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  • 1985-1989  (8)
  • 1960-1964  (6)
  • 1920-1924
  • 1830-1839
  • Polymerization
  • 1
    Digitale Medien
    Digitale Medien
    Polymerization of a monomeric guanosine derivative in a hydrogen-bonded aggregate (1989)
    Springer
    Journal of molecular evolution 29 (1989), S. 367-369 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Guanosine derivatives ; Self-aggregation ; Amino acids ; Polymerization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The adduct IIa, in which glycine is linked to the 3′-amino group of 3′-amino-3′-deoxyguanosine-5′-phosphate, condenses very efficientlyin aqueous solution when treated with a watersoluble carbodiimide to give long oligomeric products. The corresponding cytidine derivative IIb yields a complex mixture of very short oligomers. We believe that the efficient condensation reaction occurs in a hydrogen-bonded tetrahelical aggregate of a type that is known to form with many guanosine derivatives.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02103623
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  • 2
    Digitale Medien
    Digitale Medien
    Selective amidation of carboxyl groups of the intermolecular contact regions of hemoglobin S: Structural aspects (1989)
    Springer
    The protein journal 8 (1989), S. 231-237 
    Details
    ISSN: 1573-4943
    Schlagwort(e): Polymerization ; carboxylate reactivity ; isopeptide bond ; erythrocyte sickling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Carboxyl groups of HbS are readily activated by water-soluble carbodiimide atpH 6.0 and room temperature. These o-acylurea intermediates (activated carboxyl) are accessible for nucleophilic attack by amines. With glycine ethyl ester, the amidation is very selective for the γ-carboxyl of Glu-43(β) and more than 65% of the glycine ethyl ester incorporated is on this carboxyl group. In contrast, glucosamine derivatizes the γ-carboxyl group of Glu-22(β) as well as that of Glu-43(β) to nearly the same degree. However, the total amidation of HbS by glucosamine is lower than that with glycine ethyl ester. The differential selectivity of the two amines is apparently related to the differences in the microenvironment of the γ-carboxyl groups of Glu-22(β) and Glu-43(β), which either facilitates or refracts the aminolysis of the activated carboxyl with the two amines to different degrees. The carboxyl groups of isolated β-chain exhibit a higher reactivity for amidation with glycine ethyl ester than does the tetramer. The carboxyl groups of Glu-22(β) and Glu-43(β) and that of Asp-47(β) are all activated by carbodiimide suggesting that the higherpKa of these carboxyl groups (facilitating the activation) is a property of tertiary interaction of the polypeptide chain. The interaction of the β-chain with α-chain, i.e., generation of the quaternary interactions, reduces overall reactivity of the carboxyl groups of the protein. The higher selectivity of hemoglobin S for amidation at Glu-43(β) with glycine ethyl ester compared with that of isolated β-chain appears to be primarily a consequence of decreased amidation at sites other than at Glu-43(β).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01024946
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  • 3
    Digitale Medien
    Digitale Medien
    Unifying principles in intermediate filament (IF) structure and assembly (1988)
    Springer
    Protoplasma 145 (1988), S. 73-81 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Intermediate filament structure ; Intermediate filament assembly ; Desmin ; Keratins ; Neurofilaments ; Nuclear lamins ; Cytoskeleton ; Electron microscopy ; Polymerization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01349341
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  • 4
    Digitale Medien
    Digitale Medien
    Comportement rhéologique de sols d'acide polysilicique. (1988)
    Springer
    Rheologica acta 27 (1988), S. 52-60 
    Details
    ISSN: 1435-1528
    Schlagwort(e): Polymerization ; sol-geltransition ; breakpoint ; pH value ; polysilicic acid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Abstract The rheological behaviour of silicic acid in aqueous solutions was studied over a period of time for pH values between 6 and 8 at the concentration 10 g ⋅ 1−1, and at pH = 8 for different concentrations varying from 0.5 to 10 g ⋅ 1−1. The shear stress-shear rate curves indicate a very complex character of rheological behaviour. Its analysis with respect to the influence of time, pH and concentration contributes to the knowledge of the structure of the polymer during the process of gel formation. It is shown that the inital shear-thickening behaviour of the colloïdal sol at low concentrations is followed by a shear-thinning behaviour under conditions of polymerization of the silicic acid. The sol-gel transition is marked by a breakpoint. When measurements pass beyond this point, plastic flow behaviour is observed because of the shear induced formation of amorphous silicic aggregates. All rheological processes of silicic acid sols are intensified at pH = 8.
