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  • Wiley-Blackwell  (28)
  • Blackwell Publishing Ltd  (1)
  • 1
    Electronic Resource
    Electronic Resource
    SOME ASPECTS OF HYDROGEN ACTIVATION IN HYDROFORMYLATION (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 415 (1983), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1983.tb47352.x
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  • 2
    Electronic Resource
    Electronic Resource
    The influence of asymmetric carbon atoms of the side chains on the conformational properties of polypeptides: Comparison of diastereomeric homooligopeptides of L-isoleucine and D-alloisoleucineTaken in part from a dissertation submitted by U.W. in partial fulfillment of the requirements for the Ph.D. degree, Eidg. Technische Hochschule. (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 239-256 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conventionally protected oligopeptides of the two homologous series Boc-(L-Ile)n-OMe and Boc-(D-aIle)n-OMe (n = 2-6) were synthesized in a standard stepwise fashion and their uv and CD spectra in 2,2,2-trifluoroethanol, and solid-state ir spectra were investigated. In addition, two oligomeric products derived from the NCAs of L-isoleucine and of D-allo-isoleucine and having a DP of 20 and 12, respectively, were studied in the solid state by x-ray and ir. No substantial differences between the properties of the diastereomeric oligomers in the solid state were noticed, a β-structure being very likely at least for the Boc-protected hexapeptides and the higher oligomers. In contrast, differences were observed between the spectroscopic properties of the diastereomeric oligopeptides, and especially of the hexapeptides, in trifluoroethanol solution. The different properties of the hexapeptides in solution were related to the existence, in the case of Boc-(L-Ile)6-OMe, of soluble molecular aggregates in which the peptide chains assume the β-conformation. These results provide an additional example of the influence of the configuration of asymmetric carbon atoms of the side chains on the conformational properties of peptide molecules in solution.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180202
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  • 3
    Electronic Resource
    Electronic Resource
    Stereochemistry of the Platinum Catalyzed Hydroformylation of Olefins (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1865-1869 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The deuterioformylation of (Z)- or (E)-2-butene catalyzed by [DIOP]Pt(SnCl3)-ClDIOP=2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane. gives predominantly erythro- or threo-1,3-[2H]2-2-methylbutanal respectively. Hence, hydroformylation by this catalytic system must take place with cis-stereochemistry.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640620
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  • 4
    Electronic Resource
    Electronic Resource
    Hydroformylation of 1, 1, 1-d3-2-butene. Isotope Effect on the Product Composition (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1703-1707 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the hydroformylation of 1,1,1-trideuterio-2-butene with Rh4 (CO)12 the deuterated pentanals formed contain 75% of 5,5,5-trideuterio-pentanal, the rest being substantially 2,2-dideuterio-pentanal. On the contrary, using Co2 (CO)8 as the catalyst precursor, position 1 and 4 are formylated to the same extent.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610518
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  • 5
    Electronic Resource
    Electronic Resource
    Konstitutionsisomerie in Polykondensaten. Teil VITeil V: [1].. Synthese und Eigenschaften von völlig geordneten und ungeordneten Bipolyamiden aus cis-2,6-Dimethylpiperazin und 1,2,5-Thiadiazol-3,4-dicarbonyl-dichlorid (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 839-855 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Constitutional Isomerism in Polycondensates. Synthesis and Properties of Perfectly Regular and Random Bipolyamides from cis-2,6-Dimethylpiperazine and 1,2,5-Thiadiazole-3,4-dicarbonyl DichlorideThe synthesis of constitutionally perfectly regular and random alternating copolyamides from the ‘symmetric’ monomer 1,2,5-thiadiazol-3,4-dicarbonyl dichloride (4) and the ‘non-symmetric’ monomer cis-2,6-dimethylpiper-azine (7) by solution and interfacial polycondensation methods is described. Their constitutional regularities (s values) were determined by high-resolution 13C-NMR spectroscopy in CDCl3 solutions. Ordered and random copolyamides were amorphous with Tg values of ca. 200°. However, the regular head/tail and the random copolyamides with low molecular weights could be partially crystallized by annealing and showed large differences in their melting points (54°). Beside other physical properties, the membrane properties of the copolyamides were carefully investigated. In H2O desalination by reverse osmosis, no differences in salt rejections and permeabilities between constitutionally regular and random copolyamides were found (within experimental errors). In contrast, the regular head/head/tail/tail- and head/tail-type copolyamides showed considerably larger separation factors in the gas separation (methane/hydrogen) than the random ones.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730409
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  • 6
    Electronic Resource
    Electronic Resource
