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  • 1
    Electronic Resource
    Electronic Resource
    13C-Kernresonanz-Spektroskopie an diastereomeren Dicarbonsäuren: 2,3-Dimethylbernsteinsäure, 2-Äthyl-3-methylbernstein-säure und 3-Äthyl-4-methyladipinsäure (1974)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 3771-3779 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 13C Nuclear Magnetic Resonance Spectroscopy of Diastercomeric Dicarboxylic Acids: 2,3-Dimethylsuccinic, 2-Ethyl-3-methylsuccinic, and 3-Ethyl-4-methyladipic AcidsProton noise-decoupled 13C n.m.r. spectra of 2,3-dimethyl- (1m/1r) and 2-ethyl-3-methyl-succinic acid (2e/2t) as well as of 3-ethyl-4-methyladipic acid (3e/3t) in [D6]acetone show differences in chemical shifts for all carbons between meso and racemic (1) and between erythro and threo (2 and 3) diastereomers, respectively. The chemical shift differences allow conclusions to be made about the relative populations of rotamers in the conformational equilibria.
    Notes: Die unter Rauschentkopplung der Protonen erhaltenen 13C-NMR-Spektren von 2,3-Dimethyl-(1m/1r) und 2-Äthyl-3-methylbernsteinsäure (2e/2t) sowie von 3-Äthyl-4-methyladipinsäure (3e/3t) in [D6]Aceton zeigen für alle Kohlenstoffatome unterschiedliche chemische Verschiebungen in den meso- und racem.-(bei1) bzw. den erythro- und threo-Diastereomeren (bei 2 und 3). Die Verschiebungsdifferenzen ermöglichen Aussagen über die relativen Besetzungszustände der einzelnen Rotameren in den konformativen Gleichgewichten.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19741071207
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  • 2
    Electronic Resource
    Electronic Resource
    INDO- und CNDO-MO-Berechnungen von weitreichenden H, H-Kopplungen im Vinylcyclopropan (1972)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 2368-2374 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: INDO and CNDO MO Calculations of Long-Range Coupling Constants in VinylcyclopropaneINDO and CNDO MO calculations of long-range coupling constants in vinylcyclopropane and comparison with analogous calculations of propane, propene, and butadiene as well as with experimental values show that the magnitudes of the allylic couplings J2,4 and J3,4 (numbering see formula 1) are compatible with hybridization of the cyclopropyl carbon atoms between sp2 and sp3. Conjugation between ring and double bond, however, is not reflected by large π-contributions to pseudoallylic (J1,5 and J1,6) nor to five bond couplings.
    Notes: INDO- und CNDO-MO-Berechnungen der weitreichenden Kopplungen im Vinylcyclopropan und Vergleich mit entsprechenden Rechnungen an Propan, Propen und Butadien sowie mit experimentellen Ergebnissen zeigen, daß die Größe der allylischen Kopplungen J2,4 und J3,4 (Numerierung s. Formel 1) mit einem Hybridisierungsgrad der Cyclopropyl-Kohlenstoffatome zwischen sp2 und sp3 vereinbar ist. Die Konjugation zwischen Ring und Doppelbindung kommt jedoch weder in großen π-Beiträgen zu den pseudoallylischen (J1,5 und J1,6) noch zu den Kopplungen über fünf Bindungen zum Ausdruck.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19721050730
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  • 3
    Electronic Resource
    Electronic Resource
    13C-NMR-Spektroskopie an polycyclischen Aromaten, I. Naphthole, Naphthalindiole und Monomethoxynaphthaline. Vollständige Zuordnung der 13C-NMR-Spektren und Untersuchung der Substituenteneffekte auf die chemischen Verschiebungen (1975)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2030-2039 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 13C.N.M.R. Spectroscoopy of Polycyclic Aromatics, I Naphthols, Naphthalenediols, and Methoxynaphthalenes. Complete Assignment of the 13C.N.M.R. Spectra and Investigation of Substituent Effect on chemical ShiftsIn the 13C n.m.r. spectra of 1-naphthol (1), 2-naphthol (2), 1-methoxynaphthalene (4), 2-methoxynaphthalene (5), 1,5-naphthalenediol (7), 2,6-naphthalenediol (8), and 2,7-naphthalenediol (9) in [D6]acetone and CDCl3 all signals have been assigned. Proton-coupled and selectively decoupled spectra proved to be valuable aids. The lower number of signals and the strict additivity of substituent effects upon the chemical shifts in the symmetrical diols further confirmed the assignments in the monohydroxy derivatives. Strong substituent effects over the maximum possible number of bonds were observed and could be rationalized by considering those canonical structures that contribute mostly to the resonance hybrid.
