Phase equilibria in the Ag4SSe-SnTe system

The phase diagram of the system Ag₄SSe-SnTe is studied by means of X-ray diffraction, differential thermal and metallographic analyses and measurements of the microhardness and the density of the material. This diagram is divided into two eutectic-type subdiagrams by the composition Ag₄SSe·2SnTe. The unit-cell parameters of the intermediate phases 3Ag₄SSe·SnTe (phase A) and -Ag₄SSe·2SnTe (phase B) are determined as follows: for phase A: a=0.7851 nm, b=0.7196 nm, c=0.6296 nm, =101.32°, =85.90°, =111.36°; for phase B: a=0.3662 nm, b=0.3303 nm, c=0.3343 nm, =90.74°, =108.94°, =91.91°. The phase Ag4SSe·2SnTe melts congruently at 615°C and a polymorphic transition of the phase takes place at T _- =110°C.This revised version was published online in November 2005 with corrections to the Cover Date.     

Study of interaction between trimethyl-substituted silanes and silica surface

Interaction mechanism of (CH₃)₃SiX silanes (X=Br, I, N₃, NCS, NCO, CN, NCNSi(CH₃)₃ and SO₄Si(CH₃)₃ with dehydrated silica surface has been studied by IR spectroscopy. It has been established that (CH₃)₃SiCN, (CH₃)₃SiBr, (CH₃)₃SiI and [(CH₃)₃Si]₂SO₄ can be used as soft silylating agents for endcapping.

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(CH₃)₃SiX (X=Br, I, N₃, NCS, NCO, CN, NCNSi(CH₃)₃, SO₄Si(CH₃)₃) -. , (CH₃)₃SiCN, (CH₃)₃SiBr, (CH₃)₃SiI [(CH₃)₃Si]₂SO₄ .

     

The effects of cyclodextrin inclusion of the ferrocenemonocarboxylate anion on the kinetics of its oxidation by bis(pyridine-2,6-dicarboxylato)cobaltate(III) in aqueous solution

The effects of -, -, dm-(heptakis(2,6-di-O-methyl)--) and -cyclodextrins (CD) on the kinetics of the electron-transfer reaction of the ferrocenemonocarboxylate anion (FCA^–) with bis(pyridine-2,6-dicarboxylato)cobaltate(III) have been investigated in aqueous solution (0.20 M Na₂HPO₄, pH 9.2) at 25.0°C. Substantial decreases in the rate constants for the electron-transfer reactions were observed upon cyclodextrin inclusion of the reductant, due to an increase in the FCA^0/– reduction potential and to the insulation of the reductant from oxidant. The inclusion stability constants for {FCA·CD}^– were evaluated from the¹H NMR and kinetic data, and the order of the stability constants was found to be -CDdm-CD-CD>-CD.     

Quantum chemical study of the physical characteristics of the hydroxy groups of zeolites, III

The CNDO/2 method was applied to calculate the electronic structure of HY zeolite using cluster models Si₃AlO₁₂H ₈ ^– and Si₃AlO₁₂H₉. It has been shown that the probability of occurrence of H on a particular type of oxygen as well as the other physical characteristics of zeolite depend on both the type of oxygen and the position of the Al atom.

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/2 , Si₃AlO₁₂H₈ Si₃AlO₁₂H₉. , , , Al.

     

Investigations in the field of complex lipids

Summary 1. The synthesis of L-(+)--oleoyl--linoleoyl--glycerylphosphorylethanolamine has been effected.2. During the investigations the following substances were isolated and characterized: L--oleoyl--glycerylphosphoryl-N-phthaloylethanolamine and L---linoleoyl--glycerylphosphoryl-N-phthanoylethanolamine.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 2, pp. 80–83, 1966     

