Enthalpies de melange du systeme antimoine-tellure a 909,30 K, 911,85 K et 917,95 K

Thermodynamical data on Sb-Te system at 909,30 K, 911,85 K and 917,95 K. The integral molar enthalpies of formation of liquid Sb-Te alloys were measured at three temperatures by drop calorimetry.Partial molar enthalpies of formation of these alloys, referring to the pure liquid constituants, and enthalpie of formation at 298 K of the compound Sb₄₀₅Te₅₉₅ were deduced.

---

Zusammenfassung Thermodynamische Daten, des Systemes Sb-Te bei 909,30, 911,85 und 917,95 K. Mittels Drop-Kalorimetrie wurden die integralen molaren Bildungsenthalpien von flüssigen Sb-Te Legierungen bei drei verschiedenen Temperaturen gemessen. Die partiellen molaren Bildungsenthalpien dieser Legierungen, bezogen auf die reinen flüssigen Komponenten sowie die Bildungsenthalpie der Verbindung Sb_0.405Te_0.595 bei 298 K wurden abgeleitet.

---

Sb-Te 909,30; 911,85 917,95 . , Sb_0.4050.595 298 .

     

Catalytic performance in Co hydrogenation over triruthenium ketenylidene cluster-derived catalyst

The ruthenium catalyst prepared from triruthenium ketenylidene cluster exhibited high catalytic activity in CO hydrogenation, compared with the catalyst from [HRu₃(CO)₁₁]^–. The high activity possibly resulted from the ketenyl group (CCO) that could be partly converted to carbide species.

---

, , CO, [HRu₃(CO)₁₁]^–. , , (CCO), .

     

Catalytic preparation of diacetone alcohol in controlled flow conditions

Catalytic preparation of diacetone alcohol from acetone was studied using strong basic ion exchangers as catalysts. A continuous process was carried out in an enlarged laboratory set-up with controlled flow rate. Experiments were performed with respect to experiment duration, temperature, flow rate, catalyst porosity and catalyst-acetone ratio. The quantity of DAA was determined by gas chromatography. The effects of temperature, catalyst porosity and catalyst-acetone ratio on the reaction course were significant in comparison with other parameters examined. An exponential dependence of C/A ratio on DAA yield was found.

---

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

     

Ba(OH)2 as catalyst in organic reactions, part XIV. Michael addition catalyzed by barium complex salts in the homogeneous phase

Michael addition to chalcone is catalyzed by barium complex salts in the homogeneous phase under various conditions. The nature of these intermediates is analyzed. These complex salts are described for the first time. The Michael adduct of malonodinitrile to chalcone is described for the first time.

---

, , . . . . .

     

Quantitative thermal analysis,II

Some problems on adjustment of the equipment and on data evaluation, in view of the equations derived earlier for the calculation of specific heat and heat of transformation are discussed. It is shown that quantitative determinations are possible also if the adjustment is non-ideal and that both air and an inert material, respectively, may be used as reference material.

---

Zusammenfassung Gewisse Probleme des Adjustierens der Ausrüstung und der Auswertung der Daten in Hinsicht auf die früher abgeleiteten Gleichungen zur Errechnung der spezifischen und Umwandlungswärmen wurden besprochen. Man bewies, daß quantitative Bestimmungen auch bei nichtidealem Adjustieren möglich sind bzw. daß Luft und Inertstoff gleichwie als Referenzstoffe dienen können.

---

Résumé On discuté divers problèmes relatifs à la mise au point de l'appareillage et à l'évaluation des données, dans l'optique des équations déduites précédemment pour le calcul de la chaleur spécifique et de la chaleur de transformation. On montre qu'il est possible de faire des déterminations quantitatives même si la mise au point n'est pas idéale et que l'on peut utiliser comme substances de référence l'air aussi bien qu'un corps inerte.

---

, . ë ë . , , « » , .

     

Some peculiarities of cyclohexane conversion on zeolite catalysts

Cyclohexane conversion on zeolite and zeolite-containing catalysts has been examined. The formation of cracking, isomerization and dehydrogenation products is suggested to follow two parallel independent mechanisms through different intermediate carbocations.

---

. , .

     

On the deactivation of Fe2O3?MoO3/SiO2 catalysts in the oxidation of methanol to formaldehyde

The deactivation behavior of Fe₂O₃–MoO₃/SiO₂ catalysts with different Fe₂O₃+MoO₃ content in the oxidation of methanol to formaldehyde is investigated. A simplified reaction-deactivation kinetic model is presented and used to compare and discuss the different behaviors.

---

Fe₂O₃–MoO₃/SiO₂ Fe₂O₃+MoO₃ . : -.

     

Temperature programmed desorption of NH3 and H2O from NH4NaX and CoNH4NaX zeolites

A study has been made of temperature programmed desorption (TPD) of NH₃ and H₂O from samples of NH₄X and CoNH₄X zeolites of various degree of exchange. NH₃ TPD peaks could be explained by interaction of NH₃ with different Brönsted and Lewis acidic centers. Moreover a water peak at high temperatures allowed interpretations of the dehydroxylation, and by reason of the characteristic desorption temperatures a particular state of the Co²⁺ ions in the CoNH₄X zeolites is postulated.

---

- () NH₃ H₂O NH₄X CoNH₄X . NH₃ NH₃ =qs . . Co²⁺ CoNH₄X.

     

Oxidation of trimethoxybenzenes to benzoquinones with hydrogen peroxide in the presence of heteropolyacid

Trimethoxybenzenes were oxidized to dimethoxy-p-benzoquinones in fairly good yields (50–60%) with hydrogen peroxide in the presence of heteropolyacid in the solvent of acetic or formic acid.

---

-- (50–60%) , , .

     

Experimental study of the bifurcation diagram in the Belousov-Zhabotinskii reaction

In the citric acid-Mn²⁺–H₂SO₄–KBrO₃ system a hysteresis phenomenon in the switching on and off of the oscillations has been observed. The possible bifurcation diagrams of the system are discussed.

---

-Mn⁺²–H₂SO₄–KBrO₃ . .