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  • Organic Chemistry  (1,341)
  • Animals  (855)
  • 1995-1999
  • 1980-1984  (2,196)
  • 1975-1979
  • 1984  (1,058)
  • 1982  (1,138)
Collection
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Years
  • 1995-1999
  • 1980-1984  (2,196)
  • 1975-1979
Year
  • 1
    Electronic Resource
    Electronic Resource
    Untersuchungen über den Thermischen Zerfall von n-Dodecylcyclopentan in der Gasphase (1982)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 324 (1982), S. 964-972 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on the Thermal Decomposition of n-Dodecylcyclopentane in the Gas PhaseIn the thermal decomposition of n-dodecylcyclopentane at 670 and 750°C in a laboratory tubular reactor mixtures of hydrogen and 57 and 113 hydrocarbons respectively are formed. The mixtures have been analyzed and identified by capillary gas chromatography and by mass spectrometry. The distribution of the reaction products is used for mechanistic discussions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19823240615
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  • 2
    Electronic Resource
    Electronic Resource
    Formation and dissociation mechanism of amide complexes. VPart IV, see [1]. Interconversion of dimeric and monomeric Cu2+-complexes with 1,8-diamino-3,6-diaza-2,7-octanedione: Comparison between the reactivity of terminal and internal amide groups (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 753-761 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The protonation and deprotonation rates of the coordinated amide groups in the Cu2+-complexes of 1,8-diamino-3,6-diaza-2,7-octanedione (DED = L) have been studied by stopped-flow techniques. Starting at low pH from Cu2+ and DED the dimeric Cu2L24+-complex, fully formed within the mixing time of the stopped-flow instrument, reacts in two consecutive steps to yield the final product CuLH-2. The rate constants of the forward and backward reactions have been determined and are given in Table 1. The intermediate was identified as Cu2L2H-22+ by measuring its VIS.-absorption spectrum.The rate constants for the interconversion of the amide groups from the O- to the N-coordinated form in the Cu2+-complexes of DED, 2,10-dioxo-1, 4, 8, 11 tetraazaundecane (DANA) and triglycine (TRIGLY) are compared with each other. It is shown that these rate constants are similar, no matter whether the amide group is terminal or internal as long as the rotation is easily possible as is the case in the dimeric species Cu2L24+ and Cu2L2H-22+. However, for CuLH-2 the inter-conversion only takes place after opening of one of the chelate rings in a rapid protonation preequilibrium.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650313
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  • 3
    Electronic Resource
    Electronic Resource
    Synthese von cis- und trans-Eninen in der Reihe der 12-und 15-Ringe (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1366-1374 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of cis- and trans-Enynes in the Class of 12- and 15-membered Ring SystemsSynthesis of (E)-1-cyclododecen-3-yne (E-2a) leads to the isolation of the first trans-enyne with geometrical ring strain. E-2a isomerizes thermally to give the Z-configuration Z-2a in a very smooth reaction. For systematical investigations the 15-membered ring enynes E-5a and Z-5a were generated. They behave like openchained 1,3-enynes.
    Notes: Die Synthese von (E)-1-Cyclododecen-3-in (E-2a) führt zur Isolierung des ersten trans-Enins mit geometrischer Ringspannung. E-2a wandelt sich thermisch leicht in die Z-Konfiguration Z-2a um. Zur systematischen Untersuchung werden die 15-Ring-Enine E-5a und Z-5a hergestellt. Sie verhalten sich wie offenkettige 1,3-Enine.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198219820713
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  • 4
    Electronic Resource
    Electronic Resource
    Bromierung und Dehydrobromierung in den Seitenketten von 1,2,3-Thiadiazolen (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 683-698 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bromination and Dehydrobromination in the Side Chains of 1,2,3-ThiadiazolesThe bromination of 1,2,3-thiadiazoles with N-bromosuccinimide (NBS) is investigated. The monobromides 3 and 4 and the dibromides 5 and 6 can be isolated. Several methods have been used for the introduction of double bonds by the elimination of HBr. Besides the elimination products 9, 11, 12, and 14 the substitution products 10, 13, 15, 16, and 17 are obtained. A lot of regio- and stereoselectivities can be observed.
