Temperature induced structural changes of Cu(II) and Ni(II) complexes and their thermal decomposition

The paper discusses the structural changes of some Cu(II) and Ni(II) complexes during the heating and their influence upon the decomposition stoichiometry. The influence of the interactions inside of coordination polyhedra, bonding and stereochemical properties of the counter ions or molecules are discussed in this connection as well. The expressive influence of the plasticity or rigidity of the Cu(II) and Ni(II) coordination polyhedra, respectively, is emphasized.

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Zusammenfassung Es werden wÄrmebedingte StrukturverÄnderungen einiger Cu(II) bzw. Ni(II)-Komplexe sowie deren Einflu\ auf die Stöchiometrie der Zersetzung beschrieben. In diesem Zusammenhang wird auch ebenso der Einflu\ von Wechselwirkungen innerhalb des Koordinationspolyeders sowie von Bindungs- und stereochemischen Eigenschaften der Gegenionen oder -moleküle beleuchtet. Es wird der ausdrucksvolle Einflu\ der PlastizitÄt und HÄrte von Cu(II)- und Ni(II)-Koordinationspolyedern hervorgehoben.

     

Investigation on the chemistry of berbans—VII: Synthesis of 10,11-dimethoxy(depyrrolo)raunescine stereoisomers

Acyloxy-ketone rearrangement, proceeding by the action of base, has been observed in the case of ketone 2. By the reduction of ketones 2 and 3 with sodium boron hydride, new 10, 11-dimethoxy(depyrrolo)raunescine stereoisomers (5a–7a) have been prepared. Previously known alcohols with alloberban skeleton (12,13) have been similarly converted into tetracyclic raunescine stereoisomers (8a,9) by the oxido-reductive method. The stereochemistry of these compounds has been investigated by physical (¹H NMR, IR) and by chemical methods.     

Potentiometric studies of dithiooxamide with a sulphide-selective membrane electrode

The sulphide-selective electrode is applicable to the determination of dithiooxamide by titration with silver nitrate. The effect of the alkali content of the solutions on the reaction has been studied. The reaction products are silver sulphide, oxalic acid, and nitric acid. If the alkali concentration of the solution is lower than that equivalent to the acid formed during the titration, the amount of sulphide produced by hydrolysis decreases and the equilibrium potential is established more slowly.The determination is rapid and accurate in the presence of 1 M sodium hydroxide.     

Behavior and characteristics of biogenic amines, ornithine and lysine derivatized with the o-phthalaldehyde-ethanethiol-fluorenylmethyl chloroformate reagent

The stability and characteristics of the ornithine (Orn), lysine (Lys), putrescine (Put), cadaverine (Cad), 1,7-diaminoheptane (Diah), spermidine (Spd) and spermine (Spm) derivatives obtained with the o-phthalaldehyde (OPA)-ethanethiol (ET)-fluorenylmethyl chloroformate (FMOC) reagent has been investigated. The stoichiometry of the introduced, two-step derivatization process has been followed by photodiode array (DAD) and fluorescence (FL) detections, simultaneously, while the composition of derivatives was confirmed by on-line HPLC-electrospray ionization (ESI) MS measurements. Depending on the composition of the OPA reagents, in addition to the secondary amino group-containing Spd and Spm, under common aqueous conditions also Orn and Lys do react with FMOC resulting in derivatives of various compositions. Applying the OPA-ET reagent of increasing methanol (Met) content (38-80%, v/v) the formation of the FMOC group containing Orn and Lys derivatives could be considerably decreased. Optimum elution condition (18 min, including equilibration) was developed for the simultaneous quantitation of Orn, Lys, Put, Cad, Diah, Spd and Spm, in the presence of the rest of protein amino acids. The practical utility of the method was demonstrated by the analysis of mouse tissues. Average reproducibility of quantitations, characterized with the relative standard deviation percentages of fluorescence intensities and UV responses, in order of listing, proved to be 2.1% and 2.1%, respectively.     

