Characterization of nickel loaded mordenite catalysts by temperature programmed reduction

Temperature programmed reduction (TPR) has been used to study the redox behavior of Ni(II) ions in nickel sodium mordenite (NiNaM) and decationated nickel mordenite (NiHM). The TPR profiles suggest that Ni(II) ions occupy nonequivalent sites with different cooridination states in the mordenite. The reducibility of Ni(II) depends strongly on the zeolite acidity.

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() Ni^II NiNaM NiHM. . .

     

Electrophilic reactions of 3-hydroxyisonicotinic acid

Conclusions The aminomethylation, azo-coupling, and nitration of 3-hydroxyisonicotinic acid and its ester are directed to the 2 position, whereas their iodination proceeds with the formation of the 2-iodo and 2,6-diiodo derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 452–454, February, 1977.     

Hulthén and slater type 2d functions in some excited configurations of sulphur and phosphorus

It is shown that a substantial energy improvement is gained by the variational use of Hulthén orbitals, instead of single Slater orbitals, in the 3d shells of some excited configurations of sulphur and phosphorus. The energies obtained are close to those attained with two-term Slater functions. In some cases the radial distribution functions from Hulthén orbitals are as good an approximation of SCF radial distributions as those from two-term Slater orbitals. Single term 2d functions with only one parameter are found to give almost identical energies and radial distribution functions as those obtained from two-parameter Hulthén orbitals. It is shown that the relationship between one-term 2d orbitals and Hulthén orbitals gives a method of enforcing nuclear cusp conditions on the former with little effect on the energy.     

Semiempirical calculations on triplet and doublet states

Restricted open-shell SCF calculations are carried out on triplet states of electron systems and doublet states of some of their ions. The results are compared with the ones obtained by limited configuration interaction and by the use of Koopman's theorem. For some examples open-shell SCF wavefunctions are expanded into linear combinations of Slater determinants representing configurations built from closed-shell SCF orbitals. This allows a more detailed comparison of the different methods of calculation.

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Zusammenfassung Berechnungen nach der beschränkten SCF Methode für offene Schalen werden an Triplettzuständen von -Elektronensystemen und Dublettzuständen einiger ihrer Ionen ausgeführt. Die Resultate werden mit denjenigen verglichen, welche die beschränkte Konfigurationswechselwirkung und der Satz von Koopmans liefern. Die SCF Wellenfunktionen für offene Schalen werden, für gewisse Beispiele, in Linearkombinationen von Slater-Determinanten entwickelt, welche aus SCF Orbitalen für geschlossene Schalen aufgebaut sind und verschiedene Konfigurationen darstellen. Dies erlaubt einen eingehenderen Vergleich der verschiedenen Berechnungsmethoden.

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Résumé Des calculs selon la méthode SCF avec restriction pour les couches ouvertes sont effectués sur les états triplets de systèmes d'électrons et sur les états doublets de certains de leurs ions. Les résultats sont comparés à ceux obtenus par la méthode d'interáction de configurations limitée et par l'emploi du théorème de Koopmans. Pour certains exemples les fonctions SCF à couches ouvertes sont développées en combinaison linéaire de déterminants de Slater représentant des configurations bâties à partir d'orbitales S.C.F. de couches fermées. Cela permet une comparaison plus détaillée des différentes méthodes de calcul.

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Presented in parts at the Theoretical Chemistry Symposium in Vienna, March 1967.     

Neue stellungsisomere reineckesalzähnliche Verbindungen mit Toluidinen

Zusammenfassung Es wurden eine Reihe von Substitutionsreaktionen mit entwässertem K₃[Cr(NCS)₆] und aromatischen Aminen, ohne Verwendung von Lösungsmitteln, durchgeführt. Es wurde beobachtet, da die sehr schwachen Basen mit p_K-Werten 14–16, wie die isomeren Mono- und Dinitro-aniline, die Anthranil- und Sulfanilsäuren, für diese Substitutionsreaktionen ungeeignet sind. Die Alkyl-anilinderivate, wie daso-, m- undp-Toluidin (p_K=10–11) bilden dagegen leicht reineckesalzähnliche Verbindungen: Amin· H[Cr(Toluidin)₂(NCS)₄]. Die Zusammensetzung der neuen Komplexanionen wurde bei einer Reihe von doppelten Umsetzungsreaktionen mit den Chlorhydraten einiger heterocyclischen Aminen festgestellt.Für die Klärung einiger Strukturfragen wurden spektrophotometrische Untersuchungen im UV und IR durchgeführt und die thermische Stabilität bzw. der Mechanismus des Pyrolysenvorganges auf thermogravimetrischem Wege verfolgt.

