Triplet state formation and type II decomposition in the photochemistry of pentanone-2

The concentration dependences of the quantum yields of Norrish type II decomposition from the singlet and triplet states and of the triplet yiel were determined in pentanone-2 photolysis in iso-octane. The results were interpreted by postulating dissociative intersystem crossing of a singlet exciplex as an additional route for the population of the molecular triplet state.

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II -2 . , .

     

Studies on catalytically active surface compounds: XVIII. Photoreduction of oxidic vanadium clusters on aerosil and their chemisorptive properties

Photoreduction by CO of silica supported vanadia catalysts of different cluster size has been studied. It was found that the rates of photoreduction and the highest attainable degrees of reduction depend on the size of vanadia clusters. The chemisorptive properties of photoreduced catalysts toward but-1-ene and O₂ are studied and discussed in terms of the distribution of V³⁺ ions in partially reduced clusters.

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. , -1 O₂. V³+ .

     

Energetic state of hydrogen on Os-black

Hydrogen adsorption on Os-black has been studied by the TPD method in the range from –85 to 450°C. Energetic inhomogeneity of hydrogen chemisorbed at adsorption temperatures of 150 to 450°C has been elucidated.

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OS (–85)–450°C. , 150 450°C.

     

A device for pulse investigation of heterogeneous catalytic reactions

In the present work a simple device is described for the pulse investigation of heterogeneous catalytic reactions and catalysts. Owing to the possibility for separate adjustment of the gas flow rate in the catalytic reactor and in the chromatographic column, it can be used for kinetic measurements too.

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- . , .

     

Kinetics and isotope effect of brown coal liquefaction in ethanol

Liquefaction kinetics are described by a first-order equation. Deuterium introduction into the -position of ethyl alcohol produces a considerable kinetic isotope effect. This effect is suggested to be due to the hydrogen donor capacity of the initial ethyl alcohol -CH₂-groups or of ethyl substituents inserted into the aromatic fragments of coal after alkylation.

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. -, , - -CH₂- , .

     

Studies on water retention and water release from some protein systems

The hydrogen-bond properties (WBI index), water retention and water release from the protein-water systems gluten-water, soya protein- water and casein-water, have been investigated using differential scanning calorimetry in the temperature range 223–423 K. The proteins were characterized by their isoelectric point, contents of carboxyl groups and sulfur-containing groups, and readiness of undergo chloromethylation. It was concluded that the marked difference in water-release behaviour is chiefly explained by conformational differences and charge effects.

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Zusammenfassung Wasserstoffbrückenbindugseigenschaften (WBI-Index), Wasserretention und Wasserabgabe von Protein-Masser-Systemen — Gluten-Wasser, Sojaprotein-Wasser und Casein-Wasser — wurden im Temperaturbereich von 233–423 K mit einem Scanning-Kalorimeter untersucht. Die Proteine wurden durch ihren isoelektrischen Punkt, den Gehalt an Carbonylgruppen und Schwefel enthaltenden Gruppen und durch ihre Reaktivität in der Chlormethylierung charakterisiert. Es wurde gefolgert, dass der ausgesprochene Unterschied im Wasserabgabeverhalten in erster Linie auf strukturelle Unterschiede und Ladungseffekte zurückzuführen ist.

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223–423 K , , — , — — . , , . , .

     

Fossil age determination by thermal analysis

Subsequent to a comparative examination of recent bone material the author has recently completed the paleobiogeochemical evaluation of classical Quaternary and Pliocene terrestrial fossils of vertebrata from Hungary. A derivatograph (MOM) has been used to determine two thermoanalytical parameters which are closely associated with the passage of geological time: the total bound organic-matter content of the fossil and the fossilization cofficient.Derivatographic measurement of the organic matter in the bones is supplemented by fine-structure analysis of bone-tissue slides.Sample material of unknown age from several provenances was evaluated with the new dating method. The importance of the procedure is even greater in cases when only indefinite sporadic finds can be obtained from the sediments.

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Zusammenfassung Nach einer vergleichenden Untersuchung an neuzeitlichem Knochenmaterial hat der Autor kürzlich die paleobiogeochemische Auswertung der klassischen Quaternären und Pliocenen terrestren Fossilien von Vertebraten aus Ungarn ergänzt.Ein Derivatograph (MOM) wurde zur Bestimmung zweier thermoanalytischer Parameter eingesetzt, die eng mit dem Fortschreiten der geologischen Zeit verbunden waren: dem Gesamtgehalt an gebundenem organischem Material und dem Fossilisationskoeffizienten.Die derivatographische Messung der organischen Substanz in den Knochen wurde durch die Feinstrukturanalyse von Knochengewebeschnitten ergänzt.Probenmaterial unbekannten Alters verschiedener Herkunft wurde mit der neuen Methode ausgewertet. Die Bedeutung des Verfahrens ist in den Fällen noch grösser, wenn aus den Sedimenten nur unbestimmte sporadische Funde erhalten werden können.

