Synthesis of potential antagonists to amino acids in the quinoline series

The following potential antagonists to amino acids were synthesized: -(6-quinolyl)--alanine, -(8-quinolyl)--alanine, and -(2-phenyl-4-carboxy-6-quinolyl)--alanine.     

Formation of aromatic carbonium ions on V2O5/Al2O3

A comparison of IR spectra of individual toluene, mesitylene, hexamethylbenzene, triene and their carbonium ions with IR spectra of the same molecules adsorbed on V₂O₅/Al₂O₃ has indicated the formation of carbonium ions on catalyst surface.

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- , , , , - , V₂O₅/Al₂O₃ Al₂O₃, t, V₂O₅/Al₂O₃ .

     

Evaluation of the degree of hydration of tricalcium silicate pastes by quantitative differential thermal analysis

The hydration kinetics of C₃S pastes can be easily evaluated by DTA using the most intense and reversible transition of C₃S. Some modifications are proposed to Ramachandran's method concerning the measurement of this effect, the weight of the sample used for each experiment and the heating rate. The results of the hydration degree versus times of C₃S agree reasonably with those reported by Ramachandran, while still better agreement is observed with those of Locher who used X-ray quantitative analysis.

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Zusammenfassung Die Hydratisierungskinetik von C₃S Pasten kann mittels DTA leicht bewertet werden, falls der intensivste und am meisten reversible Übergang von C₃S genutzt wird. Einige Änderungen zur Methode von Ramachandran bezüglich der Messung dieses Effekts, des Gewichts der bei den einzelnen Messungen eingesetzten Proben und der Aufheizgeschwindigkeit werden vorgeschlagen. Die Ergebnisse des Hydratisierungsgrades von C₃S in Abhängigkeit von der Zeit sind in guter Übereinstimmung mit denen von Ramachandran, während eine noch bessere Übereinstimmung mit den Werten von Locher beobachtet werden kann, welcher sich jedoch der quantitativen Röntgenanalyse bediente.

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Résumé La cinétique de l'hydratation des pâtes de C₃S peut être facilement déterminée par ATD, en utilisant la transition de C₃S la plus intense, qui est réversible.On propose des modifications à la méthode de Ramachandran, concernant la mesure du phénomène, le poids des échantillons utilisés pour chaque expérience et le choix de la vitesse de chauffage. Les résultats donnant le degré d'hydratation de C₃S en fonction du temps sont en bonne concordance avec ceux publiés par Ramachandran tandis qu'une concordance encore meilleure est observée avec les résultats de Locher obtenus par analyse quantitative aux rayons X.

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C₃S C₃S. , : , . , , , .

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Financial support by Consiglio Nazionale delle Ricerche (Italy).     

On some peculiarities of phthalimide formation in the oxidative ammonolysis of o-xylene

In the oxidative ammonolysis of o-xylene on oxide catalysts, phthalimide can be obtained from phthalodinitrile through an intermediate phthalocyanine step. The catalyst ability to form phthalocyanine can be used to estimate its selectivity to phthalimide.

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Steroid compounds from the starfish Lysastrosoma anthosticta collected in the Sea of Japan

Six polyhydroxylated steroids and their derivatives were isolated from the starfish Lysastrosoma anthosticta collected in the Posyet Bay, Sea of Japan. These include a new glycoside of the steroid polyol, lysastroside A (1), which was identified as (25S)-26-O--d-xylopyranosyl-5-cholestane-3,6,8,15,16,26-hexaol, and the previously known pycnopodioside C monoglycoside (2), marthasterone sulfate (3), (25S)-5-cholestane-3,6,8,15,16,26-hexaol (4), (25S)-5-cholestane-3,6,7,8,15,16,26-heptaol (5), and (25S)-5-cholestane-3,6,7,8,15,16,26-heptaol (6). The compounds were tested for the haemolytic activity and the action on the embryogenesis of the sea urchin Strongylocentrotus intermedius.     

