Adaptation d'une methode d'analyse debitmetrique aux mesures sous pression de gaz carbonique. Application a l'etude de la reaction CdCO3 ⇄ CdO+CO2 jusqu'a 300 bar

Résumé Une méthode de mesure de débit de gaz associée à l'ATD est appliquée à l'étude de la réaction CdCO₃ CdO+CO₂. Après avoir présenté une adaptation du dispositif expérimental aux mesures sous pression de gaz carbonique et l'étalonnage correspondant, on donne les résultats obtenus jusqu'à 300 bar pour deux variétés de carbonate.

---

A method based on the measurement of gas flow rate combined with DTA has been applied to the study of the reaction CdCO₃ CdO+CO₂. The construction of the experimental apparatus for the measurement of pressure and calibration are described, and results obtained with two different carbonates up to 300 bar are given.

---

Zusammenfassung Eine auf Gasströmungsmessung beruhende Methode verbunden mit der DTA wurde zur Untersuchung der Reaktion CdCO₃ CdO+CO₂ herangezogen. Es wurde der Aufbau der Versuchseinrichtung zur Messung unter Druck und die Eichung beschrieben, sowie weiterhin die bis 300 bar mit zweierlei Karbonaten erhaltenen Versuchsergebnisse mitgeteilt.

---

CdCO₃ CdO + ₂ , . . 300 .

     

Microthermogravimetric studies of the kinetics and thermodynamics of heterogeneous reactions in sulfur-containing atmospheres

A thermobalance for studies of the high-temperature sulfidation of metals and alloys is described. This apparatus permits the determination of mass changes in the sulfidized sample as functions of temperature and sulfur vapour pressure with an accuracy of 10^–6 g. Besides heterogeneous kinetics measurements, it has been shown that the chemical diffusion coefficients and deviations from stoichiometry of metal sulfides can also be studied as functions of temperature and sulfur pressure by means of equilibration measurements.

---

Zusammenfassung Es wird eine Thermowaage zur Untersuchung der Hochtemperatur-Sulfidierung von Metallen und Legierungen beschrieben. Diese Apparatur ermöglicht die Bestimmung von MassenverÄnderungen der sulfidierten Proben in AbhÄngigkeit von der Temperatur und dem Schwefeldampfdruck mit einer Genauigkeit von 10^–6 g. Es wird gezeigt, da\ damit, sofern Gleichgewichtsmessungen ausgeführt werden, auch die chemischen Diffusionskoeffizienten und Abweichungen der Metallsulfide von der Stöchiometrie in AbhÄngigkeit von der Temperatur und dem Schwefeldampfdruck untersucht werden können.

---

. 10^–6 . , , , .

     

Thermochemical studies on the systems ACl/CeCl3 (A=Na-Cs)

The pseudobinary systems ACl/CeCl₃ (A=Na-Cs) were reinvestigated by means of DTA. The following compounds were found and identified through their X-ray patterns (primarily detected compounds in italics):NaCe _1.67 Cl ₆; K₃CeCl₆, K₂CeCl₅,KCe _1.67 Cl ₆;Rb ₃ CeCl ₆, Rb₂CeCl₅,RbCe ₂ Cl ₇; Cs₃CeCl₆, Cs₂CeCl₅,CsCe ₂ Cl ₇. The compounds A₂CeCl₅ crystallize with the K₂PrCl₅ structure. The high-temperature modifications of the compounds A₃CeCl₆ have the cubic elpasolite structure. The hexagonal unit cell of KCe_1.67Cl₆ is related to the CeCl₃ structure: 0.33 Ce³⁺ are substituted by one K^s+. The structure of CsCe₂Cl₇ can be described with a hexagonal subcellZ=4,a=9.72 andc=14.94 Å; however, small superstructure reflexions reduce the symmetry.The thermodynamic functions for the reactionsnACl+CeCl₃=A _n CeCl _n+3(A=K, Rb) were determined by means of e.m.f. measurements.Measurements of the e.m.f.E vs. T yielded the Gibbs enthalpiesG ^r . The temperature-dependence was found to be linear.The most important result is the formation of the elpasolites (A₃CeCl₆) and ACe₂Cl₇.

