Ru(III) catalyzed oxidation of some aliphatic alcohols by N-bromosuccinimide (NBS). A kinetic study

Kinetics of Ru(III) catalyzed oxidation of methanol, ethanol, n-propanol, n-butanol, isopropanol and iso-butanol by N-bromosuccinimide (NBS) in the presence of Hg(II) acetate have been studied in acid medium. The oxidation exhibits a fractional order in [alcohol] and first order in [NBS]. The applicability of Taft's equation was tested. The probable mechanism is discussed.

---

, , -, -, - () Hg(II), Ru(III), . . . .

     

The direction of elimination in the pyrolysis kinetics of 3-bromobutyronitrile

The gas phase elimination of 3-bromobutyronitrile, examined in a static system and seasoned vessel, follows a first-order rate law. The reaction in the temperature range of 370.0–420.1°C and pressure range of 54–198 torr, is homogeneous and unimolecular. The temperature dependence of the rate coefficient is given by the equation: log k₁ (s^–1)=(13.74±0.25)–(213.7±3.2) kJ mol^–1 (2.303RT)^–1. The cyano substituent has been found to retard the elimination process through its electronwithdrawing resonance effect. Most of the dehydrobromination product is cis-trans-crotonitrile, while very little of allyl cyanide is obtained. This result is rationalized in terms of electronic factors.

---

3- , . . 370,0–420,1°C 54–198 . : log k₁ (cek^–1)=(13,74±0,25)–(213,7±3,2)(/)×(2,303 RT)^–1. - . --, . .

     

Comparative selectivities of two copper-based catalysts: Mixed Cu?Cr and Cu?Al oxides for allylic alcohol reactions in the presence of molecular hydrogen

In the presence of mixed copper-chromium (aluminium) oxide, allylic alcohols react with molecular hydrogen and lead to several primary products. This is due to the simultaneous presence of two active sites in the mixed oxides. Copper species (Cu⁺) are responsible for hydrogenation (HYD) and the chromium (Cr³⁺) (aluminium [Al³⁺]) species for the isomerization (I) and the hydrodeoxygenation (HDO) reactions. However, the stronger acidic character of Al³⁺, compared with Cr³⁺, entails some differences evidenced by the HYD/(I+HDO) and HDO/I ratios.

---

- () , . . (Cu⁺ (), (Cr³⁺) ( Al³⁺) (), (). , Al³⁺ Cr³⁺ , /(+) /.

     

Thermal and some other properties of the complexes crystallizing from the system Ni(II)-en-[Ni(CN)4]2−-H2O

Seven complex compounds exhibiting the compositions Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) and-Ni(en)₂Ni(CN)₄ (VII) were prepared from the system Ni-en-[Ni(CN)₄]^2–-H₂O. These compounds were examined by the methods of infrared spectroscopy, X-ray powder diffractometry, UV-VIS reflectance spectroscopy, and also by the measurement of magnetic moments. The thermal stability, the stoichiometry of thermal decomposition and the mutual transformations were investigated with a derivatograph. The reactions proceeding according to the following schemes were observed if the system was heated to appropriate temperature: (I)(II)(III)(V)(IV) and (VI)(VII)(III)(V)(IV) Process (VII)(III) represents isomerization. The reversibility of the process (V)(IV) is due to the high hygroscopicity of the anhydrous complex. The changes in structure in the course of the individual processes are discussed.

---

Zusammenfassung Aus einem System Ni-en-[Ni(CN)₄]^2–-H₂O wurden sieben Komplexe der Formeln Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) und-Ni(en)₂Ni(CN)₄ (VII) hergestellt. Diese Verbindungen wurden mittels IR-Spektroskopie, Röntgenpulverdiffraktometrie, UV-Reflexionsspektroskopie und durch Messungen des magnetischen Momentes untersucht. Die Wärmestabilität, die Stöchiometrie des thermischen Zerfalles und die gegenseitigen Umwandlungen wurden mittels eines Derivatographen untersucht. Wird das System auf geeignete Temperaturen erhitzt, kann der Reaktionsverlauf durch folgendes Schema dargestellt werden: (I)(II)(III)(V)(IV) und (VI)(VII)(III)(V)(IV).Der Prozeß (VII)(III) verkörpert eine Isomerisierung. Die Umkehrbarkeit von Prozeß (V)(IV) ist auf die ausgeprägten Hygroskopieeigenschaften des wasserfreien Komplexes zurückzuführen. Es werden die im Ablaufe der einzelnen Prozesse vorgehenden Strukturveränderungen besprochen.

