Calorimetric study of molecular interactions in mixtures of substances containing carbonyl and dialkylamino groups

A Tian-Calvet type calorimeter has been used to determine molar excess enthalpies at 298.15 K as a function of concentration for mixtures ofN,N-dialkylated aminoketones or amides+n-heptane. These data are examined on the basis of a quasi-chemical theory using group-surface interactions. The occurrence of the hetero-proximity effect between -CO- and-N < groups is suggested by the variation of the interchange parameters.

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Zusammenfassung Ein Kalorimeter vom Tian-Calvet-Typ wurde zur Bestimmung der molaren Überschußenthalpie von Mischungen vonn-Heptan mitN,N-dialkylierten Aminoketonen bzw. Amiden bei 298.15 K in Abhängigkeit von der Konzentration verwendet. Die erhaltenen Daten wurden nach der quasi-chemischen Theorie unter Verwendung von Wechselwirkungen zwischen Gruppen und Überfläche ausgewertet. Das Auftreten des hetero-proximity-Effektes zwischen-CO- und -N <-Gruppen wird durch Veränderung der Austauschparameter angezeigt.

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- 298.15 N,N- -. - , . -- -N < .

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This is evidence indeed that proton acceptors, such as tertiary amines, shift the ketoenol equilibrium towards the formation of enols [3].     

Study of the heterogeneous decomposition of tertiary-butyl alcohol and di-tertiary-butyl peroxide on SiO2 by temperature programmed desorption

In the study of the interaction of tertiary-butyl alcohol and di-tertiary-butyl peroxide with SiO₂ treated with KCl by means of temperature programmed desorption, pulsation desorption (oscilatory behavior) is observed.

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- - SiO₂, KCl - , ( ).

     

Thermooxidative investigation of silylated cellulose derivatives

Cellulose substituted by organosilicon groups represents a new type of modified cellulose. The silylation changes the physical and chemical properties of cellulose drastically. The thermoanalytical investigation of differently trimethylsilylated cellulose derivatives was carried out under static conditions in air atmosphere. The DTA curves of the cellulose used as starting material are different from those of its silylated derivatives. In the latter a new characteristic exothermic peak appears in the range 320–370°. The value of this maximum depends on the grade of silylation, being shifted towards higher temperatures with higher degrees of substitution.

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Zusammenfassung Die durch Organosilikongruppen substituierte Zellulose stellt einen neuen Typ modifizierter Zellulose dar. Die Silylierung ändert die physikalischen und chemischen Eigenschaften der Zellulose drastisch. Die thermoanalytische Prüfung verschieden trimethylsilylierter Zellulosederivate wurde in Luft unter statischen Bedingungen durchgeführt. Die DTA-Kurven der als Ausgangsmaterial eingesetzten Zellulose sind von denen ihrer Silylderivate verschieden. In den letzteren erscheint ein neuer charakteristischer exothermer Peak im Bereich von 320 bis 370°C. Die Temperaturlage dieses Maximums hängt vom Silylierungsgrad ab und wird bei höherem Substitutionsgrad in Richtung höherer Temperaturen verschoben.

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Résumé La cellulose substituée par des groupes silico-organiques représente un nouveau type de celluloses modifiées. La présence du silicium change complètement les caractéristiques physiques et chimiques de la cellulose. L'étude thermo-analytique de divers dérivés de la cellulose triméthylsilylée a été effectuée dans l'air en atmosphère statique. Les courbes ATD de la cellulose utilisée comme matériau de départ sont différentes de celles de ses dérivés silylés. Pour ceux-ci, un nouveau pic exothermique caractéristique apparaît entre 320 et 370°C. La température du maximum du pic dépend du degré de la silylation et se déplace vers les valeurs plus élevées si le degré de substitution augmente.

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— . . . DTA , , . 320–370°C. .

     

Exchange of propene-d6 with hydrogen of HY zeolites

The exchange of C₃D₆ with hydroxylated and partially dehydroxylated HY zeolites was studied by the analysis of the gas (MS) and the solid (IR) phase at 300°C and at the temperature of the IR beam.

