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  • Polymer and Materials Science  (10)
  • Cervimunida johni  (7)
  • Sulfoxides
  • 1
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The diester of itaconic acid with decyl and methyl groups was prepared and polymerized. The dilute solution behaviour of poly(methyl decyl itaconate) poly{1-(decyloxycarbonylmethyl)-1-(methoxycarbonyl)ethylene} (PMeDI) was studied in tetrahydrofuran and 1-butanol at 298 K, by light scattering, size-exclusion chromatography, and viscometric measurements. The empirical Kuhn-Mark-Houwink-Sakurada relationships were established. The molecular parameters were calculated using one theory of the excluded volume.
    Additional Material: 3 Ill.
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  • 2
    ISSN: 1434-193X
    Keywords: Fluorine ; Lactones ; Annulation ; Ketene ; Sulfoxides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Enantiomerically pure α,α-dichloro β-fluoroalkyl γ-p-tolylthio γ-butyrolactones trans-6a-c have been obtained with excellent stereocontrol (〉 98:2) and enantiomeric purity (〉 98:2) by sulfoxide-directed lactonization (Marino's annu-lation reaction) of β-fluoroalkyl vinyl sulfoxides (R)-(E)-5a-c with dichloroketene. Highly chemoselective dechlorination and desulfurization reactions performed on trans-6c efficiently provided the β-chlorodifluoromethyl γ-butyrolactone (S)-8c, the absolute stereochemistry of which was determined by X-ray diffraction analysis of its γ-p-tolylthio precursor (2R,3S)-7c.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 3863-3869 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two poly(2-vinylpyridine)s fully quaternized with a ω-(4′-methoxy-4-biphenylyloxy)-alkyl group (alkyl chain of 9 and 11 carbon atoms) have been synthesized by the well known spontaneous polymerization of vinylpyridinium salts. When heated, these polymers (P2VPC9 and P2VPC11) show thermotropic liquid crystal properties. According to the X-ray diffraction data, the observed smectic mesophase in both polymers is of the type A (SA). Results are discussed in comparison with other molecular and polymeric pyridinium salts previously described. A molecular arrangement model for the P2VP derivatives is proposed.
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  • 4
    ISSN: 1434-193X
    Keywords: Fluorine ; Pheromones ; Sulfoxides ; Sulcatol ; Asymmetric synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The pheromone (R)-(-)-sulcatol (10a) and three of its enantiomeric mono-, di-, and trifluoro analogues 10b-d have been synthesized, in six steps and with good overall yields, starting from chiral (R)-2-methyl-5-[(4-methylphenyl)sulfinyl]pent-2-ene (1) and commercially available fluorinated or non-fluorinated acetates.Supporting information for this article is available on the WWW under http://www.wileY-Vch.de/contents/jc_2046/1999/98375_s.pdf or from the author.
    Additional Material: 2 Tab.
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  • 5
    ISSN: 1434-193X
    Keywords: Fluorine ; Cycloadditions ; Nitrones ; Asymmetric induction ; Sulfoxides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-(Fluoroalkyl)isoxazolidines 6 and -2,3-dihydroisoxazoles 8 have been obtained in enantiomerically pure form with good diastereoselectivity by 1,3-dipolar cycloaddition of diethyl fumarate and dimethylacetylene dicarboxylate, respectively, to the chiral fluorinated nitrone (R)-5. The latter has been prepared from the β-fluoromethyl-β-oxo sulfoxide (RS)-1, by a synthetic sequence where the chiral and enantiomerically pure sulfinyl function acts as a removable source of chirality. Reductive opening of isoxazolidines 6 then afforded amino fluoromethyl diols 7 in good yields.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 1349-1360 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Model compounds for a series of polyesters in which 3,6,9, and 12-rotatable CH2—O and CH2—CH2 bonds separate rigid units have been studied using the efficiency of nonradiative singlet energy transfer from naphthalene to anthracene. The model compounds have the structure naph-CO—(OCH2CH2)m—OOC-anth with m of 1-4, where naph and anth denote 2-naphthyl and 9-anthranyl groups, respectively. This series of compounds covers a larger range of potential separation of the two chromophores than was possible in an earlier study, in which the flexible spacers consisted of 2-6 methylene units. The nonradiative singlet energy transfer has an efficiency that depends on the solvent viscosity and on m. The theoretical analysis employs a rotational isomeric state model for the conformations of these molecules. The Förster radius for transfer from naphthalene to anthracene in this system is 16 ± 2 Å, and is nearly independent of whether the spacers are constructed from oxyethylene or methylene units.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 1511-1519 
    ISSN: 0887-6266
