ISSN:
0025-116X
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Base-catalyzed intramolecular nucleophilic substitution of various dianhydrosorbitol derivatives (2, 4, or 6) led to formation of trianhydromannitol (7), a tricyclic system of three interlinked oxolane rings. By treatment with trifluoromethanesulfonic acid, ring-opening reactions were achieved to give oligomeric soluble material with a number-average degree of polymerization \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {DP} _n \approx 5 - 10 $\end{document} Molecular weights were determined by GPC, and by desorptive chemical ionization (DCI) with ammonia a molecular weight assignment gave information on the degree of crosslinking. A complex but consistent picture allows to explain the propagation reactions of protonated trianhydromannitols 8 and 9, and further reactions of the protonated intermediates 13-15 to result in crosslinked products 16 and 17. By semiempirical quantum chemical calculations, geometries, energies and charge distributions of 7 as well as its protonated species were obtained. This allowed comparisons with their chemical reactivity and ring-opening specificity.
Zusätzliches Material:
3 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/macp.1991.021920214
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