Selective Arylation of β-Cyclodextrin with an Ethylenediamino Group and Characteristics of Arylated β-Cyclodextrin Derivatives in Host–Guest Complexation

Mono-3-deoxy-(N-benzoyl-ethylenediamino)--CD, mono-3-deoxy-(N-benzylidene-ethylenediamino)--CD and mono-3-deoxy-(N-salicylidene-ethylenediamino)--CD, each having a flexible chain that bonds the aryl moiety on the secondary side of -CD, were prepared. The reaction processes might involve the formation of mono-(2,3-manno-epoxide)--CD as an intermediate under our reaction conditions. Further experiments showed that the aryl moiety which was bonded as a functional group on the primary side of -CD or on the secondary side of -CD with or without an ethylenediamino chain show remarkably different complexation properties in the complexation with small molecular guests such as alkanes, cycloketones etc.     

Temperature-dependence of electromechanical coupling and strain in barium titanate hafnate transducer

The electromechanical coupling factor and ferroelectric hysteresis loops were investigated at different temperatures for BaTi_0.85Hf_0.15O₃ transducer. Maximum polarization and strain were obtained near the transition of the crystal structure. This correlated with increases in the ease and extent of ferroelectric domain boundary motion. The change in the crystal structure varied the unit cell volume, leading to higher strain.

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Zusammenfassung Der elektromechanische Kopplungsfaktor und die ferroelektrische Hysteresisschleife wurde für BaTi_0.85Hf_0.15O₃-Transducer bei verschiedenen Temperaturen untersucht. Polarisation und Deformation nehmen in der Nähe des Umwandlungspunktes der Kristallstruktur maximale Werte an. Dies korreliert mit Leichtigkeit und Außmaß der Grenzbewegung im ferromagnetischen Bereich. Die mit der Umwandlung der Kristallstruktur zusammenhängende Veränderung des Elementarzellenvolumens führt zu größerer Verformung.

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BaTi_0.85Hf_0.15O₃ . . . , .

     

Studies on water retention and water release from some protein systems

The hydrogen-bond properties (WBI index), water retention and water release from the protein-water systems gluten-water, soya protein- water and casein-water, have been investigated using differential scanning calorimetry in the temperature range 223–423 K. The proteins were characterized by their isoelectric point, contents of carboxyl groups and sulfur-containing groups, and readiness of undergo chloromethylation. It was concluded that the marked difference in water-release behaviour is chiefly explained by conformational differences and charge effects.

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Zusammenfassung Wasserstoffbrückenbindugseigenschaften (WBI-Index), Wasserretention und Wasserabgabe von Protein-Masser-Systemen — Gluten-Wasser, Sojaprotein-Wasser und Casein-Wasser — wurden im Temperaturbereich von 233–423 K mit einem Scanning-Kalorimeter untersucht. Die Proteine wurden durch ihren isoelektrischen Punkt, den Gehalt an Carbonylgruppen und Schwefel enthaltenden Gruppen und durch ihre Reaktivität in der Chlormethylierung charakterisiert. Es wurde gefolgert, dass der ausgesprochene Unterschied im Wasserabgabeverhalten in erster Linie auf strukturelle Unterschiede und Ladungseffekte zurückzuführen ist.

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223–423 K , , — , — — . , , . , .

     

Thermal conductivities of polytetrafluoroethylene and polychlorotrifluoroethylene between 4.2 and 20 K

The thermal conductivities of bulk technical samples of polytetrafluoroethylene and polychlorotrifluoroethylene were measured in the temperature range 4.2–20 K by application of the steady-state method. An interpretation of the thermal conductivity data in terms of the available theoretical and empirical models is presented.

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Zusammenfassung Die thermischen Leitfähigkeiten technischer Einzelproben von Polytetrafluoräthylen und Polychlortrifluoräthylen wurden im Temperaturbereich von 4.2 bis 20 K durch Einsatz der Festkörper-Methode gemessen. Eine Deutung der thermischen Leitfähigkeitsangaben wird anhand der zur Verfügung stehenden theoretischen und empirischen Modelle gegeben.