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, . (MOM) , : . - . . , .

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The author wishes to thank the staff of the Department of Experimental Physics of L. Kossuth University for the neutron activation measurements and the Computer Center of the University for the calculation work.     

Hydrodenitrogenation activity of sulfided catalysts

Activities of hydrodenitrogenation catalysts were compared using a batch mode autoclave reactor. The hydrodenitrogenation of carbazole, a model coal nitrogen compound, was the reaction studied. The highest activity and the highest rate constant for carbazole and total nitrogen removal were found in the case of NiMo/Al₂O₃ catalyst.

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. , . , NiMo/Al₂O₃.

     

Binding energy of oxygen to the surface of promoted V?Mo?O catalysts for acrolein oxidation to acrylic acid

It has been established that P, Cs and Cu additives to V–Mo–O catalysts affect essentially both binding energy of surface oxygen and mobility of bulk oxygen.

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P, Cs Cu V–Mo–O .

     

Catalysis of thiophene hydrogenolysis by bimetallic sulfide catalysts of different compositions

The activity of sulfide catalysts M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ and (Ni,M_II)/SiO₂ (M_I is a first row transition metal, and M_II=Nb, Mo, W or Re) in the thiophene hydrogenolysis reaction has been studied. Activities of mono- and bimetallic catalysts are found to change in the same manner depending upon the nature of M_I. The formation of a sulfide bimetallic species (SBMS) is suggested.

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M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ (Ni, M_II)/SiO₂, M_I — , M_II–Nb, Mo, W, Re. - M_I. .

     

The determination of quartz in clay materials

The quartz contents (maximum, 4 wt.%) of four clay materials and a tourmaline were determined by differential thermal analysis, by X-ray diffraction and by chemical analysis. The results are used to make a critical comparison of these three methods. DTA gives a better precision than X-ray diffraction analysis. The chemical method is judged unreliable in that feldspar and mica, present as minor components, are recorded in part as quartz.

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Zusammenfassung Der Quarzgehalt (max. 4%) von vier Tonmineralien und von Turmalin wurde durch Differentialthermoanalyse, Röntgendiffraktion und chemische Analyse bestimmt. Die Ergebnisse ermöglichten einen kritischen Vergleich der drei Methoden. Die DTA ist genauer als die Röntgendiffraktion. Die Chemische Analyse ist unzuverläßlich, da kleinere Mengen an Feldspat und Glimmer ebenfalls teilweise als Quarz erfaßt werden.

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Résumé On a déterminé la teneur en quartz (4% en poids au maximum) de quatre argiles et d'une tourmaline en se servant de l'analyse thermique différentielle, de la diffraction de rayons X et de l'analyse chimique. On a utilisé les résultats pour faire une étude critique des trois méthodes. L'ATD donne une meilleure précision que l'analyse par diffraction X. L'analyse chimique présente peu de sûreté car le feldspath et le mica, présents à l'état de constituants mineurs, interviennent en partie comme le quartz.

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, - . 4 % . . , , — . , , .. .

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The authors express their thanks to the Directors of English Clays Lovering Pochin & Co. Ltd. for permission to publish this paper.     

Acetylene adsorption on a clean iridium surface

The interaction of C₂H₂ with a polycrystalline iridium surface at 140 KT500 K has been studied by AES, XPS and UPS. A model of the bonding between C₂H₂ and Ir by the 1 orbitals of the hydrocarbon is proposed. The more pronounced energy splitting between the orbitals of acetylene during adsorption compared to that in the gas phase is ascribed to deformation of the acetylene molecule.

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C₂H₂ . 140 KT500 K AES, XPS UPS. C₂H₂ Ir 1- . - , , .

     

Quantum-chemical studies of the interaction between furan and pyridine molecules and surface fragments of vanadium oxide catalysts

CNDO/2 studies of the interaction between furan and pyridine molecules and coordinatively unsaturated surface centers of vanadium oxide catalysts indicate that these molecules are more tightly bound and undergo more substantial changes in their electronic structure upon coordination to centers, containing reduced vanadium ions.

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/2 - - , , .