---

Zusammenfassung Die pseudobinären Systeme ACl/CeCl₃ (A=Na-Cs) wurden mittels Differenzthermoanalyse (DTA) neu untersucht. Folgende Verbindungen wurden gefunden und durch ihre Röntgenbeugungsmuster charakterisiert (erstmalig nachgewiesene Verbindungen sind kursiv):NaCe _1.67 Cl ₆; K₃CeCl₆, K₂CeCl₅,KCe _1.67 Cl ₆;Rb ₃ CeCl ₆, Rb₂CeCl₅,RbCe ₂ Cl ₇; Cs₃CeCl₆, Cs₂CeCl₅,CsCe ₂ Cl ₇. Die Verbindungen A₂CeCl₅ kristallisieren im K₂PrCl₅-Typ. Die Hochtemperaturmodifikationen der Verbindungen A₃CeCl₆ liegen in der kubischen Elpasolith-Struktur vor. Die hexagonale Elementarzelle des KCe_1.67Cl₆ ist mit der CeCl₃-Struktur verwandt: 0,33 Ce³⁺ sind durch ein K⁺ ersetzt. Die Struktur des CsCe₂Cl₇ kann mit einer hexagonalen Pseudozelle beschrieben werden:a=9,72;c=14,94Å;Z=4; schwache Überstrukturreflexe reduzieren jedoch die Symmetrie. Die thermodynamischen Funktionen für die Reaktionen:n ACl + CeCl₃=A _n CeCl _n+3 (A=K, Rb) wurden durch EMK-Messungen bestimmt. Messungen der Abhängigkeit von e. m. f.E gegenT ergaben die Gibbs-EnthalpienG ^r . Es wurde eine lineare Temperaturabhängigkeit gefunden. Als wichtigstes Resultat ist die Bildung von Elpasoliten (A₃CeCl₆) und von Verbindungen (ACe₂Cl₇) anzusehen.

---

ACl/CeCl₃, A . - ( ):NaCe _1.67 Cl ₆; K₃CeCl₆, K₂CeCl₅,KCe _1.67 Cl ₆;Rb ₃ CeCl ₆, Rb₂CeCl₅,RbCe ₂ Cl ₇; Cs₃CeCl₆, Cs₂CeCl₅ CsCe ₂Cl₇. A₂CeCl₅ K₂PrCl₅. A₃CeCl₆ . KCe_1.67Cl₆ CeCl₃, 0,33 Ce³⁺ . CsCe₂Cl₇ a=9,72 Å,c=14,94 Å Z=4. , . n ACl + CeCl₃=A _n CeCl _n+3(A=K, Rb) . . . . . .E , G ^r . ACe₂Cl₇.

---

---

Presented as a poster at the 8th ICTA, Bratislava, 1985.

---

This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.     

Reactivity of coordinated O2? ion-radicals in the oxidation of organic compounds

By the flow ESR method, the rates of the reaction of the radical complex Ti(IV)(O ₂ ^– ) with some aromatic compounds in aqueous solution have been measured. An elementary step of these reactions seems to be one-electron oxidation with the formation of a substrate cation-radical.

---

- Ti(IV)(O ₂ ^– ) . - -.

     

Nature of intermediates in the synthesis of hydrocarbons from methanol

According to the GC-MS analysis of the composition of liquid hydrocarbons obtained in methanol conversion on ZSM-5 zeolites and the selectivity of cyclohexene conversion on these catalysts, the sequence of the aromatization reaction steps is discussed.

---

-- , ZSM-5, .