Substitution of halogen atom in α-halonitro compounds of the aliphatic series

Ethyl -halo--nitropropionate and -butyrate were prepared by alkylating ammonium salts of ethyl bromo- and chloronitroacetates. The addition of alkyl acrylates to alkyl chloronitroacetates or their salts gives dialkyl -chloro--nitroglutarates. Sodium salts of ethyl -nitro--sulfo--hydroxypropionate and -butyrate were obtained by the sulfodehalogenation of ethyl -chloro--nitro--hydroxypropionate and -butyrate with sodium dithionite. Esters of -amino acid hydrochlorides were prepared by the reduction of alkyl -chloro--nitrocarboxylates. The hydrogenation of alkyl nitrosulfoacetates leads to the corresponding disodium salts of alkyl aminodisulfoacetates and piperazine-2,5-dione.For communication 5 seeIvz. Akad. Nauk SSSR, Ser. Khim., 1990, 2012 [Bull. Acad. Sci. USSR, Div. Chem. Sci., 1990,39, 1826].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 872–876, May, 1994.     

Negativer linearer thermischer Ausdehnungskoeffizient von verstrecktem Polyäthylen

Zusammenfassung Der lineare thermische Ausdehnungskoeffizient von linearem Polyäthylen hoher Dichte wurde im Temperaturbereich –20 °C bis + 40°C bestimmt. Bei isotropen Proben besteht eine lineare Beziehung zwischen Dichte bzw. Kristallisationsgrad _v und. Die gemessenen Koeffizienten liegen fürT ₀ = 20 °C im Bereich = 110 ... 130 · 10^–6 K^–1.Kalt verstreckte Proben mit Verstreckungsgraden = 8 ... 15 haben beiT ₀ = 20 °C in Verstreckrichtung den Koeffizienten _l = –24 · 10^–6 K^–1. Der negative Zahlenwert von _tl ist unabhängig von und weiteren Herstellungsparametern. Seine Ursache ist einerseits die Orientierung derc-Achsen der Kristallite in Verstreckrichtung mit _c = –12 · 10^–6 K^–1 und andererseits der negative Koeffizient _am * –50 · 10^–6 K^–1 der verspannten amorphen Phase, der auf dem gummielastischen Verhalten der tie-molecules beruht.Beim Tempern oberhalb von +40 °C schrumpfen die Proben irreversibel, wobei _| ansteigt und nach dem Aufschmelzen der Proben wieder den Wert des isotropen Materials annimmt. Nach dem Tempern wenig unterhalb der Schmelztemperatur der Kristallite wurden überhöhte Koeffizienten _| gemessen, die eine Rotation der Kristallite um dieb-Achsen erkennen lassen.

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Summary The linear thermal coefficient of expansion,, of high density linear polyethylene has been determined in the temperature range of –20 ° ... + 40 °C. For isotropic samples a linear relationship between density or crystallinity _v and is valid. Measured values of forT ₀ = 20 °C amount to = 110 ... 130 · 10^–6 K^–1.Cold drawn samples of draw ratios = 8 ... 15 yield _| = –24 · 10^–6 K^–1 atT ₀ = 20 °C parallel to the draw axis. The negative value of _| does not depend on draw ratio or other parameters of sample processing. It is caused byc-axis orientation of the crystallites in draw direction with _c = –12 · 10^–6 K^–1 and by a negative coefficient _am * = –50 · 10^–6 K^–1 of the stressed amorphous phase, which is due to rubber elastic behaviour of the tie molecules.When annealed above 40 °C the samples shrink irreversibly and _| is augmented. After melting the samples the value of isotropic material is restored. Annealing the samples little below the melting temperature of the crystallites leads to superelevated values all which reflect| rotation of the crystallites around theb-axis.