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Substitution reactions of anhydrous K₃[Cr(NCS)₆] with aromatic amines without applying of solvents were studied.It was observed, that the very weak bases (pK-values 14–16, e.g. isomeric mono- and dinitro-anilines, the anthranilic and sulfanilic acids) are unsuitable for substitution reactions. The alkylaniline derivates e.g.o-, m- andp-toluidine (pK=10–11) form easily reineckesalt analogous compounds: Amin· ·H[Cr(toluidine)₂(NCS)₄]·The formula of the 3 new complex anions: [Cr(toluidine)₂ (NCS)₄]- was established by preparative methods, with a series of double decomposition reactions, using chlorohydrates of some heterocyclic amines for this purpose. From spectroscopical investigations (UV and IR) some structural problems are resolved and discussed.The thermal stability and the mechanism of pyrolysis of these salts was studied by thermogravimetric analysis.

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Mit 8 Abbildungen     

Determination of the position of the acyl groups and the nature of some amino alcohols in native ester alkaloids of the genusVeratrum

Conclusions 1. On the basis of literature data on the structure of theVeratrum alkaloids, a definite law for the arrangement of the acyl radicals in these ester alkaloids and an interrelationship between the melting point and the structure of the substituent in the C₇ position, and between the melting point and the types of amino alcohols upon which the ester alkaloids are based, has been found.2. The features mentioned may be used in studying the structure of theVeratrum ester alkaloids according to a scheme which we propose.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 4, pp. 440–443, 1970     

Atomic emission spectrometry with an induction-coupled high-frequency plasma source: The determination of iodine,mercury, arsenic and selenium

The application of an inductively coupled high-frequency plasma source to the determination of iodine, mercury, arsenic and selenium by atomic emission spectrometry at wavelengths less than 200 nm is described. Optimal conditions have been established, and the spectral interference effects at different atomic lines for each element have been investigated. With the type of instrumentation employed, the determination of iodine at 183.04 nm, mercury at 184.96 nm, arsenic at 189.0 nm and selenium at 196.09 nm is recommended to minimize spectral interferences. No chemical or physical interferences resulting from the influence of foreign ions on the solute vaporization process have been noted.     

Reduction of 2,3,4-substituted quinolines with sodium borohydride

1,2-Dihydroquinolines were obtained by the reduction of 3-substituted 2-methyl-4-phenylquinolines with sodium borohydride in aliphatic carboxylic acids; N-alkyl derivatives are also formed. The corresponding 1,4-dihydroquinoline was obtained in the reaction of 2-methyl-3-nitroquinolinium perchlorate with sodium borohydride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1680–1686, December, 1991.     

The determination of molybdenum and tungsten in sea and surface water

A simple method for the determination of molybdenum and tungsten in sea and surface water is presented. Molybdenum and tungsten are concentrated on activated charcoal by adsorption as the ammonium pyrrolidine dithiocarbamate complex; the optimal pH for adsorption is 1.3. Mo and W are then determined by thermal neutron activation, forming ⁹⁹Mo (T_{$\text{1}\text{2}$} = 66.7 h) and ¹³⁷W (T_{$\text{1}\text{2}$} = 23.8 h), respectively. The ^99mTc daughter of ⁹⁹Mo is measured as soon as the equilibrium between ^99mTc(T_{$\text{1}\text{2}$}= 6 h) and ⁹⁹Mo is established. The detection limits are 0.05 μg Mo l^-1 and 0.05 μg W l^-1 (or 0.001 μg W l^-1 after a simple chemical separation).     

A hydrodynamic voltammetric study of the ferricyanide/ferrocyanide system with convective electrodes of platinum,gold, glassy carbon,carbon film,and boron carbide

Hydrodynamic voltammetry employing empirically determined mass transport coefficients is used to determine heterogeneous rate constants and transport coefficients for the ferricyanide/ferrocyanide system in 0.1 M phosphate buffer and other supporting electrolytes with turbulent tubular and rotated disk electrodes of platinum, gold, glassy carbon, carbon film, and boron carbide. Different kinetic parameters are obtained at the various electrode materials. For the platinum, gold, and boron carbide electrodes, the magnitudes of the rate parameters depend on scan direction. The nature of this hysteresis varies with the electrode material and is explained in terms of adsorbed oxide and ionic layers or other phenomena not described by simple double layer theory.