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  • Organic Chemistry  (5)
  • 2005-2009
  • 1980-1984  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    Hammett-Beziehungen zwischen 1H-NMR- bzw. 31P-NMR-chemischen Verschiebungen und Substituenten-konstanten in ω-Diphenylphosphinyl-und ω-Diphenylthiophosphinyl-trans-styrenen (1983)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 325 (1983), S. 269-275 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hammett Relationships between 1H-NMR and 31P-NMR Chemical Shifts, Respectively, and Substituent Constants in ω-Diphenylphosphinyl and ω-Diphenylthiophosphinyl trans-StyrenesA well linear correlation between the chemical shifts of the ethylenic protons HB and the 31P nuclei, respectively, and the Hammett constants σp of substituents R in 4-position for diphenylphosphinyl trans-styrenes 1 and the analogous diphenylthiophosphinyl trans-styrenes 2 has been found. A similar relationship for the proton HA has been observed in the case of 1 only, but the substituent-induced shifts are not so sensitive. Donor substituents R in 1 and 2 effect an increase in the shielding of HB and a deshielding of the P atom being connected with shifts of the i. r. P=O absorption bands in 1 in the direction of lower wavenumbers. A mesomeric interaction between R and P=Y substituents (Y = O, S) is concluded to produce polymethin-like π-electron density distribution.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19833250213
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  • 2
    Electronic Resource
    Electronic Resource
    Substituenteneinfluß auf die T1- Energie und auf S1-T1-Energiegap bei ω-Phosphor-substituierten trans-Styrenen (1982)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 324 (1982), S. 107-116 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influence of Substituents on the T1 Energy and the S1-T1 Energy Gap in ω-Phosphorus Substituted trans-StyrenesThe fluorescence and the phosphorescence of 4-substituted ω-diphenylphosphinyl trans-styrenes 1 and analogous diphenylthiophosphinyl trans-styrenes 2 at 77 K indicate together with some oxygen-induced singlet-triplet absorption spectra a bathochromic shift of the lowest singlet (S1) and the lowest triplet level (T1) relatively to the S1 and T1 level of the unsubstituted compounds 1a and 2a, respectively. Donor substituents X in 4-position give rise to a shift of S1, which is in the most cases much greater than that of T1, so that the S1-T1 energy gap decreases. P(Y)R1R2 groups (Y = O, S) in ω-position of 1 and 2 effect a small bathochromic shift of the T1 energy level only (130-900 cm-1 relatively to unsubstituted styrene). S1 is shifted 860-2080 cm-1 to lower energies, however.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19823240114
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  • 3
    Electronic Resource
    Electronic Resource
    Elektronenstoßinduzierte Fragmentierung von para-substituierten Styryl-diphenylphosphinoxiden (1981)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 445-450 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron Impact Fragmentation of para-Substituted Styryl-diphenylphosphine OxidesPara-substituted styryl-diphenylphosphine oxides 1 exhibit a phosphine oxide-like fragmentation. There are two competing ways, A and B, for electron impact fragmentation with the para-substituent of the styrene part determining the A or B way, respectively. A styrene-like fragmentation is to be excluded in respect to the observed mass spectra.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19813230311
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  • 4
    Electronic Resource
    Electronic Resource
    Peptide, 119. Peptidsynthese mit N-Carboxy-α-aminosäureanhydriden (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 275-284 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Peptides 119.  -  Peptide Synthesis with N-Carboxy-α-amino Acid AnhydridesOn reaction of N-carboxy-α-amino acid anhydrides (NCA) with equimolar amounts of amino-acids or excess NCA in potassium borate buffer of pH 10.2 (0°C) considerable amounts of homo-oligomers and homopolymers are formed. If an excess of amino acid is used formation of the above mentioned by-products can be suppressed. The extent of homooligomerization and homopolymerization and hydrolysis occurring during the reaction of NCA under the conditions of peptide synthesis is described.
    Notes: Bei der Umsetzung von N-Carboxy-α-aminosäureanhydriden (NCA) in äquimolaren Mengen oder im überschuß mit Aminosäuren in Kaliumborat-Puffer vom pH 10.2 (0°C) wurde die Bildung beachtlicher Mengen Homooligomere und Homopolymere beobachtet. Durch überschüssige Aminokomponente konnte die Bildung dieser Nebenprodukte unterdrückt werden. Das Ausmaß der Homooligomeren- und Homopolymerenbildung sowie das der Hydrolyse während der Reaktion von NCA unter Peptidsynthesebedingungen wird beschrieben.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800213
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  • 5
    Electronic Resource
    Electronic Resource
    Synthese und Reaktivität von 4H-Dithieno[2,3-b: 3′,2′-e]-thiopyran-Derivaten (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 863-866 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Reactivity of 4H-Dithieno[2,3-b: 3′,2′-e]-thiopyran DerivatenDiethyl 4-hydroxy-2-thioxo-2H-thiopyran-3,5-dicarboxylate reacts with 2a-b to give the substitution products 3a-b. These compounds cyclize to give the diethyl 3,5-dihydroxy-4-oxo-4H-dithieno[2,3-b: 3′,2′-e]thiopyran-2,6-dicarboxylates 4a-b, which react with acyl halides to give acyl- or aryl derivatives 6a-d.
    Notes: 4-Hydroxy-2-thioxo-2H-thiopyran-3,5-dicarbonsäure-diethylester2) (1) reagiert mit 2a - b zu den Substitutionsprodukten 3a-b. Diese cyclisieren zu den 3,5-Dihydroxy-4-oxo-4H-dithieno-[2,3-b: 3′,2′-e]thiopyran-2,6-dicarbonsäure-diethylestern 4a-b, welche mit Säurehalogeniden die Acyl- und Arylderivate 6a-d bilden.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800606
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