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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 23-30 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rate of emulsion polymerization of vinylidene chloride has been measured as a function of catalyst and surfactant concentration in the system consisting of vinylidene chloride, water, ammonium persulfate, sodium metabisulfite, and sodium lauryl sulfate. The polymerization may be divided into three rather well-demarcated stages. In the first, a normal emulsion polymerization occurs at a rate which depends on the 0.6-power of the catalyst concentration and the 0.6-power of the surfactant concentration. In the second stage, the rate drops to less than half that of Stage I. The percentage conversion at which Stage II begins increases with increasing surfactant concentration. Stage II is absent at very high surfactant concentrations (10 g./100 g. monomer). In the third stage, the rate increases and may exceed the rate of Stage I; it depends on the first power of the catalyst concentration and is independent of surfactant concentration. Addition of catalyst at the end of the first stage does not affect the rate of Stage II but increases the rate of Stage III. These results are discussed in relation to the theories of Harkins, Smith, and Ewart.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 39-47 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of stirring speed on the rate of the persulfate-catalyzed polymerization of vinylidene chloride has been determined. It was found that the first-stage rate decreases with increasing stirring speed, that the second-stage rate increases with increasing stirring speed, and that the rate of the third stage is independent of stirring speed. These results, as well as those of an earlier paper, may be explained in the following manner. The second stage slow-down results from monomer starvation, caused by slow diffusion from coalesced droplets. Recovery is caused by transfer of monomer at the time of collision between a polymer particle and a monomer droplet. These collisions are allowed when the repulsive forces between monomer droplet and polymer particle are reduced because of surfactant deficiency.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 9 (1996), S. 751-758 
    ISSN: 0894-3230
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Absolute rate studies were carried out on a series of C(SINGLE BOND)H insertion reactions of dimethyldioxirane (1a). The substrates were chosen so that the distance between a single tertiary C(SINGLE BOND)H bond and an OH group could be varied. The measured rate constants indicate that a rate acceleration occurs when the distance between the reacting C(SINGLE BOND)H bond and the OH group permits intramolecular H-bonding stabilization of the transition state. A similar study in related compounds without the OH group showed no effect of chain length on the rate of the C(SINGLE BOND)H insertion reaction. A related study of the epoxidation reaction of la also found an increased rate when chain length permitted intramolecular H-bonding by an OH group.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 9 (1998), S. 347-350 
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some secondary amines of varying structural type have been oxidized by the methyltrioxorhenium/hydrogen peroxide system to the corresponding nitroxides in excellent yield. These results, coupled with our earlier work using this system, indicate the striking parallel between this chemistry and that of the dioxiranes. While the yields in the dioxirane and methyltrioxorhenium/hydrogen peroxide methods are comparable, the latter method must be regarded as superior since it is catalytic. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:347-350, 1998
    Additional Material: 1 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 29 (1991), S. 962-963 
    ISSN: 0749-1581
    Keywords: Nitrones 1H NMR 13C NMR ; Dimethyldioxirane ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H and 13C NMR spectra of 12 (Z)-C-aryl N-tert-butyl nitrones were measured and proton and carbon assignments made. The nitrones were synthesized by the dimethyldioxirane method.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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