A definitive method for the determination of trace amounts of cobalt in biological materials by neutron activation analysis

A new, very accurate (definitive) method for the determination of trace amounts of cobalt in biological materials has been devised. The method is based on combination of neutron irradiation with quantitative and selective post-irradiation separation of cobalt from all accompanying radionuclides followed by measurement by -ray spectrometry. Column chromatography in which owing to addition of Co carrier the course of separation can be followed visually is the key element of the separation scheme. Several criteria have been formulated which must be simultaneously fulfilled in order to acknowledge the result as obtained by a definitive method. The high accuracy of the method has been demonstrated by the analysis of several certified reference materials of widely different Co contents.     

Synthesis and characterization of cyclopentadienyl halides of transition metals: Part II,chromium halides

Summary -Cp₂Cr reacts with PX₃ (X = Cl, Br or I) to give monocyclopentadienylchromium(III) derivatives -CpCrX₂ (X = Cl, Br or I), while oxidative additions of IBr and ICl to -Cp₂Cr give the corresponding mixed halogenated derivatives, -Cp₂CrIX (X = Cl or Br). All products have been characterized by elemental analyses, magnetic moment measurements and by i.r. and e.p.r. spectra.     

Iridoid glycosides ofVerbascum laxum

The epigeal part ofVerbascum laxum Filar, ét Jav. has yielded in addition to the known sinuatol, a new iridoid glycoside — 6-0-(3-0-p-coumaroyl--L-rhamnopyranosyl)aucubin (I), [] _D ²⁰ –174.2±0.7° (c 1.4; MeOH). From the roots of the plant, as the main components giving an iridoid reaction, have been isolated harpagoside and the new iridoid glycoside 6-0-(2,3-di-0-acyl[acetyl,p-methoxy-trans-cinnamoyl]--L-rhamnopyranosyl)aucubin (V) [] _D ¹⁸ –130±2° (c 0.5; MeOH). The structures of the substances isolated were established with the aid of UV, IR, NMR, and mass spectra.A. L. Mndzhoyan Institute of Fine Organic Chemistry, Academy of Sciences of the Armenian SSR, Erevan. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 90–96, January–February, 1987.     

Complex Sorption Kinetics of Carbon Dioxide in NaX-Zeolite Crystals

Ad-/desorption-kinetic measurements were performed for carbon dioxide on a mono-disperse crystal sample of NaX-type zeolite (mean crystal diameter: 2R (100 ± 6) m) by a constant-volume–variable-pressure method in a differential concentration mode over ranges of temperature, (193–293) K, and pressure, (20–26,700) Pa. They revealed a complex sorption process in sorbate uptake and release during experiments of ad- and desorption, respectively, which is comprised of a slow, hitherto unknown rate mechanism superimposed on very fast intracrystalline diffusion of carbon dioxide. IR-spectroscopic data that evidence formation of chemisorption species in CO₂-NaX sorption systems may allow for a tentative interpretation of this finding. Circumstantial evidence for the correctness of this conclusion follows from sorption–kinetic experiments for carbon dioxide on BaKX-type zeolite crystals (mean crystal diameter: 2R (120 ± 6) m).     

Eine neue Synthese der 4-Hydroxyphenylbrenztraubensäure

Zusammenfassung 4-Hydroxybenzaldehyd wird mit Hydantoin zum 5-(4-Hydroxybenzal)-hydantoin kondensiert, welches mittels 20proz. NaOH in guter Ausbeute zur 4-Hydroxyphenylbrenztraubensäure gespalten werden kann.In alkal. Lösung wird 4-Hydroxyphenylbrenztraubensäure leicht durch Sauerstoff oxydiert; als vorwiegendes Zersetzungsprodukt konnte 4-Hydroxybenzaldehyd nachgewiesen werden. Unter Ausschluß von Luftsauerstoff tritt in alkal. Lösung in geringem Umfang eine Kondensation zu einer dimeren 4-Hydroxyphenylbrenztraubensäure ein, die als -(4-Hydroxybenzyl)--(4-hydroxyphenyl)--oxoglutaconsäure formuliert werden konnte.Mit 1 Abbildung1. Mitt.:G. Billek undE. F. Herrmann, Mh. Chem.90, 89 (1959).     