     

Triterpene glycosides ofHedera canariensis. I. Structures of glycosides L-A,L-B1, L-B2, L-C,L-D,L-E1 1, L-G1, L-G2, L-G3, L-G4, L-H1, L-H2, AND L-I1 from the leaves ofHedera canariensis

From the leaves of Algerian ivyHedera canariensis Willd. (fam. Aralaceae) we have isolated 13 triterpene glycosides: the 3-O--L-arabinopyranosides of oleanolic acid (A), of echinocystic acid (B₁), and of hederagenin (B₂); the 3-O-[O--L-rhamnopyranosyl-(2)--L-arabinopyranoside]s of oleanolic acid (C), of echinocystic acid (D), and of hederagenin (E₁); the 3-O--L-rhamnopyranoside] 28-O-[O--L-rhamnopyranosyl-(14)--gentiobioside of hederagenin (G₁); the 3-O-[O--L-rhamnopyranosyl-(12)--L-arabinopyranoside] 28-O--gentiobioside of hederagenin (G3); the 3-O-[O--L-rhamnopyranosyl-(12)--L-arabinopyranoside] 28-O-[O--L-rhamnopyranosyl-(14)--gentiobioside]s of oleanolic acid (G₂), of echinocystic acid (H₁), and of hederagenin (H₂); the 3-O-[O--L-rhanmopyranosyl-(12)--D-glucopyranoside] 28-O-(O--L-rhamno-pyranosyl-(14)--gentiobioside] of hederagenin (H₂); and the 3-O-(O--L-rhamnopyranosyl-(12)-O-gentiobiosyl)-O-(14)--L-rhamnopyranosyl-(12)-a-L-arabinopyranoside] of hederagenin (G₄). The structures of the substances isolated have been established on the basis of chemical transformations and¹³C NMR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 377–383, May–June, 1996. Original article submitted December 3, 1995.     

First and second thermodynamic mixing properties of ethylbenzene +n-alkanes: Experimental and theory

Isobaric expansibilities _P and isothermal compressibilities _T have been determined at 25 and 45°C for binary mixtures of ethylbenzene + n-tetradecane and + n-hexadecane and the corresponding excess functions (V ^E /T)_P and (V ^E /P)_T have also been obtained. With these data and supplementary literature values, the following second order mixing properties are also reported at 25°C: _S ^E , (V ^E /P)_T, C_V and (VT). All mixing quantities have been compared with the results obtained at 25°C by using the Prigogine-Flory-Patterson theory of liquid mixtures. The predicted values suggest that the ability of ethylbenzene as a breaker of the pure n-C_n orientations is similar to what we found for toluene and higher than for p-xylene.     

Methane synthesis from CO/H2O mixture on supported nickel catalysts, II. Surface species in CO?H2 and CO?D2O interaction by IR spectroscopy

The species resulting in CO, CO+H₂ or CO+D₂O adsorption on supported Ni catalysts were followed by IR spectroscopy and their role in methane synthesis mechanism is discussed.

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- , CO, CO+H₂ CO+D₂O . .

     

Zwitterionic [(H3NCH2C≡CC≡CCH2NH3)]Cu2Cl4 π-Complex: Template Synthesis and Crystal Structure

Crystals of the [(H₃NCH₂CCCCCH₂NH₃)]Cu₂Cl₄ -complex, formed in the oxidative dimerization of propargylammonium cations, were obtained by ac electrochemical synthesis from CuCl₂ · 2H₂O and propargylammonium chloride ([CCCH₂NH₃]Cl) and studied by X-ray diffraction analysis (DARCh automated diffractometer, MoK radiation, /2 scan mode; 2275 reflections with F 4(F), R = 0.048). Crystals are monoclinic: space group B2/b, a = 19.591(6) Å, b = 7.299(3) Å, c = 8.636(3) Å, = 106.83(3)°, Z = 4. The structure consists of individual [(H₃NCH₂CCCCCH₂NH₃)]Cu₂Cl₄ moietes united through the elongated Cu···Cl contacts (2.827(5) Å) into chains oriented along the [010] direction. The bond of the centrosymmetric propargylammonium dimer is -coordintated by copper(I) atom and is elongated to 1.227(6) Å.     

