ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Wiley-Blackwell  (24)
  • 1990-1994  (2)
  • 1970-1974  (22)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    About the structure of phosphorus ylids: Electron distribution and geometry (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 1 (1990), S. 151-156 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using 13C-chemical shifts as a probe for the electronic environment of carbon centers, triphenylphosphoniomethanide, the model case of a “reactive” phosphorus ylid, was found to have much more zwitterion than PC double bond character (resonance structure 1a being dominant). Triphenylphosphonio-propenide (“triphenylphosphonium-allylid”), a “moderated” ylid, accumulates electron excess mainly at the α-carbon atom (resonance structure 6a being dominant) whereas triphenylphosphonio-ethenoate (formyl-methylene-triphenylphosphorane) and other “stabilized” ylids carry roughly equal fractions of negative charge at the α-carbon and the oxygen atom (resonance formulas a and b being of comparable importance). The one-bond C,H coupling constant of triphenylphosphonio-methanide (1) argues against a perfectly planar ylid center. The three-bond P,C coupling constants permit the assignment of endo- or exo-configurations to ylids having an allyl-type side-chain.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hc.520010205
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Does the ipso-carbon chemical shift tell us anything about the structure of phenylated phosphorus compounds?This article is dedicated to Leopold Horner on the occasion of his eightieth birthday. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 2 (1991), S. 515-519 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nuclear magnetic resonance signals exhibited by the ipso-carbon atoms of a variety of phenylated phosphorus compounds were found to span over the remarkably wide range of + 162 to + 117 ppm. Nevertheless, these changes in chemical shifts have little diagnostic value. They are tentatively attributed to a charge-mediated contraction and expansion of the C,P σ-bond orbital on one hand and to a σ-bond induced deformation of the aromatic π-electron cloud on the other.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hc.520020503
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Basen-induzierte Eliminierungen, V Reaktionen zwischen Vinylfluoriden und Lithiumorganylen (1971)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 2885-2895 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Base-induced Eliminations, V Reactions of Vinyl Fluorides with Organolithium CompoundsUnder the influence of organolithium compounds styryl fluorides suffer elimination as well as substitution. The olefins resulting from substitution are formed stereoselectively with retention of configuration.  -  The elimination reaction follows Mainly the E2cb-pathway. The substitution reaction is accomplished by an addition-elimination sequence with extremely short-lived intermediates. Evidence for these mechanisms has been derived from isotope effect, β-ligand effect and F/Cl elemental effect measurements.  -  The enhanced reactivity of vinyl fluorides towards substitution might be caused by repulsive interactions of neighbouring non-bonding p-electrons.
    Notes: Styrylfluoride reagieren mit lithiumorganischen Reagenzien sowohl unter Eliminierung als auch unter Substitution. Die Olefine, die durch Substitution hervorgehen, entstehen stereoselektiv unter Konfigurationserhalt.  -  Gestützt auf kinetische Isotopeneffekte, β-Ligand-Einflüsse und den Fluor-/Chlor-Elementeffekt lassen sich die Mechanismen aufklären. Die Eliminierung gehört  -  zumindest vorwiegend  -  dem E2cb-Typ an. Die Substitution kommt im Zuge aufeinanderfolgender Addition und Eliminierung zustande; die intermediären Addukte sind außerordentlich kurzlebig.  -  Die erhöhte Substitutionsbereitschaft der Vinylfluoride wird möglicherweise durch die gegenseitige Abstoßung benachbarter, nichtbindender p-Elektronen hervorgerufen.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19711040930
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Fluororganische Synthesen, III. Monofluorcarben (1971)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 1934-1941 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fluoro Organic Syntheses, III. MonofluorocarbeneFluorocyclopropanes are obtained by treating a mixture of dibromofluoromethane and an olefin with organolithium compounds.  -  The addition of the monofluorocarbene occurs stereospecifically with retention of the olefin configuration and stereoselectively with preference of the syn-isomeric fluorocyclopropane. Therefore, London dispersion forces seem not to be the origin of the syn-stereoselectivity observed with carbene addition reactions.
    Notes: Die Einwirkung lithiumorganischer Reagenzien auf ein Gemisch von Fluordibrommethan und einem Olefin bietet einen direkten Zugang zu Fluorcyclopropanen.  -  Die Addition des Fluorcarbens vollzieht sich stereospezifisch unter Erhalt der vom Olefin vorgegebenen Konfiguration. Sie verläuft außerdem stereoselektiv unter Bevorzugung des syn-isomeren Fluorcyclopropans. Londonsche Dispersionskräfte scheinen demnach für die syn-Stereoselektivität der Carben-Addition nicht verantwortlich zu sein.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19711040633
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Stereoselektivität diastereogener CC-Verknüpfungen, IV. Verlaufen 1,3-Eliminierungen konzertiert oder nicht? (1974)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 1171-1187 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoselectivity of Diastereogenic Carbon-Carbon Linking Reactions, IV. 1,3-Elimination Reactions  -  are the Concerted or not?6-Bromo-4-iodononane (6), 4-bromo-4-fluorononane (5), and 4,6-dibromononane )4) are converted to 1,2-dipropylcyclopropane (7) by a variety of metallic or organometallic reducing agents. Normally cyclization occurs in a stereoconvergent manner, i.e. diastereoisomeric dihalides usually lead to the same mixture of cis/trans- isomeric reaction products. Therefore it seems that the two halogen atoms are generally cleaved off in a non-concerted mode.  -  Isomer ratios depend in a very pronounced manner on the nature of the reducing agents and on any salt additives that may be present. This behavior seems to be typical for reactions of short-lived intermediates and is compatible with the assumed one-electron transfer mechanism.  -  Again „endo tendency“ is observed. Though thermodynamically less stable, the cis-disubstituted cyclopropane is formed predominantly in most cases.