     

Comparative thermogravimetric study of chlorinations of hematite and wustite

The reactions of hematite and wustite with Cl₂, COCl₂, CO+Cl₂ and gaseous CCl₄ were studied by thermogravimetry, X-ray diffraction and computer-assisted thermodynamic calculations. During the chlorination of hematite, only gaseous products were formed. The apparent activation energies were calculated from the isothermal TG curves. The chlorination of wustite involves the formation and transformation of a series of solid chloride products. FeCl₂(s), FeCl₃(s) and FeOCl(s) were found as intermediates during chlorination with Cl₂ or Cl₂+CO, while only FeCl₂(s) was detected in reactions with COCl₂ oe CCl₄. The chlorinations of the iron oxides with various agents were compared, and the differences in reactivity sequences were established.

---

Zusammenfassung Die Reaktionen von HÄmatit und Wustit mit Cl₂, COCl₂, CO+Cl₂ and gasförmigen CCl₄ wurden thermogravimetrisch und röntgendiffraktometrisch untersucht. Thermodynamische Berechnungen wurden mit Computern ausgeführt. Bei der Chlorierung von HÄmatit entstehen nur gasförmige Reaktionsprodukte. Die scheinbaren Aktivierungsenergien wurden aus isothermen TG-Kurven berechnet. Bei der Chlorierung von Wustit wird eine Reihe von festen Chloriden gebildet. FeCl₂(s), FeCl₃(s) und FeOCl(s) treten bei der Chlorierung mit Cl₂ oder Cl₂ + CO als intermediÄre Produkte auf, wÄhrend bei Reaktionen mit COCl₂ oder CCl₄ nur FeCl₂(s) nachgewiesen wurde. Die verschiedenen Chlorierungsmittel wurden hinsichtlich ihrer Wirksamkeit miteinander verglichen und in einer entsprechenden Reihenfolge eingeordnet.

---

Cl₂, COCl₂, CO+Cl₂ CCl_{2 4} , , . . . . Cl₂ Cl₂ + CO , FeCl₂, FeCl₃ FeOCl, COCl₂ CCl₄ — FeCl₂. .

     

Fluorometric assay of amino acids and amines by use of 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole(NBD-F) in high-performance liquid chromatography

Summary The reaction of a newly developed fluoregenic reagent, 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole(NBD-F), with amino acids and biogenic amines was investigated. NBD-F was reactive to both primary and secondary amines including amino acids and biogenic amines such as catecholamines. The amino acids were reacted with the reagent, separated by high-performance liquid chromatography on -Bondapak C₁₈ and detected at 10 to 100 fmol level. A few g of protein hydrolysates, rabbit pyruvate kinase M₁, rabbit aldolase A and papain, were adequate for the amino acids quantitation. An automatic amino acid analyzer with fluorometric detection by the post-column derivatization with NBD-F enabled the amino acid profile analysis in blood samples present in a paper disc of 3 mm diameter.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Crystal and molecular structure of trans-diiodobis-(1-methyl-5-nitroimidazole)platinum(II)

Summary A new platinum complex of 1-methyl-5-nitroimidazole has been obtained and characterized by elemental analysis, i.r. and n.m.r. spectroscopy. The structure of [PtI₂-(C₄ H₅N₃O₂)₂] has been determined by single-crystal X-ray diffraction. The crystals are triclinic: P1, a = 15.640(3), b = 12.617(2), c = 6.701(1) , = 102.77(5), = 101.15(5), = 100.71(5)°, V = 1228.6(3) ³, Z = 3, D_x = 2.851(6) Mg m^–3, (MoK ) = 0.71069 , = 12.85 mm^–, F(000) = 948, final R = 0.038 for 2859 reflections. The complex consists of monomeric PtI₂(1-methyl-5-nitroimidazole)₂ units. The coordination geometry is square-planar. The two 1-methyl-5-nitroimidazole ligands are trans coordinated to platinum.     