Über N-(α-Aminoacyl)-sulfonamide, 2. Mitt.

Zusammenfassung Es wird über die Synthese von N-(-Aminoacyl)-p-toluolsulfonamiden und N-(-Aminoacyl)-methansulfonamiden berichtet, deren Acylreste sich vonl-Tyrosin,d,l--Methyl-tyrosin undd,l-3,4-Dihydroxy-phenylalanin ableiten.

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The synthesis of N-(-aminoacyl)-p-toluenesulfonamides and N-(-aminoacyl)-methanesulfonamides containing the acyl groups ofl-tyrosine,d,l--methyltyrosine andd,l-3,4-dihydroxy-phenylalanine is described.

     

Equilibres solide ⇄ liquide ⇆ vapeur du systeme binaire CoCl2-H2O

Résumé Les équilibres solide liquide vapeur du système binaire CoCl₂-H₂O sont étudiés dans le domaine de température 120–720. La pression de la solution saturée est mesurée entre 1 et 60 atm. et le diagramme de phases est établi.Deux composés intermédiaires: CoCl₂ · 2H₂O et CoCl₂ · H₂O sont observés; ils subissent une décomposition péritectique à 206 et 335.Un tri et un tétrahydrate n'ont pas été obtenus malgré une étude systématique faisant intervenir des mesures d'analyse thermique, de thermogravimétrie et d'ébulliométrie.L'enthalpie et l'entropie de fusion du chlorure de cobalt sont évaluées à partir de la pente de la courbe de liquidus.Les valeurs calculées de l'enthalpie de déshydration de CoCl₂ · 2H₂O et CoCl₂ · H₂O entre 1 et 60 bars sont respectivement de 17 et 16 Kcal. mole^–1.

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Solid liquid vapor equilibria of the binary system CoCl₂-H₂O are investigated in the temperature range 120–720. The pressure of saturated solutions is measured between 1 and 60 atm, and the phase-diagram is established.Two intermediate compounds, CoCl₂ · 2H₂O and CoCl₂ · H₂O, are observed; they undergo peritectic decomposition at 206 and 335.Tri- and tetrahydrate have not been detected in spite of systematic research involving thermal analysis, thermogravimetry and ebulliometry.The enthalpy and entropy of fusion of cobalt chloride are calculated from the slope of the liquidus curve.The calculated enthalpy of dehydration values of CoCl₂ · 2H₂O and CoCl₂ · H₂O between 1 and 60 atm are 17 and 16 Kcal · mole^–1, respectively.

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Zusammenfassung Die Gleichgewichte Festkörper Flüssigkeit Dampf des binären Systems CoCl₂-H₂O wurden im Temperaturbereich von 120 bis 720C untersucht. Der Druck der gesättigten Lösung wurde zwischen 1 und 60 Atm. gemessen und das Phasendiagramm aufgenommen.Zwei Intermediärverbindungen: CoCl₂ · 2H₂O und CoCl₂ · H₂O wurden beobachtet; diese zersetzen sich bei 206 und 335 peritektisch.Ein Tri- und ein Tetrahydrat wurden trotz systematischer Untersuchungen mittels thermoanalytischer, thermogravimetrischer und ebulliometrischer Messung nicht gefunden.Die Enthalpie und Entropie der Kobaltchloridschmelze wurden aus der Steigung der Liquiduskurve ermittelt.Die errechneten Werte der Dehydratierungsenthalpie betrugen für CoCl₂ · 2H ₂ O und CoCl₂ · H₂O zwischen 1 und 60 bar 17 bzw. 16 Kcal₂ mol^–1.

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l₂-₂ 120–720. 1 60 . . CoCl₂. 2₂ l₂ · ₂, 206 335. , , , . . l₂. 2₂ l₂. ₂ 1 60 ., , 17 16 . ^–1.

