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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of natural products 50 (1987), S. 1141-1145 
    ISSN: 1520-6025
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 98 (1967), S. 1682-1689 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract The theoretical and experimental dipole moments for a number ofsyn- andanti-α-oximino esters are determined.NMR- andIR-spectra are reported. On the basis of these and previous chemical investigations the preferred steric structures of thesyn- andanti-forms are ascertained. Two rotational isomers exist in the same degree with thesyn-forms. Due to resonance effects and hydrogen bonds they are relatively stable.
    Notes: Zusammenfassung Für eine Anzahl vonsyn- undanti-α-Oximino-fettsäureestern werden theoretisch und experimentell die Dipolmomente bestimmt undNMR- sowieIR-Spektren aufgenommen. Auf Grund dieser und früherer chemischer Untersuchungen werden die bevorzugten Raumstrukturen dersyn- undanti-Formen ermittelt. Bei densyn-Formen sind in gleichem Maße zwei Rotationsisomere vertreten, die auf Grund von Resonanzeffekten und der Wasserstoffbindung relativ stabil sind.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract The reaction of diphenylacetylene with N-bromosuccinimide and 80–90% aqueous acetic acid gives bromoacetoxystilbene (70% yield, mixture ofcis- andtrans-isomers 25∶75) and dibromodesoxybenzoin (15–20% yield). Up to about 30% conversion the reaction follows a second-order rate equation, but further the rate increases. For the temperature interval 25–50°C activation energyE a =12,6±1,0 kcal/mole, andArrhenius-factor logA=7,4±0,6 are calculated.
    Notes: Zusammenfassung Die Umsetzung des Diphenylacetylens mit N-Brom-succinimid in 80–90proz. Essigsäure führt zu Brom-acetoxystilben (70% d. Th.,cis-:trans-Form=25∶75) und Dibrom-desoxybenzion (15–20% d. Th.). Bis zu einem Umsatz von ca. 30% befolgt die Umsetzung eine kinetische Gleichung zweiter Ordnung, dann steigt die Geschwindigkeitskonstante weiter an. Für 25° bis 50°C werden eine Aktivierungsenergie vonE a =12,6±±1,0 kcal/Mol und einArrhenius-Faktor von lgA=7,4±±0,6 gefunden.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Unlike many other acetylenic compounds, 4-phenyl-3-butin-1-ol reacts at room temperature with N-bromosuccinimide in anhydrous acetic acid, yielding an equilibrium mixture of 3,3-dibromo-3-benzoyl-propanol and its cyclic tautomere, 2-phenyl-2-hydroxy-3,3-dibromo-tetrahydrofuran. The same product is obtained also by addition of HOBr to the acetylenic alcohol mentioned above. An assumption is made that the corresponding dibromodiacetoxy derivative is involved as an intermediate in the reaction with N-bromosuccinimide. 3-Phenyl-2-propin-1-ol interacts with N-bromosuccinimide and acetic acid in presence of water only, giving 2,2-dibromo-2-benzoyl-ethanol. The reaction with N-bromosuccinimide is a convenient method for synthesis of α,α-dibromo-ketones from acetylenic compounds, preserving unchanged the hydroxyl groups.
    Notes: Zusammenfassung Im Gegensatz zu anderen Acetylen-Verbindungen reagiert 4-Phenyl-3-butin-1-ol mit N-Bromsuccinimid in Eisessig bei Raumtemp. zu einem Gleichgewichts-Gemisch von 3,3-Dibrom-3-benzoylpropanol und dessen cyclischem Tautomeren (2-Phenyl-2-hydroxy-3,3-dibrom-tetrahydrofuran), das auch durch Anlagerung von unterbromiger Säure an denselben Acetylen-Alkohol herzustellen ist. Es wird vermutet, daß das entsprechende Dibrom-diacetoxy-derivat als Zwischenprodukt entsteht. 3-Phenyl-2-propin-1-ol reagiert mit N-Bromsuccinimid in Essigsäure nur in Gegenwart von Wasser zu 2,2-Dibrom-2-benzoyläthanol. Die Umsetzung von Acetylen-Verbindungen mit N-Bromsuccinimid in Essigsäure ist eine bequeme Methode zur Herstellung von α,α-Dibromketonen, wobei vorhandene OH-Gruppen nicht angegriffen werden.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Kinetic and NMR data of the reaction of acetylenes with N-bromosuccinimide in anhydrous and aqueous acetic acid are interpreted assuming mechanisms which involve the electrophilic addition of a bromo cation to the triple bond.
    Notes: Zusammenfassung An Hand von NMR- und kinetischen Untersuchungen werden einige elektrophile Mechanismen der Umsetzung von Acetylenverbindungen mit N-Bromsuccinimid in Eisessig oder in wäßriger Essigsäure diskutiert.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract The coupled addition of bromo cations, arising from N-bromosuccinimide, and acetoxy anions from acetic acid, to 4-substituted chalcones yielded a mixture of the position isomers of the corresponding 4-substituted β-phenyl bromoacetoxypropiophenones. The dependence of the rate of bromoacetoxylation on the nature of substituents in position 4 was found to increase in the following order: nitro, chloro, hydrogen, methyl, methoxy. The ratio of isomers formed and their preferred conformations were deduced from their NMR spectra.
    Notes: Zusammenfassung Die gekoppelte Anlagerung von Bromkation (aus N-Bromsuccinimid) und Acetatanion (aus Eisessig) an 4-substituierte Chalkone gestattet, die entsprechenden 4-substituierten β-Phenylbromacetoxypropiophenone zu gewinnen. Die Geschwindigkeit der Bromacetoxylierung steigt in der folgenden Reihe an: 4-Nitro-, 4-Chlor-, Chalkon, 4-Methyl- und 4-Methoxychalkon. Das Verhältnis der Stellungsisomeren der Bromacetoxyderivate und ihre bevorzugten Konformationen lassen sich auf NMR-spektroskopischem Wege ermitteln.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 253 (1975), S. 338-338 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of the N,N,N′,N′-tetramethyldiamides of phthalic, isophthalic and terephthalic acids have been determined by the iterative total line shape NMR method. Some evidence about the conformation of these compounds in solution has also been obtained by infrared and dipole moment studies.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of the N,N-dimethylamides of propiolic, methylpropiolic and phenylpropiolic acids have been determined by the iterative total line shape nuclear magnetic resonance method.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 11 (1978), S. 390-394 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 1H and 13C NMR chemical shifts as well as vicinal HH coupling constants of substituted 5-phenyl-2,4-pentadienoic acids Ar—CH=CH—CR=CR—COOH are reported and discussed in connection with the molecular structure. The 13C chemical shift values show an alternation along the chain and can be linearly correlated to the π-electron charge densities as calculated by use of the PPP-method. The effect of para-substituents and solvents upon the 13C chemical shifts can be described in terms of the mutual atom-atom polarizabilities.
    Notes: 1H- und 13C-NMR-chemische Verschiebungen sowie vicinale HH-Kopplungskonstanten von verschieden substituierten 5-Phenyl-2,4-pentadiensäuren Ar—CH=CH—CR=CR—COOH werden mitgeteilt und im Zusammenhang mit der Molekülstruktur diskutiert. Die entlang der Molekülkette alternierenden 13C-chemischen Verschiebungen können linear mit den entsprechenden in PPP-Näherung berechneten π-Elektronenladungsdichten korreliert werden. Die ebenfalls alternierenden Einflüsse der paraständigen Substituenten bzw. der Lösungsmittel auf die 13C-chemischen Verschiebungen sind mittels Atom-Atom-Polarisierbarkeiten beschreibbar.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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