The mass spectra of some phenyl pyridyl ketones

The mass spectra of phenyl 2-pyridyl, phenyl 3-methoxy-2-pyridyl, phenyl 4-methoxy-2-pyridyl, phenyl 5-methoxy-2-pyridyl, phenyl 6-methoxy-2-pyridyl ketones, phenyl 3-pyridyl and phenyl 6-methoxy-3-pyridyl ketones, and phenyl 4-pyridyl ketone were studied. The major fragmentation pathway of all the ketones results in the formation of[C₆H₅CO]⁺ and [C₅H₄NCO]⁺ type ions. Another fragmentation path is the loss of carbon monoxide with formation of an [M ? CO]⁺ ion after skeletal rearrangement.     

The acid-catalyzed and neutral solvolysis of benzoylphenyldiazomethane in water,aqueous t-butanol,and aqueous salt solutions

The acid-catalyzed and water-catalyzed solvolysis ofbenzoylphenyldiazomethane (1) have been studied in water and in t-butanol-water mixtures, the mole fraction of water (n_H2O) being varied from 0·75-1·00. Increasing t-butanol concentrations produce a pronounced decrease in both k_H⊕ and k_H2O. In the “water reaction” mutually compensatory changes of AH

and AS

are associated with the rate variations, with minima in AH

and AS

at about n_H2O = 0·95. In addition it was found that the magnitude of the salt effect of (n-Bu)₄NCl on the rate of hydrolysis of 1 in water at 25° is much larger than that of LiCl, NaCl and NaBr. Assuming that the rate of the “water reaction” is largely determined by water acidity, the data are suggestive for the existence of a relation between water acidity and solvent structural integrity in highly aqueous t-butanol-water solutions.     

Influence of the water molecule on cation-pi interaction: ab initio second order Møller-Plesset perturbation theory (MP2) calculations

The influence of introducing water molecules into a cation-pi complex on the interaction between the cation and the pi system was investigated using the MP2/6-311++G method to explore how a cation-pi complex changes in terms of both its geometry and its binding strength during the hydration. The calculation on the methylammonium-benzene complex showed that the cation-pi interaction is weakened by introducing H(2)O molecules into the system. For example, the optimized interaction distance between the cation and the benzene becomes longer and longer, the transferred charge between them becomes less and less, and the cation-pi binding strength becomes weaker and weaker as the water molecule is introduced one by one. Furthermore, the introduction of the third water molecule leads to a dramatic change in both the complex geometry and the binding energy, resulting in the destruction of the cation-pi interaction. The decomposition on the binding energy shows that the influence is mostly brought out through the electrostatic and induction interactions. This study also demonstrated that the basis set superposition error, thermal energy, and zero-point vibrational energy are significant and needed to be corrected for accurately predicting the binding strength in a hydrated cation-pi complex at the MP2/6-311++G level. Therefore, the results are helpful to better understand the role of water molecules in some biological processes involving cation-pi interactions.     

Trace-Aktivitätskoeffizienten und Ionenassoziation von Natriummetawolframat im System Natriummetawolframat-Natriumperchlorat-Wasser

Zusammenfassung In der vorliegenden Arbeit wird das Sedimentations-gleichgewicht des Systems Na₆[H₂W₁₂O₄₀]-NaClO₄-H₂O bei 25 °C untersucht. Die scheinbare Ladungszahl des Natriummetawolframats wird als Funktion der NaClO₄-MolalitätmNaClO₄ ermittelt. Aus dieser Abhängigkeit kann für die summarische Dissoziation des NatriummetawolframatsNa₂[H₂W₁₂O_4o] 6Na⁺ + [H₂W₁₂O₄₀]^6– die DissoziationskonstanteK in Gegenwart von NaClO₄ als Fremdelektrolyt zuK=0,08 mol⁶·kg^–6 bestimmt werden.Der Kreuzdifferentialquotient ( _PXz , ist der Trace-Aktivitätskoeffizient des Natriummetawolframats) wird ebenfalls als Funktion der NaClO₄-Molalität ermittelt.Die Konzentrationsabhängigkeit des Trace-Aktivitätskoeffizienten zeigt einen Verlauf, wie er unseres Wissens nach noch nicht von anderen Autoren beobachtet wurde.

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Summary An ultracentrifugal study of the sedimentation equilibrium of the system Na₂[H₂W₁₂O₄₀]-NaClO₄-H₂Oat 25 °C is presented. The dependency of the apparent charge of the sodium metatungstate on NaClO₄-molality is investigated. From these data the dissociation constant for the dissociation of the sodium metatungstate in the presence of NaClO₄ according to the equationNa[H₂W₁₂O₄₀] 6Na⁺ + [H₂W₁₂O₄₀]^6– is calculated toK=0.08 mol⁶·kg^–6. The cross differential quotient ( _PXz is the trace activity coefficient of the sodium metatungstate) shows a behavior in its dependence on NaClO₄-molality which to our knowledge has not yet been reported by other authors.

