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  • 1
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Regioselektivität von Wittig-Horner- und Reformatsky-Reaktionen an ausgewählten 3,17-Dioxosteroiden (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 367-374 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on Regioselectivity of Wittig-Horner and Reformatsky-Reactions on Selected 3,17-Dioxo SteroidsThe Reformatsky synthesis and the Wittig-Horner olefination of 3,17-dioxo steroids like androsta-1,4-diene-3,17-dione (ADD) 1 and androst-4-ene-3,17-dione (AD) 2 is described. There are differences in the regioselective introduction of identical substructures with these two methods resulting from different nucleophilicity and stereoelectronical relations of these two reagents. In Reformatsky synthesis the oxo group in 3-position predominantly reacts, whereas in the Wittig-Horner olefination (in the case of 1) the reaction occurs mainly in the 17-position.The structures of all new compounds has been confirmed by spectroscopical data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320314
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  • 2
    Electronic Resource
    Electronic Resource
    Stickstoffhaltige Steroide. XXI. Isomerisierungsreaktionen der epimeren 2,3-Benzoylimino-cholestane (1968)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 38 (1968), S. 168-176 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2α, 3α- und 2β, 3β- Benzoylimino-cholestan werden durch Natriumjodid in siedendem Aceton zu 2′-Phenyl-(2α, 3α)-oxazolino-[5′, 4′:2, 3]-cholestan bzw. 2′-Phenyl-(2β, 3β)-oxazolino-[5′, 4′:3, 2]-cholestan umgelagert. Mit Bortrifluoridätherat in absolutem Äther bildet 2α, 3α-Benzoylimino-cholestan ebenfalls 2′-Phenyl-(2α, 3α)-oxazolino-[5′, 4′:2, 3]-cholestan. Dagegen erfolgt durch verdünnte Schwefelsäure oder Pikrinsäure in Aceton sowie durch Benzoesäureanhydrid oder Pikrinsäure in Alkohol Ringöffnung zu 2-Hydroxybzw. Alkoxybenzamiden. Die Ringschlußreaktion des diaxialen 2β-Chlor-3α-benzaminocholestan führt mit Natriumhydrogenkarbonat zum Oxazolin, während mit Kaliumhydroxid 2α, 3α-Imino-cholestan entsteht.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19680380310
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  • 3
    Electronic Resource
    Electronic Resource
    Synthese photochromer 2-(2′,4′-Dinitrobenzyl)-pyridine (1975)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 317 (1975), S. 761-770 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird die Synthese von 9 neuen photochromen Verbindungen beschrieben, die sich von 2-(2′,4′-Dinitrobenzyl)-pyridin 1 durch Einführen von weiteren Substituenten in die Methylengruppe, in 5′-Position des Phenylringes und in Position 4 des Pyridinringes ableiten.Die Synthese der α-Substitutionsprodukte erfolgt durch NBS-Bromierung und Mannich-Reaktion von 1 und durch Folgereaktionen der α-Bromverbindung und der Mannich-Base. In 5′- und 4-Position substituierte Dinitrobenzylpyridine werden durch Nitrierung der entsprechenden substituierten Benzylpyridine erhalten. 2-(2′,′ 4-Dinitro-5′ -natriumsulfonatobenzyl)-pyridin 9f ist wasserlöslich, thermisch stabiler als 1, und die blaue Farbform besitzt eine größere Lebensdauer als die von 1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19753170509
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  • 4
    Electronic Resource
    Electronic Resource
    Neue Polyadditionskomponenten. N-Alkylierung einiger Diamine mit langer verzweigter Zwischenkette (1976)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 318 (1976), S. 173-176 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19763180120
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  • 5
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Einfluß der Polymermatrix auf die thermische Rückreaktion von photochromen 2,4-Dinitrobenzylpyridinen (1977)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 319 (1977), S. 647-654 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Influence of the Polymer Matrix on the Thermal Back Reaction of Photochromic 2,4-Dinitrobenzyl PyridinesIn solid solution with polymers (polymethylmethacrylate, polyethyl acrylate and polystyrene) below Tg the thermal back reaction of the coloured forms of photochromic 2-(2′,4′-dinitrobenzyl)pyridines 1-3 can be described by second-order kinetics whereas above Tg (in polyethyl acrylate) the reaction is first order. The life time of coloured form depends on polymer structure and is longest in polar polymers of high molar mass. These results as well as the Δ≠ and ΔH≠ values are discussed applying the concept of reaction cavity to the solid solutions.
