Zur Synthese von Human-Big-Gastrin I und seinem 32-Leucin-Analogon 2. Mitteilung: Darstellung der Teilsequenzen 9–14 und 1–8

The syntheses of the hexapeptide and octapeptide derivative corresponding to the sequences 9–14 and 1–8 of human-big-gastrin I, respectively, are described. The two fragments obtained predominantly by stepwise procedures, represent in the suitably protected form building blocks for the total syntheses of human-big-gastrin I and its 32-leucine-analogue.

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Abkürzungen DCCD Dicyclohexylcarbodiimid - HONSu N-Hydroxysuccinimid - TFE Trifluoressigsäure - DMF Dimethylformamid - DCHA Dicyclohexylamin Es werden hier die von der IUPAC-IUB Commission on Biochemical Nomenclature empfohlenen Abkürzungen für Aminosäuren und Schutzgruppen verwendet. Andere Abkürzungen     

Bond properties of metal-ligand bonds

An empirical relation has been developed to compute the bond order of ionic systems. The computed values have been compared with those calculated by using the experimental values of bond polarizability derivatives and are found to be in fair agreement. This shows that the proposed empirical relation for computing bond orders is quite suitable for ions.

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Bindungseigenschaften von Metall-Ligand-Bindungen

Zusammenfassung Es wurde eine empirische Beziehung entwickelt, die die Berechnung von Bindungsordnungen für ionische Systeme erlaubt. Ein Vergleich der berechneten Werte mit solchen, die aus experimentellen Daten für Differentiale von Bindungspolarisierbarkeiten erhalten wurden, zeigte die Brauchbarkeit der Methode für Ionen.

     

Elektronenlokalisierung im Grundzustand und in angeregten Zuständen Pars-Orbital-Methode, 12. Mitt

UsingGleason's theorem the pars orbital concept is developed for excited states of conjugated systems described by CI-methods. A significance index is introduced to evaluate different patterns of fragmentation. The usefulness of this approach is illustrated for butadiene, biphenyl, naphthalene, and azulene.

11. Mitt.:H. Karpf, O. E. Polansky undM. Zander, Tetrahedron Lett.1978, 2069.     

Zur Synthese von Human-Big-Gastrin I und seinem 32-Leucin-Analogon 1. Mitteilung: Darstellung der Teilsequenzen 28–34, 23–27, 21–22 und 15–20

Human-Big-Gastrin I, a peptide hormone of 34 amino acid residues, and the 32-leucine analogue were synthesized. For this purpose six suitable peptide fragments were prepared at first, which subsequently were condensed to the total sequence. In this paper we describe the syntheses of four suitably protected peptide fragments corresponding to the sequences 28–34, 23–27, 21–22 and 15–20 of human-big-gastrin I. For the protection of the side-chain functionstert-butanol derived groups removable in the final step by acidolytic cleavage were used. The -amino-functions were selectively blocked as benzyloxycarbonyl-and 2-nitrophenylsulfenyl-derivatives, respectively.

Abkürzungen: Es werden hier vorwiegend die von der IUPAC-IUB Commission on Biochemical Nomenclature empfohlenen Abkürzungen für Aminosäuren und Schutzgruppen verwendet. Wegen der universellen Anwendbarkeit bedienen sich die Autoren auch der imHouben-Weyl ² niedergelegten und eingehend erläuterten Abkürzungen.DCCD=N,N-Dicyclohexylcarbodiimid,HONSu=N-Hydroxysuccinimid.     

Benzothiazolo[3,2-c]-1,3-dioxolo[4,5-g]quinazolines

Zusammenfassung Es wurde eine Reihe von 5,12a-Dihydro-6-alkyl/aryl-6H-benzothiazolo [3,2-c]-1,3-dioxolo[4,5-g]chinazoline, sowohl mitcis-als auchtrans-ständigen Wasserstoffatomen an Kohlenstoff 6 und 12a, synthetisiert. Ebenso wurden auch Verbindungen dieses Systems mit Thiazol an Position 6 hergestellt. Die Strukturen wurden mittels IR- und NMR-spektroskopischen Daten abgesichert.

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Benzothiazolo[3,2-c]-1,3-dioxolo[4,5-g]quinazolines

Some 5,12a-dihydro-6-alkyl/aryl-6H-benzothiazolo[3,2-c]-1,3-dioxolo [4,5-g]quinazolines withcis as well astrans stereochemistry of the hydrogens at carbon 6 and 12a have been synthesised. The synthesis of another series of compounds of the above system with thiazole ring at position 6 has also been accomplished. The structures have been established on the basis of IR and PMR data.

