Catalytic behaviour of Mo-based catalysts in liquid phase epoxidation of propylene by hydroperoxides

The activity of different Mo-based catalysts in propylene epoxidation by t-BuO₂H was investigated. MoO₂(C₁₃H₁₀O₂N)₂ and MoO₂ (oxine)₂ gave quantitative yields in propylene oxide; other compounds were inactive and MoO₂ (acac)₂ was less active and selective.The different catalytic behaviour of these catalysts is attributed to the different strength of Mo-ligand bonds.

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t-BuO₂H. MoO₂ (C₁₃H₁₀O₂N)₂ MoO₂ ()₂ ; , MoO₂ (acac)₂ . Mo-.

     

Flow-pulsation method to study the activity of catalyst in high-pressure processes

Generation of gradientless conditions by the pulsation method with variable reciprocating gas flow method through the isothermal catalyst bed is suggested as one of the trends in the further development of external circulation flow systems. The conditions ensuring continuous stirring have been established. Flowcirculation and pulsation methods have been tested under similar conditions.

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- - . , , - .

     

Studies on the V?Ti?O system obtained by thermal decomposition of vanadyl and titanyl oxalates in argon atmosphere

The V–Ti–O system as a product of thermal decomposition of vanadyl and titanyl oxalates at 873 and 1173 K in argon atmosphere was studied by X-ray diffraction and infrared spectroscopy. The results obtained, the analysis and surface measurement data suggest that a V³⁺–V⁴⁺–Ti⁴⁺–O solid solution is formed. Spectroscopic measurements reveal the presence of a V=O bond in the system obtained at 873 K.

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V–Ti–O, 873 1173 - . , , V⁺³–V⁺⁴–O . V=O , 873 .

     

Photocatalytic electron transfer across the membranes of lipid vesicles mediated by diglycylamide of mesoporphyrin-IX N-metylglycomate

A peculiarity of the photocatalytic action of porphyrin molecules with different localization inside lipid bilayers of lecithin vesicles has been studied. The influence of an electrostatic field in the lipid membrane on the efficiency of electron photocatalytic transfer across the membrane is discussed.

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, - . . .

     

UV-spectroscopic studies on the interaction of triethyl aluminium with cobalt and aluminium acetylacetonates

The Al(acac)₃/Et₂Al(acac) ratio depends on the Al/Co and the solvent. The solvent contains Et₂Al(acac) as a dimer, which is stabilized in the presence of Co(O) and arenes. The role of Et₂Al(acac) dimer in the formation of active Co(O) complexes is discussed.

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, Al(acac)₃/Et₂ Al(acac) Al/Co . (Et₂Al(acac) Co(O) . Et₂Al(acac) Co(O).

     

Ba(OH)2 as catalyst in organic reactions: I. Nature of active sites in the michael addition

In order to determine the nature of active sites that act in the Michael addition of ethyl malonate to chalcone in EtOH, catalyzed by activated barium hydroxide, selective poisoning experiments have been carried out. It has been found that the catalytic activity of the C-200 catalyst is related to the strong basic sites titrated by TBMPHE.

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, - . , C-200 - , TBMPHE.

     

X-ray and thermal analysis of a 1:1 nickel-vanadium catalyst for methanol oxidation

In the X-ray diffraction and thermal investigations of a V/Ni=1 catalyst, obtained by calcination of V₂O₅ and Ni(NO₃)₂·6H₂O, it has been shown that at 600–700 °C a phase characterized by a rather poor crystalline state is formed, in which Ni₂V₂O₇ with smaller amounts of Ni(VO₃)₂ and Ni₃(VO₄)₂ have been identified.

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- V/Ni=1, V₂O₅ Ni(NO₃)₂·6H₂O, , 600–700°C , , Ni₂V₂O₇ Ni(VO₃)₂ Ni₃(VO₄)₂.

     

Novel multiple methods and results in thermal analysis

The development of the multiple thermal methods and the results obtained with them during the past three years are discussed.

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Zusammenfassung Es wird ein Überblick der vielseitigen thermischen Methoden gegeben und die wesentlichsten in den letzten drei Jahren erzielten Ergebnisse vorgestellt.

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Résumé Mise au point sur le développement des méthodes thermiques associées au cours des trois dernières années et discussion des résultats obtenus.