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Mit 5 Abbildungen und 1 Tabelle     

Kalorimetrische messungen zur ermittlung der spezifischen grenzflächenenergie einer zweiphasigen Cu-7,5 At.-% In-legierung

With the help of a commercial heat-flux calorimeter the enthalpy change was measured as a function of the interlamellar spacing for lamellar precipitated Cu-In samples. This is related to the replacement of the two-phase structure (α + δ) by the homogeneous solid solution (α₀. From this, the specific interfacial enthalpy of the α-δ interface was determined to be ΔH^δ = 1100 ± 550 mJ m^?2. A value of ΔH^c = 1320 ± 60 J mol^?1 results for the chemical part of the total measured transformation enthalpy. A value of ΔS^δ = 0.66 mJ m^?2 K^?1 was estimated for the specific interfacial entropy and using the Gibbs-Helmholtz equation the specific interfacial free energy was calculated as ΔG^δ = 700 ± 400 mJ m^?2 at 600 K.     

Determination des fonctions d'excitation des reactions19F(p, α0)16O et7Li(p, α0)4He entre 150 et 1800 keV

The experimental device used is described. Excitation functions are given for an angle of observation 150° with respect to the incident beam. The possibilities of applying these reactions to the measurement of surface lithium and fluorine concentrations are considered. The detection limits for these two elements are shown to be 5·10⁻³ μg·cm⁻² with protons of energy between 1,350 and 1,500 keV. The method is compared with that based on the detection of prompt γ-rays from the reactions⁷Li(p, γ)⁸Be and¹⁹F(p, α γ)¹⁶O.      

Synthesis of phosphorus-containing polyurethanes from oligoethers prepared from bis(chloromethyl) methylphosphine oxide and glycols

Oligoethers with hydroxyl end-groups were prepared in boiling toluene from bis(chloromethyl)methylphosphine oxide and glycols used as monosodium glycolates. From these oligoethers and diisocyanates (hexamethylenediisocyanate and 2,4-toluene-diisocyanate), phosphorus-containing polyurethanes were synthesized.     

The study of coordinative interaction in the organoaluminium derivatives of substituted phenols

Intramolecular coordination in dimethylaluminium phenoxides (with an ortho-substituted ring) was investigated. Only strongly donating groups in the phenoxy ring (COOMe) displayed strong intramolecular coordination. All compounds investigated formed donor-acceptor complexes with hexamethylphosphoramide (HMPA). Dimethylaluminium methylsalicilate coordinated HMPA without splitting the intramolecular carbonyl oxygen—aluminium bond, which suggests formation of the pentacoordinated aluminium atom.     

Measurement of the Compton profiles of CH4 and C2H4 by high energy electron impact spectroscopy

We present a new experimental determination of the Compton profiles of CH₄ and C₂H₄ molecules using high energy electron impact. The observable q range has been extended up to 10 au (6 au for C₂H₄). Good agreement is found with an earlier X-ray scattering experiment and with new theoretical calculations.     

The thermal decomposition of ammonium metavanadate,I

The stoichiometry of the various stages involved in the thermal decomposition of ammonium metavanadate has been shown to correspond to a stepwise decrease in the ratio of ammonia and water to V₂O₅, with V₂O₅ being the final product in vacuum, in air and in argon. In ammonia, VO₂ is formed. The actual stages and intermediates are dependent upon the prevailing atmosphere. Chemical analyses, together with infrared absorption spectra and X-ray powder data, have enabled the intermediates and products to be characterized and the structural changes involved in the decomposition to be discussed.

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Zusammenfassung Es wurde gezeigt, daß die verschiedenen Stufen in der thermischen Zersetzung von Ammoniummetavanadat dem stufenweisen stöchiometrischen Verlust von Ammonia und Wasser entsprechen. In Vakuum, Sauerstoff und Argon ist V₂O₅, in Ammoniak VO₂ das Endprodukt. Die Zwischenprodukte der einzelnen Stufen sind von der umgebenden Gasatmosphäre abhängig. Durch chemische, infrarot- und röntgenspektroskopische Analyse gelang es, diese zu charakterisieren und so die durch die Zersetzung hervorgerufenen strukturellen Umlagerungen zu deuten.

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Résumé On montre que les différentes étapes de la décomposition thermique du métavanadate d'ammonium correspondent à la diminution progressive de l'eau et de l'ammoniac par rapport à V₂O₅; cet oxyde constitue le produit final dans le vide, dans l'air et dans l'argon. Dans l'ammoniac, c'est VO₂ qui se forme. Les étapes respectives et les intermédiaires dépendent de l'atmosphère qui prévaut. A l'aide de l'analyse chimique, des spectres d'absorption infrarouge et des données de rayons X sur poudre, on a pu caractériser les intermédiaires et les produits formés, ainsi que les changements structuraux provoqués par la décomposition.

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, V₂O₅. , V₂O₅. . , , .

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We wish to acknowledge helpful comments from Prof. L. Glasser and Dr. N. H. Agnew and financial support from the National Institute for Metallurgy, Johannesburg, South Africa.