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Garist I.V.,University of Rostock | Garist I.V.,Mogilev State University of Food Technologies | Verevkin S.P.,University of Rostock | Bara J.E.,University of Alabama | And 3 more authors.
Journal of Chemical and Engineering Data | Year: 2012

Vapor pressures of 1-(n-alkyl)-benzimidazoles with chain lengths from methyl to pentyl (C 1-C 5) have been determined as a function of temperature by the transpiration method. From these data, the molar enthalpies of vaporization (Δ1 gH m) were calculated, and a linear correlation with the number of carbon atoms was found. At a given temperature, 1-n-alkylbenzimidazole vapor pressures were found to decrease with the increasing length of alkyl chain, and the fused ring system was found to lower vapor pressures and increase heats of vaporization relative to the corresponding 1-n-alkylimidazoles. © 2012 American Chemical Society.


Thornton M.,University of Missouri-St. Louis | Chickos J.,University of Missouri-St. Louis | Garist I.V.,University of Rostock | Garist I.V.,Mogilev State University of Food Technologies | And 5 more authors.
Journal of Chemical and Engineering Data | Year: 2013

The vapor pressures of several aliphatic and phenyl substituted primary amines at T/K = 298.15 are measured by transpiration studies, and their vaporization enthalpies are calculated. The results were combined with compatible literature values to evaluate both the vaporization enthalpy and vapor pressure of (d)-amphetamine by correlation gas chromatography. The results are compared to existing values either estimated or measured for racemic amphetamine. Vaporization enthalpies and vapor pressures at T/K = 298.15 of the following were measured by transpiration (kJ·mol-1, p/Pa): 1-heptanamine, (49.75 ± 0.38, 291); 1-octanamine, (55.05 ± 0.29, 108); 1-decanamine, (64.94 ± 0.32, 12); benzylamine, (54.32 ± 0.32, 88); (dl)-α-methylbenzylamine, (55.26 ± 0.33, 82); 2-phenethylamine (57.51 ± 0.35, 43). The use of several of these materials as standards resulted in a vaporization enthalpy and vapor pressure for (d)-amphetamine at T/K = 298.15 of (58.2 ± 2.7) kJ mol-1 and (38 ± 12) Pa. © 2013 American Chemical Society.


Matveichuk Y.V.,Mogilev State University of Food Technologies | Rakhman'ko E.M.,Belarusian State University
Journal of Analytical Chemistry | Year: 2016

Concentrations of zinc and cobalt in beer, mineral water, beets, cheese, potatoes, and soil are determined by potentiometry, using film Zn(NCS)4 2- and Co(NCS)4 2--selective electrodes based on higher quaternary ammonium salts. The developed electrodes enable the determination of zinc and cobalt in concentrations lower than their maximum permissible concentrations (MPCs). The procedures do not require complex or long sample preparation or expensive equipment. The results agree well with the data of atomic emission spectrometry and atomic absorption spectrometry. © 2016, Pleiades Publishing, Ltd.


Rakhman'ko E.M.,Belarusian State University | Matveichuk Y.V.,Mogilev State University of Food Technologies | Stanishevskii L.S.,Belarusian State University | Yasinetskii V.V.,Mogilev State University of Food Technologies
Journal of Analytical Chemistry | Year: 2015

It is shown that the improvement of the steric accessibility of exchange centers of higher quaternary ammonium salts by replacing three long-chain radicals (octadecyl) with three methyl radicals and the addition of a neutral carrier, p-trifluoroacetylbenzoic acid heptyl ester, significantly enhance the selectivity of an oxalate-selective electrode and lower the detection limit. An electrode reversible to oxalate ions is proposed. A procedure is developed for determining oxalate ions in green and black tea. © 2015, Pleiades Publishing, Ltd.


Emel'Yanenko V.N.,University of Rostock | Verevkin S.P.,University of Rostock | Stepurko E.N.,Mogilev State University of Food Technologies | Roganov G.N.,Mogilev State University of Food Technologies
Russian Journal of Physical Chemistry A | Year: 2011

The 11-undecanolide enthalpy of vaporization is obtained from the temperature dependence of the vapor pressure measured by transpiration. A conformational analysis of 8-octanolide (I), 11-undecanolide (II), and 13-tridecanolide (III) is performed. Quantum-chemical calculations are performed to study the moments of inertia, vibrational spectra, and most favorable conformations. The ideal gas thermodynamic properties of these compounds in the temperature range of 0-1500 K are determined. A procedure for the additive determination of polynomial coefficients for temperature-dependent properties is developed to assess the thermochemical data for lactones, lactides, and carboxylic hydroxyacids at 298.15-1000 K. © 2011 Pleiades Publishing, Ltd.