    Notes: Bei den 1,2,3-Thiadiazolen 2a-h wird die Bromierung mit N-Bromsuccinimid (NBS) untersucht. Es können die Monobromide 3 und 4 sowie die Dibromide 5 und 6 isoliert werden. Zur Einführung von Doppelbindungen unter HBr-Abspaltung werden mehrere Verfahren geprüft. Neben den Eliminierungsprodukten 9, 11, 12 und 14 erhält man die Substitutionsprodukte 10, 13, 15, 16 und 17. Man beobachtet dabei eine Reihe von Regio- und Stereoselektivitäten.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198219820408
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  • 5
    Electronic Resource
    Electronic Resource
    Quantenchemische Berechnungen an Radikalen vom Allyltyp: Cycloalkenyl- und Cycloalk-1-enylmethylradikale (1984)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 326 (1984), S. 139-144 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantum-Chemical Calculations on Allyl-Type Radicals: Cycloalkenyl- and Cycloalk-1-enylmethyl RadicalsThe ability of the MINDO/3-HE-method for predicting various molecular properties was tested for cycloalkenyl- (1 to 4), cycloalk-1-enylmethyl-(5 to 8), and for the resonance-stabilized cyclic radicals (9 to 12). Close by it was established that the calculated heats of formation are largely correct. The electronic distribution in the allylic part of 1 to 12 is evidently too levelled.Based on the defination of allyl resonance energy (ARE - SZWARC (1948)) a mean value for the ARE of 1 to 8 is derived to 55 ± 12 kJ · mol-1.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19843260119
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  • 6
    Electronic Resource
    Electronic Resource
    The Circular Dichroism of 5,6-Dimethylidene-2-bicyclo[2.2.n]alky Esters. Chiral Exciton Coupling between Benzoate and Exocyclic s-cis-Butadiene Chromophores (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 600-611 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optically pure aryl-substituted 5,6-dimethylidene-2-bicyclo[2.2.1]heptyl benzoates 12-21 were prepared; their UV absorption and CD spectra are reported. The (-)-(1S,2S)-esters 17-21 with carbonyl groups in endo-position exhibit typical excitonsplit Cotton effects whereas the corresponding (-)-(1S,2R)-esters 12-16 with carbonyl groups in exo-position do not present such effects. The chiral exciton coupling between the exocyclic diene and a remote p-substituted benzoate chromophore can be used for unambiguous assignment of the absolute configuration of 5,6-dimethylidene-2-endo-bicyclo[2.2.1]heptyl derivatives. The method is applied to establish the absolute configuration of 5,6-dimethylidene-2-exo and -2-endo-bicyclo[2.2.2.]octyl p-bromobenzoates (-)-24 and (-)-25.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670228
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  • 7
    Electronic Resource
    Electronic Resource
    Reactions of 4-Chloro-9H-xanthene-9-thione with Tetrachloro-o-benzoquinone (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 196-198 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaktionen von 4-Chlor-9H-xanthen-9-thion mit Tetrachlor-O-benzochinon4-Chlor-9H-xanthen-9-thion (1) reagiert mit Tetrachlor-o-benzochinon zu dem cyclischen Acetal 2. Zur Struktursicherung wurde 2 auf unabhängigen Wegen aus Tetrachlor-o-benzochinon und 4-Chlor-9-diazo-9H-xanthen oder 4-Chlor-9H-xanthen-9-on-hydrazon sowie aus Tetrachlorbrenzcatechin und 4,9,9-Trichlor-9H-xanthen synthetisiert. Die Spaltung der Acetalgruppe in 2 mit Salzsäure, Malononitril, Cyanessigsäure-ethylester und Hydrazinhydrat wurde studiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840120
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  • 8
    Electronic Resource
    Electronic Resource
    Reactions with 2-methyl- and 2-styryl-4-thiochromones (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 186-190 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaktionen mit 2-Methyl- und 2-Styryl-4-thiochromonenDiazoalkane reagieren mit 2-Methyl- und 2-Styryl-4-thiochromonen zu 1,3-Dithiolanen 1 und/oder Ethylenen 2-4. Letztere werden mit Thionylchlorid zu den entsprechenden Ketonen gespalten während beim Schmelzen mit Schwefel die entsprechenden Thioketone entstehen. 2-Methyl-und 2-Styryl-4-thiochromone kondensieren mit CH-aciden Verbindungen wie Malononitril und Cyanessigsäure-ethylester zu 5. Oxidation der 2-Methyl- und 2-Styryl-4-thiochromone mit gelbem Quecksilber(II)-oxid oder mit Tetrahalogen-o-benzochinon ergibt die entsprechenden Ketone. Die biologische Aktivität ausgewählter Verbindungen gegenüber Gram-positiven und Gramnegativen Bakterien wurde untersucht.
    Notes: Diazoalkanes react with 2-methyl- and 2-styryl-4-thiochromones to yield the 1,3-dithiolanes 1 and/or ethylenes 2-4. The latter are cleaved with thionyl chloride to give the corresponding ketones, while on fusion with sulfur they afford the corresponding thioketones. By condensation with compounds containing active hydrogen, such as malononitrile and ethyl cyanoacetate, the 2-methyl- and 2-styryl-4-thiochromones yield the compounds 5. Oxidation of 2-methyl- and 2-styryl-4-thiochromones was accomplished by yellow mercury(II) oxide as well as with tetrahalo-o-benzoquinones to give the corresponding ketones. The biological activity of some selected compounds prepared during this work has been tested towards Gram-positive and Gram-negative bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840118
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  • 9
    Electronic Resource
    Electronic Resource
    Carbonyl and Thiocarbonyl Compounds: Reactions of 4-Chloroxanthione with Diazoalkanes and Compounds containing Active Hydrogen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 191-195 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbonyl und Thiocarbonylverbindungen: Reaktionen von 4-Chlorxanthion mit Diazoalkanen und Ch-aciden verbindungenWährend 4-Chlorxanthion 1 mit Diazomethan das Dithiolan 2 ergibt, entstehen mit anderen Diazoalkanen die Episulfide 3-5, deren Entschwefelung zu den entsprechenden Ethylenen 6-7 führt. Malononitril und Cyanessigsäure-ethylester reagieren mit 1 zu den Cyanderivaten 8a, b. Mit Hydrazinen und p-Toluidin ergibt 4-Chlorxanthion (1) die Hydrazone 9a, b und die Schiff-Base 9c. In Abhängigkeit von den Reaktionsbedingungen liefert die Oxidation des Hydrazons 9a die Diazoverbindung 10 oder das Ketazin 11. Hydroxylamin reagiert mit 1 zum Oxim 9d, das mit Phenylisocynat zum N-Phenylcarbamat 9e reagiert.