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, .

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The author wishes to express her thanks to Miss Beata Androsits for her valuable help in assembling the material.     

Effect of the secondary structure of poly-L-lysine on the adsorption at the water/dodecane interface

The adsorption of poly-L-lysine of different conformation (-helix, -sheet and random coil) at the water/dodecane interface has been studied by interfacial tension measurements using the drop volume method. The experimental adsorption isotherms provide information about a critical aggregation concentration, the maximum interfacial tension depression_max and the minimum area A occupied by adsorbed molecules at the interface. Differences in_max exist between -helix and -sheet and, moreover, in the area values between random-coil on the one side and -helix and -sheet on the other hand.     

Determination of ten anti-inflammatory drugs in serum by isocratic liquid chromatography

Summary A high performance liquid chromatographic system has been developed for the resolution of ten anti-inflammatory drugs. Isocratic separation was achieved using a Spherisorb 5m ODS column with an eluent consisting of water-orthophosphoric acid to pH 3.2: acetonitrile: methanol (523513). A comparison was made between chloroform/acetonitrile (32) and hexane/ether (11) as solvents for the extraction of these drugs from serum.     

Kinetic study of the thermal dehydration of layered [Ni2Al(OH)6]2SO4.nH 2O

The kinetics of thermal dehydration of [Ni₂Al(OH)₆]₂SO₄.nH₂O has been studied through the analysis of isothermal weight loss data. The results obtained seem to indicate that the process is governed by a diffusion mechanism up to an value which is dependent on the temperature. An explanation is provided for this behaviour on the basis of the structural properties of the compound and the nature of the water loss.

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Zusammenfassung Die Kinetik der thermischen Dehydratisierung von [Ni₂Al(OH)₆]₂SO₄.nH₂O wurde mittels isothermer TG untersucht. Die Ergebnisse scheinen darauf hinzudeuten, daß der Prozeß bis zu einem von der Temperatur abhängigen -Wert von einem Diffusionsmechanismus bestimmt wird. Für dieses Verhalten wird basierend auf den strukturellen Eigenschaften der Verbindung und der Natur der Wasserabgabe eine Erklärung gegeben.

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, [Ni₂Al(OH)₆]₂SO₄.nH₂O. , , . , .

     

The economical parameter survey program for long-term transient temperature distribution and stress analysis around the sodium level of the liquid metal fast breeder reactor

The thermal stress around the sodium level of the LMFBR reactor vessel, caused by the axial temperature distribution during heat-up and cool-down transient conditions, is one of the most important problems for a reactor vessel designer, especially in a conceptual design stage. Key parameters relating to plant operating transient conditions and reactor vessel main configuration should be settled carefully, thermal stresses not being allowed to exceed design stress limits. In order to examine the sodium level thermal stress easily and economically, a simple computer program for parameter survey has been developed. This program uses a one-dimensional Fourier series solution in transient temperature distribution analysis, and an analytical stress solution based on shell theory in stress value estimation. This paper presents a simplified and economical calculation method for the axial temperature distribution and stress value in the LMFBR operating transient conditions, and analysis examples obtained with this computer program.

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Zusammenfassung Der durch die axiale Temperaturverteilung während der Übergangsphase von Aufheizen und Abkühlen verursachte thermische Streß rund um den Natriumfüllstand des LMFBR-Reaktorkessels ist für den Reaktorkesselkonstrukteur, besonders im Entwurfstadiuni eines der wichtigsten Probleme. Die mit den transienten Operationsbedingungen der Anlage und der Gestaltung des Reaktorkessels in Beziehung stehenden Grundparameter müssen sorgfältig ermittelt werden, um zu verhindern, daß der thermische Streß die geplanten Streßgrenzen nicht überschreitet. Um den thermischen Streß um den Natriumfüllstand, leicht und ökonomisch zu bestimmen, wurde ein Komputerprogramm für die Parameterübersicht aufgestellt. In diesem Programm wird von einer eindimensionalen Fourrierreihe zur Analyse der transienten Temperaturverteilung und einer auf der Schalentheorie von Streßwertbestimmungen basierende analytische Lösung Gebrauch gemacht. Im vorliegenden Artikel werden eine vereinfachte und wirtschaftliche Berechnungsmethode für die axiale Temperaturverteilung und Streßwerte bei transienten Arbeitsbedingungen mitgeteilt und mit diesem Komputerprogramm ausgeführte Analysenbeispiele angegeben.