     

Enhanced dissolution and oral bioavailability of α-tocopheryl esters by dimethyl-β-cyclodextrin complexation

Inclusion complexation of heptakis (2,6-di-O-methyl)--cyclodextrin (DM--CyD) with -tocopheryl acetate and -tocopheryl nicotinate in aqueous solution was studied by the solubility method. The aqueous solubilities of the esters were about 10⁵ times increased by DM--CyD complexation. The phase-solubility diagram of the tocopheryl ester-DM--CyD systems showed a typicalA _p type, and the stability constants (K) of high-order complexes were estimated by analyzing the upward curvature of the diagrams. The solid complex of -tocopheryl nicotinate with DM--CyD in a molar ratio of 12 was prepared by the kneading method. The dissolution rate of the solid complex was much greater than that of the drug itself, and the rapidly dissolving form of -tocopheryl nicotinate, as an example, showed a markedly increased bioavailability (about 70-fold) after oral administration to fasted dogs.     

Kinetic analysis of thermogravimetric data. XII

Shape and position parameters and are proposed for the characterization of TG curves and are defined by Eqs (6), (7) and (8), respectively. These parameters being reduced to the standard conditionsn=0 andq=1/6 K sec^–1, the nomogram given in Fig. 1 can be constructed by means fo Eqs (9), (11) and (12). An iteration method is proposed, allowing derivation of the kinetic parametersn, E andZ of simple thermal decomposition reactions, from the parameters n,E andZ, by using the empirica formulae (9), (10), (11) and (12) and the nomogram. Table 3 contains data necessary to construct this nomogram.

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Zusammenfassung Die Gestalts- und Positionsparameter , und werden zur Charakterisierung von TG-Kurven vorgeschlagen, bzw. durch die Gleichungen (6), (7) und (8) definiert. Durch Reduktion dieser Parameter auf die Standardbedingungenn=0 undq=1/6 K sec^–1 mit Hilfe der Gleichungen (9), (11) und (12) kann das Nomogramm in Abb. 1 konstruiert werden. Eine Iterationsmethode wird vorgeschlagen, welche die Ableitung der kinetischen Parameter,n, E undZ einfacher thermischer Zersetzungsreaktionen aus den Parametern and unter Anwendung der empirischen Formeln (9), (10), (11) und (12) sowie des Nomogramms ermöglicht. Tabelle 3 enthält die zur Konstruktion des Nomogramms nötigen Angaben.

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Résumé Pour caractériser les courbes TG, on propose les paramètres de forme et de position , et définis par les équations (6), (7) et (8). En réduisant ces paramètres aux conditions standardsn=0 etq=1/6 K sec^–1, à l'aide des équations (9), (11) et (12), le nomogramme donné dans la figure 1 peut être construit. On propose une méthode d'itération pour déduire les paramètres cinétiquesn, E etZ à partir des paramètres , et dans le cas des réactions simples de décomposition thermique, en utilisant les formules empiriques (9), (10), (11) et (12) ainsi que le nomogramme. Le tableau 3 contient les données nécessaires pour construire ce nomogramme.

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G , , (6), (7) (8). « » =0 q=1/6 ^–1 , . 1, (9), (11) (12). , , E Z , (9), (10), (11) (12) . 3 , .

     

Thermal behaviour of some 2-benzylamino-2-deoxyheptonic acids

The thermal behaviour of some 2-benzylamino-2-deoxyheptonic acids obtained from 2-benzylamino-2-deoxy-D-glycero-L-gluco, 2-benzylamino-2-deoxy-D-glycero-D-ido and 2-benzylamino-2-deoxy-D-glycero-D-taloheptononitriles (reported) previously has been studied in air (static atmosphere) and N₂ (dynamic atmosphere, flow rate 200 ml/min).

