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  • Articles  (3)
  • Data
  • Articles: DFG German National Licenses  (3)
  • Chemistry  (2)
  • anionic surfactants  (1)
  • 1995-1999  (3)
  • Chemistry and Pharmacology  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Rheological study of the pH-dependence of interactions between gelatin and anionic surfactants: flow behaviour and gelation (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 1044-1053 
    Details
    ISSN: 1435-1536
    Keywords: Rheology ; gelatin ; anionic surfactants ; interactions ; gelation ; surface tension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The interactions between gelatin and two anionic surfactants (sodium di-sec-butylnaphthalenesulfonate and sodium dodecylbenzenesulfonate, respectively) were investigated using rheological methods, charge and surface tension measurements. Upon the addition of surfactants, the viscosity of aqueous gelatin solutions increases at pH values higher than the isoelectric point (IEP) of the gelatin, provided that a distinct surfactant concentration is exceeded. The increase in viscosity depends on the structure of the hydrophobic moiety of the surfactant. Surface tension measurements suggest the formation of gelatin-surfactant-complexes. If the surfactant is added in high concentration, the viscosity does not further increase, and free micelles are formed in the solution. Directly at the IEP and at pH values below, the addition of surfactants leads to flocculation because of electrostatic interactions. At all surfactant concentrations, the flow behaviour was strictly Newtonian. As a model of the structure of the complex, a modified ‘bead and necklace’-model is suggested. This model proposes the nucleation of micelles at the hydrophobic gelatin regions (‘micellar surfactant-gelatin complexes’). The number of micelle moieties per gelatin chain could be estimated to be about three. The complex stability is dependent on the extent of hydrophobic interaction. The gelation behaviour of gelatin is strongly affected by the addition of the surfactant. The ratio between the attainable linear storage and loss moduli,G′ andG″, decreases strongly. Gelation is generally hindered, but the effect is stronger at pH values below the IEP than above.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00658369
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  • 2
    Electronic Resource
    Electronic Resource
    Literaturkarussell. Biologie (1998)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 32 (1998), S. VI 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19980320215
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  • 3
    Electronic Resource
    Electronic Resource
    Die 2,6-Diisopropyl-phenylgruppe als sperriger Substituent in Bor-Stickstoff-Verbindungen. II [1] (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 1995-2000 
    Details
    ISSN: 0044-2313
    Keywords: 2,6-Diisopropylphenyl-, Amino(fluoro)boranes ; Amino-imino-boranes ; Diazadiboretidines ; Diazasilaboretidines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 2,6-Diisopropyl-phenyl Group as a Bulky Substituent in Boron-Nitrogen Compounds. IIFluoro-bis(amino)boranes R′ (Me3Si)N-BF-NHR (R = 2,6-)Me2CH)2C6H3, R′ = Me (Ia), CH2Me (Ib), CHMe2 (Ic), CMe (Id), SiMe3 (Ie), R (If) react with t-butyllithium (molar ratio 1:1) by elimination of HF to give the amino-imino-boranes (IIa - f). The thermal stabilities of the latter depend upon the steric requirement of the substituent R′, IIa - c and IIe dimerize to yield the diazaboretidines IIIa - c and IIIe. IId remains unchanged at 200°C and above, and IIf isomerizes forming the B-Me substituted diazasilaboretidine IVf. If a twofold amount of t-butyllithium is employed, B-CMe3 substituted diazasilaboretidines (Va - f) are the main products. All compounds are characterized by elemental (C, H) analyses and their mass- and n.m.r. (1H, 13C, 15N (in part), 19F, 29Si) spectra. Characteristic i.r.-bands are reported for the amino-imino-boranes (II). An X-ray structure analysis is presented for IVf.
    Notes: Die HF-Eliminierung aus Fluorbis(amino)boranen des Typs R′ (Me3Si)NBFNHR (R = 2,6-)Me2CH)2C6H3, R′ = Me (Ia), CH2Me (Ib), CHMe2 (Ic), CMe3 (Id), SiMe3 (Ie), R (If)) mit t-Butyllithium im Molverhältnis 1:1 führt zu den Amino-imino-boranen (IIa-f), die - abhängig von der Größe des Substituenten R′ - unterschiedliche thermische Stabilität aufweisen. IIa - c und IIe dimerisieren zu den Diazadiboretidinen IIIa - c und IIIe. IId ist bis über 200°C stabil, während sich IIf bei dem Versuch seiner Isolierung zum Bor-Methyl-substituierten Diazasila-boretidin IVf umlagert. Führt man die gleiche Umsetzung mit t-Butyllithium im überschuß (Molverhältnis 1:2) durch, erhält man fast ausschließlich die Bor-t-Butyl-substituierten Diaza-sila-boretidine Va - Vf.Alle Verbindungen sind elementaranalytisch (C, H) und spektroskopisch MS, NMR (1H, 13C, 15N (teilweise), 19F, 29Si) charakterisiert. Charakteristische IR-Banden werden für die Amino-imino-borane (II) angegeben. Eine Röntgenstruktur-analyse wurde von IVf angefertigt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19956211204
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