Hydrogenolysis of n-butane on Ni-Pd/SiO2 catalysts

Supported Ni-Pd/SiO₂ catalysts of different Ni and Pd composition were studied in n-butane hydrogenolysis. The reaction rate, selectivity towards methane, ethane and propane were determined. On the basis of these data the relationship between the size and composition of the active center and the possibility of surface segregation of one of the components is discussed.

---

Ni-Pd/SiO₂ Ni Pd -. , . .

     

Violation of steady state process in CO hydrogenation to alcohols

Studies of the effect of iron supported on the surface of a K₂CO₃-doped zinc-chromium catalyst or entrapped from synthesis gas, have revealed violation of the steady state process in alcohol synthesis. Periodic oscillations in temperature and concentrations of reactants and reaction products are observed.

---

, K₂CO₃ - -, , , , .

     

A simple method of determining the activation energy of an isothermal solid-state decomposition reaction

A simple approach to determine the activation energy (E) of solid-state decomposition reactions is described. The activation energy is calculated from the slope of the logarithm of the maximum peak height of the isothermal DTA trace versus the reciprocal of the absolute temperature. The proposed method is applied in the study of the kinetics of thermal decomposition of cadmium carbonate. The activation energy calculated from this method (90.8±2.2 kJ mole^–1) is in very good agreement with the value (87.5±2.5 kJ mole^–1) obtained by the conventional method.

---

Zusammenfassung Eine einfache Annäherung zur Bestimmung der Aktivierungsenergie (E) von Festphasenzersetzungsreaktionen wird beschrieben. Die Aktivierungsenergie wird aus dem Anstieg des Logarithmus der maximalen Peakhöhe der isothermen DTA-Kurve als Funktion der reziproken absoluten Temperatur errechnet. Die vorgeschlagene Methode wird zur Untersuchung der Zersetzungskinetik von Cadmiumcarbonat eingesetzt. Die hiernach berechnete Aktivierungsenergie (90.8±2.2 kJ mol^–1) ist in guter Übereinstimmung mit dem durch die konventionelle Methode erhaltenen Wert (87.5±2.5 kJ mol^–1).

---

Résumé On décrit une méthode simple d'approximation pour déterminer l'énergie d'activation (E) des réactions de décomposition en phase solide. Le calcul de l'énergie d'activation s'effectue à partir de la pente du logarithme de la hauteur maximale du pic de la courbe d'ATD isotherme en fonction de l'inverse de la température absolue. On a appliqué la méthode proposée lors de l'étude de la cinétique de la décomposition thermique du carbonate de cadmium. L'énergie d'activation calculée à partir de cette méthode (90.8±2.2 kJ mole^–1) est en bon accord avec la valeur (87.5±2.5 kJ mole^–1) obtenue par la méthode conventionnelle.

---

. . . (90.8+2.2 .^–1) 87.5± 2.5 .^–1, .

---

---

The authors express their thanks to Dr. V. V. Deshpande and to Shri M. S. Kumbhar for their help in the DTA studies.     

Kinetics of isotope exchange of dioxygen with a powdered high-temperature superconducting material Ba2YCu3O7?x

It has been found that the rate of isotope exchange in Ba₂YCu₃O_7–x–O₂ system is high. Its kinetics is exponential, first order with respect to dioxygen and the exchange is of the mixed first/third type.

---

Ba₂YCu₃O_7–x–O₂ . -, -, - .

     

New Molybdenum(V) Complexes Prepared by the Oxidation of Dinuclear Quadruply-Bonded Molybdenum(II) Monothiocarboxylates

Oxidation of molybdenum(II) thiopivalate and thiobenzoate in the presence of -picoline or pyridine results in the formation of dinuclear molybdenum(V) complexes of the general formulae [Mo₂O₂(-O)₂(-SO₄)L₄] with L = -picoline or pyridine and [Mo₂O₂(-O)(-S)(-SO₄)L₄] with L = -picoline. As determined by X-ray structure analysis, two complexes with -picoline differ in their bridging cores: In one complex, two Mo atoms are doubly bridged through two oxygen atoms; in the other, one Mo atom is doubly bridged through oxygen and sulfur atoms. However, they both crystallize together. The product is solvated with -picoline and water molecules. Molybdenum atoms exhibit distorted octahedral coordinations. The same complexes were prepared also through direct reactions of [Mo₂O₃(O₂CCH₃)₄] with thiopivalic and thiobenzoic acid in the presence of -picoline or pyridine. The appearance of the oxo-oxygens and sulfido-sulfur as well as sulfato ligand is explained by the molybdenum-catalyzed oxidation of thiocarboxylates.     

Oxidation of thermally degraded PVC

The decrease of polyene concentration and the elimination of hydrogen chloride have been studied in the oxidation of thermally predegraded PVC powder samples. The rate of both processes increases with increasing predegradation time and oxygen pressure. The close correlation between the thermooxidative hydrogen chloride elimination and polyene oxidation has been shown.

---

, . . HC1 .