    Notizen: Résumé Le comportement rhéologique de sols d'acide silicique a été examiné au cours du temps à des pH compris entre 6 et 8 à la concentration de 10 g ⋅ 1−1 de silice, et à pH = 8 à des concentrations variant entre 0,5 et 10 g ⋅ 1−1. Les courbes d'écoulement révélent un comportement rhéologique complexe. L'analyse des rhéogrammes en fonction du temps, du pH et de la concentration contribue à la connaissance de l'état structural du polymère au cours de la formation du gel. Il ressort que le comportement initialement rhéoépaississant aux faibles concentrations correspondant à l'état d'une solution colloïdale, laisse place à un écoulement rhéofluidifiant dans les conditions favorables á la polymérisation de l'acide silicique. La transition sol-gel est marquée par un breakpoint; en prolongeant les mesures on observe un comportement plastique dû à l'apparition d'agrégats sous l'effet du cisaillement. Tous les processus rhéologiques se trouvent exacerbées à pH = 8.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01372450
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  • 5
    Digitale Medien
    Digitale Medien
    Contributions to Organo-Nickel ChemistryIncluding unpublished results by A. Aradi, O. Behrens, H. Kuhn, T. Leven, J. Neuffer, J. Monkiewicz, K. R. Pörschke, L. Stehling, and K. H. Walter and unpublished crystal structure determinations by C. Krüger, E. Raabe, and Y.-H. Tsay, and model calculations by K. Angermund. The preceding page shows Figure 19 of this article. (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 185-206 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Organonickel compounds ; Polymerization ; Hydrogenation ; Homogeneous catalysis ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: One hundred years of organonickel chemistry have generated a wealth of new knowledge and a history of examples of accidental discoveries which have finally led to industrial applications. The historical development is associated with the names of Mond, Sabatier, Reppe and Ziegler and, with the methods and techniques available today, many of the original discoveries and unsolved problems are attracting renewed attention. For example, 70 years were to go by before a synthesis first conceived by Sabatier could finally be realized. The path leading from nickel-catalyzed hydrogenation to highly enantioselective homogeneous catalysts is one of the contributions to organonickel chemistry which is described here.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198801851
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  • 6
    Digitale Medien
    Digitale Medien
    An improved method for the polymerization of ethynylferrocene. Conducting properties of doped polyethynylferrocene (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 533-537 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Polymerization ; ethynylferrocene ; conductivity ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The catalytic activity of the [Rh(cod)Cl]2 complex (cod = cis, cis-cyclo-octa-1,5-diene) with respect to the polymerization of ethynylferrocene (EFc) was examined. A good yield (about 80%) of polyethynylferrocene (PEFc) was obtained in benzene by addition of sodium hydroxide as co-catalyst. PEFc was insoluble in most organic solvents. The conductivity (s̰) of the undoped polymer is about 10-11 ohm-1 cm-1; upon doping PEFc with iodine in tetrahydrofuran the conductivity can be increased to 10-100 ohm-1 cm-1. The influence of other doping agents was also examined.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590020606
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  • 7
    Digitale Medien
    Digitale Medien
    Oligoglyceric acid synthesis by autocondensation of glyceroyl thioester (1987)
    Springer
    Journal of molecular evolution 25 (1987), S. 191-196 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Glyceroyl thioester ; Polymerization ; Polyester ; Oligoglyceric acid ; Thioester ; Prebiotic chemistry ; Molecular evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The autocondensation of the glyceroyl thioesterS-glyceroyl-ethanethiol yielded oligoglyceric acid. The rates of autocondensation and hydrolysis of the thioester increased from pH 6.5 to pH 7.5 in 2,6-lutidine and imidazole buffers. Autocondensation and hydrolysis were much more rapid in imidazole buffers than in 2,6-lutidine buffers of the same pH. The efficiency of ester bond synthesis was about 20% for 40 mMS-glyceroylethanethiol in 2,6-lutidine and imidazole buffers near neutral pH. The size and yield of the oligoglyceric acid products increased when the concentration of the thioester was increased. The relationship of these results to prebiotic polymer synthesis is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02100011
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  • 8
    Digitale Medien
    Digitale Medien
