Library

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
  • 1970-1974  (16)
Source
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Untersuchungen über ein „Kriterium für die Aromatizität”: Die Konzentrationsabhängigkeit der molaren magnetischen Drehung (1970)
    Springer
    Monatshefte für Chemie 101 (1970), S. 469-476 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract It was attempted to determine the relative aromaticities of metallocenes by means of a recently stated criterion (“Labarre's 4th criterion”), which is based on the concentration dependence of the molar magnetic rotation. The results of the investigation of these and other aromatic systems lead to the conclusion that this concentration dependence does not correlate with diamagnetic effects of an induced ring current; it rather is associated with the concentration dependent change of the internal field of the solute. Consequently, it does not reflect the aromaticity of a system.
    Notes: Zusammenfassung Es wurde der Versuch unternommen, ein für die Aromatizität angegebenes Kriterium (“4.Labarresches Kriterium”), nämlich den Verlauf der Konzentrationsabhängigkeit der molaren magnetischen Drehung, auf Metallocene anzuwenden. Die dabei und bei anderen aromatischen Systemen erhaltenen Ergebnisse führen zu dem Schluß, daß diese Konzentrations-abhängigkeit nicht auf diamagnetische Effekte eines induzierten Ringstromes zurückzuführen ist, sondern von der konzentrationsbedingten Änderung des inneren Feldes herrührt. Sie spiegelt also nicht die Aromatizität eines Systems wider.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00910232
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Zur Racemisierung von optisch aktiven Ferrocenderivaten (1970)
    Springer
    Monatshefte für Chemie 101 (1970), S. 941-943 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00909914
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Stereochemie von Metallocenen, 32. Mitt.: Optisch aktive Aryl-ferrocene, 3. Mitt.: Darstellung, absolute Konfiguration und Circulardichroismus von α-(2-Thienyl)-methylferrocenen (53. Mitt. über Ferrocenderivate) (1970)
    Springer
    Monatshefte für Chemie 101 (1970), S. 967-975 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Starting from optically active α-ethynyl methylferrocene (2) of known absolute configuration (1R) and optical purity several (α-methylferrocenyl)butadiynes (3) were prepared by oxidative coupling with acetylenes R−C≡CH. Subsequent cyclization with H2S gave the optically active α-(2-thienyl)-methylferrocenes (4). The circular dichroism curves of3 and4 were recorded and subjected to a band analysis with the aid of a curve fit-computer program.
    Notes: Zusammenfassung Ausgehend von optisch aktivem α-Äthinyl-methylferrocen (2) bekannter Absolutkonfiguration (1R) und optischer Reinheit wurden durch oxidative Kupplung mit Acetylenen R−C≡CH einige (α-Methylferrocenyl)-butadiine (3) und daraus durch Cyclisierung mit H2S optisch aktive α-(2-Thienyl)-methyl-ferrocene (4) dargestellt. Der Circulardichroismus von3 und4 wurde gemessen, und die Kurven mit Hilfe eines Kurvenanpassung-Rechenprogramms einer Bandenanalyse unterworfen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00908537
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Gezielte Konformationsänderungen an cyclischen Systemen, 1. Mitt.: Das Isokonformationskonzept (1974)
    Springer
    Monatshefte für Chemie 105 (1974), S. 895-906 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract By means of the “isoconformational concept” it is shown that a correlation of conformations of ring compounds with the corresponding patern of signs for their torsional angles and an equal number of torsional degrees of freedom is feasible, as far as geometrically required conformational changes are concerned (i.e. disregarding secondary, system inherent effects). The applicability of the concept is studied by means of 1- and 1,10-substituted [2.2]metacyclophanes, the conformations of which can be deduced from the “geometric behaviour” of cyclohexane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00910255
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Wirkung von Usninsäure auf die Grünalge Chlamydomonas reinhardii (1973)
    Springer
    Archives of microbiology 93 (1973), S. 145-154 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Usninsäure wirkt in relativ geringen Konzentrationen wachstumshemmend auf die einzellige Grünalge Chlamydomonas reinhardii. 2. Nach längerer Kultivierung in Gegenwart subletaler Usninsäuredosen konnten 2 usninsäureresistente Algenstämme isoliert werden, die 20 μg Usninsäure/ml ohne Wachstumseinschränkung tolerierten. Die Resistenz konnte durch Kreuzung nicht auf die Nachkommen übertragen werden, blieb aber bei vegetativer Vermehrung über längere Zeit auch ohne Usninsäurekontakt erhalten. Sie gleicht in diesem Verhalten den Dauermodifikationen. 3. Die Gametenbildung und die Kopulation der Gameten war unter Usninsäureeinfluß nicht erkennbar gestört. Allerdings war die Keimung der daraus entstandenen Zygoten merklich gehemmt oder verzögert. 4. Usninsäurezugabe führte zu einem Geißelverlust. Eine Regeneration erfolgte erst nach mehrmaliger Erneuerung des Mediums. Aus den Ergebnissen wird gefolgert, daß Usninsäure an Algenzellen Veränderungen in Gang bringen kann, die dem tatsächlichen Verhalten der Algen in der Flechtensymbiose entsprechen.
