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

3-10

Authors: R. Apostolova, E. Shembel, B. Markovsky, D. Aurbach

Thin-layer Со9S8 electrodes were synthesized via the electrolysis technique onto aluminum foil and tested in redox reactions with lithium in polymer and liquid electrolytes. It was established the difference between the discharge characteristics of the Co9S8-electrode in the polymer electrolyte with a gel-like consistency and in solid film electrolyte. The starting discharge capacity of Со9S8 both in a gel-like electrolyte and in a liquid electrolyte may reach 600 mAh/g, which exceeds its theoretical value (544 mAh/g). The reversible capacity of Со9S8/Li in the polymer electrolyte is about 280–250 mAh/g at the average discharge voltage of 1.40–1.45 V. During a long cycling, the discharge capacity of Co9S8 decreases both in the polymer electrolyte and in the liquid electrolyte. The discharge capacity of a metal-sulfide material/Li system in the polymer electrolyte is mainly reduced due to an increase in the polarization resistance of the lithium electrode caused by the disruption of its contact with the polymer electrolyte and a drying of the electrolyte in the porous space of the polymer gel matrix. The irreversible capacity of Со9S8/Li can be reduced under the influence of an anionic polyelectrolyte (sodium polyacrylate) that was used as an additive to the electrolyte for the synthesis of Со9S8. Norit conductive filler added to the electrolyte for the synthesis of Со9S8 was tested to improve the electrochemical characteristics of Co9S8. A positive effect of Norit may be associated with the stabilization of the reversible capacity of Со9S8 electrodes that reaches 400 mAh/g.

18-23

Authors: D.S. Katruk, V.Ye. Levytskyi, A.S. Masyuk, B.I. Kulish, Yu.Ya. Melnyk

The influence of polymer modifier of polyvinyl chloride on the structuring process of unsaturated polyester resins in the presence of dibutyl phthalate was investigated. The results of viscometric study of modified polyester materials showed that the introduction of polyvinyl chloride into the polyester composition accelerates an increase in the viscosity of the studied systems. It was established that the modification of unsaturated polyester resin by polyvinyl chloride in the presence of a plasticizer, particularly dibutyl phthalate, is accompanied by the following physicochemical processes: swelling and partial dissolution of polyvinyl chloride in styrene solution of polyester and plasticizer, diffusion of system components, and sedimentation of polymer macromolecules. The passage of these processes is determined by the nature of intermolecular and interfacial interactions between all components. The effect of polymer modifier of polyvinyl chloride on the morphology and nature of intermolecular interactions in polyester compositions was established. Polyester materials modified by polyvinyl chloride exhibited the changes in the intensities of the absorption bands and their shifts in the spectra, which was obviously due to both the influence of the polymer modifier on the process of polyesters structuring and the occurrence of hydrophobic interactions between the polyester matrix and the macromolecules of polyvinyl chloride. The influence of the nature of metal-containing silicate fillers on the kinetic and thermometric patterns of curing of composites based on modified polyester oligomers was investigated.

30-35

Authors: E.E. Kostenko, E.N. Butenko, M.A. Bondarenko

This work was devoted to the study of the complexation of Pb(II), Hg(II) and Cd(II) with ethyl maltol (EtMal). Formation of complexes with the following ratio of components M:EtMal=1:1 was established by the method of equilibrium shift using metallochromic indicators. The concentration of ligand (EtMal) was used as a criterion for assessing the relative stability of the complexes of lead(II), mercury(II) and cadmium(II) with ethyl maltol, which is necessary to reduce the output color of the solution of the indicator complex by half, that is to create a certain equilibrium concentration of free metal ions in the system. This value was determined by studying the equilibrium in comparison systems Cdxylenol orange–C2O42–; Pbsulfonazo III–C2O42– and Hgsulfonazo ІІІ–CH3COO–, since there are reference data on the stability of oxalate complexes of cadmium and lead as well as acetate complexes of mercury. The conditional stability constants of the complexes were established as follows: lgPb(EtMal)=5.870.28, lgHg(EtMal)=5.750.13 and lgCd(EtMal)=5.000.18. It was found that the stability of complexes of Pb(II) and Cd(II) with EtMal is higher than with Mal. This means that the introduction of an ethyl radical into the maltol molecule promotes the formation of complex compounds. It was shown that the stability of the complexes of Pb(II) and Hg(II) with EtMal is higher than that of the Cd(II) complex. The information obtained can be used to develop new spectrophotometric methods for the determination of ethyl maltol in different food and cosmetic products as well as metal ions which form complexes with EtMal.