---

Ni- -[No(N)]² -₂ Ni(en)₃Ni(CN)₄ · ₂ (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄-2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2,5H₂O (VI) -Ni(en)₂Ni(CN)₄ (VII). , , - , . , . (I)(II)(III)(V)(IV) (VI)(VII)(III)(V)(IV). (VII)(III) . (V)(IV) . .

     

Thermal decomposition of hydrazinium monoperchlorate in the molten state

The thermal decomposition of hydrazinium monoperchlorate (HP-1) in the molten state has been investigated using differential thermal analysis, thermogravimetric analysis, a constant volume manometric technique and mass-spectrometry. The stoichiometry of the reaction can be represented by the equation: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + + 23.5 H₂OThe data seem to indicate that the mechanism, which involves an associated complex, remains unchanged from 140 to 190°. Consequently, impurities capable of forming associated complexes with the hydrazinium or the perchlorate ion desensitize the thermal decomposition of HP-1, the extent of desensitization being determined by the size, the charge and the concentration of the impurity.

---

Zusammenfassung Die thermische Zersetzung von Hydrazin-monoperchlorat (HP-1) im geschmolzenen Zustand wurde unter Einsatz der Differentialthermoanalyse, der thermogravimetrischen Analyse, der manometrischen Methode mit konstrantem Volumen und der Maßenspektrometrie untersucht. Die Stöchiometrie der Reaktion kann durch folgender Gleichung dargestellt werden: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 20₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂ODie Angaben zeigen, dass der Mechanismus, in welchen ein assoziierter Komplex mit inbegriffen ist, im Temperaturenbereich von 140° bis 190° C unverändert bleibt. Folglich setzen Verunreinigungen, die mit dem Hydrazinoder dem Perchlorat-Ion assozüerte Komplexe zu bilden imstande sind, die Empfindlichkeit der thermischen Zersetzung von HP-1 herab, wobei das Ausmaß der Herabsetzung von der Grösse, der Ladung und der Konzentration der Verunreinigung abhängt.

---

Résumé La décomposition thermique en milieu fondu du monoperchlorate d'hydrazinium (HP-1) a été étudiée par analyse thermique différentielle, thermogravimétrie, manométrie à volume constant et spectromètrie de masse. La réaction peut être représentée par l'équation suivante: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂OLes données semblent indiquer que le mécanisme mettant en jeu un complexe associé reste inaltéré dans l'intervalle de températures allant de 140 à 190°. Par conséquent, les impuretés qui pourraient former des complexes associés avec les ions hydrazinium ou perchlorate désensibilisent la décomposition thermique de HP-1, le taux de désensibilisation étant déterminé par la taille, la charge et la concentration de l'impureté.

---

(-1), , , - -. : 20 N₂H₅ClO₄ 13 NH₄ClO₄ + 3.5 l₂ + 2 ₂ + 13 N₂ + 0.5 N₂O + 0.5 ₂ + 23.5 ₂ , , - , 140° 190°. , , - , -1, , .

     

Coadsorption of ethylene and oxygen on an iridium surface

It is established that the hydrocarbon coverage (0<1) formed at T<400 K on the Ir surface is oxidized upon oxygen exposures to CO and H₂O by an adsorption mechanism. Complete oxidation to CO₂ and H₂O is achieved at T350 K after C₂H₄ exposures of the oxygen coverage.

---

, (<1), T<400 K Ir, CO H₂O . CO₂ H₂O T350 K C₂H₄ .

     

Certified reference materials for thermal analysis

Eight inorganic substances recommended by ICTA as temperature standard reference materials for DTA and DSC were studied: KNO₃, KClO₄, Ag₂SO₄, K₂CrO₄, quartz, K₂SO₄, BaCO₃ and SrCO₃. The content of pure component in each of these substances was determined by classical chemical analysis. The temperatures and the heats of polymorphic transformations of these substances were measured with a Perkin-Elmer DSC-2 differential scanning calorimeter, and DTA studies were performed on a MOM 1500 D Q-derivatograph. The plot heat of transformation by DSCvs. DTA peak area is advanced as a calibration line for the approximate estimation of quantitative DTA effects. The substances studied will be certified as temperature standard reference materials for use in DTA and DSC.