    1,3-Adamantanyl dimethylsiloxane copolymers. Preparation and properties (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 1 (1987), S. 171-176 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Condensation ; Polymerization ; Silyladamantane ; Thermal stability ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,3-bis(Dimethylhydroxysilyl)adamantane(I) has been prepared. Thermal condensation polymerization of this monomer yields poly-1,3-adamantyl-1,1,3,3-tetramethyldisiloxane. Condensation of I with bis(dimethylamino)dimethylsilane or 1,3-bis(dimethylamino)-1,1,3,3-tetramethyldisiloxane gave the expected 1,3-adamantyl dimethylsiloxane copolymers (II and III) respectively. These polymers have been characterized by 1H,13C, and 29SiNMR as well as GPC and TGA. They have unusually high thermal stability.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590010208
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  • 9
    Digitale Medien
    Digitale Medien
    Stereospecific Homopolymerization of CyclopenteneLecture given by Dall' Asta at the Gordon Research Conference on Polymers, Santa Barbara, Calif. (U.S.A.) in January, 1964, and to the Macromolecular Colloquium in Freiburg/Breisgau (Germany), in March, 1964. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 723-729 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Stereospecific polymerization ; Polymerization ; Polycyclopentene ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polymerization of cyclo-olefins, like that of olefins with an internal double bond, is sterically hindered. Within recent years it has become possible to prepare copolymers of these compounds with ethylene, with the aid of anionic coordination Ziegler catalysts. This copolymerization always results in cis-opening of the double bond. Despite the steric hindrance, cyclobutene and cyclopropene have also been homopolymerized, with opening of the double bond. - Rather surprisingly, the best catalysts for homopolymerization of cyclopentene are those which exhibit low activity in the polymerization of ethylene. Ring cleavage occurs with MoCl5/Al(C2H5)3 to give the cis-polypentenamer, whereas WCl6/Al(C2H5)3 gives the trans-polypentenamer. Both polypentenamers exhibit elastomeric properties. - Evidence from infrared spectra and oxidative degradation indicates that the monomer units in the trans-polypentenamer are linked head-to-tail. It is presumably the single bond adjacent to the double bond that is broken. Using X-ray methods at -50 °C, it was possible to determine the crystal structure of the crystalline trans-polypentenamer at about 400% elongation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196407231
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  • 10
    Digitale Medien
    Digitale Medien
    Low-Temperature Polymerization of EthylenePublished on the occasion of the 100th anniversary of the founding of Farbwerke Hoechst on January 11th, 1963 (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 32-41 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Polymerization ; Polyethylene ; Titanium ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A two-component organometallic catalyst of composition CH3TiCl3·CH3AlCl2 effects high-speed polymerization of ethylene in the presence of chlorinated hydrocarbons at low temperatures. The catalyst does not undergo any alteration in the process. In contrast to the Ziegler catalysts, the titanium remains quadrivalent. Olefins of low-molecular-weight and with branched structures are produced. It proved possible to isolate the primary products of the polymerization at -50 to -100°C and to elucidate the mode of their formation from a knowledge of their structures. The findings are incompatible with either a cationic or anionic reaction mechanism. A novel type of mechanism is proposed, whereby the catalyst is supposed to have an ionic structure and molecular growth proceeds via π-complex formation of the olefin with the titanium cation. The formation of ethylene/olefin copolymers is also discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196300321
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  • 11
    Digitale Medien
    Digitale Medien
    Emulsion Polymerization of Vinyl Monomers under the Influence of Ionizing Radiation (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 295-308 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Emulsion polymerization ; Polymerization ; Polymerization ; Alkenes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ionizing radiation induces the polymerization of some vinyl monomers in aqueous emulsion with high radiation yields. With identical emulsion compositions, the kinetics of this reaction and the kinetics of emulsion polymerization induced by water-soluble initiators are very similar. The rate of reaction in emulsion polymerization is about one hundred times greater than in bulk polymerization. The initiation of emulsion polymerization by means of ionizing radiation permits uniform “illumination” of the reacting volume, as well as almost any desired variation in the frequency of initiation during the reaction. The sharp decrease in the overall rate of reaction when initiation is interrupted during emulsion polymerization of styrene induced by γ-rays contradicts the earlier concept of sharply separated reaction zones.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196302951
