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  • 1
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: From the mixture of homologous sodium diamido-imidophosphates obtained by heating sodium diamidophosphate, by means of an anion exchanger in fluoride form and a KF solution as eluant the dimeric, trimeric and tetrameric compounds are isolated in solution. From this the silver salts are precipitated. On re-precipitation at pH 9, they yield silver salts in which the imido hydrogen also is substituted by silver.
    Notes: Aus dem Gemisch homologer Natrium-diamido-imidophosphate NanPnO2n(NH)n-1(NH2)2, das beim Erhitzen von Natriumdiamidophosphat entsteht, werden mit Hilfe eines Anionenaustauschers in Fluoridform und einer KF-Lösung als Eluiermittel die dimere, trimere und tetramere Verbindung in Lösung isoliert. Daraus werden die Silbersalze gefällt, die bei Umfällung bei pH 9 Silbersalze liefern, in denen auch der Imidowasserstoff durch Silber ersetzt ist.
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  • 2
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 4
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [1-(Arylcarbonyloxy)alkyl]phosphonium Salts, 31). Reductive C-Acylation of Aromatic AldehydesThe phosphonium salts 5 are synthesized from aldehydes 1, arenecarbonyl chlorides 2 and triphenylphosphane (4), and can then be deprotonated to 7. 7 react as acyl anion equivalents with aromatic aldehydes 9 forming enol esters 10, which are transformed to alkanones 11. The new aldehyde 9 → alkanone 11-transformation is characterised as a reductive C-acylation of aromatic aldehydes.
    Notes: Aus Aldehyden 1, Arencarbonsäurechloriden 2 und Triphenylphosphan 4 entstehen die Phosphoniumsalze 5, die zu 7 deprotoniert werden. 7 reagiert wie Acylanionäquivalente mit aromatischen Aldehyden 9 zunächst zu Enolestern 10, aus denen die Alkanone 11 hergestellt werden. Die neuartige Aldehyd 9 → Keton 11-Umwandlung wird als reduktive C-Acylierung der Aldehyde 9 charakterisiert.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [1-(Aryl- and Alkylcarbonyloxy)alkyl]phosphonium Salts, 4 Synthetic MethodsFour syntheses A  -  D are described for the phosphonium salts 1, which are precursors of the highly reactive phosphoranes 3. Whereas the usual method B fails in some cases it is now possible to prepare 1 with a wide variety of substitutents R1, R2, and R3 and anions X-.
    Notes: Für die Phosphoniumsalze 1, Vorstufen der hochreaktiven Phosphorane 3, werden vier Synthesemöglichkeiten A  -  D beschrieben. Während das bisherige Verfahren B in einigen Fällen versagt, sind die Salze 1 nunmehr bei großer Variationsbreite der Reste R1, R2 und R3 sowie der Anionen X- herstellbar.
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  • 6
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N[1-(Acyloxy)alkyl]heteroarylium Salts in Synthesis, 3. Intramolecular ortho-Acylation of Some N-Heteroaromatic Ring SystemsThe title compounds 17 (prepared by methods A—C) have been reacted with sodium bis(trimethylsilyl)amide (18) in a heterogeneous mixture (-80°C, 2-60 h). The ortho-substituted N-heteroaromatic compounds 4 are isolated exclusively after an intramolecular and regiospecific reaction [Scheme 1, Eq. (5)]. This method represents the first widely applicable acylation technique for N-heteroaromatic compounds in which the incoming substituent (R1CO) functions as an internal electrophile and in which the formation of isomeric or polyacylated products has not yet been observed. Both experimental and theoretical (MNDO) investigations show that the substitution reaction (5) is primarily determined by the conformational and electronic properties of the deprotonation product 25 [Eq. (7)], which is formed preferentially.
    Notes: Die Titelverbindungen 17 (Herstellungsmethoden A—C) werden in heterogener Phase mit Natrium-bis(trimethylsilyl)amid (18) umgesetzt (-80°C, 2-60 h). Nach einem intramolekular und regiospezifisch verlaufenden Folgeschritt werden ausschließlich die ortho-substituierten N-heteroaromatischen Verbindungen 4 isoliert [Schema 1, Gl. (5)]. Diese Methode repräsentiert das erste breit anwendbare Acylierungsverfahren in der N-heteroaromatischen Reihe, bei dem der hinzukommende Substituent (R1CO) als internes Elektrophil eingesetzt wird und die Entstehung isomerer oder mehrfach acylierter Substitutionsprodukte bisher nicht beobachtet wurde. Aus experimentellen und theoretischen Untersuchungen (MNDO-Methode) folgt übereinstimmend, daß der Verlauf der Substitutionsreaktion (5) maßgeblich von den konformativen und elektronischen Eigenschaften des bevorzugt entstehenden Deprotonierungsprodukts 25 [Gl. (7)] bestimmt wird.