     

Extension of theHüttig isotherm on mixed gas adsorption

Hüttig's theory was extended for mixed gas adsorption. The derived equation is the same as the one that has been obtained byGonzalez andHolland for bilayer adsorption.

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Erweiterung der Hüttig-Isotherme für Gasmischungen (Kurze Mitteilung)

Zusammenfassung Die Theorie vonHüttig wurde auf gemischte Gase ausgedehnt. Die dabei abgeleitete Gleichung ist dieselbe wie die vonGonzalez undHolland für Zweischichtadsorption.

     

Thermodynamische Untersuchungen ann-Alkan/n-Alkin-Systemen

The vapour-liquid equilibrium data obtained from isobarict-x-measurements have been used for calculation of the group UNIFAC parameters and excess free enthalpyG ^E of binary mixturesn-alkanes with isomericn-alkynes. The UNIFAC model gives satisfactory predictions for the systems studied. The temperature dependence ofG ^E was estimated on the basis of the heats of mixing measured earlier. The influence of the position of triple bond in the molecules ofn-alkynes on the excess thermodynamic functions is considered.

     

Über Erdalkalimetalloxogallate. VIII Synthese und Aufbau eines neuen Calciumoxogallats: Ca3Ga4O9

The hitherto unknown compound Ca₃Ga₄O₉ was prepared and investigated by X-ray single crystal methods. Ca₃Ga₄O₉ has orthorhombic symmetry:a=1435.8;b=1682.5;c=532.1 pm; space group C _2v ¹¹ –Cmm2,Z=6. The tetrahedra network (circles of 4 and 5 GaO₄-tetrahedra) and the surrounding of Ca²⁺ are described and discussed with respect to other oxogallates.

     

Die Kristallstruktur des Komplexnitrides NbMoN1−x (x≤0,1)

The crystal structure of NbMoN_1–x has been determined from X-ray powder patterns. It is isotypic with the formerly described^1,2 complex nitrides NbCrN and Ta_1–x Cr_1+x N. The tetragonal unit cell contains 6 atoms and belongs to the space groupP4/nmm-D _4h ⁷. The lattice parameters are:a=3,095 Å,c=7,799 Å. The structure is characterized by relatively close packed double layers of Nb-atoms and Mo-atoms parallel to the base plane. The nitrogen atoms are within the octahedral interstitial sites.

     

Magnetische Eigenschaften von Hf2Fe und Hf2FeH x

The weakly temperature dependent paramagnetic compound Hf₂Fe becomes ferromagnetic by hydrogen absorption, theCurie-temperature of the resulting hydrides depends on the hydrogen content.

     

Kinetische Untersuchungen über die Silicium—Aryl-Spaltung mit Bromwasserstoff

Rate constants of the cleavage reaction of silicon aryl linkages with HBr were estimated for various aryl derivatives by means of NMR. A row of substituents was obtained, dependent on the cleavage rates. Correlation with theHammett function shows the electrophilic character of the reaction. The different cleavage rates give the possibility for specific cleavages of aryl groups from silanes.

     

Physikalisch-chemische Eigenschaften der Halbleiter im System GeS x Se1−x

Specimens of the system GeS _x Se_1–x were examined by means of X-ray and differential thermal analysis for 0x1. The activation energy of the specimens was calculated according to a semi-empirical method on the basis of the known thermodynamic parameters of the components.

     

Asymmetrische Hg(II)-Komplexe mit Organothiolato- bzw. Organoselenolato-und Triazenato-Liganden

The mixed mercury complexes (2XC₆H₄)₂N₃HgY (X=CH₃, F, Cl, Br, I;Y=SC₂H₅, SC₆H₅, SeC₆H₅) have been prepared. Both the Hg–S and Hg–Se bonds and, in contrast to other mixed triazenato-mercury compounds, the triazenato-mercury bonds have been shown to be kinetically labile on the NMR time scale by means of⁷⁷Se and¹⁹⁹Hg NMR spectroscopy. Evidence has been obtained for the presence of (2XC₆H₄)₂N₃HgY together with HgY ₂ and [(2XC₆H₄)₂N₃]₂Hg in solution.

     

Die Schwingungsspektren einiger kristalliner Dekavanadate

The infrared andRaman spectra of Ba₃V₁₀O₂₈·19 H₂O has been recorded and an assignement for the internal vibrations of the V₁₀O ₂₈ ^6– anion is given. Infrared data of the hydrated decavanadates of silver, cadmium, magnesium and lanthanum are also reported and briefly discussed.