Thermal and FTIR spectroscopic analysis of the interactions of aniline adsorbed on to MCM-41 mesoporous material

The adsorption of aniline on Na-AlMCM-41 synthesized by us has been characterized by infrared spectroscopy, temperature programmed desorption (TPD), and differential thermal analysis methods. Aniline would be mostly bound to the mesostructure through weak pi interactions. On the mesostructure containing adsorbed water, the co-adsorption of aniline could occur by weak hydrogen bonding through surface water molecules. For water, two possible modes of adsorption have been identified. Different associations between aniline and hydrated and nonhydrated mesostructures have been evaluated in order to favor the posterior in situ polymerization of adsorbed aniline.     

Prediction of chromatographic parameters for some anilines by molecular connectivity

Summary The possible relation existing between R_F values obtained by thin-layer chromatography for a group of anilines with connectivity indices proposed by Kier and Hall has been studied. Using multivariable regression the corresponding connectivity functions, selected for their respective correlation coefficients, standard deviations, Snedecor's F and Student's t were obtained. Regression analysis of the connectivity functions gives a correct prediction of the experimental elution sequence for this group of substances on silica gel stationary phases and various mobile phases of different polarity. The corresponding random and stability studies of the different prediction models selected were carried out, showing good stability and null randomness in all cases.     

Thermochemical properties of benzoic acid derivatives VIII. Enthalpies of combustion and formation of o-, m-, and p- t-butylbenzoic acids

The enthalpies of formation in the crystalline state at 298.15 K of o-, m-, and p-t-butyl-benzoic acids have been determined by static-bomb calorimetry. Vapour-pressure determinations were made by the Knudsen-effusion technique and the sublimation enthalpies at the mean temperatures of the measurement ranges have been derived for the three acids. The values obtained are:

     

68.

Gravimetrische Halogenbestimmung in organischen Verbindungen nach dem Hydrierverfahren     

Mlinkó  S. 《Mikrochimica acta》1961,49(6):854-859

Zusammenfassung Es wurde eine gravimetrische Halogenbestimmung zur Analyse organischer Substanzen ausgearbeitet. Die Pyrolyse und Hydrierung wird in ammoniakhaltigem Wasserstoffstrom ausgeführt, die gebildeten Ammoniumhalogenide werden in einem nach dem Hydrierrohr geschalteten Absorptionsrohr gesammelt. Die Analyse läßt sich durch Wägung des Absorptionsrohres ausführen. Gleichzeitige Gegenwart von Schwefel stört die Analyse nicht.

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Summary A gravimetric method has been worked out for determining the halogens in organic materials. The pyrolysis and hydrogenation are conducted in a current of hydrogen containing ammonia, and the ammonium halides formed are collected in an absorption tube attached to the hydrogenation tube. The analysis can be done by weighing the absorption tube. The presence of sulfur does not interfere with the analysis.

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Résumé On a élaboré un dosage gravimétrique des halogènes dans l'analyse des substances organiques. On réalise la pyrolyse et l'hydrogénation dans un courant d'hydrogène contenant de l'ammoniac et l'on recueille les halogénures d'ammonium formés dans un tube à absorption disposé après le tube à hydrogénation. On peut effectuer l'analyse en pesant le tube à absorption. La présence simultanée du soufre ne gêne pas l'analyse.

     

69.

Correlation between transport and equilibrium properties through the ternary interaction parameter for cosolvent and cononsolvent polymeric systems     

C. M. Gómez  V. Soria  A. Campos 《Colloid and polymer science》1992,270(3):197-206

A study of the ternary polymer systems dimethyl formamide-ethyl acetate-polystyrene, chloroform-1,4 dioxane-polystyrene and tetrahydrofuran-chloroform-polystyrene was carried out by viscosity and light scattering at 298 K. A good correlation has been found between the excess intrinsic viscosity, unperturbed polymer dimensions, second virial coefficient and the excess Gibbs free energy by using a ternary interaction parameter, dependent on molecular weight. This modification enables the conversion between transport and equilibrium properties.     

