Reaction kinetics in replacement of zinc ions by copper ions in complexes with cyclic and noncyclic tetramines

A kinetic study has been made of reactions of zinc ion replacement by copper in complexes with macrocyclic and noncyclic tetramines. The activation parameters of these processes have been determined, and reaction mechanisms are proposed. A kinetic macrocyclic effect has been found in reactions of central atom replacement in tetraazamacrocyclic complexes of zinc.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 2, pp. 175–182, March–April, 1985.     

Thermodynamic and kinetic characteristics of the adsorption of acetone on the KU-23 sulfo-cation exchanger in the absence and presence of palladium

The thermodynamic and kinetic parameters of the adsorption of acetone on the sulfo-cation exchanger KU-23 and Pd/KU-23 have been determined. It has been found that application of palladium to the sulfo-cation exchanger strengthens the bond between acetone and the surface and increases the degree of localization of the adsorbed molecules.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 1, pp. 87–91, January–February, 1986.     

Kinetics of reduction of hydroxycuprate(III) in KOH solution

The solution of an unstable copper(III) complex, hydroxycuprate(III) i.e. Cu(OH)^– ₄, has been obtained by oxidising a copper anode in 0.5–3 M KOH solution. The kinetics of the copper(III) reduction in KOH solution has been studied spectrophotometrically and is first order with respect to copper(III), and the pseudo-first order rate constant increases as the KOH concentration increases. The kinetic data is explained by a scheme according to which a Cu^III intermediate, in equilibrium with Cu(OH)^– ₄, reacts with OH^–. On the basis of the kinetic data, the molar absorptivity of the Cu(OH)^– ₄ solution has been determined.     

Electroxidation of the alkaloids anabasine,cytisine, and lupinine at a platinum electrode in acetonitrile

The anodic behavior of anabasine, cytisine, and lupinine at a platinum electrode in anhydrous acetonitrile has been investigated and the basic kinetic parameters of their oxidation have been established.Institute of Organic Synthesis and Coal Chemistry Academy of Sciences of the Kazakh SSR, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 251–253, March–April, 1991.     

pH Dependence of the kinetic parameters of nitrotyrosyl-asparaginase

Summary The kinetic parameters, K_M and k_cat of the hydrolysis of L-asparagine by nitrotyrosyl-asparaginase have been determined over a wide pH range of 4.50–8.85. It has been shown that the modification of the asparaginase leads to a marked increase in the Michaelis constant and to an insignificant change in k_cat. A hypothesis has been put forward concerning the possible participation of the hydroxy group of the tyrosine residue in the formation of the enzyme-substrate complex.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 364–367, May–June, 1978.     

Adsorption of low level51Cr(VI) from aqueous solution by bismuth trioxide: Kinetic and IR study

Radiotracer technique has been used for the investigation of adsorption of chromium (VI) traces on bismuth trioxide from aqueous solution. The effect of pH (2–10), concentration of chromate solution (10^–6–10^–2M) and temperature (303–323 K) has been thoroughly investigated. The influence of certain foreign ions has also been studied. The calculated kinetic and thermodynamic parameters indicate the first order rate law, spontaneity and exothermic nature of the adsorption process. Further, IR studies have established the chemical interaction between the sorbate and sorbent and a possible mechanism of the sorption process based on ligand exchange has been proposed.     

Solvatochromy and solvatofluorochromy of erythrosine

A study has been made of the spectral-luminescence and kinetic characteristics of erythrosine in various solvents. By means of the solvatochromic comparison technique, relationships have been established for the influence of the bulk properties and microproperties of the solvent on the luminescence and kinetic characteristics. The relative changes in the dipole moment of the erythrosine molecules upon electronic excitation have been determined.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 2, pp. 196–202, March–April, 1986.     

Investigating the kinetics of the adsorption process of polyamideamine on cellulose

The kinetic dependences have been investigated of the adsorption process of polyamideamine on monocarboxyl cellulose, bleached sulphate cellulose pulp of softwood and bleached sulphite cellulose pulp of hardwood. It has been found that the process kinetics can be described by means of the Elovich-Tyomkin exponential kinetic equation; the influence of the entropy factors plays a decisive role in changing the process speed; the activation energy is of the order of 6.5–8.0 kJ/mol.     

Some kinetic features of the hydrolysis of L-asparagine withE. coli asparaginase

The influence of various effectors (methanol, neutral salts) on the kinetic parameters K_M and k_cat has been studied. The hypothesis has been expressed that chloride ions are responsible for the worsening of the binding of the substrate to the enzyme. The temperature dependence of the kinetic parameters K_M and k_cat for the enzymatic hydrolysis of L-asparagine has been obtained. It has been shown that the graph of log k_cat versus 1/T has a break at 30°C. The effective activation energies below and above the critical point are 6.5 and 3.6 kcal/mole, respectively.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 707–709, September–October, 1979.     

Vapor-phase hydrogenation of acetone on applied metals of the platinum group

Ruthenium, rhodium, iridium, and platinum, applied on -Al₂O₃, show a high catalytic activity in the vapor-phase hydrogenation of acetone to isopropanol at 337–393K; under these conditions palladium is inactive. A reaction mechanism has been derived from kinetic measurements, adsorption and thermal desorption data, and IR spectra includes as a limiting stage the reaction of acetone adsorbed on the metal with atomic or molecular hydrogen. The kinetic and thermodynamic characteristics of the reaction have been established. The order of the specific catalytic activity of the metals has been determined, the mechanism of adsorption of alcohols on transition metals has been discussed, and the inhibition of the reaction by isopropanol adsorbed on the Ru catalyst has been interpreted.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 698–706, November–December, 1986.     

