Effect of nitrogen oxides NOx on gas-phase oxidation of methane by oxygen

We propose a kinetic model for gas-phase oxidation of methane by oxygen in the presence of nitrogen oxides NOx. The model calculations agree satisfactorily with experimental kinetic data provided in the literature. We consider the basic principles for the effect of nitrogen oxides on the rate of the process and the selectivity with respect to methanol and formaldehyde. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 2, pp. 113–118, March–April, 2006.     

Synthesis of organic phosphines and phosphine oxides from elemental phosphorus and phosphine in the presence of strong bases

Data on the reactions of elemental phosphorus and phosphine with electrophilic reagents are described systematically and analyzed. These reactions occur in the presence of strong bases and yield primary, secondary, and tertiary phosphines and phosphine oxides. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1695–1702, September, 1998.     

Influence of aluminium precursor on physico-chemical properties of aluminium hydroxides and oxides

An attempt to obtain aluminium hydroxide that could give aluminium oxides of increased thermal stability was made. Aluminium hydroxide was precipitated during a hydrolysis of aluminium chloride in ammonia medium. The influence of preparative conditions, such as a dosing rate of aluminium precursor, pH, duration of the precipitate refluxing and temperature of calcination, on the properties of obtained hydroxides and oxides was investigated. The materials were studied with the following methods: thermal analysis, IR spectroscopy, low-temperature nitrogen adsorption and adsorption–desorption of benzene vapours. Precipitated boehmites had high values of S _BET determined from nitrogen adsorption (220–300 m²g^–1), good sorption capacity for benzene vapours, developed mesoporous structure and hydrophilic character. It has been proved that a high pH value during the precipitation of aluminium hydroxide favoured better crystallisation of boehmite structure, higher temperature of its dehydroxylation into γ-Al₂O₃, and delayed transformation of γ phase into α-Al₂O₃. Aluminium oxides derived from the hydroxides precipitated at a high pH were the most stable at high temperatures, and were characterised with the best surface properties. The online version of the original article can be found at     

Absolute rate constants of decay of aryl-substituted carbonyl oxides

The decay kinetics of a series of carbonyl oxides (CbO)—4-methylbenzophenone oxide, 2,5-dimethylbenzophenone oxide, 4-chlorobenzophenone oxide, 2-bromobenzophenone oxide, and acetophenone oxide—were studied by the pulse photolysis technique in acetonitrile, benzene,n-decane, andn-pentane. The absorption spectra were studied, and the absorption coefficients and absolute rate constants of CbO decay were determined. The absorption maxima observed in the spectra of carbonyl oxides range within 405±25 nm. The decay rate constant was found to depend on both the CbO structure and the medium. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 677–681, April, 1999.     

Electrochemical reactions of La(Ni,Cr)O3 and La(Ni,Fe)O3 in acidic aqueous solutions

Voltammetry of immobilised microcrystalline perovskites La(Ni,Cr)O₃ and La(Ni,Fe)O₃ revealed that these oxides yield three types of reactions in acidic aqueous solutions (0.1 M HClO₄): irreversible oxidative dissolution of Cr-rich oxides, irreversible reductive dissolution of Fe-rich oxides, and a quasi-reversible reaction most likely related to alteration of the valencies of Cr, Fe and/or Ni in the solid state. The samples of La(Cr_{1− x} Ni _x )O₃ with x = 0.3 and 0.5 especially showed limited cycling stability that is particularly surprising in the very strongly acidic solution. Received: 4 January 1999 / Accepted: 16 February 1999     

Formation of high-spin complexes in reactions of oxides of the γ-Al2O3 type with radical pairs of sterically shielded semiquinones: A new procedure for the preparation of organometallic polyradicals and their ESR spectra

A new simple method was developed for the preparation of organometallic bi- and triradicals by the heterogeneous reaction of γ-Al₂O₃ or analogous oxides with free radicals generated in solution through the interaction of 3,6-di-tert-butyl-o-benzoquinone with 3,6-di-tert-butylpyrocatechol. An explanation was offered for the plus sign of the dipoledipole coupling constant observed previously in the ESR spectra recorded in a superstrong field at low temperatures. Deceased. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 298–302, February, 1997.     

Synthesis and properties of nanosized tin-zinc composite oxides as lithium storage materials

After preparing the precursor by a liquid precipitation method, a series of tin-zinc composite oxides with different components and structures were synthesized as the anode materials for lithium ion batteries when the precursor was pyrolyzed at different temperatures. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical measurements. The reversible capacity of amorphous ZnSnO₃ is 844 mA · h/g in the first cycle and the charge capacity is 695 mA · h/g in the tenth cycle. The reversible capacity of ZnO · SnO₂ is 845 mA · h/g in the first cycle and the charge capacity is 508 mA · h/g in the tenth cycle. The reversible capacity of SnO₂ · Zn₂SnO₄ is 758 mA · h/g in the first cycle and the charge capacity is 455 mA · h/g in the tenth cycle. Results show that amorphous ZnSnO₃ exhibits the best electrochemical property among all of the tin-zinc composite oxides. With the formation of crystallites in the samples, the electrochemical property of the tin-zinc composite oxides decreases. Translated from Chem J Chin Univ, 2006, 27(12): 2252–2255 [译自: 高等学校化学学报]     