---

Zusammenfassung Acht von der ICTA als Temperaturstandard-Referenzmaterialien für DTA und DSC empfohlene und im Lande verfügbare Substanzen wurden untersucht: KNO₃,KClO₄, Ag₂SO₄, K₂Cr₂O₄, Quarz, K₂SO₄, BaCO₃ und SrCO₃. Der Gehalt der Substanzen an diesen Verbindungen wurde klassisch chemisch-analytisch bestimmt. Temperaturen und Enthalpien der polymorphen Umwandlungen wurden mit dem Gerät DSC 2 (Perkin-Elmer) bestimmt, DTA-Untersuchungen erfolgten mittels Derivatograph Q 1500 D (MOM). Eine Darstellung (Umwandlungsenthalpie aus DSC-Messung) über der DTA-peak-Flä-che wird als Eichgerade für die näherungsweise quantitative Bewertung der DTA-Effekte vorgeschlagen. Die genannten Substanzen sollen als Temperaturstandards für DTA und DSC geprüft werden.

---

(-, -, , , , , ), . . -2 -, Q- 1500 . ( ) — . .

     

A method to calculate density distribution of adsorption centers from temperature-programmed desorption spectra

A new method to calculate the function of density distribution of adsorption centers according to the activation energies of desorption by using temperature-programmed desorption curves is suggested. The application of this method is exemplified by toluene desorption from ZSM-5 zeolite.

---

, . .

     

Glass transition and crystallization effects demonstrated by thermal analysis of liquid-quenched ternary glasses Te80Ge20−xA x V (AV=Sb,Bi)

In DSC studies of liquid-quenched ternary chalcogenide glasses Te₈₀Ge_20–xA _x ^V (A^V=Sb, Bi), the characteristic temperatures (glass transition and crystallization temperatures) were determined. Changes in the thermal stabilities of these glasses, depending on the element A (Sb, Bi) from group V of the periodic table and on its content in the alloy were evaluated. Moreover, the effect of changes in the glass composition on the glass formation ability expressed by the parameter K_g1 was determined.

---

Zusammenfassung In DSC-Untersuchungen abgeschreckter ternärer Chalkogenidgläser des Typs Te₈₀Ge_20–xA _x ^v (A^x=Sb, Bi) wurden die charakteristischen Temperaturen (die GlasÜbergangs- und Kristallisationstemperaturen) bestimmt. Die Änderungen der Thermostabilität dieser Gläser wurden in Abhängigkeit von dem Element A (=Sb, Bi) aus der V Gruppe der Periodensystems und von seinem Gehalt in der Legierung ausgewertet. Ausserdem wurde der Einfluß der Änderungen in der Glaszusammensetzung auf die Glasbildungsfähigkeit, ausgedrückt durch den Parameter K_g1, bestimmt.

---

Résumé On a déterminé par analyse calorimétrique différentielle (DSC) les températures caractéristiques (températures de transition vitreuse et de cristallisation), des verres ternaires à chalcogénures formés par trempe à partir du liquide, du type Te₈₀Ge_20–xA _x ^v (A^v=Sb, Bi). On a évalué la variation de la stabilité thermique de ces verres en fonction de l'élément A (=Sb, Bi) du Vème groupe du tableau périodique et de sa teneur dans l'alliage. De plus, on a déterminé l'effet des variations de la composition du verre sur la capacité de formation du verre qui s'exprime par le paramètreK _g1.

---

Te₈₀Ge_20–xA _x ^v (A^v=Sb, Bi), , . A(=Sb,Bi) . , K _gl, .

---

---

Research supported by the U. S. National Science Foundation under Grant No. GF 421 76     

Dependence between electrocatalytic activity and the size of platinum crystallites

The dependence of the electrocatalytic activity of platinum deposited on a carbon carrier by anodic oxidation of hydrogen on the size of platinum crystallites has been investigated. The influence of the basic character of the surface compounds existing on the carbon carrier on the size of the crystallites and the rate of their growth has been established.

---

, , . , , .

     

Thermogravimetric and kinetic study of a clodronic acid complex formed with sodium

Thermal stability of the clodronic acid complex formed with sodium (Na₂CCl₂(HPO₃)₂ ·4H₂O) was studied using both dynamic and isothermal thermogravimetric analyses as well as mass spectra. The thermal decomposition has two stages: dehydration and loss of two molecules of hydrogen chloride. Using the isothermal TG data the first step was found to be a phase-boundary reaction while the second step obviously cannot be described with just one reaction mechanism. The final residue of the dynamic TG analyses above 810 K was found to be sodium metaphosphate.