     

Modifying action of carbon dioxide in catalytic oxidation of ethylene on silver

Carbon dioxide exerts a strong inhibitory effect on oxygen adsorption and complete oxidation of ethylene on silver but has little effect on the rate of ethylene oxidation to ethylene oxide.

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.

     

A new procedure for determination of the acid and base strength distribution of colored catalysts

A new procedure for determining the strength distribution of acid and base centers of colored catalysts by the indicator method has been proposed. The procedure basing on the use of a platinum gauze container for the colored catalyst enables us to eliminate the difficulties in the identification of the color of the indicator.

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. , , , .

     

The question of thermal decomposition of pyrite

The thermal decomposition of monomineral pyrite was studied in an inert atmostphere. From an analysis of the values of the thermal effects, an interpretation of the hree physicochemical processes recorded in the thermoanalytical curves is proposed.

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Zusammenfassung Die thermische Zersetzung von monomineralem Pyrit wurde in inerter Atmosphäre untersucht. An Hand der Analyse der Werte der thermischen Effekte wird eine Beschreibung dreier, in den thermoanalytischen Kurven festgehaltener physikalischchemischer Vorgänge vorgeschlagen.

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Résumé On a étudié la décomposition thermique de la pyrite, en atmosphère inerte. On propose une interprétation des trois processus physicochimiques enregistrés sur les courbes thermoanalytiques, qui repose sur l'analyse des effects thermiques.

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- , .

     

Thermal analysis of Sb2O3 /Organohalide-based flame retardants including atomic absorption detection of the evolved species

The mechanism of evaporation of Sb₂O₃ and the mechanism of formation and evaporation of antimony trihalides (SbX₃) from Sb₂O₃ + halogen, which play important roles in the flame retardation of plastics, have been studied in the case of chlorine- and bromine-containing additives at different Sb/X mole ratios by means of complex thermal analysis, and massspectrometers. The temperatures of SbCl₃ formation and its evaporation have been determined for PVC and Cerechlor 70 as chloride donors. The formation of SbBr₃ could not be verified when Flammex (decabromodiphenyl ether) was used. A close correlation has been found between conventional and atomic absorption thermoanalytical curves recorded under identical experimental conditions. The atomic absorption detection of the thermally evolved products provides valuable information on flame retardation process.

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Zusammenfassung Der Mechanismus der Bildung und Verdampfung des bei der Brennverzögerung von Kunststoffen eine wichtige Rolle spielenden Sb₂O₃ und der sich aus Sb₂O₃ und Halogenen bildenden Antimontrihalogenide (SbX₃) kann im Falle von chlor- und bromhaltigen Additiven bei unterschiedlichen Sb/X-Molverhältnissen durch komplexe thermische Analyse und damit gekoppelter Atomabsorptionsspektrophotometrie und Massenspektrometrie untersucht werden.Die Bildungs- und Verflüchtigungstemperatur des SbCl₃ wurde im Falle von PVC und Cereklor 70 als Chloriddonor bestimmt. Bei Verwendung von Flammex (Dekabromdiphenyläther) wurde keine Bildung von SbBr₃ beobachtet. Eine strenge Korrelation wurde zwischen unter gleichen Versuchsbedingungen erhaltenen thermoanalytischen und atomabsorptionsspektrophotometrischen Kurven gefunden. Mit der Kombination der TA mit der Atomabsorptionsmethode eröffnet sich die Möglichkeit, den Prosess der Brennverzögerung von der Gasphase her zu untersuchen.

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, , . , . - , — , - , -. 70, , . / / . , - . - .

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The authors are grateful to Dr. T. Müller for recording and evaluating the mass-spectra.     

ESR studies of N2O interaction with photoinduced centers on ZnO and MgO

According to the analysis of the formation of O^– anion radicals stabilized on the surface of oxides, it has been shown that on ZnO, only O _s ^– hole centers are formed, whereas in the presence of N₂O molecules, besidese the above centers, MgO surface contains O _ads ^– electron centers.

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- O^–, . , ZnO O _s ^– , MgO N₂O O _s ^– O ^– .

     

Mechanism of ascorbic acid oxidation by molecular oxygen in aqueous pyridine catalyzed by CO2+, Ni2+, Mn2+ and Zn2+

Data on the radical non-chain mechanism of ascorbic acid oxidation by molecular oxygen catalyzed by Co²⁺, Ni²⁺, Mn²⁺ and Zn²⁺ ions are reported.

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Co²⁺, Ni²⁺, Mn²⁺ Zn²⁺.