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4.2–20 . .

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This work was done in the International Laboratory of High Magnetic Fields and Low Temperatures, Wrocaw, Poland.     

Thermal and photochemical stability of polystyrene and its blends with polyvinyl chloride

The influence of some irregularities in polystyrene (PS) and polyvinyl chloride (PVC) chains on their thermal stability was investigated. UV irradiation caused an increase in the content of these irregularities in the polymers. It was found that the presence of carbonyl groups and crosslinking of the polymer chains hamper the thermal dehydrochlorination of PVC and the total decomposition of both polymers. On the other hand, weak peroxy linkages (which facilitate degradation processes) and conjugated double bonds decrease the temperature of total decomposition of PS and PVC blends.

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Zusammenfassung Es wurde der Einfluß von Unregmlmäßigkeiten in Polystyrol (PS)- und Polyvinylchlorid (PVC)-Ketten auf deren thermische Stabilität untersucht. UV-Bestrahlung verursacht ein Ansteigen des Gehaltes an Unregelmäßigkeiten in den Polymeren. Es wurde festgestellt, daß die Gegenwart von Carbonylgruppen und Querverbindungen der Polymerketten die thermische Dehydrochlorierung von PVC und eine vollständige Zersetzung beider Polymere verhindern. Andererseits senken Peroxidverknüpfungen (die die Degradierungsvorgänge erleichtern) und konjugierte Doppelbindungen die Temperatur für eine vollständige Zersetzung von PS und PVC Gemischen.

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. - . , . , , , .

     

Formation of oxalates and carbonates in the thermal decompositions of alkali metal formates

The influences of gaseous and solid reactants on the yields of oxalates and carbonates in the thermal decompositions of alkali metal formates have been studied. A mechanism of formation of these products is proposed, which explains the influences of basic and acidic species formed in the medium on the thermal decompositions of the alkali metal formates.

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Zusammenfassung Der einfluß von gasförmigen und festen Reaktanten auf die Ausbeute von oxalaten und Karbonaten bei der thermischen Zersetzung von Alkalimetallformiaten wurde untersucht. Es wurde ein Mechanismus für die Bildung dieser Produkte vorgeschlagen, der den Einfluß der während der thermischen Zersetzung von Alkalimetallformiaten entstehenden Basen und Säuren erklärt.

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, . , , .

     

Kinetics and isotope effect of brown coal liquefaction in ethanol

Liquefaction kinetics are described by a first-order equation. Deuterium introduction into the -position of ethyl alcohol produces a considerable kinetic isotope effect. This effect is suggested to be due to the hydrogen donor capacity of the initial ethyl alcohol -CH₂-groups or of ethyl substituents inserted into the aromatic fragments of coal after alkylation.

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. -, , - -CH₂- , .

     

Flow injection-mini-column technique with ICP-AES detection for the isolation and preconcentration of the fast reactive aluminium fraction in waters

A flow injection mini-column system based on short reaction times with 8-hydroxyquinoline (oxine) with ICP-AES detection is described for the isolation and preconcentration of the fast reactive or toxic aluminium fraction in water samples. Using a 3 s reaction time with oxine (5 × 10^–4 mol/l) at pH 5.0, the fast reactive aluminium fraction is shown not to include the non-toxic AlF²⁺ species at low F^–: Al³⁺ molar ratios (0.3 : 1). The complexed aluminium is isolated in a stable and recoverable form on mini-columns of Amberlite XAD-2 (0.3 cm × 5.0 cm, resin particle size range 0.08 mm–0.16 mm)). The retained aluminium is recovered by back-flushing the analytical column with 1 mol/l HCl for final element specific detection by ICP-AES. Detection limits (after preconcentration) of 2 g/l, a linear range of 0–500 g/l, and possible preconcentration factors of up to 18 times are demonstrated with the present system. Implications for the possible solution of sample stability problems encountered with labile aluminium species analysis and the development of a field sampling technique are discussed, where the desired Al fraction is quantitatively retained in a stable form on mini-columns.     