     

Quantitative electron-probe microanalysis of light elements: Determination ofa-Si∶C∶N∶O∶H insulating films

Amorphous SiCNOH films (1–3 m) are studied by EPMA after deposition of gold (1–5 nm) as a conductive coating. Its influence on thek-ratios (X-ray intensity relative to an uncoated standard) of silicon, carbon, nitrogen and oxygen is described as a linear function of the simultaneously determinedk-ratio of gold. Thek-ratios representing the uncoated specimen are obtained by extrapolation and, in combination with the PAP matrix correction model, quantitative EPMA can be performed with an analytical error of 2–5%, as it is demonstrated by samples of SiC, Si₃N₄ and SiO₂. No systematic shift of the concentrations is observed for layers ofa-SiCNOH determined at various electron energies of 5–12.5 keV. Hydrogen is calculated by difference and the concentrations prove to be a useful estimate in agreement with the results of chemical analysis. Si-K/Si-K spectra recorded on organo-silicon films and binary silicon compounds point out significant differences concerning the formation of Si-C, Si-N and Si-O chemical bonds.     

Chemistry of 2-hetarylbenzimidazoles. 8. Synthesis and properties of 1-methyl-2-(5′-methyl-2′-selenienyl)benzimidazole

1-Methyl-2-(5-methyl-2-selenienyl)benzimidazole was synthesized and subjected to electrophilic-substitution reactions: nitration, bromination, sulfonation, chloromethylation, formylation, and acylation. The substituent usually enters the 4 position of the selenophene ring, but nitration with acetyl nitrate leads to a mixture of 5-nitro and 4-nitro derivatives. Oxidation of 2-selenienylbenzimidazole with potassium permanganate leads to the 5-carboxy derivative, while oxidation with selenium dioxide leads to the 5-hydroxymethyl and 5-formyl derivatives.See [1] for Communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1636–1639, December, 1987.     

Benzimidazole derivatives

-(1,3-Dimethyl-5-benzimidazolonyl)acrylic acid, -(1,3-dimethyl-5-benzimidazolonyl)propiolic acid, and 5-ethynyl-1,3-dimethylbenzimidazolone were synthesized via the Wittig reaction from 5-formyl-1,3-dimethylbenzimidazolone. The UV and IR spectra are presented.See [1] for communication XXV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 122–123, January, 1971.     

Heating and quenching of metastable superconducting compounds with a plasma jet

Superconducting compounds, such as cubic -MoC_1–x, cubic -WC_1–x, hexagonal MoB₂, and cubic -TaN, which are metastable at room temperature, have been formed by heating and quenching of their respective equilibrium phases, such as hexagonal -MoC_1–x, hexagonal WC, rhombohedral Mo₂B₅, and hexagonal -TaN in a plasma jet. From calculations based on a simple model, the quenching rate of particles has been estimated to be 10⁵ deg s^–1.     

Hydrogen pressure dependence of the reaction of neopentane with hydrogen over Pd/SiO2 and Pt/SiO2 catalysts

H₂ pressure influences in different ways the reaction rates of neopentane conversion over Pd/SiO₂ and Pt/SiO₂ catalysts. It seems that on Pt/SiO₂ both isomerization and hydrogenolysis involve a common surface intermediate (probably an adalkyl), whereas on Pd/SiO₂ the hydrogenolysis goes via more dehydrogenated species than those involved in isomerization.

---

H₂ Pt/SiO₂ Pd/SiO₂. , Pt/SiO₂ (, ), Pd/SiO₂ , .

     

Parent and mixed ligand complexes in the copper(II)-ethylene glycol-sulphate system

Eleven copper(II)-ethylene glycol-sulphate complexes of different compositions were prepared, one of them-CuGl₂(H₂O)₂SO₄-in single-crystal form. A thermoanalytical study of these complexes revealed three types of thermal decomposition pattern. The X-ray structure of the single-crystal demonstrated the presence of ethylene glycol bridges resulting in endless chains in the crystal.

---

Zusammenfassung Elf Kupfer(II)-äthylenglykol-sulfat-Komplexe unterschiedlicher Zusammensetzung wurden dargestellt, einer davon — CuGl₂(H₂O)₂SO₄ — in Form von Einkristallen. Die thermoanalytische Untersuchung dieser Komplexe ergab drei Typen der thermischen Zersetzung. Die röntgendiffraktometrische Bestimmung der Struktur des in Form von Einkristallen erhaltenen Komplexes zeigte, daß den Kristall endlose Ketten von Äthylenglykolbrücken durchziehen.

---

() — , — CuGl₂(H₂O)₂SO₄ — . . , , .

     

Triterpene glycosides ofHedera taurica XV. Structures of glycosides St-I3, St-I4a, St-I4b, and St-I5 from the stems of Crimean ivy

From the stems of Crimean ivyHedera taurica Carr. (fam. Araliaceae) we have isolated the new triterpene glycosides St-I₃, St-I₅, and St-I_4a, which are, respectively, the 3–0--D-glucopyranoside 28-O-[O--L-rhamnopyranosyl-(14)-O-(6-O-acetyl--D-glucopyranosyl)-(16)-O--D-glucopyranosides] of oleanolic acid and of hederagenin and the 3-O--D-glucopyranuronoside 28-O--gentiobioside of oleanolic acid, and also the previously known 3-O-[O--D-galactopyranosyl-(12)--D-glucopyranuronoside 28-O--D-glucopyranoside] of oleanolic acid (glycoside Rb-4).Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 404–410, May–June, 1997.     