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C₃D₆ HY () () 300°C .

     

Localization of gallium in erionite type Ga?Al zeolites by71Ga,27Al and29Si NMR

The state of Al³⁺, Ga³⁺ and Si⁴⁺ in erionites obtained by hydrothermal crystallization from Ga–Al–Si gels has been examined. The results suggest that gallium cations can isomorphously substitute a part of silicon cations in the zeolite framework, to a notable extent in the sites having no aluminium cations in the second coordination sphere of silicon.

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Al³⁺, Ga³⁺ Si⁴⁺ , . , , .

     

Characterization of [Ni(py)4]Cl2 and its thermal decomposition

The stepwise thermal decomposition of [Ni(py)₄]Cl₂ was studied by means of a derivatograph. The stepwise mode of thermal decomposition allowed the preparation of new complexes. X-ray powder diffraction and IR methods were used to study the structures of the decomposition intermediates. [Ni(py)₄]Cl₂ was applied as a model substance. The decompositions of a great number of complex compounds of similar type have been reported, but only a few of them have been investigated structurally by single-crystal X-ray diffraction techniques due to the difficulty of obtaining large single-crystals.

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Zusammenfassung Die schrittweise thermische Zersetzung von [Ni(py)₄]Cl₂ wurde mit einem Derivatographen untersucht. Diese Methode ermöglicht die Darstellung neuer Komplexverbindungen. Zur Untersuchung der Struktur der intermediären Zersetzungsprodukte wurden ebenfalls XPD und IR-Spektroskopie angewandt. [Ni(py)₄]Cl₂ wurde als Modellsubstanz gewählt. Eine große Zahl ähnlicher Komplexverbindungen ist bekannt, aber nur von wenigen wurde die Kristallstruktur wegen der Schwierigkeiten, entsprechend große Einkristalle zu erhalten, durch Einkristall-Röntgendiffraktometrie bestimmt.

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[Ni(py)₄]Cl₄) . . , .

     

Temperature-programmed reduction and oxidation of bimetallic catalysts Rh?Ag/Al2O3

Investigations of temperature-programmed reduction and oxidation of bimetallic catalysts Rh–Al₂O₃ seem to indicate that there are no strong interactions between rhodium and silver. Bimetallic catalysts rather show the additive properties of individual components, i. e. rhodium and silver.

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- Rh–Al/Al₂O₃ . , .

     

The relationship between the structures of Cu(II) complexes and their chemical transformations: VII

The thermal decompositions of Cu(en)₂(NCS)X. where X^–=Cl^–, Br^–, NO ₃ ^– , BF ₄ ^– and ClO ₄ ^– , have been studied in comparison with the courses of Cu(en)₂(SCN)₂ and Cu(en)₂X₂ decomposition. It is shown that the presence of the thiocyanate group in the complexes Cu(en)₂(NCS)X is the most important factor in the decomposition course, in agreement with the fact that the anions X^– are not coordinated. or are only semicoordinated. Significant differences were found in the courses of thermal decomposition of two forms of Cu(en)₂(NCS)(BF₄) differing in the structure of their coordination polyhedra.

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Zusammenfassung Die thermische Zersetzung von Cu(en)₂(NCS)X (X=Cl Br, NO₃, BF₄ und ClO₄) wurde untersucht und mit der von Cu(en₂(SCN)₂ und Cu(en)₂X₂ verglichem. Der den Verlauf der Zersetzung entscheidend bestimmende Faktor isi die Anw esenheit der Thiocyanat-Gruppe in den Cu(en)₂(NCS)X-Komplexen, was in Übereinstimmung damit steht,. daß die Anionen X nicht oder nur teilweise koordiniert sind. Es wurden signifikante Unterschiedeim Verlauf der thermischen Zersetzung von zwei sich in der Struktur ihrer Kordinationspolyeder unter-, heidenden Formen von Cu(en)₂(NCS)(BF₄) gefunden.