Effect of the ZnNi y Mn2– y O4 (0 ≤ y ≤ 1) spinel composition on electrochemical lithium insertion

The electrochemical insertion of lithium in the spinel-type manganite with the formula ZnNi _y Mn_{2– y} O₄ has been studied. The galvanostatic discharge curves show that the best performance is obtained for y = 0.25, where a tetragonal to cubic structural transformation occurs. The thermodynamics and kinetics of the process of insertion of the lithium into the tetragonal spinel Li _x ZnNi_0.25Mn_1.75O₄ (x = 0.05–1.3) have been studied. The molar thermodynamic quantities, such as enthalpy, entropy and free energy determined by EMF-T measurements, varied with the lithium concentration in the oxide structure, and a major variation was observed around x = 0.8. The chemical diffusion coefficient of lithium in these spinels was also determined. Structural analysis, degree of oxidation and magnetic susceptibility measurements were carried out for the lithiated oxides in order to obtain the cationic distribution as a function of x. It has been possible to demonstrate that, upon lithium insertion, Mn⁴⁺ ions on B sites are reduced to Mn³⁺ and then to Mn²⁺. A cooperative Jahn-Teller effect is present in these spinel manganese-nickel oxides. Received: 4 February 1997 / Accepted: 11 April 1997     

Phenomenological kinetics of irreversible electrochemical dissolution of metal-oxide microparticles

The electrochemical dissolution of metal oxides and other stable solid phases composed of nano- to micro-crystalline particles is generally a complex process. It can be simplified by distinguishing two main contributions to the reactivity of the solid: the potential-dependent rate coefficient k(E), and the conversion-dependent function f(y). These contributions can be evaluated by a combination of potentiostatic and potentiodynamic experiments. Both k(E) and f(y) were obtained experimentally for the dissolution of iron and chromium oxides, and theoretical consequences of their particular forms are discussed. A peak-shaped function k(E) was observed in the case of γ-Fe₂O₃, whereas, for α-Cr₂O₃ and CrO₂, a different model based on intermediate surface complexes is proposed. This model also explains the complete electrochemical dissolution of metal oxides regardless of their low intrinsic electric conductivity. Received: 2 July 1997 / Accepted: 3 November 1997     

Conversion of nitrogen(I,II) oxides on nanodispersed [Pt(Pd)-Au]/HY zeolite catalysts

We have shown that conversion of nitrogen(I,II) oxides in reduction by carbon monoxide and light C₁, C₃–C₄ alkanes in the presence of nanodispersed [Pt(Pd)-Au]/HY catalysts is determined by the reagent activation routes in an oxidizing/reducing atmosphere. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 156–161, May–June, 2006.     

Two-fragment α-adrenolytics

A method for the synthesis of hypotensive alkyl(phenyl)[ω-(N-phenylpiperazino)alkyl]-phosphine oxides by reacting alkyl(ω-haloalkyl)phenylphosphine oxides withN-phenylpiperazine was elaborated. Phenyl[γ-(N-phenylpiperazino)propyl]propylphosphine oxide reacts with alkyl halides to give [γ-(N-alkyl-N′-phenylpiperazinio)propyl]phenyl(propyl)oxophosphine halides. For Part 1 see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 488–492, March, 2000.     

Formation of stable carbonyl oxide by photooxidation of (phenyl)(2-thienyl)diazomethane

Formation of (phenyl)(2-thienyl)carbonyl oxide, which has the longest lifetime among known carbonyl oxides, has been registered by flash photolysis in acetonitrile at room temperature. It is consumed in the pseudomonomolecular reaction with the parent diazo compound. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 666–668, March, 2008.     

Influence of aluminium precursor on physico-chemical properties of aluminium hydroxides and oxides Part II. Al(ClO4)3·9H2O

Aluminium hydroxide was precipitated during a hydrolysis of aluminium perchlorate in ammonia medium. The materials were studied with the following methods: thermal analysis, IR spectroscopy, X-ray diffraction, low-temperature nitrogen adsorption and adsorption–desorption of benzene vapours. Freshly precipitated boehmite had a high value of S_BET=211 m² g^–1 determined from nitrogen adsorption, good sorption capacity for benzene vapours, developed mesoporous structure and hydrophobic character. After prolonged refluxing at elevated temperature its crystallinity increased which was accompanied by an increase of specific surface determined from nitrogen adsorption up to 262m²g^–1 , decrease of sorption capacity for benzene vapours and stronger hydrophobic character. The calcinations of all boehmites at temperature up to 1200°C resulted in formation of à-Al₂O₃ via transition form of γ-, δ- and θ-Al₂O₃. The samples of aluminium oxides obtained after calcination at 550 and 900°C were characterised with high values of specific surface area of 205–220 and 138–153 m² g^–1 , respectively. The SBET values calculated for the oxide samples derived from aged hydroxides and calcined at 1200°C are higher than for the analogous sample prepared without the ageing step. It was concluded that the process of ageing at elevated temperature developed thermal stability of aluminium oxides.     