    Notes: In fester Lösung in Polymeren (Polymethylmethacrylat, Polyäthylacrylat und Polystyrol) wird die Kinetik der thermischen Rückreaktion der Farbformen der photochromen 2-(2′,4′-Dinitrobenzyl)-pyridine 1-3 unterhalb Tg durch ein Zeitgesetz 2. Ordnung, oberhalb Tg (in Polyäthylacrylat) durch ein Zeitgesetz 1. Ordnung beschrieben. Die Lebensdauer der Farbform ist von der Konstitution des Polymeren abhängig und ist am größten in polaren Polymeren hoher Molmasse. Diese Ergebnisse und die ΔS≠ - und ΔH≠ - Werte werden unter Anwendung des Begriffes der Reaktionshöhlung auf die festen Lösungen diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19773190415
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  • 6
    Electronic Resource
    Electronic Resource
    Zur Photochromie von ortho-Nitrobenzylpyridinen in unterkühlter Schmelze (1979)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 321 (1979), S. 404-406 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochromism of the o-Nitrobenzylpyridines in Supercooled Melts2-(2′, 4′-dinitrobenzyl)-pyridines 1 a-g and 4-(2′,4′-dinitrobenzyl)-pyridine 2 form supercooled melts which are photochromic on u.v.-irradiation. The photochromism and the kinetic stability of the coloured form in supercooled melts are quite different from the behaviour in ethanolic solution. The differences are explained on the basis of a polymethin constitution of the coloured form.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19793210308
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  • 7
    Electronic Resource
    Electronic Resource
    Zur Konstitution der Farbform der photochromen ortho-Nitrobenzylverbindungen (1979)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 321 (1979), S. 407-414 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Constitution of the Coloured Form of Photochromic o-NitrobenzylpyridinesThe reversibly highly coloured photochromic forms of dinitrobenzyl pyridines and tetranitro diphenylmethanes have structure of polymethines as evidenced by u.v.-vis, i.r. and 1H-n.m.r. spectra. There exists an analogy to the polymethines formed from 1-methyl-2-(2′,4′-dinitrobenzyl)-pyridinium iodid and tetranitrodiphenylmethane and potassium hydroxide. The structure of the coloured form of the dinitrobenzylpyridines and tetranitrodiphenylmethanes are in agreement with their photochromic properties, especially with the u.v.-vis-absorption, the photochromism in substance and the influence of substituents on the photochromism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19793210309
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  • 8
    Electronic Resource
    Electronic Resource
    Nanosekunden-Laserabsorptionsspektroskopie an 4-(2′,4′-Dinitrobenzyl)-pyridin (1980)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 322 (1980), S. 348-352 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nanosecond Laser Absorption Spectroscopy of 4-(2′,-4′-Dinitrobenzyl)-Pyridine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19803220224
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  • 9
    Electronic Resource
    Electronic Resource
    Komplexbildung eines linearen Amin-Epoxid-Polyadduktes mit Bariumrhodanid (1980)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 322 (1980), S. 445-449 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complex Formation of a Linear Amine Epoxide Polyadduct with Barium RhodanideN,N′-Dibenzyl-3,6-dioxa-octanediamine-1,8 and the linear polyadduct (Mn = 8000) obtained from this amine and diglycidyl ether of bisphenol A form 1:1 complexes with barium rhodanide in organic solutions. This result is of importance for the surface chemistry of epoxide resins in adhesive processes and for the interaction with mineral fillers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19803220315
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  • 10
    Electronic Resource
    Electronic Resource
    Kurzzeitspektroskopische Untersuchungen an photochromen N-substituierten Dinitrobenzylpyridinen (1979)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 321 (1979), S. 415-419 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Short-Time Spectroscopic Investigations of Photochromic N-Substituted DinitrobenzylpyridinesBy means of nanosecond laser absorption spectroscopy of N-substituted photochromic dinitrobenzylpyridines is shown that in polar solvents the long wave absorbing polymethin coloured form forms independently on the electronic properties of the substituents at the pyridine nitrogen. The polymethin is formed either directly or via the nitronic acid immediately after irradiation by the laser impulse (20 ns). In nonpolar solvents, on the other hand, the polymethin is only produced if the substituent (e.g. in N-oxide 6) is able to bind the hydrogen splitted from the methylen group by photoreaction. If this is impossible (e.g. N-Methyl-compound 5) only absorption of nitronic acid occur.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19793210310
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