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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 91 (1969), S. 3851-3859 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 90 (1968), S. 4646-4653 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 60 (1995), S. 5494-5503 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 47-50 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hexaazapolycycles by Selective Multimethylenations with Dichloromethane and Base or with HexamethylenetetramineMultiple methylenations of 2-aminomethylbenzimidazole with dichloromethane and methylamine or ammonia or with hexamethylenetetramine lead to highly selective formations of 6 new single bonds to give only a polycyclic bis-spiro-1,5-diazocine 2 or only a polycyclic spiro-1,3,6-triazonine 4 or only a polycyclic 1,3,6,8-tetrazecine derivative 6. 4 and 6 may be equally well obtained starting with 2-chloromethyl-benzimidazole. All of these selectively formed products are concave cryptands with 6 amino nitrogen atoms. No template metals are used in their syntheses. The reasons for the unusual changes in selectivity are investigated using semi-empirical PM3 calculations and mechanistic considerations. Experimental and spectroscopic details are given.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iminium Salts in Quantitative Gas/Solid and Solid/Solid ReactionsIminium salts that are highly susceptible to hydrolysis are quantitatively prepared and reacted in the solid state without solvents or liquid phases. Atomic force microscopy AFM helps in elucidating the mechanism of these still unusual gas-solid and solid-solid syntheses by recording surface topographies of reacting crystals of L-histidine (10) and triphenylverdazyl (15). Various imines add gaseous HCl or HBr to form stable iminium halides (1, 3, 4, 5, 11) even if frozen liquids of very weak heterocyclic bases are treated at low temperatures. Another way for quantitative yields of iminium salt hydrates (6) starts with solid primary ammonium halides and gaseous acetone. o-Phenylenediamines (7) give quantitatively 1,5-benzodiazepines (9) by solid state cyclization of bis-iminium salt intermediates (8). Crystalline nitroxyls (12) and triphenylverdazyl (15) undergo stoichiometric one-electron transfer with gaseous NO2 or XeF2 to give nitrosonium (14) and azonium salts (17). The solid state chlorination of tetramethylthiuramdisulfide (18) or dimethylthiocarbamoylchloride (20) yields phosgene dimethyliminiumchloride (Viehe salt 21) in quantitative yield. Solid Viehe salt is quantitatively treated with gaseous Cl2 to give the trichloride 19 and solid SbCl5 or PCl5 to produce the hexachloroantimoniates (22), -phosphates (23). Solid brenzcatechol (24), mercaptobenzimidazole (27), p-nitroaniline (30), N-methylbenzothiazolone-2-hydrazone (34) and acetophenone (41) are treated with 21 to give the corresponding chloroiminium salts (25, 28, 31, 35, 43). p-Toluenesulfonamide (37) and 22 give the chloroiminium salt 38. These quantitative solid-solid reactions are most easily run in ball mills with cooling device. The “waste-free” techniques achieve exclusion of moisture in an elegant way. The preparative use of the versatile products with nucleophiles is indicated. The three-step solid-state mechanisms are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 101 (1968), S. 1729-1735 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Im geschwindigkeitsbestimmenden Schritt der Autoxydation in Methanol/Methylat reagiert Sauerstoff mit dem Monoanion von Hydrazobenzol. In stark basischem Dimethylsulfoxid/tert.-Butylalkohol kann ein Ablauf über das Dianion und Radikalanion des Hydrazobenzols erzwungen werden; dabei entsteht Kaliumhyperoxid (KO2). Im Licht dieser Ergebnisse werden die Autoxydation von Anilin und Benzhydrol diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 2288-2301 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemical Transformations, 33Upon direct photoexcitation the three 7-azabenzonorbornadienes 12a, b, c are isomerized to the 3-benzazepines 22a, b, c. At temperatures above -40° the azaquadricyclanes 19a, b, c, postulated as intermediates, cannot be found. The sensitized reaction of 12a yields the 6-aminobenzofulvenes 23a and 24a preferentially.
