Reaction mechanism in hydrogenolysis of chlorobenzene over nickel-chromium catalyst

The reaction mechanism in the hydrogenolysis of chlorobenzene over nickel-chromium catalyst has been investigated. It is concluded that the process takes place on the catalyst surface, through dissociatively adsorbed chlorobenzene and hydrogen. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospect Nauki, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 5, pp. 306–309, September–October, 1998.     

Interparticle diffusion of aromatic hydrocarbons on aerosil surface

It has been demonstrated by the photobleaching method that the photostability of pyrene molecules on the surface of pyrogenic nonporous SiO₂ (aerosil) is independent of the surface concentration of the fluophor. Through a kinetic analysis of the recovery of fluorescence of the luminophore and solution of the two-dimensional diffusion equation, coefficients of interparticle diffusion were estimated for the molecules of pyrene and N,N-dimethylaniline. Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 31 Nauki Prospect, Kiev, Ukraine 252039. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 1, pp. 23–26, January–February, 1998.     

Photocatalysis of reaction of hydrogen production by cadmium and zinc sulfide nanoparticles incorporated into silicate matrices

Novel nanostructural materials have been prepared, their diffuse reflection spectra have been studied, and their electrophysical characteristics (width of forbidden band, position of conduction band) have been evaluated. It has been established that these materials have high photocatalytic activity, and the factors influencing this activity have been examined. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, 252039 Kiev, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 32–35, January–February, 1997.     

Kinetic and mechanistic features of carbon monoxide hydrogenation over supported transition metals

Data on the kinetics and mechanism of carbon monoxide hydrogenation to form alkanes, alkenes, and alcohols over supported transition metals are summarized and correlated. The observed kinetics of the overall carbon monoxide conversion can be interpreted on the basis of a mechanism that includes equilibrium adsorption of CO in the molecular form and equilibrium dissociative adsorption of hydrogen. Detailed mechanistic schemes and the corresponding kinetic models are presented for the reactions of formation of alkanes, alkanes, and alcohols. Catalytic activity and selectivity are examined in relation to the adsorptive and physicochemical properties of the catalysts. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 33, No. 5, pp. 291–305, September–October, 1997.     

Third-order nonlinear optical response of a new polymeric material based on epoxides containing a nickel(II) complex

A novel polymeric material having nonlinear optical properties has been prepared from the diglycidyl ether of bisphenol A and a macrocyclic complex of nickel(II). It has been shown that relatively high levels of third-order nonlinear susceptibility of polymers can be obtained without the use of highly conjugated systems. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 165–169, May–June, 1997.     

Influence of alkali metal salts on the processes of activation and oxidation of carbonaceous sorbents

It has been established that the preliminary introduction of alkali metal salts (specifically, K₂CO₃) onto the surface of activated fruit-pit charcoal tends to improve certain structural-sorption characteristics of the activated samples that are obtained, so that the carbonaceous material can be oxidized up to the required level of parameters within a short time at temperatures considerably lower than usual; i.e., the oxidation temperature can be lowered by some 120–150°C. Institute of Sorption and Problems of Endoecology, Ukrainian National Academy of Sciences, 32/34 Academician Palladin Prospect, Kiev-142 252680, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 4, pp. 257–261, July–August, 1998.     

Formation of ternary excited donor-acceptor complexes in systems containing benzophenone and an amine

On the basis of data on the influence of butyl methacrylate on the primary processes of photoreduction of benzophenone by triethylamine, an analysis has been made of the concept that ternary exciplexes (donor + acceptor + unsaturated compound) participate in electron phototransfer processes. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, 109–112, March–April, 1998.     

Influence of reactant structure on composition and stability of adducts of bis-macrocyclic complexes of copper(II) with aliphatic α,ω-diamines

On the basis of spectrophotometric measurements, constants have been determined for adduct formation between bis-macrocyclic complexes of copper(II) and aliphatic diamines. For these systems, the influence of reactant structure on the specific features of complexation has been established. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 2, pp. 83–87, March–April, 1997.     

Photochemical and photocatalytic properties of zeolites containing titanium(iv) complexes and metallic palladium

An attempt has been made to create organized, highly efficient photocatalytic systems in the example of composite materials consisting of blocks of a metallocomplex photocatalyst and a dark-stage catalyst, assembled on a zeolite matrix. The spectral and photochemical properties of these systems have been investigated, and also their use in catalysis of hydrogen evolution from alcohol-water media. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 103–108, March–April, 1998.     

The C−C bond chain termination mechanism in Fischer-Tropsch synthesis on a Co/SiO2·Zr(IV) catalyst

Two forms of chain termination are considered: on account of hydrogenation of metal-carbon bonds in surface intermediates and because of the elimination of hydrogen, which leads to the formation of α-olefins as primary products. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 35, No. 1, pp. 44–49, January–February, 1999.     