Effect of the composition and topology of the coordination polyhedron on electron transfer in d 9/d 10 redox systems

The effect of the composition and topology of the coordination sphere on the redox potentials of d⁹/d¹⁰ pairs and the kinetic parameters of electron transfer reactions involving such pairs has been reviewed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 31, No. 1, pp. 1–28, January–February, 1995.     

Kinetics of the Dissolution of Silver in Thiocarbamide Solutions

The dependence of the rate of solution of silver on the pH of the solution, the ratio of the iron(III) and thiocarbamide concentrations, and the temperature has been determined. The rate constants for the solution of silver (k _i = 2.3·10^–4 to 9.6·10^–4s^–1) at temperatures from 283-298 K have been calculated and from the temperature dependence of the rate constant the activation energies have been calculated: 68.84 kJ/mol for kinetic control of the rate of solution and 26.06 kJ/mol in the adsorption inhibition region.     

Kinetics of the thermal desorption of O2, HCl,and H2O from the surface of cobalt chromite

A study has been carried out on the kinetics of the temperature-programmed desorption of O₂, HCl, and H₂O from the surface of cobalt chromite. A mathematic model was obtained for the kinetics of the thermal desorption and a method was developed for determining the kinetic constants. The kinetic parameters of the desorption of O₂, HCl, and H₂O were calculated using these experimental data.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 5, pp. 449–455, September–October, 1993.     

Kinetics of hydrogenation of cyclododeca-3,7-diene-1-one on supported metal catalysts

The kinetics of hydrogenation of cyclododeca-3,7-diene-1-one on commercially available supported metal catalysts has been studied in ethyl alcohol solutions at 323–363 K and 0.1–2.5 MP a pressure of hydrogen. The experimental data have been related to kinetic equations of the Langmuir-Hinshelwood type. The reaction schemes which best fit the experimental data are shown.     

Influence of metal ions on the activity and stability of the glucose isomerase from Streptomyces atratus

The influence of a number of bivalent metals on the activity ofStreptomyces atratus glucose isomerase has been studied. Mg²⁺ ions are activators and Co²⁺ ions are stabilizers of the glucose isomerase activity. The effective kinetic parameters for the action of the enzyme have been determined.Institute of Microbiology, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 838–842, November–December, 1991.     

Spectroscopic kinetic characteristics of the fluorescence of anthracene sorbed on silica gel

The spectroscopic kinetic characteristics of the fluorescence of anthracene adsorbed on silica gel have been investigated. The formation of charge-transfer (CT) complexes between the anthracene molecules and acceptor sites on silica gel which had been heat-treated in a vacuum has been discovered. Along with the emission of the CT complexes, the luminescence of an excited CT complex, i.e., an exciplex, has been detected. Hypotheses regarding the nature of the electron-acceptor sites on silica gel have been advanced.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 118–123, January–February, 1985.     

Mechanism of the reaction of CO with NO on palladium catalysts

A mechanism has been proposed for the reaction of CO + NO + (O₂) on palladium catalysts and the elementary stages of the reaction have been subjected to thermodynamic analysis. A kinetic model of the reaction has been constructed. The model of the reaction CO + NO has been analyzed in comparison with the reaction CO + O₂; the existence of a multiplicity of stationary states and critical transitions in the system CO + NO has been demonstrated. Numerical calculation has explained the accelerating influence of oxygen and the inhibiting influence of CO on the rate of the reaction CO + NO, observed experimentally.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 4, pp. 484–489, July–August 1987.     

Photoreduction dehalogenation of polychlorobenzenes by ethanol

It has been demonstrated that in ethanolic solutions in the presence of oxygen the photochemical and photocatalytic consecutive dehalogenation of hexachlorobenzene to benzene can take place. The kinetic rules governing the processes have been established and the possible mechanisms discussed.Translated from Teoreticheskaya i Éxperimental'naya Khimiya, Vol. 30, No. 1, pp. 34–38, March–April, 1994.     

Influence of cation structure on decomposition of diacyl peroxides activated by chloride salts of amines

A kinetic study has been made of the interaction of benzoyl peroxide with a number of chloride salts of amines. It is shown that a change of the cation in quaternary ammonium salts does not have any significant effect on the kinetic parameters of the reaction. By means of NMR spectroscopy it has been determined that the structure of the NR₄ ⁺ cation does not change during the course of the reaction. The role of the cation in the process of activation of a diacyl peroxide by chloride salts of amines has been investigated by means of MNDO calculations.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 324–328, July–August, 1992.     

Kinetic salt effects in the reaction of permanganate ions with iodide ions in concentrated electrolyte solutions

The oxidation of iodide ion by permanganate ion has been studied in several electrolyte solutions over the concentration range (0–6M). The observed kinetic salt effect may be interpreted as arising as a result of ionsolvent interactions. This salt effect is additive for different salts. Support for these conclusions comes from an examination of the activity coefficients of species estimated from the treatment given by Pitzer. It has also been shown that the species relevant in terms of kinetic control are unassociated.