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  • Chemistry  (58)
  • Best. von Wasser in organ. Lösungsmitteln  (2)
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  • 11
    Electronic Resource
    Electronic Resource
    Darstellung und Fluoreszenzverhalten von 2,3,4,4a,10a,11,12,13-Octahydro-1,4a,10a,14-tetraazaviolanthron-Derivaten (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3524-3528 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Flouorescene of 2,3,4,4a,10a,11,12,13-Octahydro-1,4a,10a,14-tetraazaviolanthron-Derivatives.The tetramethyl derivative 2 of the title compound was prepared by the condensation of neopentanediamine with 3,4:9,10-perylenebis(dicarboxylic anhydride). The spectra of absorption and fluorescence with λmax = 541 and 563 nm, respectively, show a bathochromic shift versus those of the perylene dyes. The quantum yield of fluorescence is 60 percent. The analogue condensation of the anhydride with ethylenediamine gives a perylene fluorescent dye as an intermediate which contains an amino group and may, therefore, be used in acid aqueous solutions.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831161027
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  • 12
    Electronic Resource
    Electronic Resource
    Synthese von Reinst-Rubicen und Rubicen-Derivaten (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1981-1987 
    Details
    ISSN: 0009-2940
    Keywords: Rubicene ; Hydrocarbons, polycyclic ; Dyes, fluorescent ; Singlet oxygen sensitizer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Highly Pure Rubicene and Rubicene DerivativesA simple one-step synthesis of highly pure rubicene (2) from fluorenone (1) and magnesium with 24% yield is described and compared with other preparation procedures. Mono- and disubstituted rubicene derivatives are prepared by electrophilic aromatic substitution.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231009
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  • 13
    Electronic Resource
    Electronic Resource
    Synthese von nichtsymmetrisch substituierten Perylen-Fluoreszenzfarbstoffen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 529-535 
    Details
    ISSN: 0009-2940
    Keywords: Perylene dyes ; Hydrocarbons polycyclic ; Fluorescent dyes ; Fluorescent labelling ; Fluorescent tracer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Nonsymmetrically Substituted Perylene Fluorescent DyesA general method for the preparation of perylene-3,4:9,10-tetracarboxdiimides 1 with two different substituents at the nitrogen atoms is described: The easily prepared symmetrical tetracarboxdiimides 1 (R1=R2) are transformed into carboxdiimide anhydrides 2 and condensed with primary amines to the corresponding tetracarboxdiimides 1 (R1 ≢ R2). Applications as fluorescent tracers in biochemistry and polymer chemistry are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240319
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  • 14
    Electronic Resource
    Electronic Resource
    Wanderungstendenzen cyclischer, polycyclischer und methylverzweigter Alkylreste bei der Beckmann-Umlagerung (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3831-3854 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Migration Aptitudes of Cyclic, Polycyclic, and Branched Alkyl Groups in the Beckmann RearrangementsThe migration aptitudes of polycyclic bridgehead groups, cycloalkyl groups as well as of β-γ-and δ-branched alkyl groups in the Chapman variant of the Beckmann rearrangement were determined. From these data it is concluded that at transition state 2 the migrating group is not resembling a planarised carbenium ion R+, but rather a pentacoordinated carbonium ion structure. Because only small geometrical changes occur in the migrating group vertical stabilisation4) of charge at transition state is believed to have significant influence on the migration aptitudes.
    Notes: Die Wanderungstendenzen von polycyclischen Brückenkopfresten, Cycloalkylresten sowie β, γ-und -δ-verzweigten Alkylresten bei der Chapman-Variante der Beckmann-Umlagerung wurden bestimmt. Sie zeigen, daß die wandernde Gruppe im Übergangszustand 2 nicht Carbenium-Ionen-Charakter hat, sondern nach weitgehender Beibehaltung ihrer Geometrie eher einer Fünffach koordinierten Carboniumstruktur entspricht, die im Zuge der Umlagerungsreaktion vertikal stabilisiert4 werden kann.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811141208
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  • 15
    Electronic Resource
    Electronic Resource
    Alkylwanderungen bei Sextettumlagerungen (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3813-3830 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Migration of Alkyl Group in Sextett RearrangementsThe migration aptitude of alkyl groups in the Beckmann-, the Criegee-, and the isonitrile-nitrile rearrangements were investigated. The relative rearrangement rates of substituted benzyl groups are an expression of the charge on the migrating carbon at transition state. From the relative rates of migration of exo- and endo- 2- norbornyl group the geometrical changes at the migrating carbon are estimated. Finally, The different influence of α-branching in the migrating group is discussed for these and some other rearrangements.