Silva V.M.T.M.,University of Porto | Pereira C.S.M.,University of Porto | Rodrigues A.E.,University of Porto | Verevkin S.P.,University of Rostock | And 4 more authors.
Industrial and Engineering Chemistry Research | Year: 2012

The chemical equilibria of acetals of acetaldehyde reactive systems (with methanol, ethanol, and n-butanol to form 1,1-dimethoxyethane, 1,1-diethoxyethane, and 1,1-dibuthoxyethane, respectively) were studied in the temperature range (293-333 K) in the liquid phase. The three reactive systems exhibit a strong nonideal behavior in the liquid phase. The knowledge of the activity coefficients is required to obtain the thermodynamic equilibrium constants K a. The activity coefficients were estimated by the modified UNIFAC method, which already includes the parameters for the acetal group. The reaction enthalpies for the three acetalizations in the liquid phase were obtained from the temperature dependences of the corresponding thermodynamic equilibrium constants. These values were compared to those obtained by high-level ab initio calculations of the reaction participants using the Gaussian 03 program package. Absolute electronic energy values of the molecules have been obtained using G3(MP2) level. Using these results, calculated equilibrium constants and enthalpies of reaction of the acetals synthesis in the liquid phase based on the principles of statistical thermodynamics are found to be in acceptable agreement with the data obtained from the thermochemical measurements. © 2012 American Chemical Society.


Matveichuk Yu.V.,Mogilev State University of Food Technologies | Rakhman'Ko E.M.,Belarussian State University | Yasinetskii V.V.,Mogilev State University of Food Technologies
Russian Journal of Inorganic Chemistry | Year: 2015

Aqueous solutions of thiocyanates of divalent cations, Cd, Hg, Ni, Mn, Fe, Zn, and Co, were studied by IR spectrometry. It was found that Cd(II), Hg(II), Ni(II), and Fe(II) coordinate NCS- in the thiocyanate mode, Zn(II) coordination is in the isothiocyanate mode, and Co(II) and Mn(II) change the mode of coordination depending on the KNCS concentration in solution. The UV and visible spectra of solutions of d-metal thiocyanates were characterized. © 2015 Pleiades Publishing, Ltd.


Malyshev V.L.,Mogilev State University of Food Technologies
Theoretical Foundations of Chemical Engineering | Year: 2015

The evaporation of the liquid from porous materials under intense heat effect has been studied. The process of the formation of the surface film has been simulated. The capillary has been considered as a system of the confusor type with a decrease in the cross section of the mouth according to the diaphragm principle. © 2015, Pleiades Publishing, Ltd.


Timoshchenko E.V.,Mogilev State University of Food Technologies | Yurevich V.A.,Mogilev State University of Food Technologies | Yurevich Y.V.,Mogilev State University of Food Technologies
Technical Physics | Year: 2013

The possibility of hysteretic behavior of resonant reflection spectral curves is determined analytically for the conditions of the dipole-dipole interaction and spectral shift of the field. The phase shift of the acting field is associated with the variation of the energy state of a dense resonant medium forming a thin boundary layer. The problem is considered for the parameters of quantum-size structures based on semiconductors used in optics. © 2013 Pleiades Publishing, Ltd.


Stepurko E.N.,Mogilev State University of Food Technologies | Marenich Yu.A.,Mogilev State University of Food Technologies | Roganov G.N.,Mogilev State University of Food Technologies
Polymer Science - Series A | Year: 2012

Conditions for increasing the accuracy and reliability of calculation of the thermodynamic properties of polymers by additive methods have been formulated; they are necessary for determining the parameters of additive methods using the experimental values of polymer properties for each component of the polymer physical modification separately with the subsequent determination of properties of real polymers according to their degree of crystallinity. An additive technique has been developed, and sets of numerical values of additive parameters have been derived for practical calculations of the values of the enthalpies of formation, the absolute entropies, and the isobaric heat capacities of a number of polymers in the range 100-600 K with an accuracy comparable to that of the experimental data. © Pleiades Publishing, Ltd., 2012.

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