Mass spectrometric study of monoalkyl-substituted thiacyclanes

Monosubstituted - and -alkylthiophans and -, -, and -alkylthiacyclohexanes were subjected to a comparative mass spectrometric study. The stability of the M⁺ ion increases on passing from - to -alkylthiophans and from - to - and -alkylthiacyclohexanes. In the case of -alkylthiophans and - and -alkylthia-cyclohexanes the principal process is associated with ejection of the substituent as a whole, whereas a portion of the alkyl substituent, with retention of one CH₂ group in the composition of the charged fragment, is eliminated from the molecular ions of -alkylthiophans and -alkylthiacyclohexanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–181, February, 1978.     

Evaluation of crystallization kinetics by means of DTA

The kinetics of bulk crystallization of Se_61.5Ge_{15 4}Sb_23.1 glasses was investigated from their thermal behaviour. In the thermal characterization of a glass the recrystallization temperature is highly dependent on both the rate of heating and the thermal history of the glass. Vitreous samples were prepared by quenching. From ratedependent curves it was found that the recrystallization process obeys first-order kinetics with an apparent activation enthalpy of 48±5 kcal/mole. Further analysis allows determination of both the activation enthalpy,H=90±4 kcal/mole, and the kinetic exponent of the Avrami equation,n=1.9±0.3.

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Zusammenfassung Die Kinetik der Massenkristallisation von Glas-Arten der Zusammensetzung Se_61.5Ge_15.4Sb_23.1 wurde an Hand ihres thermischen Verhaltens studiert. Bei der thermischen Charakterisireung von Glas hängt die Rekristallisationstemperatur stark sowohl von der Aufheizgeschwindigkeit als auch von der Wärmevorgeschichte des Glases ab. Glasige Proben wurden durch rasches Abkühlen hergestellt. Aus den geschwindigkeitsabhängigen Thermogrammen geht hervor, dass der Rekristallisierungsprozess der Kinetik erster Ordnung gehorcht, mit einer scheinbaren Aktivierungsenthalpie von 48±5 kcal/mol. Die weitere Analyse ermöglicht die Bestimmung sowohl der AktivierungsenthalpieH=90±4 kcal/mol als auch des kinetischen Exponentenn=1.9±0.3 der Avrami-Gleichung.

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Résumé Etude de la cinétique de la cristallisation dans la masse de verres Se_61.5Ge_15.4Sb_23.1 à partir de leur comportement thermique. La température de recristallisation dépend fortement tant de la vitesse de chauffage que de l'histoire thermique du verre. Des échantillons vitreux ont été préparés par refroidissement rapide. La recristallisation obéit à une cinétique du premier ordre, avec une enthalpie d'activation apparente de 48±5 kcal·mol^–1. Une analyse ultérieure permet de déterminer l'enthalpie d'activationH=90±4 kcal-mol^–1 ainis que l'exposant cinétiquen=1.9±0.3 de l'équation d'Avrami.

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Se_61.5Ge_15.4Sb_23.1 . , , . . , 48±5 /. H=90±4/ , n=1.9±0.3 .

     

Dilatometric studies of Leh clay Part II

Clay from the Leh area of J&K State (India) was separated into various size fractions by the method of sedimentation and with Sharpie's supercentrifuge process. The results of dilatometric studies of the fractions are discussed in detail.

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Zusammenfassung Ton aus dem Leh-Gebiet des J&K Staates (Indien) wurde mittels Sedimentation und nach dem Ultrazentrifugenverfahren nach Sharple in Fraktionen unterschiedlicher Grösse zerlegt. Die Ergebnisse von dilatometrischen Untersuchungen dieser Fraktionen werden detailliert diskutiert.

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() . .

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The authors are grateful to the Director, Regional Research Laboratory, Jammu, for his kind permission to publish this paper. Thanks are also due to Professor G. Mandal, Department of Chemical Engineering, IIT, Bombay, for his suggestions during the study.     