Quantitative thermodynamic evidence of transition from hexacoordinated to tetra- and pentacoordinated structures in aqueous copper(II) and zinc(II) complexes

A calculation method previously used in the study of simple ion pairs is extended in the present work to the entropies of formation of copper(II) and zinc(II) complexes with polydentate ligands in aqueous solution. Not only a qualitative, but also a quantitative and more significant discussion of the entropy data seems possible by this method. In particular, if the literature entropy data for copper(II) complexes with some carboxylic ligands and for zinc(II) with polyamines are used, the change from 6 to 4 in the coordination number of the cation is demonstrated, in accordance with previous suggestions. In the complex(Zntren)²⁺, the metal shows a coordination number of 5, in agreement with previous X-ray results.

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Zusammenfassung Eine früher schon bei der Untersuchung einfacher Ionenpaare benutzte Berechnungsmethode wird auf die Entropiewerte der Bildung von Kupfer(II)- und Zink(II)-Komplexen mit Polydentat-Liganden in wässriger Lösung erweitert. Diese Methode scheint nicht nur eine qualitative, sondern auch eine quantitative und aussagekräftigere Diskussion der Entropiedaten zu ermöglichen. Ausgehend von Literaturangaben über die Entropie von Kupfer(II)-Komplexen mit einigen Carboxylgruppen enthaltenden Liganden und von Zink(II) mit Polyaminen wird, in Übereinstimmung mit früheren Annahmen, der Übergang von der 6-er in die 4-er Koordination demonstriert. Im Komplex (Zn tren)²⁺ ist die Koordinationszahl des Metalls 5, in Übereinstimmung mit früheren Röntgenergebnissen.

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, , . , . , 6 4, . (Zn tren)²⁺ 5, - .

     

Influence of molecular nitrogen and irradiation temperature on radiolysis of N2O?Al2O3 system

Molecular nitrogen and irradiation temperature are shown to affect the radiationchemical yield of O _st ^– in the radiolysis of N₂O adsorbed on alumina with large surface areas and to exert no influence in the case of small surface areas of Al₂O₃.

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, - O _st ^– N₂O, Al₂O₃ .

     

The thermometric and enthalpimetric determination of organic compounds

Two main parameters determine the methods for the assay of organic compounds in industrial systems; these are the rates of reaction of the molecular organic and often non-aqueous systems which differ from those in ionic and aqueous systems, and secondly, the fact that in most organic systems an organic functional group is required to be determined by a general method applicable to the functional group in a variety of chemical environments. In pharmaceutical products it is desired to determine the functional groups without prior separation from excipients of various kinds and to obtain rapid assays, often with precision much lower than those normally required in inorganic systems. These methods are discussed with examples taken from the foodstuff industry, the pharmaceutical industry, etc.

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: , . , - , . . , . , , .

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Partly presented at the II. Seminar Thermometric Analysis, Budapest, September 2–7, 1980.     

Improved deactivation profile observed for Pt/H-chabazites and Pt/H-Y zeolite

The presence of small platinum crystallites in the framework of protonic offretite, erionite and Y-zeolite causes an improved deactivation profile during n-butane conversion and reflects a stronger shape-selectivity compared to the analogous behavior of the monofuctional (protonic) zeolites.

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, - - () .

     

Kinetics of propylene oxidation in the region of negative temperature coefficients of the rate

Kinetic regularities in the consumption of initial reactants and the accumulation of propylene oxidation products has been studied in the region of negative temperature coefficients of the maximum reaction rate (T=648–723 K). It has been revealed that for prolynene-enriched mixtures (C₃H₆:O₂=3:1) at P-20.66 kPa, the reaction rate is practically independent of the temperature, whereas for poor mixtures (C₃H₆:O₂=1:5) it decreases with increasing temperature.