    Keywords: conformation ; excimer ; fluorescence ; hairpins ; polyester ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fluorescence in dilute solution has been measured as a function of solvent viscosity for four bichromophoric models for polyesters with naphthalene in the rigid aromatic unit and diols derived from cyclohexane as the flexible spacer. The spacers are 1,2-cis-cyclohexanediol, 1,2-trans-cyclohexanediol, a 1:2 mixture of 1,3-cis- and 1,3-trans-cyclohexanediols, and a 1:2 mixture of 1,4-cis- and 1,4-trans-cyclohexanediols. The shape of the emission spectra for the molecules in this series is less sensitive to the viscosity of the medium than was the case for an analogous series in which a methylene or oxyethylene spacer replaces the cyclohexanediol spacer. The dependence of the excimer emission on the type of spacer is different also in the series in which the rigid units contain naphthalene or benzene. When the rigid units contain naphthalene, excimer formation is maximal if the spacer contains 1,2-trans-cyclohexanediol, but this spacer produces a molecule with a very small tendency for excimer formation in its polymers with terephthalate. A conformational analysis correctly concludes that the spacer most conducive to excimer formation should be 1,2-trans-cyclohexanediol, but it does not identify the correct order of the remaining three bichromophoric model compounds. The problem may reside in the method for taking into account the finite width of the torsional well associated with each rotational isomer. © 1994 John Wiley & Sons, Inc.
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  • 8
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Steady state fluorescence has been used to study the efficiency of nonradiative singlet energy transfer from naphthalene to anthracene in naph-COO—(CH2)m—OOC-anth for m of 2-6. A theoretical analysis has also been performed, using the rotational isomeric state model, of the conformations of these molecules. The experiments clearly demonstrate the presence of nonradiative singlet energy transfer in the bichromophoric compounds, with an efficiency that depends on the solvent and on m. The combination of the experiments and the theoretical analysis establishes that the Förster radius for this system is 1,6 ± 0,2 nm.
    Additional Material: 12 Ill.
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  • 9
    ISSN: 0959-8103
    Keywords: anthracene ; fluorescence ; naphthalene ; non-radiative singlet energy transfer ; polyesters ; 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: Steady state fluorescence has been used to study the efficiency of nonradiative single energy transfer for naphthalene → naphthalene and naphthalene → anthracene for polyesters and their bichromophoric model compounds. Polyesters containing only naphthalene groups were derived from 2,6-naphthalene dicarboxylic acid as the rigid unit, and two series of glycols, HO—(CH2)m—OH and HO—(CH2CH2O)n;—OH, where m=2-6 and n=1-4, as flexible spacers. Bichromophoric model compounds were derived from 2-naphthoic acid and the same glycols. In order to study the transfer for naphthalene → anthracene, a first attempt was made by studying bichromophoric model compounds D—(CH2)m—A, where D and A denote 2-naphthoate (donor) and 9-anthranoate (acceptor) groups, respectively. The fluorescence anisotropy measurements in a solid matrix of glassy poly(methyl methacrylate), for the compounds containing only naphthalene groups, and the simple excitation and emission spectra, for the compounds containing naphthalene and antharacene groups, clearly demonstrate the presence of non-radiative singlet-singlet energy transfer, the efficiency of which depends mainly on n (or n). A theoretical treatment using the rotational isomeric state model of the conformatin of these molecules has also been performed. The combination of the experiments and the theoretical analysis establishes that the Förster radii are 1.2 and 1.4 nm for the naphthalene → naphthalene transfer in the bichromophoric model compounds and polyesters, respectively, and 1.6 ± 0.2 nm for the naphthalene → anthracene transfer in the model compounds studied.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 1741-1748 
    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 migration of compounds from polymer-based packaging may impart undesirable odors to foods. We, therefore, undertook a study of the volatile compounds produced during the heating of polyethylene (PE) in the presence of excess O2 at temperatures of 150-350°C and for heating times of 5-15 min. Eightyfour volatile compounds in the range of C5 - C23 were identified by gas chromatography mass spectrometry. The major products were aliphatic hydrocarbons, aldehydes, ketones, and olefins. Changes in temperature and heating times affected the amount and type of compounds produced, with hexanal being found in the largest amount and 300°C resulting in the greatest quantity of volatile compounds. At 350°C, greater amounts and numbers of low-boiling and fewer high-boiling compounds were formed. Only small amounts of volatiles were produced at 150°C. Many of the compounds identified have been reported to have odor and/or toxicological significance. © 1993 John Wiley & Sons, Inc.
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