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Cu(en)₂(NCS)X (X^–=Cl^–, Br^–, NO ₄ ^– , NO ₃ ^– , BF₄ ClO₄, Cu(en)₂(SCN)₂ Cu(en)₂(X)₂. , Cu(en)₂(NCS)X X Cu(en) (NCS)BF₄ i .

     

Nonisothermal kinetics of independent reactions

A general approach to the solution of peak seperation problem applicable not only in nonisothermal kinetics, but also in chromatographic, spectroscopic and polarographic studies of catalysts is suggested.

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, , , , , .

     

Sulphur dioxide oxidation in aqueous solutions containing metal cations

Effect of vanadium cations as model inhibitors on SO₂ oxidation with air in iron sulfate solutions at 298–308 K has been studied and a mechanism of inhibition proposed.

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V, , SO₂ 298–308 K. .

     

Coumarins of Smyrniopsis aucheri

Chemical transformations and spectral characteristics have enabled us to establish the structure and configurations of three coumarins: (+)-2,2-dimethyl-3-hydroxy-3,4-dihydropyrano(5,6:6,7)coumarin (I); (+)-4-hydroxy-5-(1-hydroxy-1-methylethyl)-4,5-dihydrofuro(2,3:6,7)coumarin (II); and (+)-4-hydroxy-5-(1-glucopyranosyloxy-1-methylethyl)-4,5-dihydrofuro(2,3:6,7)-coumarin (III) isolated from the roots ofSmyrnopsis aucheri Karjag. This is the first time that these compounds, which have been called smyrinol, smyrindiol, and smyrindioloside, have been detected in nature.Institute of Chemistry of Plant Substances, Uzbekistan Republic Academy of Sciences, Tashkent. Azerbaidzhan State University, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 36–40, January–February, 1992.     

Vibrational relaxation by collision in polyatomic molecules

A model of a harmonic oscillator with friction is used to discuss the conversion of translational energy to vibrational by collision of an atom with a polyatomic molecule. It is shown that adiabatic conversion implies that E ² may substantially exceed the value calculated, neglecting the interaction of the bond with the rest of the molecule.     

Average electron momenta in many-electron atoms

In many-electron atoms, the average electron momentum p represents the mean momentum of a single electron when all the electron motions are averaged. If any two electrons are considered simultaneously, however, the average momentum p splits into two different momenta, low momentum p_< and high momentum p_>. For the 102 atoms He through Lr in their ground states, the momenta p_< and p_> are systematically examined at the Hartree–Fock limit level. It is also shown that the sum p_>+p_< and the difference p_>–p_< of the two momenta constitute upper and lower bounds to the electron-pair relative momentum p₁₂=|p₁–p₂| and to the electron-pair center-of-mass momentum P=|p₁+p₂|/2. The tightness of the bounds is discussed for the 102 atoms.     

Solvent Effect on the Thermodynamics of Complex Formation with Proton Transfer from 4-Nitrophenylnitromethane to Triethylamine

In studying the thermodynamics of the formation of the 4-nitrophenylnitromethane–triethylamine ion pair in different chemical solvents within the dielectric constant interval 2.4 65, an increase in the ion pair stability with an increase in the medium polarity is revealed. Account for the effect of dielectric saturation of solvent molecules through the Blok–Walker function () gives pK= f(()) (Kis the equilibrium constant of ion pair formation), which is nearly linear. The electrostatic and nonelectrostatic components of the thermodynamic parameters of the reaction are estimated. The governing role of the covalent contribution to solvents with high polarity and of the electrostatic contribution to systems with 4–7 is established. A linear correlation between the bathochromic shift of the band in the electronic absorption spectra of solutions of the ion pair and the logarithm of the stability constant of the complex is found.     

The measurement of “enhanced” L and M X-ray yields from charge-induced studies with protons and1H 2 + ion beams

Earlier work on Charge Induced X-rays (CHIX) was extended to include the X-ray energy region between 0.70 to 4.0 keV. Protons of 700 keV, and¹H ₂ ⁺ ion beams of equivalent proton energies in the range 350–450 keV were used to produce enhanced yields of L and MX-rays from a suitable selection of highly compacted non-conducting samples. Enhancement factors are given and possible applications are mentioned.     