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Zusammenfassung Das thermische Verhalten einiger aus 2-Benzylamino-2-desoxy-D-glycero-L-gluco-, 2-Benzylamino-2-desoxy-D-glycero-D-ido und 2-Benzylamino-2-desoxy-D-glycero-D-talo-heplononitril (kürzlich beschrieben) erhaltenen 2-Benzylamino-2-desoxy-heptonsäuren wurde ín Luft (statische Atmosphäre) und N₂ (dynamische Atmosphäre, Strömungsgeschwindigkeit 200 ml/min) untersucht.

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( 200 /) 2--2- , 2--2---uepo-L, 2-2- ---- 2-2--- -- 2--2----ma .

     

Investigation of the pore structure of Raney nickel catalysts

Ar and N₂ adsorption and capillary condensation studies at 77.4 and 84K on Raney nickel catalysts modified by Ti, V, Cr, Mn, Zr, Mo, Ta, W, Re and on BAU char coal show that at 77.4K, in pores with d_eff>100Å, argon exists in the solid state.

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Ar N₂ 77,4 84°K - , Ti, V, Cr, Mn, Zr, Mo, Ta, W, Re , d>100 Å 77,4 °K .

     

Mass spectrometric study of monoalkyl-substituted thiacyclanes

Monosubstituted - and -alkylthiophans and -, -, and -alkylthiacyclohexanes were subjected to a comparative mass spectrometric study. The stability of the M⁺ ion increases on passing from - to -alkylthiophans and from - to - and -alkylthiacyclohexanes. In the case of -alkylthiophans and - and -alkylthia-cyclohexanes the principal process is associated with ejection of the substituent as a whole, whereas a portion of the alkyl substituent, with retention of one CH₂ group in the composition of the charged fragment, is eliminated from the molecular ions of -alkylthiophans and -alkylthiacyclohexanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–181, February, 1978.     

Dependence of the rate of methane oxidation on the surface area of the catalysts

Specific rate of methane conversion into C₂-hydrocarbons and deep oxidation products in its interaction with O₂ or N₂O decreases with growing surface area of catalysts that are metal-like compounds of transition elements. This regularity is interpreted in terms of a heterogeneous-homogeneous mechanism.

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C₂ ( CH₄ O₂ N₂O) - . , - .

     

On the dynamic mechanical behavior of nylon 66

Summary The dynamic mechanical properties of nylon 66 films and fibers have been examined, as a function of annealing and drawing, with a Vibron viscoelastometer. It is found that the transition is little affected by annealing treatments, but increase in orientation causes the transition to move to a higher temperature. Experiments, with X-ray diffraction of samples at elevated temperatures, lead to the conclusion that the triclinic to hexagonal phase change does not contribute significantly to the transition. Samples cut parallel and perpendicular to the drawing direction of nylon 66 film, have been used to show that the curves of dynamic tensile modulus versus temperature, for the parallel and perpendicular directions, cross in the neighborhood of the transition. This observation is discussed in relation to the suggestion that the transition is the glass transition in nylon 66.

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Zusammenfassung Die dynamisch-mechanischen Eigenschaften von Filmen und Fasern aus Nylon 66 wurden als Funktion der Temperung und Verstreckung mit einem Virbon-Viskoelastometer untersucht. Die -Umwandlung wird wenig durch die Temperung beeinflußt, aber erhöhte Orientierung läßt siezu höheren Temperaturen verlagern. Messungen der Röntgenstreuung bei erhöhten Temperaturen führen zu dem Schluß, daß der Übergang triklin/hexagonal nicht wesentlich zu der -Umwandlung beiträgt. Proben aus verstrecktem Nylon-66-Film, parallel und senkrecht zur Streckrichtung geschnitten, zeigen, daß die Kurven des dynamischenE-Moduls gegen die Temperatur für beide Orientierungen sich in der Nachbarschaft der -Umwandlung überkreuzen. Diese Beobachtung wird hinsichtlich der Vermutung diskutiert, daß die -Umwandlung den Glasübergang in Nylon 66 darstellt.

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With 5 figures and 2 tables