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  • Artikel  (4)
  • 78.70  (2)
  • 13C-NMR  (1)
  • 4,5-Diamino-pyridazin-6(1H)-ones  (1)
  • Springer  (4)
  • Springer Nature
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Monatshefte für Chemie 126 (1995), S. 341-347 
    ISSN: 1434-4475
    Schlagwort(e): Chloroacetic acid chloride ; Phenylhydrazono acetamides ; Pyridines ; Pyridazin-5-ylpyridinium chlorides ; 4,5-Diamino-pyridazin-6(1H)-ones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Arylhydrazono acetamides1 react with chloroacetic acid chloride to give N-chloroacetyl derivatives2. Subsequent reaction with pyridines followed by ring closure yield 1-(4-amino-6-oxo-pyridazin-5-yl)-pyridinium chlorides3. Analogously, 1-(6-oxo-pyridazin-5-yl)-pyridinium chloride (5) and 6-oxo-5-pyridinio-pyridazin-4-olate (4) are formed from phenylhydrazono derivatives and pyridine. Treatment of3 and4 with hydrazinium hydrate gives 4,5-diamino-6-oxo-pyridazin-3-carbohydrazides6 and 5-amino-4-hydroxy-pyridazin-6(1H)-one (8). An analogous ring cleavage of3e and5 gives rise to 4,5-diamino- and 5-amino-pyridazin-6(1H)-ones7. On treatment of the pyridinium salts3 with caustic soda in water, nucleophilic addition of the amino group to the pyridinium ring takes place and stable dehydrated products9 are isolated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Monatshefte für Chemie 122 (1991), S. 195-207 
    ISSN: 1434-4475
    Schlagwort(e): 5-Dialkylamino-2-aryl-1,2,3-triazoles ; 4-Amino-2,6-dioxo-tetrahydropyrid-3-yl-pyridiniumchloride ; 2-Arylhydrazono-2-cyan-N-chloracetylacetamide ; Arylhydrazono-2-cyan-N,N-dialkylacetamidines ; Arylhydrazonomalononitriles ; 4-Imino-5-arylazo-6-dialkylamino-1,4-dihydropyrimidines ; 13C-NMR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The title compounds3 were synthesized by reaction of arlyhydrazono-malononitriles1 with secondary amines and used for subsequent cyclization reactions. Thus,3 undergoes cyclooxidation by treatment with CuSO4/pyridine to form the 5-dialkylamino-2-aryl-1,2,3-triazolo-4-carbonitriles4. From4 a and hydrazine hydrate/DMF the 4-(1,3,4-triazolyl-5)-1,2,3-triazole5 c is obtainable. The chloroacetylation of3 is accompanied by hydrolysis of the amino group to yield the arylhydrazono-N-chloracetyl cyanoacetamides6. The quaternisation of6 with pyridins is followed by the Thorpe cyclization to form the 4-amino-5-arylazo-6-hydroxy-3-pyridinio-pyrid-2-on-chlorides8, useful as cationic dyes. The reaction of3 with trichloroacetonitriles yields the 5-arylazo-4-imino-2-trichlormethyl-1,4-dihydropyrimidines10 a–c which can be converted into the 5-arylazo-2-hydrazino-pyrimidine derivatives10 d–f. From10 d the 6-phenylazo-triazolo[4,3-a]pyrimidine derivative11 is obtainable. From3 and phenylisothiocyanate the 5-arylazo-4-imino-1,4-dihydropyrimidin-2-thiones12 arise. The structures were investigated by13C-NMR-spectroscopy.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 61 (1995), S. 51-53 
    ISSN: 1432-0630
    Schlagwort(e): 61.70 ; 61.80 ; 78.70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The present paper reports on positron lifetime measurements on atomic defects in SiC after low-temperature (80 K) electron irradiation of low (0.47 MeV) and high (2.5 MeV) electron energies and doses from 1.8×1017 to 1.9×1019 e/cm2 as well as after subsequent isochronal annealing up to 1900 K. For these studies the single crystals of nitrogen doped (2–3×1018 cm−3) SiC grown by a modified Lely technique with hexagonal structure (6H polytype) were used. According to the positron lifetime measurements, very different types of vacancy-like positron traps are introducted after irradiation with electrons of either low or high energy. The formation of defect agglomerates and their decay at high temperatures is studied during isochronal annealing and related to earlier studies.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1432-0630
    Schlagwort(e): 78.70 ; 61.70 ; 07.77
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A slow-positron source has been installed in the therminal of an electrostatic 6.5 MeV accelerator and provides a monoenergetic positron beam in the few-MeV range. It will be used to operate a “fast” positron lifetime spectrometer based onβ + γ coincidences. The properties of the beam, the expected performance of the spectrometer, its advantages over conventionalγγ lifetime measurements, a number of intended applications, as well as recent positron-electron scattering experiments and plans for positron channelling and channelling-radiation studies are outlined.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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