    Notes: In den 13C-NMR-Spektren von 1-Naphthol (1), 2-Naphthol (2), 1-Methoxynaphthalin (4), 2-Methoxynaphthalin (5), 1,5-Naphthalindiol (7), 2,6-Naphthalindiol (8) und 2,7-Naphthalindiol (9) in [D6]Aceton- und CDCl3-Lösung konnten sämtliche Signale zugeordnet werden. Hierbei erwiesen sich die Aufnahme protonengekoppelter Spektren sowie selektive Entkopplung der Protonen als wertvolle Hilfsmittel. Die verringerte Anzahl der Signale und die strikte Additiviät der Substituenteneffekte auf die chemischen Verschiebungen in den symmetrischen Diolen sichert die Signalzuordnung bei den Monohydroxyderivaten zusätzlich ab. Man beobachtet starke Substituenteneffekte, die sich bis über die maximal mögliche Anzahl von Bindungen bemerkbar machen und sich anhand der kanonischen Formen deuten lassen, die am stärksten zum Resonanz-hybrid beitragen.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19751080622
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  • 4
    Electronic Resource
    Electronic Resource
    Cyclophanes, XXXV. DNMR, molecular mechanics, and crystal structures of 2,11-dithia[3.3]orthometacyclophane and 2,11-dithia[3.3]orthoparacyclophane (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2381-2386 
    Details
    ISSN: 0009-2940
    Keywords: Dithiacyclophanes ; DNMR ; Molecular mechanics ; Cyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of 2,11-dithia[3,3]orthometacyclophane (5) and 2,11-dithia[3,3]orthoparacyclophane (6) by dithiol-dibromide coupling are described. Whereas the yield of 5 is not significantly affected by the substrate pairing, that of 6 is. Both compounds exhibit a temperature-dependent 1H-NMR spectrum. An energy barrier of 11.0 ± 0.2 kcal/mol (45.7 ± 0.8 kJ/mol) has been calculated for 5, but that of 6 was too low to be determined. Slightly contrasting results were obtained from two different molecular mechanics programs for the relative energies of the six limiting conformations of 5. Crystal structure determinations of 5 and 6 have been carried out, and the conformational behavior of 5 and 6 in solution and in the solid state is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231221
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  • 5
    Electronic Resource
    Electronic Resource
    Darstellung und Kristallstrukturen einiger mit N,N'-Dimethylharnstoff verbrückter Diphosphorverbindungen; NMR-Untersuchung einer λ4P+λ4P+-Diphosphorverbindung (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 35-43 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphorus compounds, mixed valence λ4P+λ4P+, PP-bonded ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Single-Crystal X-ray Structure Investigations of some N,N′-Dimethylurea-Bridged Diphosphorus Compounds: NMR Studies of a λ4P+ λ4P+ -Diphosphorus CompoundThe synthesis of N,N′-dimethylurea-bridged diphosphorus compounds involving the structural elements λ3Pλ4P+ (3b, 3c, and 7) and λ4P+λ4P+ (4 and 8) is described. The salts 4 and 8 were obtained by methylation of the λ3Pλ4P+ compounds 3c and 7 with MeOSO2CF3. The λ3P atom in 3c and 7 coordinates to tungsten(0) with formation of the ionic pentacarbonyl derivatives 9 and 10. The NMR spectra of the diphosphonium salt 4 were completely analyzed using NOE and 2D shift correlation experiments (13C,1H and 31P,1H). The single crystal X-ray structure determinations of 3b and 9 are reported. 3b found to crystallize as a hemisolvate with dichloromethane. The RR/SS diastereomer is present in the crystal. The PP distance amounts to 219.1 pm. Both phosphorus atoms interact weakly with the chloride ion (293, 312 pm). 9 crystallizes as a hemisolvate with toluene, the RS/SR diastereomer being present. A PP distance of 224.7 pm and weak interactions between the phosphorus atoms and an oxygen atom of the anion (305, 308 pm) are found.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230108
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  • 6
    Electronic Resource
    Electronic Resource
    Neue Dienophile und Diene, III. Über die Addition von Cyanacetylen an [2.2]Paracyclophan (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2015-2022 
    Details
    ISSN: 0009-2940
    Keywords: Dienophiles, triple-bond ; Cyclobutadiene ; Cyclophanes ; Diels-Alder adducts ; Nenitzescu systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Dienophiles and Dienes, III.  -  On the Addition of Cyanoacetylene to [2.2]ParacyclophaneHeating a benzene solution of [2.2]paracyclophane (2) in the presence of excess cyanoacetylene (1b) at 160°C in a sealed ampoule provides the novel 2:1-addition product 10, as well as the previously obtained cycloadducts 7-9. It is suggested that these Nenitzescu hydrocarbon systems are formed via the cyclobutadiene intermediates 17 and 18. This hypothesis is supported by the isolation of the side-products 1,2,4-and 1,2,3-tricyanobenzene (11 and 12). When a mixture of 7 and 8 is pyrolyzed at 220°C the novel dihydronaphthalene 24 is formed; the mechanism of this isomerization is discussed. The structures of 10 and 24 were confirmed by X-ray structure determination.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231012