Thermoreversible gelation of polyacrylonitrile/dimethylformamide-solution

The thermoreversible gelation of semi-diluted atactic polyacrylnitrile (PAN)/dimethylformamide (DMF)-solutions has been studied. The structural features of PAN/DMF-gels, formed by supercooling have been investigated by DSC-, x-ray- and swelling measurements. A new structural model has been introduced to describe the morphology of the junction zones of PAN/DMF-gels and to also explain the gelation behavior of PAN/DMF-solutions as the structural features of PAN/DMF-gels. The junction zones of a PAN/DMF-gel have been defined as ordered junction zones.A gelation enthalpy of about H=–6 kJ/mol supports the idea that an ordered junction zone is formed by intermolecularly neighboring stereoregular parts of atactic PAN chains due to a nucleation process in the solution. It can be defined as a strongly distributed fringed micelle.     

Zur Totalsynthese von Human-Sekretin

Summary The synthesis of the heptacosapeptide amide with the primary structure of Human-secretin is described. For this purpose 7 fragments were designed, i.e. H-Gly-Leu-Val-NH₂ 25–27b,Z-Arg(Z ₂)-Leu-Leu-Gln-OH 21–24,Z-Arg(Z ₂)-Leu-Gln-OH 18–20,Z-Arg(Z ₂)-Glu(OtBu)-Gly-Ala-OH 14–17,Z-Arg(Z ₂)-Leu-OH 12–13,Z-Thr(tBu)-Ser(tBu)-Glu(OtBu)-Leu-Ser(tBu)-OH 7–11,Adoc-His(Adoc)-Ser(tBu)-Asp(OtBu)-Gly-Thr(tBu)-Phe-OH 1–6 these fragments were consequently assembled to the overall protected total sequence using the Wünsch/Weygand-method with dicyclohexylcarbodiimide. After deprotection by exposure to trifluoroacetic acid in presence of 1,2-ethanedithiol and water as scavenger, the isolated crude product was purified by column chromatography on CM-Sepharose, fast flow. This synthetized Human-secretin showed the full biological activity in comparison to Porcine-secretin.

Herrn Prof. Dr. E. Bayer zum 65. Geburtstag gewidmet.     

Über Verdazyliumsalze

Zusammenfassung Verdazyle reagieren mit FeCl₃ und anderen Metallhalogeniden in HCOOH unter Bildung von Doppelsalzen. Mit Tetranitromethan erhält man Verdazylium; C(NO₂)₃ ; und Verdazylium^;NO₃ ;. Verdazyliumsalze und Tetramethyl-p-phenylendiamin ergeben unter Elektronenübergang Verdazyle undWursters Blau. Dabei werden aus 2 diamagnetischen Verbindungen 2 paramagnetische Radikale gebildet. Die Absorptionsspektren verschiedenartig substituierter Verdazyliumsalze werden im Zusammenhang mit den Spektren der entsprechenden Verdazyle diskutiert.

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Verdazyls react with FeCl₃ and other metal halides in formic acid to give double-salts. Verdazylium;·C(NO₂)₃ ; and Verdazylium;NO₃ ; were obtained with tetranitromethane. Verdazyliumsalts and tetramethyl-p-phenylenediamine yield, in an electron transfer reaction, the corresponding verdazyls andWurster's-blue; i. e. two diamagnetic compounds react to give two stable paramagnetic species. The absorption spectra of different substituted verdazylium salts are discussed in relation to the spectra of the corresponding verdazyls.

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10. Mitt.:F. A. Neugebauer, Mh. Chem.97, 853 (1966).     

Two-electron atomic wave functions which satisfy proportionality relations between one-and two-electron moments

Based on momentum- and position-space analyses of the moment operators for two-electron atoms, it is shown that there exists a family of two-electron wave functions which satisfy a proportionality relation, r/ ₁ ^v /r ₁₂ ^v =p/ ₁ ^v /p ₁₂ ^v =2^–v/2, between the one and two-electron moments in position and momentum spaces, where v is an arbitrary number for which the moments are well-defined.