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  • Physics  (8)
  • Organic Chemistry  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 1 (1988), S. 359-362 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reaction rates for solvolysis of a mustard analogue are accurately correlated by the solvatochromic equation without inclusion of a nucleophilicity term, and thus the equation is shown to reveal mechanistically significant information.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 1721-1735 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new oxazoline-containing monomers, 4-acrylyloxymethyl-2,4-dimethyl-2-oxazoline (AOMO), 4-methacrylyloxymethyl-2,4-dimethyl-2-oxazoline (MAOMO), 4-methacrylyloxymethyl-2-phenyl-4-methyl-2-oxazoline (PMAOMO), and the previously known monomer, 2-isopropenyl-4,4-dimethyl-2-oxazoline (IPRO), were synthesized for addition polymerization studies. The monomers were homopolymerized in benzene using a free radical initiator and in aqueous media using emulsion techniques. Molecular weights of 8,000-15,000 (M̄w) were obtained for the homopolymers. Copolymerization studies were carried out with AOMO, MAOMO, and IPRO as M1, and methyl methacrylate (MMA), methyl acrylate (MA), styrene (STY), acrylonitrile (AN), and vinyl acetate (VA) as M2 for each case of M1. Relative reactivity ratios for the fifteen copolymers and Q and e values for the three oxazoline monomers were determined. The r1 values for AOMO and MAOMO copolymerizations indicated a lower value of k11 than expected, presumably because of steric effects. The r1 values in the IPRO copolymerizations were somewhat larger than expected. It was proposed that significant electron donation to the radical center of IPRO·by resonance effects occured.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 379-388 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudo first-order rate constants for the solvolytic displacement of benzyl bromide in 100% ethanol and in 80 and 60% aqueous ethanol (v/v) are reported. The effect of adding poly(ethylene glycol) (PEG) and PEG dithiols and diamines to the solvolytic solutions has been studied. The solvolytic rates are mildly retarded on adding PEG, MW 950, or PEG dimercaptoacetate, MW 548 or 748 (at a concentration of about 8% of the polymer) to reactions in absolute ethanol. In 80% ethanol, however, a rate acceleration by the polymers was observed, with the thiols exhibiting the largest effects. PEG di(3-mercaptopropionate) reacts slightly faster than the PEG dimercaptoacetates, but liberated acid affects the former's reaction. Three molecular weights of primary diamines structurally derived from propylene oxide-capped PEG were evaluated and found to increase solvolytic rates of benzyl bromide significantly. Kinetic evaluation and comparisons with reactions containing equivalent amine groups per gram in an appropriate model (ethanolamine) revealed that the polymer's amine groups are actively involved nucleophilically. Grunwald-Winstein plots and second-order rate constants revealed that the polymeric diamines caused the benzyl bromide to undergo polymer-assisted displacement in all solvent compositions. Since it was noted that the second-order rates increased as the PEG amine molecular weight increased, it appears that the PEG framework may be assisting the reaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 825-836 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of seven para- or meta-substituted phenylmethylbis(dimethylamino)-silane monomers has been carried out. These silanes were polymerized with 1,4-bis(hydroxydimethylsilyl)benzene in tetrahydrofuran at 30°C, and the polymerization kinetics were followed by monitoring dimethylamine evolution for 200 min. The polymers were quenched by precipitation in methanol and molecular weight data were obtained. The polymerizations followed second-order kinetics in every case as evidenced by the linear plots of 1/(a - x) versus time. The molecular weight data generally correlated with the specific reaction rate constant k2 to show an increasing polymer molecular weight with increasing polymerization rate, although the range of k2 values obtained for the substituted aminosilanes was relatively small (2.50 × 10-5-6.67 × 10-5 l./mole-sec). The value of k2 increased in the following order: p-OCH3, p-F, m-CH3, H, m-OCH3, p-CF3, 3,5-di(CF3). The logarithms of the rate constants correlated with the σ constants for the substituents, with a reaction constant, ρ of 0.391. The displacement at silicon in these reactions is discussed in terms of bimolecular mechanisms in which a four-center transition state may participate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 39-47 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polytetramethyl-p-silphenylenesiloxane (I) and polymethylphenylsiloxane (II) were prepared and subsequently reacted with hexacarbonylchromium to generate their n6-Cr(CO)3 complexed analogs, III and IV, respectively. During the complexation reaction, completing decomposition to chromium salts took place. Furthermore a competing chain scission reaction took place resulting in lower molecular weights for the complexed polymers. Heating III and IV resulted in carbon monoxide evolution and the presence of n6-Cr(CO)3 moieties lowered the thermal stability of the polymers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 837-850 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new monomer, 1,1′-bis(dimethylaminodimethylsilyl)ferrocene, was synthesized by two routes and polymerized with three aryl disilanols: dihydroxydiphenylsilane, 