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  • Chemistry  (27)
  • chemical derivatization  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Formation, derivatization and applications of bacterial cellulose
    Amsterdam : Elsevier
    International Journal of Biological Macromolecules 16 (1994), S. 343-347 
    Details
    ISSN: 0141-8130
    Keywords: Acetobacter xylinum ; bacterial cellulose ; chemical derivatization
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0141-8130(94)90067-1
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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 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
    Neuartige Steroidale Orthoester durch intramolekulare Cyclisierung von Ethinylcarbinol-Derivaten mittels OrganylhypoioditenProf. Dr. habil. K. Ponsold zum 65. Geburtstag gewidmet (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 855-862 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel Steroidal Orthoesters by Intramolecular Cyclisation of Ethynylcarbinol Derivatives with Organic HypoioditesThe iodination of the 17β-acetoxy-17-ethynylsteroid 2 using iodine/copper(II)-acetate in combination with the nucleophiles acetic acid, water and methanol is reported. Examples for chemical modification of the products are described. A cyclisation occurs in the case of iodomethoxylation as a formal through-space 1.4-addition of the reagent forming a mixture of 4 isomer iodomethylen-1,3-dioxolanes. The configuration and ratio of the isomers as well as analytical data of this hitherto unknown dioxolane-system are given.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19913330607
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Unvernetzte Epoxid-Amin-Additionspolymere. 5. Hochmolekulare Additionspolymere aus N, N′-Dibenzylethylendiamin und 2,2-Bis[4-(2,3-epoxypropoxy)phenyl]propan4. Mitteilung: [1] (1983)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 135-138 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Step growth polymerization of N, N′-dibenzylethylenediamine and 2,2-bis[4-(2,3-epoxypropoxy)phenyl]propane in bulk at 60 to 80°C results in soluble N-benzyl substituted poly(aminoalcoholether) having molecular weights M̄n of 16000 to 18000. The structural features were determined by spectroscopy, acetylation of hydroxyl groups and hydrochloride formation of amino groups.
    Notes: Die Additionspolymerisation von N, N′-Dibenzylethylendiamin und 2,2-Bis[4-(2,3-epoxypropoxy)phenyl]propan in Substanz bei 60 bis 80°C ergibt einen löslichen N-benzylsubstituierten Poly(aminoalkoholether) mit einer Molekülmasse M̄n von 16000 bis 18000. Die Struktur des Additionspolymers wird durch spektroskopische Methoden und Acetylierung der Hydroxylgruppen sowie Hydrochloridbildung der Aminogruppen belegt.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1983.010340302
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