    Notes: 4-Brom-6-jodnonan (6), 4-Brom-6-fluornonan (5) und 4,6-Dibromnonan (4) lassen sich mit einer Vielzahl metallischer oder organometallischer Reduktionsmittel in 1,2-Dipropylcyclopropan (7) überführen. Die Cyclisierung verläft im allgemeinen stereokonvergent; diastereomere Dihalogenide liefern meist gleiche Mischungen an cis/trans-isomeren Reaktionsprodukten. Im Normalfall dürften also die beiden Halogenatome nicht-konzertiert abgelöst werden.  -  Die Isomerenverhältnisse sind in ganz ausgeprägter Weise von der Art des Reduktionsmittels und eventuellen Salzzusätzen abhängig. Dieses Verhalten, das für Reaktionen kurzlebiger Zwischenstufen typisch zu sein scheint, steht mit der Annahme von Einelektrontransfer-Mechanismen im Einklang.  -  Insgesamt zeichnet sich erneut eine „endo-Tendenz“ ab: das cis-disubstituierte Cyclopropan entsteht  -  obwohl thermodynamisch weniger stabil als das trans-Isomere  -  in den meisten Fällen vorherrschend.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19741070413
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Ummetallierung und doppelter Metall-Austausch: ein bequemer Zugang zu Organolithium-Verbindungen vom Benzyl- und Allyl-TypDiese Arbeit wurde vom Schweizerischen Nationalfonds (Projekt Nr. 2.593.71) unterstützt. (1973)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 85 (1973), S. 544-545 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19730851208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Bessere CC-Verknüpfungen durch kontrollierte Kupfer-KatalyseDiese Arbeit wurde vom Schweizerischen Nationalfonds (Projekt Nr. 2.593.71) unterstützt. Der BASF, Ludwigshafen, gebührt Dank für Ausgangsmaterialien. (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 86 (1974), S. 50-51 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19740860113
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Alkyl/Halogen-Substitution an Carbenen (Carbenoiden): ein Zugang zu neuen Cyclopropan-Derivaten (1971)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 83 (1971), S. 150-151 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19710830415
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Olefinierungen mit Phosphor-Yliden, II. β-Oxido-phosphor-ylide (Betain-Ylide) in salzfreiem und salzhaltigem Medium (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 2814-2820 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Olefination Reactions with Phosphorous ylids, II. β-Oxido Phosphorus ylids in the Presence and Absence of Soluble Alkaline Metal Saltstrans-Stereoselective olefin synthesis by means of the modified Wittig reactions cannot be achieved in salt-free medium, since only in the presence of soluble lithium salts do the phosphorous betaines exist predominantly in the threo form.
    Notes: Phosphor-Betaine bevorzugen nur dann ganz eindeutig die threo-Form und können somit stereoselektiv in trans-Olefine übergeführt werden, wenn lösliche Lithiumsalze im Reaktions-gemisch zugegen sind.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701030915
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Basen-induzierte Eliminierungen, IV Die Einwirkung von Metall-alkoholaten auf cis- und trans-Styrylchlorid (1971)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 2873-2884 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Base-induced Eliminations, IV Reaction of Metal Alcoholates with cis- and trans-Styryl ChloridePossibly the dehydrochlorination of styryl chloride under the influence of an alcoholate occurs by three different, competing mechanisms: E2, Elcb and Elcb-HBA (a modification of the Elcb-mechanism). This conclusion is in accord with the following criteria: H/D-exchange, isotope effects, order of reaction and relative reaction rates as a function of substrate configuration (cis or trans) as well as nature of base (NaOC2H5 or KOC(CH3)3).
    Notes: Die alkoholat-induzierte Chlorwasserstoff-Abspaltung aus Styrylchlorid betätigt möglicherweise drei verschiedene Reaktionsmechanismen nebeneinander: E2, E1cb und E1cb-HBA (ein modifizierter Elcb-Mechanismus). Diese Schlußfolgerung stützt sich auf die folgenden Kriterien: H/D-Austausch, Isotopeneffekte, Reaktionsordnung sowie relative Eliminierungs-geschwindigkeiten in Abhängigkeit von der Konfiguration des Substrates (cis oder trans) und der Art der Base (NaOC2H5 oder KOC(CH3)3).
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19711040929
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...