    Notes: While 4-chloroxanthione 1 gives with diazomethane the dithiol 2, it reacts with other diazoalkanes to give the episulfides 3-5, desulfurization of which forms the ethylenes 6 and 7. Malononitrile and ethyl cyanoacetate react with 1 to give the cyano derivatives 8a, b. With hydrazines and p-toluidine, 4-chloroxanthione (1) give the hydrazones 9a, b and the Schiff's base 9c, respectively. The hydrazone 9a on oxidation may give either the corresponding diazo compound 10 or the ketazine 11 according to the reaction conditions. The title compound 1 reacts with hydroxylamine to yield the oxime 9d which forms the N-phenylcarbamate 9e when treated with phenyl isocyanate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840119
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  • 10
    Electronic Resource
    Electronic Resource
    Glycosylazide als Ausgangsbasis zur Gewinnung von Nucleosidanalogen, 2. Synthese von Tetrazol-Nucleosiden (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1870-1890 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosyl Azides as Starting Materials for the Synthesis of Nucleoside Analogues, 2.  -  Synthesis of Tetrazole NucleosidesThe β-D-ribofuranosyl azide derivative 1 as well as the corresponding α-anomeric compound 3 yield via Staudinger reaction the same P-N-ylide 2. Treatment with alkyl isocyanates RNCO [R = CH3, (CH3)2CH, C2H5OCOCH2, (S)-C2H5OCOCH(CH3)] affords the diastereomeric carbodiimide derivatives 5 which can be transformed by HN3 regioselectively into the 1-(β-ribofuranosyl)-5-(alkylamino)tetrazole derivatives 6. Partial or total removal of the protecting groups affords the products 7a, c, d, and 7d′-d′". The β-D-mannofuranosyl azide derivative 8 is converted via the P-N-ylide 9 into the carbodiimide 10 and the aminotetrazole derivative 11. The reaction of 2 with phenyl isocyanate yields the 5-[(β- and 5-[(α-D-ribofuranosyl)amino]-1-phenyltetrazoles 18 and 19 passing the carbodiimide intermediates 12 and 13. Additionally the 1-isocyanato sugar derivatives 14 and 15 arise which provide for the formation of the products 16, 17, and 20-22. The ethyl [(β-D-ribofuranosyl)-5-tetrazolyl]acetate 23 is formed by reaction of 2 with the azide of monoethyl malonate. The preparation of the ribosyltetrazole derivatives 26 and 27 can be achieved only by preceding synthesis of the syn/anti mixture 24a/24a originating from 2 and acetyl cyanide followed by treatment with HN3. The α-ribosyliminonitrile 25 is assumed to be an intermediate.
    Notes: Sowohl das β-D-Ribofuranosylazid 1 als auch das α-Anomere 3 liefern bei der Staudinger-Reaktion das gleiche P-N-Ylid 2. Mit Alkylisocyanaten RNCO [R - CH3, (CH3)2CH, C2H5OCOCH2 und (S)-C2H5OCOCH(CH3)] entstehen die Carbodiimidderivate als Diastereomerengemische 5, welche mit HN3 in die 1-(β-Ribofuranosyl)-5-(alkylamino)tetrazole 6 umgewandelt werden. Teilweise oder gänzliche Entfernung der Schutzgruppen führt zu den Produkten 7a, c, d und 7d′-d′". Vom β-D-Mannofuranosylazidderivat 8 aus gelangt man über das P-N-Ylid 9 zum Carbodiimidderivat 10 und schließlich zum Aminotetrazolderivat 11. Die Umsetzung von 2 mit Phenylisocyanat liefert die 5-[(β- und 5-[(α-D-Ribofuranosyl)amino]-1-phenyltetrazole 18 bzw. 19 über die Carbodiimidzwischenstufen 12 und 13. Ferner entstehen die 1-Isocyanatozuckerderivate 14 und 15, welche für die Entstehung der Folgeprodukte 16, 17 und 20-22 verantwortlich sind. Aus 2 und Malonsäure-monoethylester-azid entsteht das Nucleosidderivat 23. Die Darstellung der Ribosyltetrazole 26 und 27 aus 2 läßt sich nur mit Acetylcyanid über das syn/anti-Gemisch 24a/24a′ durch Umsetzung mit HN3 verwirklichen. Als Zwischenstufe wird das (α-Ribosylimino)nitril 25 postuliert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198219821009
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