    Notes: Summary 1. 10 μg/ml usnic acid inhibits the growth of the unicellular green alga Chlamydomonas reinhardii about 10–20%. Concentrations of 20 μg/ml or more result in a complete inhibition of growth or lethality. 2. After long cultivation in the presence of sublethal doses of usnic acid two resistant strains were isolated, which grow with the normal growth rate of the wild type strain in the presence of 20 μg/ml usnic acid. After crossing with the sensitive wild type the resistance was lost. The basis of this resistance is probably the result of an adaptation process like the persistent modifications. 3. Considerable decrease in the germinating rate of the zygotes from 70–80% to 11–44% was observed with low doses of usnic acid present in the medium but no effect on gametogenesis and the copulation process could be detected. 4. Usnic acid caused a loss of flagella without reducing of the viability. Regeneration took place, when the usnic acid medium was completely replaced by normal medium. We conclude, that usnic acid, a substance which is widely distributed in lichen genera, can effect changes in algal cells according to the really behaviour of the phycobiont in the symbiotic stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424945
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Stereochemie von Metallocenen, 33. Mitt.: Optisch aktive Aryl-ferrocene, 4. Mitt.: Optisch aktive Ferroceno[b]indene,-hydrindene und verwandte Verbindungen (1971)
    Springer
    Monatshefte für Chemie 102 (1971), S. 277-291 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Optically active ferroceno[b]indenon (2) was obtained by kinetic resolution of the easily accessibleendo ferroceno indenol (3) with (+)-α-phenylbutyric anhydride with optical yields of 20%. From the results of this resolution (also for theexo-carbinol5) on the basis of the known absolute configuration (+)-(1R)-2 the relative stereochemical sizes of ferrocene and benzene could be established for the first time:Fc〉phenyl. Several subsequent products of (+)-2 (amongst them ferroceno hydrindenes) were prepared and their chiroptical properties compared with those of structurally related ferrocenes (such as13–18) (and discussed). TheCD-curves were subjected to a band analysis.