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  • 7
    Electronic Resource
    Electronic Resource
    Das Thermogramm einer C6H6-Chemie im Temperaturbereich von 450 bis 730°C (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1747-1753 
    Details
    ISSN: 0009-2940
    Keywords: Isomerization, thermal ; Radicals ; D-Labeling ; 1,5-Hexadiyne ; Pentafulvene ; Rearrangement, homoallyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal Rearrangements, XXIII[1].  -  The Thermogram of a C6H6 Chemistry in the Temperature Range from 450 to 730°CThe thermal isomerization of 1,5-hexadiyne (1) and its [1,6-D2]-labeled derivative (1a) was studied in the temperature range 450-730°C and in the presence of different carrier gases (N2, H2, D2, N2/toluene). By detailed analysis (GC, GC MS, NMR) all volatile reaction products were identified and determined quantitatively by using hexafluorobenzene as an internal standard. The experimental data show clearly that the reaction products are formed by two different routes: (i) electrocyclization leading to dimethylene cyclobutene (3) at temperatures up to about 600°C and (ii) radical reaction leading to benzene (4) and pentafulvene (5) at temperatures above 550°C. Cyclopentadienylmethyl radicals are supposed to be the essential radical intermediates.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270926
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  • 8
    Electronic Resource
    Electronic Resource
    Alkine und Cumulene, XVIII. Zur Acetylen-Oligomerisierung nach Nieuwland: Struktur der Tetrameren (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1105-1109 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkynes and Cumulenes, XVIII. On the Nieuwland Acetylene Oligomerization: Structure of the TetramersThe tetramers formed during the Nieuwland acetylene oligomerization are shown to be (E)- and (Z)-1,3,7-octatrien-5-yne [(E)- and (Z)-5] by their 1H and 13C NMR spectra as well as by chemical structure proof.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190332
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  • 9
    Electronic Resource
    Electronic Resource
    Zur Reaktion von Isocyaniden mit Nitriliminen[1] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1633-1639 
    Details
    ISSN: 0009-2940
    Keywords: Isocyanides ; Nitrile imines ; Triazolium salts ; Pyrazoles ; 1,2-Diazet-3-imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reaction of Isocyanides with Nitrile IminesFour competing reactions have been found to occur when nitrile imines 2 are generated from 1 in the presence of isocyanides 3. The products obtained include i) 1,2,3-triazolium salts 6, ii) 1,2,4-triazolium salts 8, iii) dihydrotriazolyl-substituted pyrazolamines 11, and iv) unstable 1,2-diazetimine derivatives 12 which in turn give carbodiimides 13, nitriles 14, quinoxalinamines 15, and possibly 1,2,4-triazoles 16 (after addition of 2). The proportions, in particular those of 6, 8, and 11, depend on the reaction conditions; thus, triethylamine used in excess can oppress the formation of 6 in favour of 8 and 11. - The structure of 11 has been elucidated by means of X-ray diffraction analyses of 11a and c.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270915
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  • 10
    Electronic Resource
    Electronic Resource
    Cyclophane, XXIX. Gasphasenpyrolyse von 2,11-Dithia[3.3](1,2)(1,4)cyclophan-S,S,S′,S′-tetraoxid (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1013-1016 
    Details
    ISSN: 0009-2940
    Keywords: Cyclophanes ; Sulfone pyrolysis ; Strain energy ; Medium-sized rings ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclophanes, XXIX. - Gas-phase Pyrolysis of 2, 11-Dithia[3.3] (1,2)(1,4)cyclophane S,S,S′,S′-TetraoxideWhereas p-xylylenedithiol (1) reacts with o-xylylene dibromide (2) in the presence of sodium hydroxide to give the tetrathioether 4, the ortho-dithiol 5 and para-dibromide 6 provide a mixture of 4 and the [3.3]dithiaphane 8. Stereoelectronic effects can account for the different outcome. The oxidation of 8 leads to title compound 9, which is converted into the spirotriene 13 by sulfone pyrolysis (515°C/0.01 Torr); [2.2]orthoparacyclophane (12) is not obtained. The mechanism of the pyrolysis reaction is discussed.
    Notes: Während die Reaktion von p-Xylylendithiol (1) mit o-Xylylendibromid (2) in Gegenwart von Natriumhydroxid den Tetrathioether 4 liefert, reagiert das ortho-Dithiol 5 mit dem para-Dibromid 6 zu einem Gemisch aus 4 und dem [3.3]Dithiaphan 8. Für den unterschiedlichen Verlauf werden stereoelektronische Gründe verantwortlich gemacht. Die Oxidation von 8 führt zur Titelverbindung 9, die bei der Sulfonpyrolyse (515°C/0.01 Torr) in das Spirotrien 13 übergeht; [2.2]Orthoparacyclophan (12) wird nicht erhalten. Der Reaktionsmechanismus der Pyrolysereaktion wird diskutiert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220535
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