IR-Spektroskopische Untersuchungen an 1,3-Dioxa- und 1,3-Diaza-2-boracyclopentanderivaten

Zusammenfassung Die IR-Spektren von mehreren Dioxa- und Diazaboracyclopentanderivaten wurden zusammen mit jenen von C-deuterierten Verbindungen untersucht. Besonderer Wert wurde auf die Klärung von Kopplungen zwischen BN-, BO- und CH₃-Schwingungen im Bereich zwischen 1550 bis 1300 cm^–1 gelegt.

---

IR-spectra of several dioxa- and diaza-boracyclopentanes have been studied together with those of some C-deuterated analogues. Special attention has been given to coupling effects of BN-, BO-, and CH₃-modes in the 1550–1300 cm^–1 region.

---

---

Mit 3 Abbildungen     

Research on vinyl ethers of the furan series VIII. Vinyl ethers of 2-(α-furyl)ethanols

Vinyl ethers of-furyl-,-(5-methylfuryl)-,-furfuryloxy-, and-tetrahydrofurfuryl-oxyethanols were synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1593–1595, December, 1971.     

Formation of methyl platinum complex in the reaction of methane with chloroplatinic acid

The¹HNMR method and chemical analysis indicate that a complex of Pt(IV) containing a CH₃–Pt fragment is formed in the reaction of H₂PtCl₆+H₂PtCl₄ with methane at 120 °C in aqueous CF₃CO₂H. The complex was isolated from the solution as an adduct of Ph₃P.

---

, H₂PtCl₆ H₂PtCl₄ CF₃COOH 120°C (IV), Pt–CH₃. Ph₃P , .

     

Thermal decomposition of the solvent-extracted chloro complexes of vanadium(IV) with trioctylamine and trioctylmethylammonium chloride

The complexes (R₃NHVO(OH)Cl₂)₂ and (R₃RNVO(OH)Cl₂)₂ prepared by drying in vacuo the organic solutions from the extraction into benzene of aqueous vanadyl chloride solution with trioctylamine (TOA, R₃N) and trioctylmethylammonium chloride (TOMAC, R₃RNCl), were studied by thermogravimetry and differential thermal analysis under an atmosphere of nitrogen, and the products of their thermal decomposition, such as volatile matter and residues, by gas chromatography. X-ray diffraction and infrared spectroscopy. It was found that the complexes with TOA and TOMAC thermally decompose to V₂O₃ at 200–300° by cracking of the compounds R₃NHVO(OH)Cl₂ and R₃RNVO(OH)Cl₂ formed via dissociation of the complexes at about 150°.

---

Zusammenfassung Die Komplexe (R₃NHVO(OH)Cl₂)₂ und (R₃RNVO(OH)Cl₂)₂ wurden hergestellt, indem benzolische und wässrige Vanadylchlorid-Lösungen mit Trioctylamin (TOA, R₃N) und Trioctylmethylammoniumchlorid (TOMAC, R₃RNCl) extrahiert und die erhaltenen Lösungen im Vakuum eingedampft wurden. Die Komplexen wurden in Stickstoffatmosphäre mittels TG und DTA untersucht und die thermischen Zersetzungsprodukte, und zwar sowohl die flüchtigen Verbindungen als auch die Rückstände, gaschromatographisch bzw. röntgendiffraktometrisch und IR-spektroskopisch bestimmt. Es wurde festgestellt, daß die Komplexe mit TOA und TOMAC bei 150° in die Verbindungen R₃NHVO(OH)Cl₂ und R₃RNVO(OH)Cl₂ dissoziieren, die bei 200–300° thermisch zu V₂O₃ zersetzt werden.

---

(R₃NHVO(OH)Cl₂)₂ (R₃RNVO(OH)Cl₂)₂ (R₃,) ( , R₃RNCl). , , . , 200–300° V₂₃ R₃NV()l₂ R₃RNVO(OH)Cl₂, 150°.

---

---

We wish to thank the Koei Chemical Co. Ltd. for samples of TOA and TOMAC.     

Radiolysis of nitrous oxide adsorbed on alumina ionic mechanism of radiolysis of nitrous oxide on alumina with small surface areas

A mechanism is proposed for the radiolysis of adsorbed N₂O describing the experimental dependences of the radiation-chemical yields of O _st ^– and N₂ on N₂O coverages.

---

N₂O, - O _st ^– N₂ N₂O.

     

Basicity of alumina-magnesia catalysts

In the series of Al₂O₃, MgO and Al₂O₃–MgO catalysts, those containing about 75% Al₂O₃ and 25% MgO show the highest activity in the decomposition of diacetone alcohol in non-polar solvents. The fastest rates of reaction, which follows the zero-order kinetics over the whole range of conversion, coincide with the occurrence of strong basic sites on the catalyst surface.

---

Al₂O₃, MgO Al₂O₃–MgO , 75% Al₂O₃ 25% MgO, . , .