Synthesis,spectral and electrochemical studies of alkoxo-bonded mixed-ligand oxovanadium(IV) and oxovanadium(V) complexes incorporating tridentate ONO donor azophenolalcoholate/aldiminealcoholates

Mixed-ligand vanadyl(IV) and vanadyl(V) complexes with tridentate ONO donor azophenolalcoholate/aldiminealcoholates [viz., 2-hydroxy-2-hydroxymethyl-5-methylazobenzene (H₂L¹), N-(2-hydroxymethylphenyl)-salicylaldimine (H₂L²) and N-(2-hydroxymethylphenyl)1-hydroxy-2-naphthaldimine (H₂L³)] and bidentate NN [viz., 2,2-bipyridine (bipy) and 1,10-phenanthroline (phen)] or NO [viz., 8-hydroxyquinoline (Hhq)] donor ligands have been prepared and characterized by elemental analyses and by i.r., e.p.r. and u.v.–vis. spectroscopies. The data show that the vanadyl(IV) complexes exist in two isomeric solid forms viz., monomers and polymers, whereas vanadyl(V) complexes exist only in the monomeric form. The polymeric structure results from intermolecular V=OV=O interactions. The complexes with NN donor ligands are one electron paramagnetic and display two ligand-field transitions in the visible region, whereas the complexes with ON donor ligands are diamagnetic and exhibit only LMCT bands. The vanadyl(IV) complexes display an irreversible oxidation peak near +0.30 V for complexes with (L¹)^2– and near +0.55 V for complexes with (L²)^2– and (L³)^2– ligands, while the vanadyl(V) complexes display a quasi-reversible one electron reduction couple near –0.23 V versus s.c.e. The trends in the (V=O), values for the visible region transitions and the redox potential values for the vanadyl(IV) complexes have been scrutinized.     

Polyhydroxysteroids from the Far-Eastern starfishCtenodiscus crispatus

Four new polyhydroxysteroids, 5-cholesta-3,5,6,15,16,25,26-heptaol, 24-ethyl-5-cholesta-3,5,6,15,28,29-heptaol-29-sulfate, (22E)-24-methyl-5-cholest-22-ene-3,5,6,15,25,26-hexaol-26-sulfate, 24-propyl-5-cholesta-3,5,6,8,15,28,29-heptaol, and the known 5-cholesta-3,5,6,15,16,26-hexaol, have been isolated from the starfishCtenodiscus crispatus.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1821–1825, October, 1994.     

Effect of electronic interaction between metal and support, II. TPD, TPR and chemisorption studies on Ru/Al2O3?MgO catalysts

TPD, TPR and chemisorption were used to characterize Ru/Al₂O₃–MgO catalysts. It is suggested that the acidity of support may influence the properties of catalysts significantly.

---

, Ru/Al₂O₃–MgO. , .

     

Preparation of micron-size monodisperse polymer particles by seeded polymerization utilizing the dynamic monomer swelling method

Utilizing a new type of monomer swelling method, 6.1 m-size monodisperse polymer particles were prepared by seeded polymerization. 1.8 m-size monodisperse polystyrene (PS) seed particles (1.8 m in size) were prepared by dispersion polymerization in ethanol-water (80/20, v/v) medium in the presence of poly(acrylic acid) as stabilizer with 2,2-azobisisobutyronitrile as initiator. The PS seed dispersion was mixed with ethanol-water (60/40, v/v) solution dissolving styrene (S) monomer, benzoyl peroxide as initiator, and poly(vinyl alcohol) as stabilizer. By slow, continuous, dropwise addition of water with a micro feeder into the mixture, the PS particles absorbed the many S monomers, which were separated from the medium and swelled from 1.8 m to 8.4 m while keeping the monodispersity high. We named this procedure the dynamic swelling method. Then, the seeded polymerization of the absorbed S monomer was carried out in the presence of NaNO₂ as water-solube inhibitor.Part CXXII of the series Studies on Suspension and Emulsion.     

Deutung der K α-satelliten bei leichten Elementen

Zusammenfassung Ausgehend von der KL-Ionisation wurden die K -Satelliten(, , ₃, ₃, ₄) der Elemente Z=8 bis Z=12 den entsprechenden Übergängen zugeordnet. Die Berechnung der Übergänge wurde nach der Z-Dependence-Theorie bis einschließlich zweiter Näherung durchgeführt.