46-52

Authors: O.B. Mykhalichko, V.M. Mykhalichko, A.O. Fedorchuk, M.F. Fedyna

Crystal structures of the following ternary compounds were studied by X-ray powder method: NdCu5Ga6 (DRON-4.0 diffractometer, FeK-radiation, structure type (ST) BaCd11, Pearson symbol (PS) tI48, space group (SG) I41/amd, a=10.298(2) Å, c=6.625(2) Å, RB=0.0478, Rp=0.0454, 2=2.89), GdCu6.87Ga4.13 (DRON-4.0 diffractometer, FeK-radiation, ST BaCd11, PS tI48, SG I41/amd, a=10.2687(15) Å, c =6.60034(10) Å, RB=0.0414, Rp=0.0274, 2=1.86); and YbCu4.75Ga6.25 (STOE STADI P diffractometer, CuK1-radiation, ST BaCd11, PS tI48, SG I41/amd, a=10.3088(11) Å, c=6.6136(8) Å, RB=0.03854, Rp=0.0348, 2=3.46). The crystal structure of R(Cu,Ga)11 compounds is closely related to SmCu6.2Ga4.8 structure type according to the nearest coordination environment around the least electronegative atoms. The both structure types are realized at 8.33 at.% of R in the ternary systems R–Cu–Ga. The crystal structure of investigated compounds can be deduced from the structure of binary (RCu6, RGa6) and ternary (R2(Cu,Ga)17, R(Cu,Ga)12) phases. All structure types involve polyhedron in the form of a hexagonal prism with different number of additional atoms. The nearest coordination environment around R atoms transforms into the hexagonal antiprism with ten additional atoms in the structure of R(Cu,Ga)11 compounds.

63-67

Authors: O.P. Perepelytsya, V.M. Ischenko, T.V. Petrenko, V.І. Maksin, T.I. Ushchapivska

In this study, X-ray amorphous double molybdates of rare earth elements and methylammonium CH3NH3R(MoO4)2H2O (where R=Ce–Lu) were synthesized in aqueous solutions of rare earth elements salts and methylammonium chloride under the excess of methylammonium molybdate at the temperature of 20–250C. It was established that these substances have a stoichiometric composition with the following formula CH3NH3R(MoO4)2H2O. The study demonstrated that the compounds CH3NH3R(MoO4)2H2O (R=La–Y) belong to -TlYb(MoO4)2H2O structural type with distorted monoclinic structure of a layered rhombic KY(MoO4)2. According to the obtained data, the synthesized substances are X-ray amorphous with particle size less than 100 nm; therefore, they may be used in catalytic processes without additional grinding. We showed the possibility of deposition of double molybdates of rare earth elements and methylammonium on the carriers containing hydroxyl groups or oxygen-containing anions (such as hydroxides of aluminum, iron (III) or cobalt (II), silica gel and natural clays). It was stated that the prepared compounds may be used as components in catalysts of oxidative dehydrogenation of alkanes and alcohols. The products of thermal decomposition of CH3NH3R(MoO4)2H2O in a vacuum, protective or hydrogen atmosphere at the temperatures of up to 4500C can be used as catalysts for fuel cell anodes due to the lower degrees of molybdenum oxidation.

