Redistribution kinetics of isotope molecules due to reversible bimolecular reactions with several atomic channels

Isotope kinetic equations for reversible bimolecular reactions describe the rearrangement of atoms in activated complexes. It has been established from the model reaction CH₄+HCH₃+H₂ that the isotopic homoexchange of methane via two atomic channels is given by one set of equations with different sets of parameters.

---

- . CH₄+HCH₃+H₂ , .

     

Liquid-phase hydrogenation of cyclohexene by dihydrogen in the presence of dimolybdenum tetraacetate

Catalytic liquid-phase hydrogenation of cyclohexene in DMF by dihydrogen in the presence of dinuclear bridged complex Mo₂(OAc)₄ has been studied. A kinetic equation for the steady-state rate of cyclohexene hydrogenation and the activation parameters are suggested.

---

Mo₂(OAc)₄. .

     

Methods for finding steady-state solutions of mathematical models for chemico-technological schemes

Gradient and Newton methods are suggested for searching for steady-state solutions of chemico-technological schemes to obtain synthetic fuels.

---

- .

     

Kinetic model for methanol conversion over Mg-ZSM-5 zeolite

The catalytic conversion of methanol to olefins over ZSM-5 zeolite modified by ion exchange with Mg exhibits an autocatalytic character. On this basis an overall kinetic model of the reaction was proposed which allowed the determination of rate constants and apparent activation energy.

---

ZSM-5, Mg, . , .

     

Studies of the structure of multicomponent Raney nickel catalysts

Genesis and structure of Raney nickel catalysts modified by Mo, Fe and Ca have been studied by XPS, SIMS and Auger and electron microprobe methods. It has been established that these catalysts are inhomogeneous and their structure can be described by models accounting for the interaction and localization character of metal components, their oxides and hydroxides.

---

, - Ni-, Mo, Fe Ca. , , , .

     

The maximum kinetic mechanism and rate constants in the H2?O2 system

The maximum (in a combinatorial sense) kinetic mechanism of hydrogen oxidation is defined and the rate constants of all elementary steps are given. The possible error limit is given for each elementary step.

---

( ) . .

     

Reactivity of allyl (o-halophenyl) ethers with organonickel (0) complexes

The reactivity of allyl (o-halophenyl) ethers with zerovalent nickel complexes, with triphenylphosphine and pyridine as ligands, leading to benzo[b]furan derivatives has been checked. Cyclization products were not isolated, but deallylation, substitution, reduction and rearrangement products were obtained in low to moderate yields. Mechanisms are proposed to explain the formation of these side products.

---

-(o-) , , [b] . , , , , . .

     

Neighboring amide group participation in ester aminolysis in aprotic solvents

The piperidinolysis of 8-quinolyl-, p-nitrophenyl-, o-, and p-piperidinocarbonylphenyl acetates in acetonitrile and in chlorobenzene was studied at 25°C. The strictly second order kinetic behaviour and the weaks solvent-dependence of the rate of the reaction of o-piperidinocarbonylphenyl acetate indicate anchimeric assistance by the o-amide group, and support the suggestion that amide groups of hydrophobic enzyme active sites may act as general base catalysts.

---

8--, --, - - 25°C. - - , .

     

Selectivity in cobaloxime catalyzed hydrogenation of nitrobenzene in the presence of olefins. Remarkable effect of isoprene

It has been found that nitrobenzene, in the presence of monoolefins, is effectively hydrogenated with the cobaloxime catalyst. Conjugated dienes and nitrobenzene are both hydrogenated; the extent of hydrogenation of dienes depends upon the structure. A remarkable exception is isoprene, whose presence in the reacting solution completely inhibits the hydrogenation of nitrobenzene. No organometallic compounds of Co(III) have been isolated. Homolytic activation of hydrogen is therefore rather unlikely in this system.

---

, . , , , . , . - Co(III). , , - .

     

New instruments and methods for enthalpimetric analysis and calibration

A review is given of recently developed instruments used in thermometric analysis and new methods of direct injection enthalpimetry.In the past two years, several types of Tronac (Orem, Utah) and Setaram (Lyon, France) calorimeters have been developed. A new mixing cell construction led to development of a flow instrument for automated thermometric analyses (Technicon, Tarrytown N. Y.). A new type of Hungarian instrument, Ditermanal (Orion, Budapest) permits arbitrary analyses.At the Technical University in Brno, small table twin isoperibol instruments allowing the direct analyses of solid samples have been developed. The use of PTC thermistors and a calibration device improved the accuracy of measurements.Many new methods of silicate and lime analysis, water determination, etc. have been elaborated.

---

Zusammenfassung Eine Übersicht über die zur thermometrischen Analyse eingesetzten, entwickelten Instrumente und neuen Methoden der Direkt-Injektion Enthalpimetrie wird gegeben.In den zwei vergangenen Jahren wurden verschiedene Kalorimetertypen TRONAC (Orem, Utah) und SETARAM (Lyon, France) entwickelt. Eine neue Mischzellenkonstruktion ermöglichte es ein Durchflussinstrument für automatische thermometrische Analysen (TECHNICON, Tarrytown, N. Y.) zu entwickeln. Ein neuer ungarischer Instrumententyp, DITERMANAL (ORION, Budapest), ermöglicht die Durchführung von Schiedsanalysen.An der Technischen Universität Brno wurden kleinen Zwillings-Isoperibol-Tisch Instrumente entwickelt, welche auch die direkten Analysen fester Proben ermöglichen. Der Einsatz von PTC-Thermistoren und einer Eichvorrichtung erhöhte die Messgenauigkeit.Viele neue Methoden der Silikat- und Kalkanalyse, Wasserbestimmungen usw. wurden erarbeitet.

