.8 and -468.0±7.3 kJ mol-1 for FO, FPA and FA, respectively). The temperature dependences of vapor pressures were determined using effusion integral Knudsen method, from which the sublimation enthalpies (subH) have been calculated (113.6±6.6 kJ mol-1 at T = 421.8 K, 194.6±10.1 kJ mol-1 at T = 450.8 K and 126.8±10.1 kJ mol-1 at T = 431.5 K for FO, FPA and FA, respectively). The sublimation enthalpies were adjusted to 298 K. From the obtained data, the formation enthalpies in the gaseous state for the studied compounds have been calculated. The values of the formation enthalpies in the gaseous state of the investigated compounds derived experimentally were compared with those calculated theoretically on the basis of Benson additive scheme. Taking into account the differences between the formation enthalpies of investigated substances in the gaseous state obtained experimentally and the calculated values from the additive scheme, some assumptions have been made concerning the intramolecular interactions in the compounds under study.

47-62

Authors: R.D. Apostolova

With the development of the technical progress the extensively claimed lithium ion batteries (LIB) lose their importance in power supply for portable electronic devices and autonomous vehicles because of insufficient power intensity, capacity, high costs and the absence of the guarantee safety. Magnesium-ion batteries (MIB) belong to promising alternatives to common accumulator systems. The literature data on the negative and positive electrodes, the electrolytes used in MIB and the whole battery behavior have been analyzed in this review. The problem of the synthesis of new magnesium electrolytes exists since the unfitness of magnesium electrolytes for MIB, these electrolytes might be analogues to usual lithium electrolytes. The electrolytes should be compatible with both magnesium and the materials of the positive electrodes. Ensuring a high coulomb efficiency of the magnesium deposition/dissolution processes is connected with the solution of the problem of oxide film formation on magnesium that is impermeable for Mg2+ ions. Searching for the material for positive electrode providing high energy MIB remains a problem. A number of the compounds investigated in magnesium electrolytes as electrode materials for MIB are shown in the review. One can judge the readiness of MIB to substitute LIB by achieved electrochemical characteristics of the investigated Mg-accumulator systems. The progress of MIB based on Chevrel phases (Мо6S8) is associated with long reversible cycling (2000-3000 cycles), low discharge capacity (Q = 100 mA h g-1) and voltage (E = 1.1-1.2 V) which are, nevertheless, not adequate to those of commercial LIB (Q = 140 mA h g-1, E = 3.7 V). Oxides with high degree of the oxidation, such as MnO2 and V2O5, seem to be the most promising; MnO2 is described in this review in detail. Their high start capacity (270-310 mA h g-1) rapidly decreases in the course of the first 10-20 cycles. The choice of hybrid magnesium-lithium-ion battery attracts attention by the possibility to realize long stable cycling; but the cost of the required membrane is high and the technical complication of the system is a lack. A number of problems should be solved to provide MIB era, but the prognosis is optimistic.

71-78

Authors: V. Korovin, Yu. Shestak, A. Valyaev

The paper deals with the measurement of fractal dimension for the acrylonitrile - divinyl benzene copolymer prepared with alkylate petrol and CCl4 pore formers, copolymer carbonizate and SCAN carbonaceous sorbent based on the mercury porosimetry results and using fractal analysis. It is found that copolymer has meso- and macroporous structure, which parameters have been determined by synthesis conditions. The pore space surface and volume of the copolymer have a multi-fractal structure. The number of pore radius ranges, for which the self-similarity of the pore space surface and volume is maintained, is from 1 to 4. Fractal dimension change within the range of 2.03±0.002 to 3.04±0.11 for the surface and within the range of 1.95±0.13 to 2.99±0.002 for the volume of pore space. It is shown that 33.05 to 90.21% of the surface and 6.38 to 87.84% of the volume for pore space have fractal properties depending upon copolymer synthesis conditions. The changes of fractal properties in the course of copolymer carbonization and activation are defined. Multi-fractal structures are formed in the pore space surface and in the volume of carbonizate and carbonaceous sorbent. An increase of the pore radius ranges, where self-similarity is maintained, is also observed.

86-91

Authors: T.V. Tsebrienko, N.V. Yarova, T.T. Alekseeva

We studied the thermophysical properties of the organic-inorganic interpenetrating polymer networks (OI IPNs) based on the cross-linked polyurethane (PU), poly (hydroxy ethyl methacrylate) (PHEMA) and poly (titanium oxide) (–TiO2–)n obtained by sol-gel method in the presence of poly (oxypropylene glycol) (POPG) at various molar ratio of titanium isopropoxide (Ti(OPri)4) to water. The samples of OI IPNs with different content of poly (titanium oxide) were synthesized. It was shown that the variation of the content of inorganic component affects their formation. The obtained OI IPNs were stated to be two-phase systems which consist of phases with almost pure components and the interfacial region (IFR). The mass fractions of polymers in the separated phases have been calculated using Fox equation. The part of the interfacial region in the studied samples (a relative value) has been calculated by Frid equation. When the molar ratio Ti(OPri)4/H2O at the formation of poly (titanium oxide) is equal to 1/1, the value of IFR increases with the growth of the quantity of inorganic component in OI IPNs, the forced compatibility of the system being retained.