Spin conversion of positronium in paramagnetic solutions studied by age-momentum-correlation method

Correlated measurement of the lifetime and of the lineshape of the 511 keV annihilation radiation of positrons (age-momentum correlation, AMOC) has become a powerful tool for investigating reactions of positron or positronium in condensed matter as a function of time. The beam-based ⁺ AMOC method installed at the Stuttgart relativistic positron beam facility (E _kin ^e+ 4MeV) offers substantial advantages over the conventional E coincidence technique resulting in a fast data taking due to the unity detection efficiency of the ⁺ scintillator which provides the start signal for the lifetime measurement. In this paper the application of AMOC to positronium chemistry is illustrated by the study of spin conversion of positronium in the system methanol/HTEMPO as a function of HTEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, a paramagnetic solute) concentration. The same technique can be applied to other systems and other reactions in positronium chemistry, e. g., oxidation or complex formation.     

XPS and chemisorption studies of the surface layer of Pd?Ag catalysts for CO oxidation

XPS and chemisorption studies of the surface composition of a Pd–Ag alloy (5% Pd) before and after its application in CO oxidation have been performed. It is shown that in a freshly prepared sample the bulk and surface layer compositions are the same. High-temperature treatment of the catalyst in the reaction medium leads to a thermodynamic equilibrium between surface and bulk.

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Pd–Ag Pd 5% CO . , . .

     

Acid-base and catalytic properties of binary oxides in the oxidative dehydrodimerization of toluene

Acidity and basicity of binary oxide catalysts measured by the CO₂ and NH₃ thermodesorption method are compared with their catalytic activity in oxidative conversion of toluene. The rate of toluene dehydrodimerization is shown to increase with the catalyst basicity.

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CO₂ NH₃ . , .

     

Thermal decompositions of complexes of metal ions with riboflavin

Two kinds of complexes of riboflavin with Zn(II), Co(II), Cu(II), Fe(III), Mg(II) and Ca(II) were synthesized, having metal: ligand molar ratios of 11 and 21. When heated, these complexes first lose water. Their thermal degradation in static air atmosphere starts at temperatures higher than, equal to, or lower than that observed for free riboflavin degradation. The rates and stages of pyrolysis were related to the structures of the complexes.

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Zusammenfassung Es wurden zwei verschiedenartige Komplexe von Riboflavin mit Zn(II), Co(II), Cu(II), Fe(III), Mg(II) und Ca(II) mit einem molaren Metall-Ligandenverhältnis von 11 und 21 dargestellt. Beim Erhitzen geben diese Komplexe zuerst Wasser ab. Ihre thermische Zersetzung beginnt in unbewegter Luftathmosphäre bei einer Temperatur, die entweder mit der für die Zersetzung freien Riboflavins übereinstimmt, größer oder kleiner als diese ist. Die Abschnitte und Geschwindigkeit der Pyrolyse werden mittels der Struktur der Komplexe erläutert.

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, , , : 11 21. . , . .

     

Interaction of O,O-Diethyl-β-hydroxy-γ-chloropropyl dithiophosphate and β-hydroxy-γ-chloropropyl thioacetate with bases

Conclusions O,O-Diethyl thioglycidylthiolphosphate was obtained by the action of base on O,O-diethyl-hydroxy--chloropropyl dithiophosphate. 3-Thietanyl acetate was obtained by the action of base on-hydroxy--chloropropyl thioacetate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 145–147, January, 1970.     

Über die Addition von Brom an 3,4,5,6-Tetrachlorcyclohexen-(1) vom Schmelzpunkt 30–31°

Zusammenfassung Bei der Addition von Brom an 3,4,5,6-Tetrachlor-cyclohexen-(1) vom Schmp. 30 bis 31° entsteht ein Reaktions-produkt, das in - und -1,2-Dibrom-2,3,4,5-tetrachlor-cyclohexan vom Schmp. 166° bzw. 123° zerlegt werden konnte. Das -Isomere hat die Konfiguration 1e2e(Br)3e4e5p6p(Cl), das -isomere die Konfiguration 1e2p(Br)3p4p5e6e(Cl).Mit 1 Abbildung.Fortsetzung von Mitt. X der Reihe Zur Chemie von Polyhalocyclohexanen, Mh. Chem.83, 403 (1952), besonders Versuch 3 d.     