1,4-bis(hydroxydimethylsilyl)benzene, and 4,4′-bis(hydroxydimethylsilyl)biphenyl, yielding three different polysiloxanes. Melt polymerizations carried out at 1 torr pressure and 100°C resulted in the highest molecular weight polymers. Intramolecular cyclization competed with intermolecular chain extension in polymerization of the bis(aminosilane) with dihydroxydiphenylsilane, resulting in isolation of a bridged derivative, 1,3,5-trisila-2,4-dioxa-1,1,5,5-tetramethyl-3,3-diphenyl[5]ferrocenophane. Cyclization did not compete significantly during the formation of polymers from this bisaminosilane and the two remaining diols, as evidenced by higher yields and greater molecular weights. These polymers could be cast as tough flexible films, and fibers could be drawn from their melts. TGA and DSC data showed the polymer formed from 1,1′-bis(dimethylaminodimethylsilyl)ferrocene and 1,4-bis(hydroxydimethylsilyl)benzene to be at least as thermally stable as an arylene siloxane polymer which differed from the ferrocenylsiloxane structure only in the replacement of the ferrocene moiety with a p-substituted phenylene linkage. The ferrocene-containing polymers were generally hydrolytically stable under conditions of refluxing THF-H2O(10 : 1) for 1 hr. The polymer-forming reaction was found to follow second-order kinetics, and the specific rate constants for formation of two of the polymers were measured.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 1715-1734 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution polycondensation of 1,4-bis(hydroxydimethylsilyl)benzene with six bis(dimethylaminosilanes) was carried out by the aminosilane deficient method to give a series of high polymers. The bis(dimethylaminosilanes) were bis(dimethylamino)dimethylsilane, bis(dimethylamino)methylphenylsilane, bis(dimethylamino)diphenylsilane, 1,4-bis(dimethylaminodimethylsilyl)benzene, 1,3-bis(dimethylamino)-1,1,3,3-tetramethyldisiloxane, and 1,5-bis(dimethylamino-1,1,3,3,5,5-hexamethyltrisiloxane). The condensation of dihydroxymethylphenylsilane with bis-(dimethylamino)methylphenylsilane to give polymethylphenylsiloxane was also performed. A detailed description of the monomer syntheses and polymerization reactions is provided, since this paper represents the first detailed and systematic description of this polycondensation as an alternative to disilanol or disilanol-dichlorosilane condensation routes. The thermal properties (i.e., Tg, TGA, DSC) of poly(p-phenylenetetramethylsiloxane) are compared to those of poly[1,4-bis(oxydimethylsilyl)benzenel] (where a —Si(Me)2O— group has been inserted between the silylphenylene units) as well as others in this series, polydimethylsiloxane, and polymethylphenylsiloxane. Similarly, these properties are compared with those of related polymers which include in-chain ferrocene units. Introduction of —Si(Me)2O— units into poly(tetramethyl-p-silylphenylenesiloxane) systematically decreases Tg and thermal stability. Replacing Si—CH3 with Si—C6H5 groups increases Tg and thermal stability. Replacing in-chain —C6H4— with ferrocene increases Tg and slightly decreases thermal stability. The values of K and A in the Mark-Houwink equation were determined for several polymers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 3187-3197 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three bis(dimethylamino)silane monomers have been polymerized with 1,1'-bis-(hydroxymethyl)ferrocene to give ferrocene-containing polyoxysilanes I and II. They were bis(dimethylamino)dimethylsilane (III), bis(dimethylamino)diphenylsilane (IV), and 1,4-bis(N,N-dimethylaminodimethylsilyl)benzene (V). Mixing of the diol and III or IV at O°C followed by heating resulted in polymerization to higher molecular weights than when the monomers were initially mixed at higher temperatures. At higher temperatures the formation of monomeric cyclic products seriously competed with polymerization, and the five atom bridged derivative, 3-sila-2,4-dioxa-3,3diphenyl[5]ferrocenophane (VI) was isolated in good yield. The use of silane V, where cyclization is not expected to compete, led to higher polymer yields and molecular weights. The polymers were low melting and I (R = C6H5) could be cast into films and weak fibers were drawn from its melt. The polymers were sensitive to hydrolytic decomposition; those containing Si-CH3 linkages were completely hydrolyzed in refluxing THF-H2O (10:1) in 1 hr. The polymers were characterized by viscosity studies, gel-permeation chromatography, and infrared and NMR spectroscopy.
    Additional Material: 1 Tab.
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  • 9
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Styrenetricarbonylchromium (IV) has been synthesized. Monomer IV did not homopolymerize with free-radical initiation but copolymerized with styrene, methyl acrylate, and vinylcymantrene. The copolymerizations were carried out in benzene solutions at 70°C with azobisisobutyronitrile as the initiator. The relative reactivity ratios were determined for the styrene and methyl acrylate copolymerizations. They were (defining M1 as monomer IV) r1 ≅ 0, r2 ≅ 1.39 for styrene copolymerizations and r1 ≅ 0, r2 ≅ 0.75 for methyl acrylate copolymerization. Polystyrene reacted with chromium-hexacarbonyl in refluxing DME to produce a polymer in which about 32% of the benzene rings were complexed with —Cr(CO)3 units. The use of a polystyrene of narrow molecular weight distribution in this reaction demonstrated that no decomposition of the polystyrene chains occurred.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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