---

Résumé On passe en revue les instruments récemment mis au point et utilisés en analyse thermométrique ainsi que les nouvelles méthodes d'enthalpimétrie par injection directe.Dans les deux dernières années, divers types de calorimètres ont été mis au point: TRONAC (Orem, Utah) et SETARAM (Lyon, France). La réalisation d'une nouvelle cellule de mélange a permis de mettre au point un appareil à flux pour les analyses thermométriques automatiques (TECHNICON, Tarrytown, N. Y.). Un nouveau type d'instrument hongrois, DITERMANAL (ORION, Budapest) permet d'effectuer des analyses arbitrales.A l'université technique de Brno de petites tables instruments jumeaux isopériboliques permettant aussi d'effectuer des analyses directes des corps solides ont été réalisés. L'application de thermistors PTC et un dispositif pour l'étalonnage augmentent l'exactitude des mesures.Des méthodes nouvelles nombreuses pour l'analyse des silicates, des pierres calcaires, de l'eau, etc., ont fait l'objet d'études.

---

, . (, ) (, ). (H, , -). (, ) . , . . , , .

     

Catalytic oxidation of carbon monoxide by oxygen and nitrogen oxides on a copper-chromium oxide catalyst

The kinetics of CO oxidation by O₂, NO and NO₂ has been studied on a Cu–Cr-oxide catalyst. A comparison with the kinetics of the CO–N₂O interaction has been made. In all cases the reaction rate is described by the equation:r=k p _CO ¹ P _0x ⁰ . The oxidation of CO has been studied in the presence of different oxidants in the reaction mixture.

---

CO , . CO . CO . CO .

     

Heterogenized rhodium complexes as hydrogen transfer catalysts

Cationic rhodium(I) norbornadiene complexes with polystyrene-immobilized imidazole, tetramethylbiimidazole or phosphine ligands in the presence of potassium hydroxide catalyze hydrogen transfer from isopropanol to acetophenone and 1-hexene. [Rh(NBD) (poly-PPh₂)₂] ClO₄ complexes are particularly efficient for the reduction of acetophenone, but slow decomposition to rhodium metal is observed.

---

(I) , , , 1-. [Rh(NBD) (-PPh₂)₂]ClO₄ , .

     

Thiophene hydrodesulfurization on P?Mo, Si?Mo and Ti?Mo catalysts

Studies of the catalysts obtained by supporting P–Mo, Si–Mo and Ti–Mo heteropolyacids on anatase in thiophene hydrodesulfurization have revealed that the presence of HPA in the initial catalysts promotes the formation of the molybdenum state ensuring high reaction rates. A possibility for HPA synthesis when supporting paramolybdate on TiO₂, accounts for the great effect of the support on the properties of the catalyst.

---

, -, -, - , . , , . .

     

Kinetics and mechanism of the oxidation of bis(acetylacetonato)-cobalt(II) by cumene hydroperoxide in the presence of pyridine

Stoichiometric reaction of bis(acetylacetonato) cobalt(II) with cumene hydroperoxide in chloroform solutions containing added pyridine has been studied by the PMR method.

---

() Co(II) , .

     

Catalysts for selective hydrogenation of conjugated dienes into olefins in the presence of PdCl2 complexes

Complexes of PdCl₂ with amines or pyridine reduced by (iso-Bu)₂ AlH are shown to be catalytically active in the selective hydrogenation of conjugated dienes into olefins in aromatic media. The promoting effect of H₂O and O₂ has been established.

---

PdCl₂ , (-Bu)₂ AlH, . H₂O O₂.

     

Adsorption characteristics of some zeolites

Attempts have been made to correlate the Si/Al atom ratio, the degree of crystallinity, crystallite dimensions and the mean diameter of crystalline particles with the relative adsorption affinity index (RAI). Differences in molecular sieving effect and in some diffusional aspects between traditional zeolites and the new shape-selective ZSM are revealed by the adsorption characteristics of cyclohexane, benzene, toluene, neopentane and xylenes.

---

Si/Al , , , (RAI). - ZSM , , , .

     

Computation in kinetics, III. A new method for kinetic model search based on simultaneous regression estimation of rate constants, stoichiometry and/or reaction order

Modified samples of natural mordenites have been found to catalyze the oxidative condensation of methane to yield ethane and ethylene. The selectivity towards C₂ hydrocarbons increases, whereas the acidity of zeolites falls.

---

, . C₂ .

     

Radical addition of methyldichlorosilane to vinyl acetate

The GC-MS method was used to identify the addition products of methyldichlorosilane to vinyl acetate. Radiation-induced addition of methyldichlorosilane to vinyl acetate produces 2-methyldichlorosilylethyl ethyl ether. The reaction follows a radical-chain mechanism. The ratio of the rate constants of methyldichlorosilyl radical addition to C=C and C=O to vinyl acetate amounts to 0.4±0.1 (303 K).

---

- . , - 2- . , C=C C=O 0,4±0,1.

     

Oxidative polymerization of durene and diphenyl oxide in the presence of palladium(II) and heteropolyacids

The possibility of obtaining tetramers from durene or diphenyl oxide in the presence of H₅PMo₁₀V₂O₄₀, a reversible oxidant, and palladium acetate as catalyst is demonstrated.

---

— H₅PMo₁₀V₂O₄₀ .

     

Mathematical model for multi-component petrochemical processes

Some principles of constructing a mathematical model and the results of studying catalytic reforming are discussed.

---

.