70.

Studies of the silica reduction process by carbon     

J. Bialoskórski 《Journal of Thermal Analysis and Calorimetry》1990,36(6):2029-2032

The reduction of amorphous silica by carbon black was studied in argon atmosphere by use of MOM Derivatograph C. The apparent kinetic parameters of the process were determined. The possible mechanism of reaction was proposed.

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Zusammenfassung Unter Verwendung eines MOM Derivatograph C wurde in Argonatmosphäre die Reduktion von Siliziumdioxid mit Ruß untersucht. Es wurden die scheinbaren kinetischen Größen des Prozesses bestimmt und ein möglicher Reaktionsmechanismus vorgeschlagen.

     

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	$\text{ΔH}{}_{\mathrm{f}}{}^{\mathrm{o}}\text{(c, 298.15 K)/kJ mol}{}^{\mathrm{?1}}$	$\text{ΔH}{}_{\mathrm{s}}\text{/kJ mol}{}^{\mathrm{?1}}$
o-t-butylbenzoic acid	476.2 ± 1.9	99.8 ± 0.4	(at 314.6 K)
m-t-butylbenzoic acid	504.3 ± 1.6	103.0 ± 0.5	(at 326.5 K)
p-t-butylbenzoic acid	502.9 ± 1.7	103.8 ± 0.4	(at 334.1 K)

Gravimetrische Halogenbestimmung in organischen Verbindungen nach dem Hydrierverfahren

Zusammenfassung Es wurde eine gravimetrische Halogenbestimmung zur Analyse organischer Substanzen ausgearbeitet. Die Pyrolyse und Hydrierung wird in ammoniakhaltigem Wasserstoffstrom ausgeführt, die gebildeten Ammoniumhalogenide werden in einem nach dem Hydrierrohr geschalteten Absorptionsrohr gesammelt. Die Analyse läßt sich durch Wägung des Absorptionsrohres ausführen. Gleichzeitige Gegenwart von Schwefel stört die Analyse nicht.

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Summary A gravimetric method has been worked out for determining the halogens in organic materials. The pyrolysis and hydrogenation are conducted in a current of hydrogen containing ammonia, and the ammonium halides formed are collected in an absorption tube attached to the hydrogenation tube. The analysis can be done by weighing the absorption tube. The presence of sulfur does not interfere with the analysis.

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Résumé On a élaboré un dosage gravimétrique des halogènes dans l'analyse des substances organiques. On réalise la pyrolyse et l'hydrogénation dans un courant d'hydrogène contenant de l'ammoniac et l'on recueille les halogénures d'ammonium formés dans un tube à absorption disposé après le tube à hydrogénation. On peut effectuer l'analyse en pesant le tube à absorption. La présence simultanée du soufre ne gêne pas l'analyse.

     

Correlation between transport and equilibrium properties through the ternary interaction parameter for cosolvent and cononsolvent polymeric systems

A study of the ternary polymer systems dimethyl formamide-ethyl acetate-polystyrene, chloroform-1,4 dioxane-polystyrene and tetrahydrofuran-chloroform-polystyrene was carried out by viscosity and light scattering at 298 K. A good correlation has been found between the excess intrinsic viscosity, unperturbed polymer dimensions, second virial coefficient and the excess Gibbs free energy by using a ternary interaction parameter, dependent on molecular weight. This modification enables the conversion between transport and equilibrium properties.     

Studies of the silica reduction process by carbon

The reduction of amorphous silica by carbon black was studied in argon atmosphere by use of MOM Derivatograph C. The apparent kinetic parameters of the process were determined. The possible mechanism of reaction was proposed.

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Zusammenfassung Unter Verwendung eines MOM Derivatograph C wurde in Argonatmosphäre die Reduktion von Siliziumdioxid mit Ruß untersucht. Es wurden die scheinbaren kinetischen Größen des Prozesses bestimmt und ein möglicher Reaktionsmechanismus vorgeschlagen.