---

Zusammenfassung Sowohl mittels dynamischer und thermogravimetrischer Untersuchungen als auch and Hand von Massenspektren wurde die thermische Stabilität des mit Natrium gebildeten Säurekomplexes Na₂CCl₂(HPO₃)₂·4H₂O untersucht. Die thermische Zersetzung vollzieht sich in zwei Schritten: Dehydratation und Verlust von zwei Molekülen HCl. Auf Grund der isothermen TG Angaben ist der erste Schritt eine Phasengrenzreaktion, während der zweite Schritt mit einem einzigen Reaktionsmechanismus nicht eindeutig beschrieben werden kann. Das Endprodukt der DTG Analyse oberhalb 810 K erwies sich als Natriummethaphosphat.

---

-Na₂CCl₂/HPO_3/2·4H₂O — , - . , , , . , , . 810 .

     

Electrocatalytic hydroxylation of aniline on metal oxides

Studies of Mn, Cr, Cu, La, Sb, V, Co and W oxides as catalysts for the electrocatalytic oxidation of aniline to p-aminophenol have revealed the electrocatalytic activity of WO₃. A mathematical model for the kinetics of analine oxidation on WO₃ is suggested that agrees fairly well with the experimental data.

---

Mn, Cr, Cu, La, Sb, V, Co, W -. , . , , .

     

Stereochemistry of heterogeneous catalytic reactions; epimerization of alicyclic diols on copper catalysts

During the reactions of 8 isomeric alicyclic diols on Cu/Al and Cu catalysts, epimerization of the isomers was observed. The epimerization proceeds via a hydroxy-oxo intermediate.

---

8 Cu/Al Cu . -.

---

---

Part XLII of the series Study of the transformations of diols and cyclic ethers.     

Influence of carbon dioxide on the position of oxygen adsorption equilibrium on silver

Due to interaction with carbon dioxide, when some adsorbed oxygen atoms on silver surfaces are converted into carbonate groups, the binding energy diminishes and the volatility of adsorbed oxygen rises.

---

, , .

     

Kinetics of ammonia decomposition of polycrystalline rhodium at pressures between 0.013 and 103 kPa

The rates of ammonia decomposition on polycrystalline Rh wires between 600 and 1800 K and at pressures between 13.3 Pa and 103 kPa were measured and fitted with a Langmuir-Hinshelwood unimolecular reaction rate expression. At high temperatures and pressures the reaction seems to be mass transfer controlled.

---

Rh 600–1800 K 13,3 –103 . , -. .

     

Sulfur poisoning of Pt/Al2O3 catalysts, II. Influence of sulfate impurities on carbon monoxide chemisorption and butane hydrogenolysis

Sulfate contamination of Pt/Al₂O₃ catalysts does not affect the metal properties for temperatures of reduction lower than 300°C. After hydrogen treatment at 500°C, the sulfate groups were reduced into hydrogen sulfide which poisons platinum. Poisoning by sulfate impurities is especially drastic for low metal loadings. The adsorption of CO in the bridged form is no longer observed for platinum sulfur coverages higher than 0.28 S/Pt_s. The rate of butane hydrogenolysis strongly decreases with the sulfur coverage. Hydrogenolysis at the end of the chain is less affected than hydrogenolysis in the middle of the molecule.

---

Pt/Al₂O₃ 300°C. 500°C , . . S/Pt_s 0,28 CO . . , .

     

Review of some metallurgical problems suitable for quantitative calorimetric treatment

A review is given of various metallurgical problems treated in the author's laboratory, for which quantitative calorimetry gave very valuable information. Measurements of thermodynamic data for phase diagram calculations, vacancies in ordered alloys, annealing of steels, and the recovery and crystallization of amorphous alloys are successively examined.

---

Zusammenfassung Es wird eine Übersicht über verschiedene, in unserem Laboratorium bearbeitete metallurgische Probleme gegeben, für die durch quantitative Kalorimetrie sehr genaue Informationen erhalten werden. Es wird auf Messungen thermodynamischer Daten für Phasendiagrammberechnungen, auf Fehlstellen in geordneten Legierungen, auf das Tempern von Stahl sowie auf Aufarbeitung und Kristallisation von amorphen Legierungen eingegangen.

---

, . , , .

---

---

Dedicated to Professor Dr Kurt Komarek on his 60th birthday.     

Preparation and properties of supported vanadium-phosphorus catalysts studied by chemical analysis and ESR

The preparation of vanadium-phosphorus catalysts is described, showing the considerable influence of phosphorus on the concentration of V⁴⁺ ions. The oxidation properties were studied by chemical analysis and electron spin resonance. Moreover, ESR spectra show a strong influence of moisture on the structure of the catalysts.

---

- , V⁺⁴. , . , , .