    Notes: Durch direkte Lichtanregung werden die drei 7-Aza-benzonorbornadiene 12a, b, c in die 3-Benzazepine 22a, b, c isomerisiert. Oberhalb -40° lassen sich die als Zwischenprodukte postulierten Azaquadricyclane 19a, b, c nicht nachweisen. Bei der sensibilisierten Anregung von 12a werden die 6-Amino-2.3-benzo-fulvene 23a, 24a bevorzugt gebildet.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 3824-3849 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 3σ → 3π-Route to 1H-Azepine DerivativesThe CO2CH3- and CF3-substituted 7-azanorbornadiene derivatives 3a-i, 9 and 12 have been synthesized. Direct and sensitized light excitation leads in good to excellent yields to the isolated (14a-d, h, i, 20) or only indirectly identified (14e-g) 3-azaquadricyclanes. On direct excitation of 9 (X = NO2) the azaquadricyclane formation, however, is clearly topped by the isomerisation to the 6-aminofulvene 19. Through a 3σ → 3π cleavage the azepines 15a- i, 1 and 16h,i are available. The influence of the N- and C-substitution upon the ease and the direction of the azaquadricyclane→azepine isomerisation and the limits of this azepine synthesis in general are discussed.
    Notes: Die CO2CH3- und CF3-substituierten 7-Azanorbornadien-Derivate 3a- i, 9 und 12 wurden synthetisiert. Direkte oder sensibilisierte Lichtanregung von 3a-i und 12 führt in guten bis sehr guten Ausbeuten zu den isolierten (14a-d, h, i, 20) bzw. nur indirekt (14e-g) nach-gewiesenen 3-Azaquadricyclanen. Hingegen ist die Azaquadricyclan-Bildung bei der direkten Belichtung von 9 (X = NO2) der Umwandlung aum 6-Aminofulven 19 deutlich untergeordnet. Über eine thermische 3σ → 3π-Spaltung sind die Azepine 15a-i, 1 und 16h, i zugänglich. Der Einfluß der N- und C-Substituenten auf die Leichtigkeit und Richtung der Azaquadri-cyclan→ Azepin-Isomerisierung sowie generell die Grenzen dieser Azepin-Synthese werden diskutiert.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3084-3110 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The cis-Effect in Photochemical Cleavages of CyclobutanesSelectivities in cleavage orientations on direct irradiation of cyclobutane derivatives are studied systematically at 20-30°C and -190°C with various examples. Phenyl and acrylic ester groups, in more or less sterically hindered environments, serve as chromophors. The cleavage reactions proceed via short-lived 1,4-diradicals. As a consequence of the two-step mechanism geometric isomerization of the cyclobutanes is observed and  -  as expected  -  there is no precisely reciprocal behaviour of fluorescence yields and photochemical quantum yields within series of related compounds. There is a clear preference for cleavage of the cyclobutane bond bearing i the chromophore and ii the substituent which sterically interacts most effectively with the chromophore (cis-effect). The application of the empirically supported effect to cyclovinylogous (retro-)Diels-Alder and [4 + 2 + 2]-reactions, e. g., is discussed. The syntheses and chemical or spectroscopic characterization (UV, fluorescence, NMR) of the compounds (phenylcyclobutanes, truxinic esters, dimers of muconic esters) investigated are described.
    Notes: Die Spaltungsorientierung von Cyclobutanderivaten nach direkter Lichtanregung wird an zahlreichen Beispielen bei 20-30°C und -190°C systematisch untersucht. Als Chromophore in sterisch mehr oder weniger stark behinderter Umgebung dienen Phenyl- und Acrylester-Gruppen. Die Spaltungsreaktionen verlaufen über kurzlebige 1,4-Diradikale. Als Folge des Zweistufenmechanismus werden geometrische Isomerisierungen der Cyclobutane beobachtet, und man erhält  -  wie erwartet  -  kein exakt reziprokes Verhalten von Fluoreszenzausbeuten und photochemischen Quantenausbeuten in Verbindungsreihen. Bevorzugt wird die Cyclobutan-Bindung gespalten, welche den Chromophor und die sterisch am stärksten auf diesen einwirkende Gruppe trägt (cis-Effekt). Die Anwendung des empirisch gesicherten Effekts, z. B. auf cyclovinyloge (Retro-)Diels-Alder- und [4 + 2 + 2]-Reaktionen wird diskutiert. Synthese und chemische sowie spektroskopische Charakterisierung (UV, Fluoreszenz, NMR) der untersuchten Verbindungen (Phenylcyclobutane, Truxinsäureester, Muconsäureester-Dimere) werden mitgeteilt.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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