Synthesis of α-alkyl- and α,α-dialkyl-β-phenyltryptamines

A new method was developed for the synthesis of -alkyl- and ,-dialkyl--phenyltryptamines based on alkylation of nitroalkanes with -phenyl-nor-gramine.     

High-temperature reduction of SO2 by methane at various CH4/SO2 ratios

The character of the effect of initial reaction mixture and temperature on the selectivity of catalytic reduction of sulfur dioxide by methane in the presence of oxygen has been studied.

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The use of calorimetric data for estimation of the point defect concentration in solids

Calorimetric methods which allow estimation of the point defect concentration in solids are reviewed. Special attention is paid to the calculation of defect parameters based on the analysis of excessive heat capacity, and to correlations between the thermodynamic parameters of melting and the energetic parameters of point defect formation. The applicability of the thermodynamic approach to the study of intrinsic disorder in solids is demonstrated.

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Zusammenfassung Kalorimetrische Methoden zur Abschätzung der Konzentration von Punktdefekten in Festkörpern werden zusammengestellt. Aufmerksamkeit verdienen die Berechnung von Defektparametern aus einer Untersuchung der Exzeß-Wärmekapazität und Korrelationen zwischen thermodynamischen Parametern des Schmelzens und energetischen Parametern der Punktdefektbildung. Die Anwendbarkeit eines thermodynamischen Ansatzes zur Untersuchung der Eigenfehlordnung in Festkörpern wird demonstriert.

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. , . .

     

Silylation of γ,γ-bis(alkoxycarbonyl)-substituted aliphatic nitro compounds: synthesis of N,N-bis(trimethylsilyloxy)aminocyclopropanes*

Silylation of ,-bis(alkyloxycarbonyl)--aryl- and ,-bis(alkyloxycarbonyl)--alkyl-substituted aliphatic nitro compounds proceeds stereoselectively to give the corresponding N,N-bis(trimethylsilyloxy)aminocyclopropanes in high yields. These compounds can be used as synthetic equivalents of nitrosocyclopropanes.     

Kinetics and mechanism of thermal decomposition of cadmium(II) complexes with substituted thioureas

From the thermal decomposition curves of cadmium(II) complexes with substituted thioureas (methyl-, dimethyl-, ethyl-, diethyl-, butyl-, dibutyl-, phenyl-, diphenyl-, acetyl- and benzoylphenylthiourea), the kinetic parameters of the thermal decompositions of these complexes were determined and a decomposition mechanism was suggested. The following thermal stability sequence is given for the Cd(II) complexes: complexes with alkylthioureas < complexes with phenylthioureas < complexes with acylthioureas.

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Zusammenfassung Die kinetischen Parameter der thermischen Zersetzung von Verbindungen der Formeln Cd(MeTM)₄(ClO₄)₂, Cd(DMeTM)₄(ClO₄)₂, Cd(EtTM)₄(ClO₄)₂, Cd(DEtTM)₄(ClO₄)₂, Cd(BuTM)₄(CtO₄)₂, Cd(DBuTM)₄(ClO₄)₂, Cd(AcTM)₃(ClO₄)₄, Cd(FTM)₄(ClO₄)₂ und Cd(DFTM)₄(ClO₄)₂ wurden mittels TG and DTG untersucht. Die Reaktionsordnung (n) und die Aktivierungsenergie (E _a) wurden nach der graphischen Methode ermittelt.

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(- , - , - , - , - -l- ), . : < < .

     

Modelling of quantitative DTA equipment I. Electric analog approach

For an electric model, relationships have been established as a function of the DTA baseline shift, the intensity of the signal, the slope of the leading edge, the heating rate, the thermal resistance of the heating disc built into the DTA apparatus, the contact resistance between the disc and the sample holders, and the heat resistance between the two measuring sites. Some of the relationships obtained supported knowledge acquired earlier by other approaches, and some furnished new information. The limits of use of this simple model are indicated.