    Circular Dichroism of Some Isomeric Alkyl Pyridines (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 2102-2109 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The UV. and CD. spectra of the optically active 2-, 3- and 4-(l-methylpropyl)-pyridines (1a, b, c) and of the corresponding (2-methylbutyl)pyridines (2a, b, c) have been investigated in hexane at RT. and at -85°, in hexane/TFA and in aqueous HCl-solution. In 1c and 2c both the n → π* and the π → π* transitions are optically active, an n → π* transition being located above 265 nm. The position and the sign of the CD. bands are greatly influenced by the position and the nature of the alkyl substituent.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650717
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  • 7
    Electronic Resource
    Electronic Resource
    Structural isomerism in Polycondensates. Part IVPart III: [1].. Synthesis and characterization of liquid crystalline poly(azomethines) and low molecular weight model compounds (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1349-1355 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the aim to investigate the influence of structural isomerism on the mesomorphic thermal stability in main chain thermotropic polycondensates, a series of poly(azomethines) and low molecular weight models have been prepared. The model compounds exhibit smectic and/or nematic mesophases whose stabilites are very sensitive to structural modifications. On the basis of the above results, monomers 2, 5, 6, 8, 9, 23, 25, and 26 were selected to synthesize oligomers 27-23. The oligomer 33 obtained from the nonsymmetric diamine 23 has a lower melting point than the symmetric oligomer 28, but a similar liquid crystalline range.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690609
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  • 8
    Electronic Resource
    Electronic Resource
    On the melting behaviour of isotactic polymers obtained from optically active and racemic 4-methyl-1-hexeneDedicated to Professor Dr. H. Mark on his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 317-327 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das thermische Verhalten von isotaktischem Poly[(S)-4-methyl-1-hexen], (P(S)4MH), Poly[(R)-4-methyl-1-hexen], (P(R)4MH), ihrer àquimolaren Mischung (r-P4MH) und von Poly[(R)(S)-4-methyl-1-hexen] (P4MH) wurde untersucht. Die DSC-Kurven von P(S)4MH und P(R)4MH ergaben beim Schmelzen zwei endotherme Peaks, während nur ein Peak in den DSC-Kurven von r-P4MH und P4MH gefunden wurde.Für die optisch aktiven Polymeren wird die Bildung einer Mesophase vorgeschlagen und die experimentellen Ergebnisse werden auf der Basis der Konformation dieser Polymeren im kristallinen und flüssigen Zustand besprochen.
    Notes: The thermal behaviour of isotactic poly[(S)-4-methyl-1-hexene], (P(S)4 MH), isotactic poly[(R)-4-methyl-1-hexene], (P(R)4 MH), of their equimolar mixture (r-P4MH) and of poly[(R)(S)-4-methyl-1-hexene], (P4MH), was investigated. The DSC curves obtained by melting P(S)4MH and P(R)4MH showed two endothermic peaks, while only one peak was found in the DSC curves obtained by melting r-P4MH or P4MH.For the optically active polymers the formation of a mesophase is proposed and the results are discussed on the basis of the conformation of these polymers in the crystalline and in the liquid state.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975122
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  • 9
    Electronic Resource
    Electronic Resource
    Enantioselective hydro-oligomerization (protio- or deuterio-) of α-olefins (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 1677-1688 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enantioselective protio(deuterio)oligomerization of propene, 1-pentene and 4-methyl-1-pentene was carried out with the diastereomerically pure catalyst precursor (-)-(R)-ethylenebis [1-3a,7a-η-(4,5,6,7-tetrahydro-1-indenyl)]zirconium (S)-1,1′-bis-2-naphtholate (3) and/or with (-)-(R)-ethylene [1-3a,7a-η-bis(4,5,6,7-tetrahydro-1-indenyl]dimethylzirconium (1) in the presence of methylalumoxanes. The enantioselectivity of both reactions which take place (deuteration and oligomerization) is from fair to high and essentially independent of the catalyst precursor. In the hydrooligomerization the enantioface of the olefinic monomer which prevailingly reacts is from a geometric point of view the same for all three substrates. In the case of 1-pentene and 4-methyl-1-pentene the enantioface prevailing embedded in the oligomers is opposite to that prevailingly deuterated. The significance of the growing chain for enantioface selection during stereospecific polymerization is thus emphasized.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910720
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  • 10
    Electronic Resource
    Electronic Resource
    The role of some bases in the stereospecific polymerization of propylene with titanium catalysts supported on magnesium chloride (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 13 (1985), S. 105-122 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of Lewis bases on the stereospecificity and productivity of catalytic systems of the type MgCl2/TiCl4/AlR3 as well as on microtacticity and molecular weight of the polymer fractions has been systematically investigated using propylene as monomer.The results are in keeping with the hypothesis that beside non stereospecific centers two types of stereospecific catalytic centers exist, in one of which the Lewis base is present.The centers can be classified according to their Lewis acidity, the more acidic centers yielding polymers with lower molecular weight and tacticity. The structure of the Lewis bases is of paramount importance in determining the stereospecificity of the catalytic systems and can be used as a probe to investigate the structure of the different catalytic centers.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.020131985109
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