Distribution of components in the rare earth ammonia synthesis catalysts and effect of additives

The distribution of components in the HG-1 ammonia catalyst promoted by rare earth oxide (successfully developed by the authors) was analyzed by electron microprobe photography. The results enable us to explain the effect of additives upon the activity as well as the remarkably high lifetime of catalyst.

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HG-1, ( ) , . , .

     

Thermal behaviour of mixed tetravalent metal salts

In contrast with the well-known zirconium and titanium phosphates, products containing these metal ions together are unknown. To investigate the thermal behaviour of such materials, samples were synthetized with various ratios of the two metal ions. The samples were identified by means of X-ray diffraction. Their thermal behaviour was investigated in the temperature interval 25–1000 °C via simultaneous TG, DTG and DTA measurements. The data obtained are presented in this paper.

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Zusammenfassung Im Gegensatz zu den wohlbekannten Zirkonium- und Titanphosphaten sind beide Metallionen gleichzeitig enthaltende Produkte unbekannt. Zur Untersuchung solcher Substanzen wurden Proben mit unterschiedlichen Mengen der beiden Metallionen gefertigt und mittels Röntgendiffraktion identifiziert. Die Proben wurden im Temperaturbereich 25–1000 °C mittels simultaner TG-, DTG- und DTA-Messungen untersucht. Die Ergebnisse werden in dieser Arbeit mitgeteilt.

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, . . - , , 25–1000°. .

     

Condensation of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester and decarboxylation of the reaction products obtained

-(1-Ethoxyvinyl)- and -(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactones were obtained by the reaction of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester. Decarboxylation of the -(1-ethoxyvinyl)--ethoxycarbonyl-butyrolactones in DMSO leads to -(1-ethoxyvinyl)--butyrolactones, the hydrolysis of which gives -acetyl-butyrolactones. Ethyl trans-3-acetyl-3-pentenoate was obtained by decarboxylation of -methyl--(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactone in DMSO.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 22–25, January, 1992.     

Studies in dipyridyl chemistry. VII. Sulfur trioxide sulfonation of γ,γ′-dipyridyl

Reaction of ,-dipyridyl with sulfur trioxide at room temperature gives ,-dipyridyld'isulfotrioxide, which latter on heating at 200° gives ,-dipyridyl-sulfonic acid. Salts of ,-dipyridyl-3-sulfonic acid are prepared, among them the potassium, sodium, barium, and 3-cyano-,-dipyridyl salts.For Part VI see [1].     

Thermal decompositions of Y,La and lanthanide 3-hydroxybenzoates in air and nitrogen atmospheres

When heated, the 3-hydroxybenzoates of Y, Sm and Eu(III) decompose in two steps. The hydrates first lose crystallization water and the anhydrous complexes are then transformed to oxides in air, and to mixtures of oxide and C in nitrogen atmosphere. When heated in air, the pentahydrates of La, Pr and Nd are dehydrated in two stages and the anhydrous complexes are then transformed to oxides; when heated in nitrogen, they are dehydrated in one step and then decomposed to mixtures of oxides and C.

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Zusammenfassung Die 3-Hydroxybenzoate von Y, Sm und Eu(III) zersetzen sich beim Erhitzen in zwei Schritten. Die Hydrate verlieren zunächst Kristallwasser und die wasserfreien Komplexe werden in Luft in die Oxide und in Stickstoffatmosphäre in ein Gemisch des betreffenden Oxids und Kohlenstoff überführt. Beim Erhitzen in Luft werden die Pentahydrate von La, Pr und Nd in zwei Schritten dehydratisiert und die wasserfreien Komplexe in die Oxide überführt; beim Erhitzen in Stickstoff erfolgt dagegen die Dehydratisierung in nur einem Schritt und Endprodukt der Zersetzung ist ein Gemisch von Kohlenstoff und dem entsprechenden Oxid.

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3- , . , — . , . , .

     

Specificity of states of Cu2+ ions in ZSM zeolites due to the cooperative Jahn-Teller effect

Crystalline silicate of ZSM zeolite structure was synthesized via hydrothermal crystallization at large contents of copper. ESR spectra of Cu²⁺ ions stabilized in this system are determined by the specific ordering due to the cooperative Jahn-Teller effect of Cu²⁺ ions with the d_x ²–y² ground state.