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  • 7
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mechanistic Studies on the Dephosphorylating Ylide-Diketone Rearrangement of [(Arylcarbonyloxy)alkylidene]phosphoranesA new rearrangement of the phosphoranes 8 to 1,2-diketones 15 can be classified as an intramolecular 3-exo-trig process on the basis of experimental results. The mechanism is discussed in terms of a polar (Route a) or alternatively a carbene (Route b) reaction. The transition state for carbene formation from the model compound 17 [(hydroxymethylene)- phosphorane] has been determined using the ab-initio RHF/6-31G*/6-31G* method. The results indicate that π-donor/σ-acceptor-substituted phosphoranes 1a and 8 can be considered as potential carbene precursors by analogy with the model compounds 16 and 17.
    Notes: Die zu den 1,2-Diketonen 15 führende neue Umlagerung der Phosphorane 8 wird auf der Basis experimenteller Ergebnisse als intramolekularer 3-exo-trig-Prozeß klassifiziert und alternativ im Sinne eines polaren (Weg a) und carbenischen (Weg b) Mechanismus diskutiert, Der Übergangszustand der Carbenbildung aus einer charakterisierenden Modellverbindung 17 [(Hydroxymethylen)phosphoran] wurde ab-initio nach der RHF/6-31G*/6-31G*-Methode mit dem Resultat berechnet, daß π-Donor/σ-Donor/σ-Akzeptor-substituierte Phosphorane 1a, 8 bzw. deren Modelle 16 und 17 als potentielle Carben-Vorstufen zu interpretieren sind.
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  • 8
    ISSN: 0009-2940
    Keywords: Ethylenes, 1,1-diactivate ; Michael acceptors ; 1-Oxa-1,3-butadienes ; Hetero Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title class of 1,1-diactivated ethylenes has been prepared in two steps from aldehydes and t-butyl acrylate by (i) DABCO-catalyzed coupling to give t-butyl 2-(hydroxyalkyl)-2-propenoates 11 and (ii) low-temperature Jones oxidation, followed by swift work up at low temperature. The resulting t-butyl 2-methylene-3-oxoalkanoates 12 are stabilized by sterically demanding and also by aromatic groups R. For primary unhindered alkyl groups, stability is low. The compounds enter into Michael reactions, hetero Diels-Alder additions with enol ethers, and self-dimerization.
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  • 9
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Acylation Reactions of Carbonyl Compounds with 1-Acylpyridinium Salts1-Acyl-4-benzylpyridinium tetrafluoroborates 5 have been used to derive generally applicable guidelines for the reaction of aldehydes 6 and ketones 7 with 1-acylpyridinium salts (scheme 2): a) Non-enolizable aldehydes 6 react with 5 to give N-[1-(aryl- or alkylcarbonyloxy)alkyl]pyridinium salts 14. b) Enolizable aldehydes 6 can be transformed by means of 5 into pyridinium salts 14 and enol esters 12, respectively. Using aldehyde 6b as an example, it was possible to show that the reaction course (formation of 12 or 14) can be controlled by simple variation of the reaction conditions. c) In general, ketones will not react with 5. The range of applicability of this guidelines has been defined. - We suggest, that the reaction course is mainly determined by the formation of the carbenium ion 19 and the aldehyde-pyridine derivative addition product 8.
    Notes: Durch die Verwendung von 1-Acyl-4-benzylpyridinium-tetrafluoroboraten 5 werden allgemein-gültige Aussagen über die Reaktionsmöglichkeiten von Aldehyden 6 und Ketonen 7 mit 1-Acylpyridiniumsalzen gewonnen (Schema 2): a) Nicht-enolisierbare Aldehyde 6 reagieren mit 5 zu N-[1-(Aryl- bzw. Alkylcarbonyloxy)alkyl]pyridiniumsalzen 14, b) enolisierbare Aldehyde 6 können mittels 5 sowohl in die Pyridiniumsalze 14 als auch in Enolester 12 übergeführt werden, der Reaktionsverlauf ist - wie vor allem am Beispiel des Aldehyds 6b gezeigt wird - bezüglich der Reaktionsverlauf ist - wie vor allem am Beispiel des Aldehyds 6b gezeigt wird - bezüglich der Natur der Produkte (12 oder 14) durch einfache Variation der Reaktionsbedingungen lenkbar. c) Ketone reagieren i. a. nicht mit 5. Der Gültigkeitsbereich dieser Aussagen wird definiert. - Wir vermuten, daß der Reaktionsverlauf durch die Bildung des Carbenium-Ions 19 sowie eines aus Aldehyd und Pyridin-Derivat entstehenden Addukts 8 bestimmt wird.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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