    Notes: Zusammenfassung Optisch aktives Ferroceno[b]indenon (2) wurde durch kinetische Racematspaltung des gut zugänglichenendo-Ferroceno-indenols3 mit (+)-α-Phenylbuttersäure-anhydrid in optischen Ausbeuten um 20% erhalten. Aus den Ergebnissen dieser Racematspaltung (auch für dasexo-Carbinol5) ließen sich auf Grund der bekannten Absolutkonfiguration (+)-(1R)-2 die relativen stereochemischen Größen von Ferrocen und Benzol (Fc〉Phenyl) erstmals festlegen. Mehrere Folgeprodukte von (+)-2 (darunter Ferrocenohydrindene) wurden dargestellt und ihre chiroptischen Eigenschaften mit jenen von strukturell verwandten Ferrocenderivaten (wie13–18) verglichen (und diskutiert). DieCD-Kurven wurden einer Bandenanalyse unterworfen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00909240
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Circulardichroismus und Elektronenanregungsspektren chiraler [2,2]Metacyclophane (1973)
    Springer
    Monatshefte für Chemie 104 (1973), S. 644-653 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Aus den optischen und chiroptischen Eigenschaften substituierter [2,2]Metacyclophane, aus einem Vergleich mit substituierten [10]Paracyclophanen sowie aus Symmetriebetrachtungen an prochiralen Carbophanen kann geschlossen werden, daß für das Zustandekommen nicht-orthogonaler elektrischer und magnetischer Momente in diesen Verbindungen Dipol-Dipol-Kopplung nicht verantwortlich ist; vielmehr scheint es sich um eine hauptsächlich durch Schwingungen vermittelte Störung eines inhärent achiralen, aromatischen Chromophors zu handeln. Auf Grund desCD scheint die Annahme transanularer π-π-Wechselwirkungen in [2,2]Metacyclophanen auch im angeregten Zustand nicht gerechtfertigt.
    Notes: Abstract From the optical and chiroptical properties of substituted [2.2]metacyclophanes and a comparison with substituted [10]paracyclophanes as well as by symmetry arguments regarding prochiral carbophanes can be deduced that dipol-dipol coupling is not responsible for the generation of non-orthogonal electrical and magnetical moments in these compounds; pressmably one is dealing with an inherently achiral aromatic chromophore mainly perturbed by vibrations. Even in the exited state the assumption of transanular π-π-interactions in [2.2]metacyclophanes is not justified as can be seen from theCD-spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00910575
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Stereoselektive Synthesen vons-Decahydropyrenen (1973)
    Springer
    Monatshefte für Chemie 104 (1973), S. 1484-1496 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Incomplete catalytic hydrogenation of [2.2]metacyclophane (1) or 5,13-dimethyl[2.2]metacyclophane (2) yields (1,2,3,3arH, 4,5,9,10,10acH, 10btH)-decahydropyrene (9) and the dimethylanalogue10, resp.via atransanular cyclisation between positions 8 and 16. Under the same reaction conditions catalytic deuteration (D2, acetic acid-d1) affords a selectively deuterated10 (10-d5).9 is identical with as-decahydropyrene, obtained by high pressure hydrogenation of pyrene. The configurations of9 and10 were established by means of13C and1H-NMR spectroscopy and by comparison with10-d5. A compound formerly believed to be as-decahydropyrene isomer is shown to be (±)-(1,2,3,3a,4,5,9,10)-octahydropyrene (4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00909632
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Zum Problem der Selektivität von Pyrrolsynthesen: Isomere und Homologe bei synthesen nach Fischer—Fink (1973)
    Springer
    Monatshefte für Chemie 104 (1973), S. 925-932 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the course of theFischer—Fink synthesis not only the expected esters of alkylpyrrole-2-carboxylic acids are obtained, but isomers and homologues as well. Their formation can be avoided by suitable variations of the starting materials. The product ratios were analyzed by means of gas chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00903906
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Stereochemie der Polycyclane, 1. Mitt.: Synthese voncis—cis—anti—cis—cis-Hexadecahydropyren durch stereoselektive hydrierung des [2.2]Metacyclophans (1973)
    Springer
    Monatshefte für Chemie 104 (1973), S. 1154-1163 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Catalytic hydrogenation of [2.2]metacyclophane yieldscis-cis-anti-cis-cis-hexadecahydropyrene (4) by a transanular cyclization between positions 8 and 16.4 can be isomerized to givetrans-trans-anti-trans-trans-hexadecahydropyrene (1), so far the only known configurational isomer of that tetracyclane series. The configuration of4 was established by means of13C-N M R- and1H-N M R-spectroscopy as well as by1H-N M R-studies of selectively deuterated4 (4-d10), accessible by catalytic deuteration of [2.2]metacyclophane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00910030
    Library Location Call Number Volume/Issue/Year 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...