Oxidation of fullerene C<Subscript>60</Subscript> with the system aluminum tri-<Emphasis Type="Italic">tert</Emphasis>-butoxide—<Emphasis Type="Italic">tert</Emphasis>-butyl hydroperoxide

Oxidation of fullerene C₆₀ with the system aluminum tri-tert-butoxide-tert-butyl hydroperoxide, in which electron-excited dioxygen is generated, gave a complex mixture of fullerene oxides C₆₀O _x (x = 1–6). The pathways of their formation were proposed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 296–300, February, 2008.     

one-pot synthesis of pyrrolo-[3,4-d]isoxazoline-4,6-diones via nitrile oxides

1,3-Dipolar cycloaddition of nitrile oxides generated in situ in the presence of variously substituted N-arylmaleimides and N-benzylmaleimide provides new pyrrolo[3,4-d]izoxazoline-4,6-diones in good yields. The whole procedure could be performed in a practical and efficient one-pot operation. All the cycloadducts were isolated in excellent yields and identified by spectral studies. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 444–448, March, 2009.     

The hierarchy of localization basins: a tool for the understanding of chemical bonding exemplified by the analysis of the VOx and VOx+ (x=1–4) systems

The hierarchy of the electron localization basins is a powerful tool of analysis of the bonding in molecules and solids within the “elfological” framework. It is a generalization of the molecular isodensity contour analysis originally proposed by Mezey. In this approach the basins are ordered with respect to the electron localization function values at the critical points which determine the reduction of the reducible localization domains. The procedure enabling the corresponding tree diagrams to be built is described and it is shown how the method can be used as a generator of mathematical definitions of chemical concepts. The possibility offered by this simple tool is illustrated by a study of the VO _x and VO _x ⁺ (x=1–4) oxides in their ground state and in some excited states. Received: 20 July 2000 / Accepted: 20 October 2000 / Published online: 23 January 2001     

Thermolysis of furoxans annulated with five-membered carbocycles in the presence of dipolarophiles

The conditions for the thermolysis of furoxans annulated with differently strained five-membered carbocycles (cyclopentafuroxan 1, norbornenofuroxan 2, and acenaphthofuroxan 3) to bis(nitrile oxides) in the presence of various dipolarophiles (diethyl acetylenedicarboxylate, benzoylformonitrile, and ethoxycarbonylformonitrile) were optimized. It was found that the reactivities of the above furoxans as sources of bis(nitrile oxides) decrease in the order 2 > 1 > 3. Among the furoxans studied, only norbornenofuroxan 2 can be recommended as a possible cross-linking reagent for polymers. The formation of di-N-oxides of 3,4-bis(cyanopropyl)-, 3,4-bis(cyanocyclopentyl)-, and 3,4-bis(cyanonaphthyl)furoxans was detected. They resulted from intermolecular cyclodimerization of bis(nitrile oxides) initially formed in the thermolysis of furoxans 1–3. Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1521–1528, August, 2007.     

Reduction of nitrogen oxides with ammonia over complex vanadium and chromium oxides

Catalytic properties of -Al₂O₃ -supported complex vanadium and chromium oxides V_2–x Cr _x O_5– (0 < × s 1.3), amorphous to X-rays, in the reduction of nitrogen oxides with ammonia were studied. Vanadium exists in these catalysts mostly in a pentavalent state and chromium exists as Cr³⁺ and Cr⁶⁺. As the content of chromium in the catalysts increases, the optimal temperature of the process decreases, and the degree of conversion of nitrogen oxides increases.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 339–342, February, 1996.     

Application of mechanochemical activation for synthesis of uranium–lanthanoid mixed oxides

The applicability of mechanochemistry to produce uranium–lanthanoid mixed oxides is presented. Phase homogeneous uranium–cerium solid solutions of the type Ce _x U_1−x O₂ (x = 0.3 ÷ 0.95) and polyphase systems containing La _y U_1−y O_2+x (y = 0.12) were prepared by mechanochemical activation in air of sol–gel produced precursors. The possibility for synthesis of urania–lanthania solid solution by mechanochemical interaction of La₂O₃ with sol–gel produced U (IV,VI) oxide is established. The crystal structures of the obtained oxides before and after the mechanochemical treatment are analysed by the use of X-ray diffraction method. The size of the crystallites (8–16 nm), lattice parameters, crystallite strains and densities of the oxides are calculated by BRASS program for Rietveld calculation.     

Polyalkoxybenzenes from plant sources 2. Synthesis of isoxazoline analogs of combretastatin from natural allyl(methylenedioxy)methoxybenzenes

A series of analogs of the natural mitostatic agent combretastatin were synthesized by the reaction of nitrile oxides with natural allylbenzenes, such as myristicin, apiol, and dillapiol. The 1,3-dipolar cycloaddition reactions in allylic systems proceed regiospecifically. The reactions with trans isomers of propenylbenzenes, viz., isomyristicin, isoapiol, and isodillapiol, as dipolarophiles produce regioisomers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2375–2380, December, 2007.