    Notes: Die Wanderungstendenzen von Alkylgruppen bei der Beckmann- Criegee- und Isonitril-Nitril-Umlagerung werden untersucht. Aus den relativen Reaktionsgeschwindigkeiten der substituierten Benzylreste werden Rückschlüsse auf die Ladungsverteilung im Übergangszustand dieser Reaktionen gezogen und aus dem Verhältnis der Wanderungstendenzen des exo und endo- 2- Norbornylrestes auf die Geometrie der wandernden Gruppe im Übergangszustand. Der in verschiedenen Sextettumlagerungen unterschiedliche Einfluß der α-Methylverzweigung in der wandernden Gruppe wird interpretiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811141207
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  • 16
    Electronic Resource
    Electronic Resource
    Eine einfache Synthese von 3-Methoxypyridin und seinen Analogen durch Alkylierungsreaktionen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2394-2397 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Synthesis of 3-Methoxypyridine and of Analogues by Alkylation ReactionsSolid potassiumhydroxide in dimethylsulfoxide has high basicity but only low nucleophilicity and is used as a base for the methylation of 3-hydroxypridine (1) and of analogues with methyliodide. The reaction is not interferred by the addition of small amounts of water and gives yields of 40 percent for the reaction of 1 and up to 100 percent for analogues. The described reagent therefore may be an alternative to lithium diisopropylamide.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160631
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  • 17
    Electronic Resource
    Electronic Resource
    Synthese von hochreinen Perylen-Fluoreszenzfarbstoffen in großen Mengen - gezielte Darstellung von Atrop-Isomeren (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4641-4645 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Highly Pure Perylene Fluorescent Dyes in Large Scale Amounts - Specific Preparation of Atropic IsomersN,N′-Bis(2,5-di-tert-butylphenyl)-3,4:9,10-perylenebis(dicarboximide) (2), an intensely coloured fluorescent dye with high photostability (Φ = 99%, λmax = 526 nm, ∊ = 95000), is prepared by reaction of the corresponding amine with 3,4:9,10-perylenetetracarboxylic dianhydride and isolated in high purity even in large amounts by an extractive recrystallisation procedure. Suitable reaction conditions allow the selective preparation of each of its atropic isomers. This is interpreted in terms of different reaction mechanisms. Applications are discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181138
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  • 18
    Electronic Resource
    Electronic Resource
    Fluoreszenzfarbstoffe mit großen Stokes-Shifts - eine einfache Synthese von [2,2′-Bipyridin]-3,3′-diol (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4674-4681 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fluorescent Dyes with Large Stokes Shifts - a Simple Synthesis of [2,2′-Bipyridine]-3,3′-diol[2,2′-Bipyridine]-3,3′-diol (4) is obtained in one step from furoin (8) by Zincke rearrangement in 32% yield. The fluorescence quantum yield of the dye is 50% in chloroform - absorption and fluorescence spectra are completely separated (TZ = 1011). The large Stokes shift is caused by a proton transfer according to the Förster mechanism.
    Notes: [2,2′-Bipyridin]-3,3′-diol (4) wird aus Furoin (8) in einem Schritt über die Zincke-Umlagerung in 32proz. Ausbeute erhalten. Die Fluoreszenzquantenausbeute des Farbstoffs beträgt in Chloroform 50% - Absorptions- und Fluoreszenzspektrum sind vollständig getrennt (TZ = 1011). Für den großen Stokes-Shift ist ein intramolekularer Protonentransfer nach dem Förster- Mechanismus verantwortlich.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181204
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  • 19
    Electronic Resource
    Electronic Resource
    Substituentenkonstanten des Pyrazol-, 1,2,3-Triazol-, Benzotriazol- und Naphthotriazol-Restes (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1627-1639 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Substituent Constants of the Pyrazol, 1,2,3-Triazol, Benzotriazol, and Naphthotriazol GroupThe synthesis of benzoic acids with the title substituents in p- and m-position (15, 13, 11, 9) and their ethyl and methyl esters is described. The σp and σm values of the substituents obtained by alkaline hydrolysis of the esters in ethanol/water and methylcellosolve/water demonstrate an inductive electron withdrawing and a mesomer electron donating effect of these groups which are important for dye chemistry.
    Notes: Die Synthese von Benzoesäuren mit den im Titel genannten Resten in m- bzw. p-Position (15, 13, 11, 9) sowie ihrer Ethyl- und Methylester wird beschrieben. Über deren alkalische Verseifung in Ethanol/Wasser und Methylcellosolve/Wasser werden die Substituentenkonstanten σp und σm der Reste bestimmt. Sie deuten auf eine induktive Elektronenacceptor-und mesomere Elektronendonator-Wirkung dieser für die Farbstoff-Chemie wichtigen Substituenten hin.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190516
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  • 20
    Electronic Resource
    Electronic Resource
    Die Isomerisierung der Homoadamantan-3-carbonsäure zur Homoadamantan-1-carbonsäure (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 1509-1524 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Isomerisation of Homoadamantane-3-carboxylic Acid into Homoadamantane-1-carboxylic AcidIt is shown by D-, 13C-, and double labelling experiments that the title isomerisation 2 → 3 unter Koch-Haaf conditions is due to reversible decarbonylation followed by intermolecular hydride transfer between the bridgehead positions of the two bridgehead homoadamantane cations and homoadamantane derivatives. The isomerisation is accompanied by complete equilibration of an isotopically labelled methylene group over all possible positions. This is due to the known adamantylmethyl-3-homoadamantyl cation rearrangement which is likewise occuring. In contrast to hydride transfer reactions in the adamantyl system the methylene groups of the homoadamantyl system are not participating in the hydride transfer between the bridgehead positions.
    Notes: Durch D-, 13C- und Doppelmarkierungsexperimente wird gezeigt, daß die Isomerisierung der Homoadamantan-3-carbonsäure (2) zur Homoadamantan-1-carbonsäure (3) unter den Bedingungen der Koch-Haaf-Synthese durch reversible Decarbonylierung zustande kommt, die von intermolekularem Hydridtransfer zwischen den Brückenkopfpositionen der Homoadamantan-1-und Homoadamantan-3-carbenium-Ionen und Homoadamantanderivaten begleitet ist. Die Umlagerung ist mit Äquilibrierung der Isotopenmarkierung aller Methylengruppen verbunden. Hierfür wird die gleichzeitig stattfindende bekannte Adamantylmethyl-3-Homoadamantylcarbenium-Umlagerung verantwortlich gemacht. Im Gegensatz zu Hydridübertragungen im Adamantyl-system beteiligen sich die Methylenwasserstoffe des Homoadamantylsystems nicht an der Hydridübertragung zwischen den Brückenköpfen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150428
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