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423° ZSM . Cu(II), , - Cu²⁺ cdx²–y²— .

     

The effect of outer sphere cations on the thermal stability of nitritocuprates(II)

Thermal analyses by Derivatograph were made for salts of the general formula M ₂ ^I M^II[Cu(NO₂)₆] where M^I=K⁺, Rb⁺ or Cs⁺; and M^II=Ca²⁺, Sr²⁺, Ba²⁺ or Pb²⁺. From the results and the chemical and diffractometric analysis of sinters of chosen salts, the mechanism of thermal decomposition was established. Some conclusions concerning the effects of outer sphere cations on the thermal stabilities of these salts are also drawn.

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Zusammenfassung Es wurden thermische Analysen mit einem Derivatographen für die Salze der allgemeinen Formel M₂ ^IM^II [Cu(NO₂)₆] durchgeführt [M^I=K⁺, Rb⁺, Cs⁺; M^II=Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺]. Aus den Ergebnissen dieser sowie der chemischen und diffraktometrischen Analysen der Sinterprodukte der jeweiligen Salze wurde der Mechanismus ihrer chemischen Zersetzung ermittelt. Einige Folgerungen bezüglich der Wirkung von Kationen der äusseren Sphäre auf die thermische Stabilität konnten ebenfalls gemacht werden.

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Résumé Le mécanisme de la décomposition thermique des sels de formule générale M₂ ^IM^II [Cu(NO₂)₆] où M^I=K⁺, Rb⁺, Cs⁺ et M^II=Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺ a été établi à partir des données thermiques obtenues à l'aide d'un Derivatograph, ainsi que par des analyses thermiques et diffractométriques sur les produits frittés. L'effet des cations de la couche externe sur la stabilité thermique de ces sels est discuté.

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M ₂ ^I M^II[Cu(NO₂)₆], M^I=K⁺, Rb⁺, Cs⁺; M^II=Ca²⁺, Sr²⁺, Ba²⁺, b²⁺. , , . , .

     

Hydrogenolysis of n-butane on low-loaded Rh/TiO2. II. Catalysts obtained by impregnation

The activity in n-butane hydrogenolysis of Rh/TiO₂ (0.6 wt. % Rh) catalysts propared by impregnation and reduced at different heating rates is reported. The catalyst reduced at 5 K/min is ten times more active than that reduced at 20 K/min, despite the fact that the dispersion values are similar in both cases.

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Rh/TiO₂ (0,6 . % Rh), qv , -. , 5 /, , 20 /, , .

     

Determination of the kinetic parameters of polyvinylchloride

Kinetic equations proposed in the literature for thermal decomposition reactions may be approximated at low conversions by the relation: ^b=Dp(x). This equation reveals three kinds of behaviour under isothermal conditions, as evidenced in the thermal dehydrochlorination of Polyvinylchloride. The kinetic parameters were determined with a computing program and its performances were tested. The calculation method was applied to some Polyvinylchloride macromodels.

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Zusammenfassung In der Literatur vorgeschlagene kinetische Gleichungen für thermische Zersetzungsreaktionen können bei niedrigen Konversionen mit der Gleichung ^b=Dp(x) genähert werden. Diese Gleichung offenbart unter isothermen Bedingungen drei Verhaltensweisen, wie an der thermischen Dehydrochlorierung von Polyvinylchlorid bewiesen wird. Die kinetischen Parameter wurden mittels eines Computerprogrammes ermittelt und ihre Leistungsfähigkeit überprüft. Das Rechenverfahren wurden an einigen Polyvinylchloridmakromodellen getestet.

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, , ^b =Dp(x). , . , . .

     

Determination of hydroxyl groups and/or water on the surface of oxide catalysts by a pulse chromatographic method

A pulse chromatographic method based on the reaction of gaseous dimethylzinc tetrahydrofura nate was developed for the determination of surface hydroxyl groups and/or adsorbed water in solid porous materials. The procedure is rapid and gives results comparable to other methods. Some heterogeneous catalysts and supports have been analyzed.

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, , / , . , . .