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a (T=648–723K). , (C₃H₆:O₂=3:1) P=20,66 , (C₃H₆:O₂=1:5) .

     

Conformational transition of kappa-carrageenan

The calorimetry of kappa carrageenan using differential scanning calorimetry and calorimetry at constant temperature is presented. Both sets of experimental results confirmed the formation of a helical dimer in the absence of gel formation. When gel is formed, the formation of a helical dimer is the major effect, the contribution of gelation represents only 20% of the enthalpy recorded.

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Zusammenfassung Es wird über die Kalorimetrie von Kappacarrageen mittels DSC und Kalorimetrie bei konstanter Temperatur berichtet. Die experimentellen Resultate bestätigen beim Ausbleiben der Gelbildung, daß ein helixartiges Dimer gebildet wird. Auch bei Gelbildung steuert die Bildung des helixartigen Dimers den Hauptanteil zum thermischen Effekt bei, der Beitrag der Gelierung stellt nur etwa 20% der registrierten Enthalpie dar.

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- . . , , 20% .

     

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.

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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.

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() — , — CuGl₂(H₂O)₂SO₄ — . . , , .

     

Effect of solvent on photochemically induced olefin metathesis by tungstenhexacarbonyl

Effect of solvents on photochemically induced metathesis of pentene-2 by W(CO)₆ has been investigated. Structure of the catalyst and a reaction mechanism are proposed.

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-2 W(CO)₆. .

     

AES studies on a Pd-modified silver catalyst

Silver crystals electrodeposited from AgNO₃ (8%) and Pd²⁺ (250 mg/dm³) electrolyte before and after exposing to the conditions of the methanol to formaldehyde oxidation process were investigated by AES. Carbon, sulfur, oxygen and palladium on the surface were observed. Higher Pd concentration on the silver surface than in the bulk was found. Its amount on the surface decreased with the temperature increase.

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, - , AgNO₃ (8%) Pd⁺² (250 /), AES. , , - . , - Pd , , .

     

Reaction kinetics of alkyl and alkylperoxide radicals

Rate constants for the reaction of alkyl and alkylperoxide radicals in solutions of cyclohexane and tridecane have been measured by flash photolysis and kinetic spectrophotometry methods, respectively.

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.

     

Thermal stabilities of selected rare earth oxyiodides

The thermal stabilities of lanthanum, neodymium, samarium and gadolinium oxyiodides were studied in a dynamic air atmosphere. Several intermediate phases with the general formulanREOI·RE₂O₃ (n=7,4,2 and 1) were observed during the decomposition scheme. The thermal stability decreases slightly with increasing atomic weight of the RE cation. Similar decreases with increasing atomic weight of the halide were observed in the lanthanum and in the gadolinium oxyhalide series. This decrease could be correlated to the changes in crystal structure.

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Zusammenfassung Die thermische Stabilität von Lanthan-, Neodym-, Samarium- und Gadoliniumoxyjodiden wurde in einer dynamischen Luftatmosphäre untersucht. Während der Zersetzung wurde das Auftreten einiger intermediärer Phasen der allgemeinen FormelnREOJ·RE₂O₃ (n=7, 4, 2 und 1) beobachtet. Die thermische Stabilität nimmt geringfügig mit steigendem Atomgewicht des RE-Kations ab. Eine ähnliche Abnahme mit steigendem Atomgewichts des Halids wurde sowohl in der Lanthan- als auch in der Gadoliniumoxyhalidreihe beobachtet. Diese Abnahme konnte mit den Veränderungen in der Kristallstruktur in Korrelation gebracht werden.

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, , . nREOI · RE₂O₃, n=7, 4, 2 1. . . .

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The author is indebted to Prof. M. Leskelä for his aid during the work. Most sincere thanks are also due to Stanton-Redcroft Ltd. for the use of their STA-780 thermoanalyser.