α-Effect of hydroxylamine in the transfer of a toluenesulfonyl group in water—Dimethyl sulfoxide mixtures

A kinetic and thermodynamic analysis of the reactions of hydroxylamine with aryltoluenesulfonates in H₂O-DMSO mixtures (0–90 vol.% DMSO) indicated that the neutral and anionic forms of hydroxylamine are strong α-nucleophiles, and the magnitude of the α-effect shows an asymmetric bell shape depending on the DMSO content. This phenomenon is interpreted. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 2, pp. 83–88, March–April, 1999.     

Influence of hydrothermal treatment conditions on the formation and breakdown of phosphates with zeolitic structure

In a study of certain features of the formation and breakdown of phosphates with zeolitic structure, manifested when the reaction mixtures and detemplated products are subjected to various schedules of heating, cooling, and holding at constant temperature, it has been shown that these features are related to a change in coordination state of the aluminum atoms in the presence of water molecules and to the transition of the aluminum atoms into an octahedral environment, with subsequent hydrolysis and breakdown. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 170–174, May–June, 1997.     

Influence of polarity of medium on formation of intermediates in photolysis of alkylaminobenzophenones in solutions

Flash photolysis has been used in a study of the absorption spectra and decay kinetics of the intermediates in photolysis of 4,4′-bis-dimethylaminobenzophenone, 4,4′-bis-diethylaminobenzophenone, and 4-dimethylamino-benzophenone in various types of solvents. It has been established that flash photolysis of solutions of alkylaminobenzophenones in polar solvents produces not only alkylamine or ketyl radicals, but also an intermediate that absorbs in the 470 nm region, the decay curves of which are described by first-order kinetic equations. In the presence of tertiary amines, the yield of this product is lower. The addition of sodium perchlorate to the solution increases the lifetime of this intermediate species. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, 252039 Kiev, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 27–31, January–February, 1997.     

Mechanism of reactions of photocatalytic synthesis of chlorohydrins

A mechanism of photocatalytic synthesis of chlorohydrins from olefins and peroxo complexes of titanium (IV) is proposed. It consists of formation of radical-containing complexes, their reactions with olefins, and decomposition of the α-oxides obtained by hydrogen chlorides. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prosp. Nauki, 252039 Kiev, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 17–21, January–February, 1997.     

Effect of titanium on the structure and properties of mesoporous MCM-41 molecular sieves

Mesoporous MSM-41 titanium silicate molecular sieves with high titanium content were synthesized. The hexagonal structure along with high specific surface and pore volume are retained up to Si/Ti≥5. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 3, pp. 177–182, May–June, 1999.     

Mechanisms of the coupling of one-and two-electron reactions in chemical and biochemical processes

The mechanisms of chemical and biochemical reactions in which one-electron stages ae coupled with two-electron stages are examined. The mechanisms of the coupling of the one- and two-electron stages in the electron-transport systems of the living cell are discussed on the basis of an analysis of chemical models. Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, 1 Murmanskaya ul., Kiev 253094, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 3, pp. 133–144, May–June, 1999.     

Principal relationships of the heterogeneous catalytic oxidation of benzene and its derivatives

The results of investigations into the processes involved in the heterogeneous catalytic oxidation of benzene and its derivatives at the L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, are summarized. The mechanisms of the full and partial oxidation of benzene, toluene, and their halogen derivatives are discussed. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, Kiev. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 3, pp. 133–147, May–June, 1998.     

Chemisorption of N-vinyl-2-pyrrolidone on the surface of hydridosilica gel

The solid phase hydrosilation of N-vinyl-2-pyrrolidone by≡Si−H bonds immobilized on a silica gel surface has been investigated. Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252022, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 4, pp. 236–239, May–June 1999.     

The effect of the nature and the state of the surface of highly dispersed silicon, aluminum, and titanium oxides on their sorption characteristics

The results of investigations into the surface of highly dispersed oxides and their interaction with water and certain other adsorbates by experimental (NMR, OS, LCS, TPD, etc.) and theoretical methods are reviewed. Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 03028, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 1, pp. 1–29, January–February, 2000.     

Nature and degree of distortion of TiO2 (Anatase) surface octahedra upon formation of Ti3+ ions

We show that in the transition from Ti(IV) to Ti(III), on the surface of anatase the TiO_6/3 octahedra undergo compressive tetragonal distortion. The axial Ti−O bond length in the octahedron decreases in this case by at least 0.0027 nm. Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252022, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 4, pp. 253–256, July–August, 1999.