     

Die IR-Spektren einiger Arsenat-Halogen-Apatite

The infrared spectra of orthoarsenates with apatite structure, of the formulaM ₅(AsO₄)₃ X (M=Ca, Sr, Ba, Pb andX=F, Cl,Br) are measured and interpreted on the basis of a site-symmetry analysis. The influence of the different cations on the internal vibrations of the AsO₃ ⁴-ions is discussed.

     

On the substituent effects of halogens in aromatic substitutions

The general kinetic features of the bromination of 4-bromophenol by molecular bromine in acetic acid medium has been studied andArrhenius activation energies for the bromination of fourpara substituted phenols of the general formulaRC₆H₄OH (R=CH₃, F, Cl, and Br) have been accurately determined. These values, which indicate an anomalous order in substituent effect of halogens, are discussed.

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Der Substituenten-Effekt von Halogenen bei der aromatischen Substitution

Zusammenfassung Die Bromierung von 4-Bromphenol mit Br₂ in Essigsäure wurde untersucht. Außerdem wurden dieArrhenius-Aktivierungs-Energien für die Bromierung von vierp-substituierten PhenolenRC₆H₄OH (R=CH₃, F, Cl und Br) genau bestimmt. Die beobachteten Substituenten-Effekte werden diskutiert und interpretiert.

     

Thermodynamics of the isopropanol/n-hexane and isopropanol/n-heptane systems. Part I. Infrared studies

The association equilibria for different conglomerates are calculated for the isopropanol/n-Hexane, isopropanol/n-Heptane systems from the infrared spectra.

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Zur Thermodynamik des Isopropanol/n-Hexan und Isopropanol/n-Heptan Systems, I. Untersuchungen mittels IR-Spektroskopie

Zusammenfassung Es werden die Assoziationsgleichgewichte für verschiedene Konglomerate im Isopropanol/n-Hexan- bzw.-/n-Heptan-System aus den IR-Spektren abgeleitet.

     

Conformational analysis and electronic structure of monothiodiacetamide: Normal coordinate analysis and molecular orbital study

The infrared spectra of monothiodiacetamide (MTDA, CH₃CONHCSCH₃) and its N-deuterated compound in solution, solid state and at low temperature are measured. Normal coordinate analysis for the planar vibrations ofMTDA-d ₀ and –d ₁ have been performed for the two most probablecis-trans-CONHCS-or-CSNHCO-conformers using a simpleUrey-Bradley force function. The conformation ofMTDA derived from the vibrational spectra is supported by the all valence CNDO/2 molecular orbital method. The vibrational assignments and the electronic structure ofMTDA are also given.

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Konformationsanalyse und elektronische Struktur von Monothiodiacetamid. Normalkoordinatenanalyse und MO-Studie

Zusammenfassung Das Infrarotspektrum von Monothiodiacetamid (MTDA, CH₃CONHCSCH₃) und der entsprechenden N-deuterierten Derivate wurde in Lösung, im Festzustand und bei tiefer Temperatur gemessen. Die Normalkoordinatenanalyse der möglichen planaren Konformeren wurde mittels einer einfachenUrey-Bradley-Funktion durchgeführt. Die dabei abgeleitete Konformation vonMTDA steht im Einklang mit einer semiempirischen quantenchemischen Rechnung (CNDO/2). Die Zuordnung der Schwingungen und die Elektronendichteverteilung inMTDA werden angegeben.

     

Untersuchungen im System V—Mo—N

The system V–Mo–N has been investigated at 1,100°C and nitrogen pressures between 1 and 300 bar by X-ray techniques. The isotypic compounds VN and Mo₂N are forming a complete series of solid solutions at nitrogen pressures>30 bar. At a nitrogen pressure of 1 bar about 10% of the V-atoms can be replaced by Mo-atoms in the MN_1-x -compounds. Within the M₂N-phase V-atoms can be replaced by Mo-atoms in the range of 10%.

     

Leitfähigkeitsmessungen an Tetraethylammoniumhexacyanoferrat(III) und Tetrabutylammoniumhexacyanoferrat(III) in verschiedenen Lösungsmitteln

Based on conductivity measurements, the dissociation of tetraalkylam-moniumhexacyanoferrates(III) in water, ethanol, formamide,N-methylformamide,N,N-dimethylformamide, propylenecarbonate and acetonitrile is discussed. Interactions of the solvent as donor and as acceptor, the latter interaction being dominant, with (et ₄N)₃Fe(CN)₆ and (bu ₄N)₃Fe(CN) were found to be important factors in the formation of solvated ions.