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  • 1
    Electronic Resource
    Electronic Resource
    Biphenyl-tricarbonylchrom-komplexe, 9. Mitt.: Synthesen, chromatographische Enantiomerentrennung, Circulardichroismus und Chiralität von mono- und bis-(Tricarbonylchrom)-Komplexen di- und tetrasubstituierter sowie überbrückter Biphenyle (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 1429-1442 
    Details
    ISSN: 1434-4475
    Keywords: Triacetylcellulose ; Recycling technique ; Enantiomeric purity ; Metallocene chirality ; Axial chirality ; Conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Chiral title compounds have been resolved by medium pressure liquid chromatography (MPLC) on triacetylcellulose in ethanol. Whereas a quantitative separation was achieved for16 and20, a recycling technique had to be applied to1,4,6,10 and15 leading to a 100% e.e. for1,6 and15 and to ca. 60% e.e. for4 and10. An unambiguous assignment of the chirality (+)-(R) a -(S) m for tricarbonylchromium-6,6′-dimethyl-diphenicacid dimethylester (4) was deduced both from the photochemical decomplexation to (-)-5 with the known chirality (R) a (whose e.e. was determined by MPLC on triacetylcellulose) and by comparison of the1H-n.m.r. spectra of4 and5 thereby proving the structure 4 for the former. Other chiralities both for mono and bis(tricarbonylchromium)biphenyl complexes were established by chemical correlations and comparison of the CD spectra with those of key compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00816342
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  • 2
    Electronic Resource
    Electronic Resource
    A recycling technique for the chromatographic separation of enantiomers and diastereomers on triacetylcellulose (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 1113-1120 
    Details
    ISSN: 1434-4475
    Keywords: Enantiomeric purity ; Centro-, Axial- and Planarchiral Arenes and Metallocenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird eine einfache und preisgünstige Anlage zur Racematspaltung und Trennung von Diastereomeren an Triacetylcellulose in Ethanol unter erhöhtem Druck beschrieben. Sie beinhaltet einen geschlossenen Lösungsmittelkreislauf (Pumpe — Säule — Detektor — Pumpe) und ermöglicht eine kontinuierliche Arbeitsweise bis zu etwa 16 Zyklen, ohne den Fluß unterbrechen oder die Fraktionen handhaben zu müssen. Diese offensichtlich universelle Methode, welche auch die Ermittlung enantiomerer Reinheiten erlaubt, wird an Hand von einigen zentro-, axial- und planarchiralen Arenen und Metallocenen vorgestellt.
    Notes: Abstract A simple and inexpensive equipment for the optical resolution of enantiomers (and separation of diastereomers) on triacetylcellulose in ethanol at elevated pressure is described. It involves a closed circuit of solvent (pump—column—detector—pump) allowing a continuous chromatography up to 16 cycles without stopping the flow or handling fractions. This useful and versatile method permitting also the determination of enantiomeric purities is illustrated by several examples of centro-, axial- and planarchiral arenes and metallocenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798778
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  • 3
    Electronic Resource
    Electronic Resource
    Asymmetric reduction of prochiral arylketones with chiral 2,2′-dihydroxy-1,1′-binaphthyl — Borane complexes (1987)
    Springer
    Monatshefte für Chemie 118 (1987), S. 127-136 
    Details
    ISSN: 1434-4475
    Keywords: Enantiomeric purity ; Absolute chirality ; Recycling chromatography on triacetylcellulose ; Transition state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Reduktion von acht Arylketonen mit chiralen Borankomplexen aus (−)(S)-2,2′-Dihydroxy-1,1′-binapthyl und BH3 ·THF oder BH3 · (CH3)2S lieferte (mit einer Ausnahme) optisch aktive (R)-Alkohole mit optischen Ausbeuten bis zu 54%. In zwei Fällen führte Zusatz aromatischer Amine zu einer signifikanten Erhöhung von e.e. unter gleichzeitiger Konfigurationsumkehr (R zuS). Modelle für einen möglichen Übergangszustand werden diskutiert.
    Notes: Abstract Reduction of eight aryl ketones with borane complexes containing (−)(S)-2,2′dihydroxy-1,1′-binapthyl as a chiral auxiliary yielded (with one exception) (R)-alcohols with enantiomeric purities up to 54% (as determined with chiral NMR-shift reagents and/or by enantioselective chromatography on triacetyl-cellulose). In two cases addition of aromatic amines caused a significant increase of e.e. together with a reversal of the absolute chirality (fromR toS). Models for a possible transition state are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810047
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  • 4
    Electronic Resource
    Electronic Resource
    Optisch aktives 1,3-Diferrocenyl-1,3-diphenyl-allen (1981)
    Springer
    Monatshefte für Chemie 112 (1981), S. 91-104 
    Details
    ISSN: 1434-4475
    Keywords: Chromatographic Resolution on Acetylcellulose ; Circular Dichroism ; 1,3-Diferrocenylbutadienes ; 1,3-Diferrocenylpropanes ; 1,3-Diferrocenylpropenes ; 1,3-Diferrocenylpropenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The title compound 2 was prepared by thermal dehydration of 1,3-diferrocenyl-1,3-diphenyl-propenol (24) with 70% yield.24 was accessible from 1,3-diferrocenyl-propanedione-1,3 (25) in two steps with 10% overall yield: Treatment of25 with phenyllithium gave 1,3-diferrocenyl-3-phenyl-propenone (8) which after repeated reaction with phenyllithium afforded24. Partial optical resolution of2 was achieved by chromatography on triacetyl cellulose in ethanol, whereby both (+)- and (−)-2 were obtained with different enantiomeric purities as could be deduced from the CD-spectra with Δε-values of +0.18 and −1.64, resp., at 480 nm. Attempts to prepare 1,3-diferrocenyl-allene and 1,3-diferrocenyl-1-phenyl-allene failed. In this context several 1,3-diferrocenyl-propenols,-propenones,-propenes,-propanones,-propanes and-butadienes were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00906246
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