Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Aromatic polyamides containing keto-benzocyclobutene pendants (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 3539-3549 
    Details
    ISSN: 0887-624X
    Keywords: benzocyclobutene ; polyamides ; crosslinking ; rigid-rod molecular composites ; poly(p-phenylenebenzobisthiazole) ; 3,5-diaminophenyl-4-benzocyclobutenyl ketone ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of novel benzocyclobutene (BCB)-pendanted polyamides (inherent viscosities: 0.20-0.69 dL/g) was synthesized from 3,5-diaminophenyl-4-benzocyclobutenyl ketone, and terephthaloyl, isophthaloyl, 4,4′-oxydibenzoyl chlorides, as well as 4,4′-(o-phenylenedioxy)dibenzoyl chloride. The DSC studies demonstrated that the BCB crosslinking exothermic transition occurred at nearly the same temperature (max. ∼ 275°C) for all the four polyamides, and they were thermally stable up to 380°C in helium, where the weight loss started to occur. TGA and DSC studies in air indicated that the polymers, in contrast to the model compound, showed evidence of oxidation just prior to or occurring simultaneously with the BCB crosslinking reaction. This could be attributed to the oxidation of the reactive diene generated from the ring-opening of the BCB competing with the process of two BCB pendant units approaching each other for crosslinking reaction. Preliminary examination of the BCB-pendanted polyamide regenerated from a methanesulfonic acid solution indicates that the BCB ring is quite stable (DSC evidence) in the strong acid medium. © 1996 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and thermal properties of thermosetting bis-benzocyclobutene-terminated arylene ether monomers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2637-2651 
    Details
    ISSN: 0887-624X
    Keywords: benzocyclobutene ; cesium fluoride ; 4-hydroxybenzocyclobutene ; 4-trimethylsiloxybenzocyclobutene ; thermosets ; arylene ether monomers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of new bis-benzocyclobutene-endcapped arylene ether monomers was prepared and characterized. Whereas 2,6-bis(4-benzocyclobutenyloxy)benzonitrile (BCB-EBN) could be prepared in good yield using the standard procedure (K2CO3/NMP/toluene/Dean-Stark trap/120°C), other bis(benzocyclobutene) (BCB)-terminated monomers containing ether-benzophenone (BCB-EK), ether-phenylsulfone (BCB-ES), and ether-6F-benzoxazole (BCB-EBO) moieties were invariably contaminated by mono-endcapped products under similar reaction conditions. This can be attributed to a much greater activating effect of the nitrile group on the ortho-fluorides in the aromatic nucleophilic displacement reaction than the carbonyl, sulfonyl, and benzoxazolyl groups. However, the latter monomers could be synthesized (70-80%) from 4-trimethylsiloxybenzocyclobutene and respective aromatic fluorides in the presence of CsF at 140°C. Similar curing behaviors under N2 (DSC: extrapolated onset and peak temperatures at 227-230° and 260-262°C, respectively) characterized all four monomers. BCB-EK, BCB-ES, and BCB-EBN showed melting transitions at 108, 119, and 146°C, in that order. As BCB-EBO contained more rigid benzoxazole segments, it only exhibited a glass transition (Tg) at 85°C prior to curing exotherm, after it had been previously heated to 125°C. The following Tgs were observed for the cured materials: BCB-EK (201°C), BCB-EBN (224°C), BCB-ES (264°C), and BCB-EBO (282°C). The relative thermal stability according to TGA (He) results is: BCB-ES 〈 BCB-EBN 〈 BCB-EK 〈 BCB-EBO. Finally, the results from thermal analysis, infrared spectroscopic, and variable temperature microscopic studies indicated that the nitrile group plays an important role in the cure chemistry, thermal, and microstructural properties of BCB-EBN. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2637-2651, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Reaction between phenyliodosoacetate and amides-a kinetic study of the oxidative rearrangement (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 773-776 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550060513
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    A kinetic study of the oxidation of α-hydroxy acids and α-hydroxy ketones by potassium bromate (1976)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 8 (1976), S. 205-214 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of α-hydroxy acids and α-hydroxy ketones by Br(V) follows the rate-law \documentclass{article}\pagestyle{empty}\begin{document}$$\frac{{- d[{\rm Br(V)}]}}{{dt}} = k_2 [{\rm Br(V)}][{\rm substrate}]$$\end{document}However, the former reaction exhibits a second-order dependence on hydrogen ion concentration while the latter reaction has a third-order dependence. A mechanism involving a slow formation of a bromate ester of the α-hydroxy acid followed by a fast decomposition is proposed. A rate-determining formation of a bromate ester from the conjugate acid of benzoin, followed by a rapid decomposition of the bromate ester, explains the kinetic data for the oxidation of benzoin.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550080205
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Dipolar aprotic-protic solvent influences in the hydrolysis of diol monoesters (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 103-110 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the alkaline hydrolysis of five diol monoesters and related esters in aqueous DMSO, aqueous acetone, and aqueous ethanol are reported. A novel solvent dependency of the reactivity pattern of the various esters is noticed. The results are explained on the basis of an internal stabilization of the transition state and the influences of the various solvent systems on such transition states. It is suggested that such dipolar aprotic-protic solvent influences on reaction rates can be used as a criterion in the assessment of anchimeric assistance in such reactions.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550060110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Thallation of fluorenes: A kinetic and mechanistic study (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 581-589 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of thallation of fluorene with thallium triacetate (TTA) in HOAc-H2SO4 solutions led to the rate expression \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm rate = [TTA]}^{\rm 2} [{\rm fluorene}] $$\end{document}The rate of thallation is found to increase with increasing acid concentration, and a sixth-order dependence on [H2SO4] is observed. Decrease in solvent polarity increases the rate of thallation. The effect of substituents is in accord with the electrophilic substitution at an aromatic system. Thallation occurs at 4-position. A mechanism similar to aromatic bromination is proposed for the thallation of fluorene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550100605
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Oxidation of fluorenes by ammonium meta vanadate - a kinetic study (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 883-897 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of fluorene by vanadium(V) in aqueous acetic acid containing sulfuric acid (1.0M) at 50°C produces fluorenone and 2-hydroxy diphenyl 2′-carboxaldehyde. The order with respect to each reactant is found to be 1. The order dependence on sulfuric acid concentration is 4, indicating that V(OH)23+ could be the active species. An increase in the acetic acid percentage in the solvent medium increases the rate of the reaction. The effect of solvent variation has been discussed in the light of the acidity function and the polarity of the medium. The effect of substituents on the rate has been studied for seven substituted fluorenes, and a linear relationship exists between log k versus σ values with the slope ρ = -3.2. A small isotope effect is observed for the oxidation of the parent compound (kH/kD = 1.2). The effect of temperature on the rate of the reaction has been studied, and the activation parameters are discussed. A mechanism involving the rate-limiting formation of a cation-radical intermediate is proposed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110807
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...