---

Interpretation of the K -satellites of the light elements

Starting from the KL-ionisation the K -satellites(, , ₃, ₃, ₄) of the elements Z=8 to Z=12 have been assigned to the corresponding transitions. The transitions have been calculated by the Z-dependence-theory including the second approximation.

---

Résumé Les satellites K (, , ₃,₃, ₄) des éléments Z= 8 à Z=12 ont été attribués aux transitions correspondantes à partir de l'ionisation KL. Les transitions ont été calculées par la théorie dépendant de Z en tenant compte de l'approximation seconde.

---

---

Herrn Prof. Timm in dankbarer Würdigung der Hilfen, die die BASF für den Aufbau unserer theoretisch-chemischen Arbeitsgruppe geleistet hat, zum 60. Geburtstag gewidmet.

---

Der Deutschen Forschungsgemeinschaft dankt D. H. für die finanzielle Unterstützung, die die Dunchführung dieser Arbeit wesentlich erleichterte.     

Effect of water vapor upon thermal dehydration of Mg(H2PO4)2·2H2O

The dehydration of Mg(H₂PO₄)₂·2H₂O was investigated by means of thermal analysis, X-ray diffraction, IR absorption and chromatographic methods. The dehydration process and the structures of the products were found to depend considerably on the water vapor partial pressure in the gas phase. Therefore, in thermal analysis, the sample holder type had an analogous influence on the results. The dehydration end-product at 550 °C when the labyrinth crucible was used was well-crystallized Mg(PO₃)₂, whereas with the multiplate sample holder it was completely amorphous condensed magnesium phosphate.

---

Zusammenfassung Mittels Thermoanalyse, Röntgendiffraktion, IR-Absorptionsspektroskopie und chromatografischen Methoden wurde die Dehydratation von Mg(H₂PO₄)₂·2H₂O untersucht. Es wurde festgestellt, daß der Dehydratationsvorgang und die Struktur der Produkte beträchtlich vom partiellen Dampfdruck von Wasser in der Gasphase abhängen. Der Probenhaltertyp in der Thermoanalyse besitzt deshalb einen analogen Einfluß auf die Ergebnisse. Wird ein Labyrinthtiegel verwendet, ist das Dehydratationsendprodukt bei 550 °C kristallines Mg(PO₃)₂, bei der Verwendung eines Mehrplattenprobenhalters hingegen erhält man amorph kondensiertes Magnesiumphosphat.

---

Mg(H₂PO₄)₂·2H₂O , , - . , , , () . , 550 °C Mg(PO₃)₂, .

     

Inductive hydrogen formation in the oxidation of ascorbic acid by nitrosylpentacyanoferrate(II)

In the first period of the reaction at pH 8 slow evolution of CO₂ and N₂O was observed. After gas evolution ceased, on adding NaOH, formation of N₂O again and, unexpectedly, H₂ was found. The amount of H₂ was measured as a function of reaction conditions. Illumination with visible light and the excess of the oxidant promote hydrogen evolution. The experiments in D₂O resulted in H₂, HD and D₂. The non-statistical isotope distribution was interpreted by a kinetic isotope effect.

---

pH=8 CO₂ N₂O. NaOH, N₂O , , H₂. H₂ . . D₂O H₂, HD D₂. .

     

Triterpene Glycosides of Astragalus and Their Genins. LXI. Occurrence of Cycloartane 6-O-Monodesmosides

Cyclosiversigenin 6-O--L-rhamnopyranoside and 6-O--D-glucopyranoside were isolated fromAstragalus coluteocarpusBoiss. (Leguminosae) andAstragalus dissectusB. Fedtsch. et N. Ivanova, respectively. Cyclosiversigenin 5-O--L-rhamnopyranoside was shown to be an artifact forAstragalus coluteocarpus.Thus, the cyclosiversigenin 6-O--D-glucopyranoside that was isolated from certainAstragalusspecies is hypothesized also to be an artifact. Glycosylation of the 6 -hydroxyl group of cycloartanes by D-glucose and D-xylose, in contrast with other substituents, does not change the low-field position of the PMR signal of the 4-CH ₃ group (1.65 2.01 ppm) that is caused by the influence of deuteropyridine directly on the 6 -hydroxyl. Obviously one of the hydroxyls of the -D-glucopyranoside or -D-xylopyranoside residues has the same effect in this instance.     