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Zusammenfassung Unter Anwendung eines elektrischen Modells wurden Zusammenhänge als Funktion der Verschiebung der Basislinie der DTA, der Signalintensität, der Steile der Leitkante, der Aufheizgeschwindigkeit, des Wärmewiderstandes der in das DTA-Gerät eingebauten Heizscheibe, des Kontaktwiderstandes, zwischen Scheibe und Probenbehälter und des Wärmewiderstandes zwischen den beiden Meßstellen ermittelt. Ein Teil der erhaltenen Zusammenhänge bestätigte von anderen Annäherungen her bereits vorliegende Kenntnisse, ein anderer Teil lieferte neue Informationen. Auf die Grenzen und der Nutzen dieses einfachen Modells wurden hingewiesen.

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Résumé A l'aide d'un modèle électrique, on a établi des relations décrivant l'influence de la dérive de la ligne de base ATD, de l'intensité du signal, de la pente du bord du pic, de la vitesse de chauffage, de la résistance thermique du disque de chauffage incorporé dans l'appareil ATD, de la résistance de contact entre le disque et les porte-échantillons et enfin, de la résistance thermique entre les deux points de mesure. Une partie des relations obtenues confirme les connaissances déjà acquises par d'autres approches, l'autre partie fournit des renseignements nouveaux. Les limites d'utilisation de ce modèle simple sont indiquées.

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, , , , , , , . , — . .

     

Determination of Attogram Quantities of Silver via Quenching of the Solid Substrate Room-Temperature Phosphorescence of Rhodamine B Based on the Catalysis of its Oxidation by Potassium Persulfate

A new method of SS-RTP for the determination of trace silver has been established. This method is based on the fact that Ag⁺, when activated by ,-bipyridyl (bipy) in a media of HAc–NaAc (pH=4.9), can catalyze the reaction of Rhodamine B (RhoB) oxidized by K₂S₂O₈, thus causing the Solid Substrate Room-Temperature Phosphorescence (SS-RTP) of RhoB to be quenched. The activating efficiency of bipy is 6.7 times higher than that of o-phenanthroline (phen). The reduction of the phosphorescence intensity (I_p) of RhoB is directly proportional to the concentration of Ag⁺ ions in the range of 1.6016.0agspot^–1 (0.40µLspot^–1). The regression equation of the working curve can be expressed as I_p=18.78+5.100m_Ag+ (agspot^–1) (r=0.9994, n=6), the detection limit is 0.28agspot^–1. This rapid, accurate and sensitive method has been successfully applied to the determination of trace silver in tea and human hair samples, and the results agree well with the Atomic Absorption Spectroscopy (AAS) method. The mechanism of the catalyzing reaction is also discussed.     

Methanol-based synthesis of hydrocarbons on bifunctional Y-type zeolites

The directions of methanol conversion on Pt, Pd, Zn, Ni metals and Y zeolites and on bifunctional metal-Y-zeolite catalysts have been studied. The increase of the hydrogenation activity of bifunctional catalysts enhances the rate of methanol conversion and decreases the selectivity of hydrocarbon formation.

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- Y, - Y.

     

Effect of reduction temperature on the dehydrocyclizing activity of pure chromia and chromia containing K2O and CaO

The dehydrocyclization of n-heptane at 520–550°C over pure chromia and chromia with added CaO and K₂O (5 wt.% each) has been investigated. Introduction of an alkaline additive into Cr₂O₃ decreases markedly the yield of toluene. Raising of the reduction temperature of alkali-containing samples from 550 to 700°C results, in contrast to pure Cr₂O₃ and chromia-alumina systems, not in diminished, but in increased yields of toluene, the activity enhancement being particularly pronounced for the CaO-containing catalyst. These increased activities cannot be correlated either with variations in specific surface area or changes in the content of Cr⁶⁺ during subsequent oxidation, and presumably should be ascribed to more extensive catalyst reduction at higher temperatures.

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- 520–550° CaO K₂O ( 5% .). Cr₂O₃ . 550° 700° , Cr₂O₃ , , , CaO. , , .

     

Heterogeneous catalytic oxidation of ethanol: A new process for acetic acid

ESR investigations on ZnO doped with various amounts of -Al₂O₃ thermally treated, are reported. Experimental data are related to the electronic structure of ZnO--Al₂O₃ and to desulfurization specific activity for natural gas.

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ZnO, -Al₂O₃. ZnO/-Al₂O₃ .