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  • 1
    Electronic Resource
    Electronic Resource
    Preparation and photochemical properties of poly[2-(4-benzoylphenyl)-2-(4-propenoylphenyl)-propane] and its copolymer with styreneIssued as NRCC-30766 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 595-608 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-(4-Benzoylphenyl)-2-phenyl propane (4) was prepared by benzoylation of 2,2-diphenylpropane (2). Acylation of (4) with 3-chloropropanoic chloride gave 2-(4-benzoylphenyl)-2-(4-propenoylphenyl)propane (5). A monomer 2-(4-benzoylphenyl)-2-(4-propenoylphenyl)propane (6) was prepared through dehydrochlorination of (5). The homopolymer of 6 (P6) and the copolymer with styrene (P6 / S) were prepared by radical polymerization. Laser flash photolysis was employed to determine the absorption and emission spectra of transients, their lifetimes (τ) and the rate constant (kq) of triplet quenching in benzene at laboratory temperature for 4, P6, and P6 / S. P6 exhibits a transient absorption maximum in a different spectral region than do the model 4 and copolymer P6/S. The products of kq and τ determined by laser flash photolysis for these transients are higher than th Stern-Volmer constants based on inhibition of degradation. Degradation leading to formation of quenchers is the likely cause of this difference although crosslinking may also contribute. Irradiation of polymers (P6 and P6/S) at 366 nm leads to main chain scission with aquantum yield of 0.13 under N2 for P6 and 0.03 for P6/S. In this bichromophoric structural unit, the benzophenone residue absorbs about 80-90% of the incident energy. Its triplet energy is about 5 kJ mol-1 lower than that of the 1-(4-alkylphenyl)-2-propene-1-one chromophore. Different possible pathways of degradation are discussed namely the Norrish Type II reaction of the alkyl aryl ketone and direct reaction of triplet benzophenone with the main chain. In the mechanism favored the benzophenone triplet is proposed to be in equilibrium with the upper acetophenone-like chromophore from which the Norrish Type II reaction leading to chain fragmentation takes place.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280311
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  • 2
    Electronic Resource
    Electronic Resource
    Phosphorescence of lyophilized complexes between cyclodextrins andβ-arylpropiophenones (1985)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 3 (1985), S. 395-401 
    Details
    ISSN: 1573-1111
    Keywords: Cyclodextrins ; phosphorescence ; β-arylpropiophenones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract β-Arylpropiophenones do not phosphoresce in homogeneous solution as a result of excited state quenching by the β-aryl group. In the presence of cyclodextrins the parent substrate, β-phenylpropiophenone, shows readily detectable phosphorescence. The complexes show strong phosphorescence after lyophilization to dryness. The phosphorescence intensity of ring-substituted derivatives is strongly dependent upon molecular size and cavity dimensions, suggesting that the β-arylpropiophenones can be used to probe these properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657491
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  • 3
    Electronic Resource
    Electronic Resource
    The mechanism of photocure of inherently photosensitive polyimides containing a benzophenone group (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 942-944 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 photochemistry of an appropriately substituted bisimide has been studied in solution by conventional means and time resolved laser techniques as a model for the behavior of inherently photosensitive solvent soluble polyimides, whose photochemistry are not well understood. A mechanism for the photochemical insolubilization of the polymer systems is suggested based on the results for the model system, which is confirmed by time resolved laser studies of polyimide solutions. Phosphorescence quenching rate constants for the model compound indicate that the triplet excited state is about one order of magnitude more reactive than triplet benzophenone, an increase most likely due to the inductive effect of the imide moieties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760291411
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  • 4
    Electronic Resource
    Electronic Resource
    Comment on “studies of the role of peroxy and hydroperoxy groups in polymer photodegradation”Issued as NRCC - 22936. (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 23 (1985), S. 487-488 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.130230907
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Electron transfer from α-aminoalkyl radicals to methyl viologen (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 16 (1984), S. 371-377 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of tert-butoxyl radicals with amines, leading to the formation of α-aminoalkyl radicals, and the reactions of these with the electron acceptor methyl viologen have been examined using laser flash photolysis techniques. For example, the radicals CH3ĊHNEt2 and HOCH2ĊH N(CH2CH2OH)2 react with methyl viologen with rate constants equal to (1.3 ± 0.1) × 109 and (2.1 ± 0.4) × 109M-1 · s-1, respectively, in wet acetonitrile at 300 K.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550160407
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