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  • 12
    Digitale Medien
    Digitale Medien
    Reactions of Olefins with the Titanium-Carbon BondDedicated to Prof. Dr. Karl Ziegler on the occasion of his 65th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 704-714 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Titanium ; Alkenes ; Polymerization ; Titanium ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: At low temperatures, ethylene and α-olefins (Δ1-olefins or 1-alkenes) are rapidly converted into oligomrs by the two-component organometallic catalyst CH3TiCl3·CH3AlCl2. To achieve smooth oligomerizations, aromatic or chlorinated hydrocarbons must be used as solvents. Although the activity of the titanium-carbon bond is enhanced by the aluminum component of the catalyst, the aluminum and its methyl group do not participate in the reaction proper; the latter proceeds exclusively at the titanium-carbon bond. The reaction will olefins can be used as an analytical method for the quantitative determination of the titanium-carbon bond in admixture with the organoaluminum component. It is thus possible to follow the reaction leading to formation of the catalyst from titanium tertrachloride, as well as the processes occurring at the titanium-carbon bond during the oligomerization of olefins. All the observations indicate that the catalyst possesses an ionic structure which is determined by the solvent. It is shown that the initial reaction step probably involves formation of a complex between the olefin and the alkyltitanium cation. The reaction scheme proposed is based on organometallic reactions which are characterized by carbanion and hydride transfers within the olefin-cation complex. This mechanism, which is unusual for Ziegler catalysts, is due to the predominance of hydride transfers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196307041
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  • 13
    Digitale Medien
    Digitale Medien
    Pyrrolidone, Capryllactam and Laurolactam as new Monomers for Polyamide FibersFrom a lecture delivered at the meeting of the Plastics and Rubber Section of the Gesellschaft Deutscher Chemiker on April 9th, 1962, in Bad Nauheim (Germany). (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 430-435 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Pyrrolidone ; Polyamides ; Fibers ; Lactams ; Polymerization ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The industrial production of capryllactam (1-azacyclononan-2-one) and of laurolactam (1-azacyclotridecan-2-one) starts with cyclization of acetylene or butadeine to give cyclooctatetraene or cyclooctadiene, or cyclization of butadiene to give cyclododecatriene. Further steps are: oxidation of the cyclic hydrocarbon to the ketone, formation of the oxime, and rearrangement of the latter with sulfuric acid. Pyrrolidone can be prepared from acetylene and formaldehyde by way of butyrolactone. The behavior of the lactams during polycondensation is described and the properties of the resulting fibers are compared with those of the known polyamide fibers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196204301
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  • 14
    Digitale Medien
    Digitale Medien
    β-Lactams, Their Polymerization and Use as Raw Materials for FibersFrom a lecture delivered on April 9th, 1962 at a meeting of the GDCh-Fachgruppe “Kunstsoffe and Kautschuk” Plastics and Rubber Division of the German Chemical Society in Bad Nauheim. (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 481-488 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Lactams ; Polymerization ; Fibers ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: β-Lactams can be prepared by cyclization of β-aimno acid esters. Recently they have become available also from olefins by addition of N-carbonysulfamyl chloride (isocyanatosulfonyl chloride) and from aldehydes by reaction with N-carbonylsulfamyl chloride and ketene. Condensative or anionic polymerization results in polyamides the chains of which contain many more amide groups than the chains of polyamides of the nylon-6 type. Hence the new polymers resemble silk moreclosely. Fibers and films can be prepared from solution.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196204811
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