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

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Paper presented at the World Conference on Thermal Analysis, Madeira (Portugal) 1986.     

Kinetic peculiarities of 8-pentadecanone in the presence of chromium stearate

Studies of the initial step of liquid-phase oxidation of 8-pentadecanone catalyzed by chromium stearate (CrSt₃) indicate that the catalyst takes part in the formation of free radicals in the interaction of ketone with dissolved oxygen. In chain propagation and termination reactions CrSt₃ does not participate.

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(CrSt₃) 8-. , . CrSt₃ .

     

Kinetic parameters obtained from TG and DTG curves of acrylamide-maleic anhydride copolymers

The thermal behaviour of acrylamide-maleic anhydride copolymers was studied by thermogravimetric (TG and DTG) analysis. The obtained data permitted the calculation of activation energies and reaction orders of the decomposition steps by the Coats-Redfern and Freeman-Carroll methods.Thermal analysis shows four distinct peaks in the case of polyacrylamide and AAMA (71) copolymer and only three for AAMA (11) copolymer.In AA:MA (11) copolymers intermolecular imidization occurs only and thermal degradation is influenced more by the anhydride groups which are equal in number with the amide ones.

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Zusammenfassung Das thermische Verhalten von Acrylamid-Maleinsäureanhydrid-Kopolymeren wurde durch thermogravimetrische Analyse (TG und DTG) untersucht. Aus den erhaltenen Daten wurden die Aktivierungsenergien und Reaktionsordnungen der Zersetzungsschritte nach den Methoden von Coats-Redfern und Freeman-Carroll berechnet. Durch thermische Analyse können im Falle von Polyacrylamid und AAMA (71 (-Kopolymeren 4 Peaks und bei AA:MA (11) -Kopolymeren nur 3 Peaks unterschieden werden. Bei AAMA (1 1)-Kopolymeren verläuft nur eine intermolekulare Imidisierung und der thermische Abbau wird mehr durch die in gleicher Zahl wie die Amidgruppen vorliegenden Anhydridgruppen beeinflußt.

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T () — (). , - -, . : ( 71) , : 11 — . : 11 , , .

     

Electronic spectral study of the interaction of CoNaX zeolite with C1?C5 hydrocarbons

Interaction of both satured and unsaturated hydrocarbons with tetrahedral Co²⁺ ion complexes lodged in the zeolite skeleton is reported on the basis of diffuse reflectance spectra. While saturated hydrocarbons do not affect the coordination sphere of the Co-complex, the unsaturated hydrocarbons change considerably the distortion of the tetrahedral Co-complex.

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- Co²⁺ - . - Co-, - - Co-.

     

Oxidation of ethanol on platinum/alumina and copper oxide catalysts

The oxidation of ethanol on CuO, CuO/Al₂O₃ and Pt/Al₂O₃ catalysts has been studied at various concentrations of alcohol, oxygen and water vapor in the reaction mixture. The reaction order and activation energies have been determined for both complete and partial oxidation processes. A consecutive oxidation scheme is suggested.

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CuO, CuO/Al₂O₃ Pt/Al₂O₃ , . . .

     

Structure of the sesquiterpene lactone tanacin

Summary From the leaves ofAtraphaxis pyrifolia Bge. we have isolated a new flavonoid glycoside. By chemical and spectroscopic investigations its structure has been established as 3,4,5,8-tetrahydroxy-7-methoxy-flavonol 3-O--L-rhamnopyranoside.S. M. Kirov Kazakh State University. Translated from Khimiya Prirodnykh Soedenenii, No. 2, pp. 136–140, March–April, 1975.     

Effect of carbon dioxide on the catalytic oxidation of ethylene over silver. Reaction rates and composition of adsorbed layer

It has been found that when the reaction is carried out at pressures of the reaction mixture ranging from 1 to 400 Pa, small surface coverages by adsorbed oxygen, carbonate groups and irreversibly adsorbed carbon-containing particles are obtained. Rate relaxations are due to the concentration variations of adsorbed oxygen and CO_3ads groups.

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, 1–400 , , . CO₃.