73-80

Authors: N.V. Polish, N.G. Marintsova, A.I. Karkhut, L.R. Zhurakhivska, R.T. Konechna, O.Y. Voskoboynik, S.I. Kovalenko, V.P. Novikov

This work describes the synthesis and a convenient method for obtaining new 1,2,4-triazine- and 1,2,4-triazole-containing 1,4-naphthoquinone derivatives. The studied 1,5-binucleophiles react with 1,4-naphthoquinone via only one nucleophilic center of the molecule, the aniline fragment. 2-(2-(6-aryl-5-oxo-2,5-dihydro-1,2,4-triazin-3-yl)phenyl) amino) naphthalene-1,4-dione and 2-((2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl) amino) naphthalene-1,4-diones were prepared by bonding of an amino group to the electron-deficient double bond of 1,4-naphthoquinone followed by oxidation of formed 1,4-diol with an excess of 1,4-naphthoquinone. The biological activity of the synthesized 1,2,4-triazine- and 1,2,4-triazole-containing 1,4-naphthoquinone derivatives was evaluated by using PASS Online and Gusar software. High anticancer and antimicrobial activity and low toxicity of the obtained substances were predicted, which allows considering this class of organic compounds as a promising one in terms of preparation of new drugs. 1,2,4-Triazole-containing naphthoquinone derivatives are likely to be histidine kinase inhibitors and may be promising antimicrobials. The conducted primary screening of biological activity and toxicity of the synthesized compounds testified to high expediency of further experimental studies of anticancer and antimicrobial activity in order to find new effective drug substances.

88-97

Authors: A.V. Slyuzar, Ya.A. Kalymon

The changes in the redox properties of the quinhydrone solutions at different concentrations and ratios of quinhydrone, Na2CO3, and Na2S2O3 during their exposure to free air were investigated by cyclic voltammetry method. It was found that the potential of platinum in the quinhydrone solutions at the concentration of 5 g dm3 (0.023 mol dm3) increased with an increase in the molar ratios of sodium carbonate to quinhydrone from 0.25:1 to 5:1 and sodium thiosulfate to quinhydrone from 0.4:1 to 40:1, whereas the potential of platinum decreased with increasing the exposure time. The cyclic voltammetry curves showed the currents peaks of the oxidation and reduction of the oligomerization products of quinhydrone. During the exposure of carbonate solutions of quinhydrone (5 g/dm3), a decrease of the current of the oxidation peaks was observed and a complete attenuation of the oxidation processes was detected by 5th day of the exposure. However, the oxidation currents were still quite high for 5 days of the exposure in the solutions with higher concentrations of quinhydrone (10–30 g dm3). Due to a high activity of oligomerized products, the formation of sulfosubstituted quinone compounds occurred in the initial stages of the exposure of carbonate-thiosulfate solutions of quinhydrone.

104-111

Authors: L.M. Yashchenko, N.V. Iarova, L.О. Voronzova, O.O. Brovko

Physical-mechanical properties of biocomposites based on epoxy urethane binders were studied as a function of the ratio of components (polyisocyanate, epoxy resin ED-20 and sodium silicate) and the amount of a filler (hemp wood core) before and after the action of some destructive factors. It was shown that the mechanical properties of the prepared biocomposites were determined by the polymer–filler interaction. The balance and distribution of physical intermolecular bonds between the components of the system play an important role too. It was established that a significant difference in the parameters of physical and mechanical properties of biocomposites with different ratios of epoxy urethane binder components was due to different thermodynamic affinity of the binder to the hemp wood core surface. The study of the effect of the amount of a filler on the physical and mechanical properties of biocomposites showed that an increase in the concentration of hemp wood core from 60 parts by weight up to 80 parts by weight reduced the flexural strength from 30.1 MPa to 25.6 MPa, respectively. This was due to the insufficient amount of binder to wet the entire surface of the filler, and, therefore, resulted in the formation of defects in the composite. With the introduction of 60 parts by weight into the epoxy urethane matrix, the tensile strength increased to 13.9 MPa as compared with 0.3 MPa for the unfilled composite. This was the result of the intermolecular interaction change in the filled biocomposite due to appearance of polymer–filler interaction, which had a positive effect on the cohesion energy of the polymer matrix. With increasing filler content in the composite to 80 parts by weight, its tensile strength decreased slightly. It was shown that the biocomposites retained good and stable physical and mechanical properties under environmental conditions under the action of some destructive factors. However, there was a significant decrease in the tensile and flexural strengths of the samples exposed to water and ground, which indicated their biodegradability.