Molecular encapsulation of transition metal complexes in cyclodextrins. Part 2. Synthesis and crystal structures of 2:1 adducts between α-cyclodextrin and metallocenium hexafluorophosphates [η5-C5H5)2M]PF6(M = Fe,Co, Rh)

The title metallocenium salts form crystalline 2:1 host:guest inclusion compounds with-cyclodextrin, [(⁵-C₅H₅)₂M]PF₆ · 2-CD · 8H₂O (1, M = Fe;2, M = Co;3, M = Rh). The X-ray crystal structures of1 and3, and the lattice constants, crystal system and space group of2 have been determined. Crystal data: triclinic, space groupP1 (No. 1),Z = 1;1,a = 13.865 (2) Å,b = 13.839 (2) Å,c = 15.520 (2) Å, = 91.43 (2)°, = 85.81 (2)°, = 120.22 (2)°, andR _F = 0.089 for 4257 observed MoK reflections [I > 3(I)];2,a = 13.810 (2) Å,b = 13.872 (2) Å,c = 15.560 (2) Å, = 93.99 (2)°, = 87.06 (2)°, = 120.04 (2)°;3,a = 13.756 (1) Å,b = 13.863 (1) Å,c = 15.561 (2) Å, =94.39 (1)°, = 86.92 (1)°, = 119.89 (1)°, andR _F = 0.061 for 11142 observed MoK reflections [I > 3(I)]. In the crystals of1 and3, two -cyclodextrin molecules are arranged head-to-head to form a dimer by means of intermolecular hydrogen bonding across the secondary hydroxyl faces of adjacent -CD monomers. The dimers are stacked along the crystallographicc axis to form a channel-type structure. The metallocenium cation is encapsulated within the cavity of the dimer, while the PF ₆ ^– anion is located outside the cavity, being centered between the primary hydroxyl faces of adjacent dimers. Eight water molecules of hydration per asymmetric unit reside in the spaces between the -CD columns. In view of the almost identical crystal data for2 a similar structure can be assumed for the cobaltocenium adduct.     

Orbital interactions in anti- and syn- tricyclooctadienes and their homoderivatives

Photoelectron spectroscopy and molecular orbital calculations of the Extended Hückel, MINDO/3 and STO-3G Hartree-Fock type have been applied to anti- and syn-tricyclo[4.2.0.0^2,5]octadiene (1 and 2) and their homo and bishomo derivatives. The resulting ordering of the one-electron levels for 1 and 2 are 7a _g ( ₊), [6b _u (), 5b _u (_–)], 4a _u (), 3a _u () and 7a ₁(₊), 5b ₂(), 6b ₂(_–), 3a ₂(), 4b ₁(), respectively. The present results differ substantially from those previously published.     

Reactive properties of phosphine complexes of some transition metals in ethylene carbonylation

Catalystic properties of Group VIII transition metals and Cu, Ag, Au and Hg compounds in diethylketon synthesis from ethylene, carbon monoxide and hydrogen in concentrated aqueous solutions of trifluoroacetic acid containing triphenylphosphine have been examined in mild conditions (70°C, 1 bar). It has been established that under these conditions, in addition to Pd axcetate, a noticeable activity in diethylketone synthesis is observed only for Pt and Rh compounds.

---

VIII , Cu, Ag, Au Hg , , , (70°C, 1 ). , Pd Pt Rh .

     

Dehydrogenation of methanol to formaldehyde over titanium alloys

The dehydrogenation of methanol to formaldehyde has been studied in the temperature range between 523 and 723 K over titanium alloys. The FeTi alloy showed a high selectivity for the formation of formaldehyde. Addition of zinc increased the specific rate of formaldehyde formation with a simultaneous decrease in its selectivity.

---

523 723 K . FeTi . Zn .