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  • 1
    Electronic Resource
    Electronic Resource
    A kinetic study of the acid catalysed degradation of cellulose triacetate in chloroform/acetic anhydride solution (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 101-120 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik des Abbaus von Cellulosetriacetat wurde im Chloroform/Acetanhydrid-Gemisch in Gegenwart von Perchlorsäure oder Schwefelsäure als Katalysator untersucht. Die zeitliche Änderung des Molekulargewichts wurde viskosimetrisch verfolgt, unter Verwendung der Maronschen “Einpunkt-Methode” zur Erimittlung der Grenzviskositäten sowie der zugehörigen Mark-Houwink-Konstanten für das Chloroform/Acetanhydrid-Gemisch. Die Abhängigkeit der Geschwindigkeitskonstante 1. Ordnung von der Konzentration des Katalysators, des Acetanhydrids und des Cellulosetriacetats sowie vom Molekulargewicht des Polymers und der Temperatur, wurde untersucht. Die Erklärung der Ergebnisse beruht auf der katalytischen Wirksamkeit von H+ und Ac+ (Acetyliumion) bei der Abbaureaktion, die bereits in ähnlichen Celluloseacetat-Systemen von früheren Autoren beobachtet wurde.
    Notes: The kinetics of the degradation of cellulose triacetate in chloroform/acetic anhydride mixtures containing a perchloric or sulphuric acid catalyst was studied. The change in molecular weight with time was followed viscometrically, employing Maron's singlepoint method to evaluate limiting viscosity number values and using appropriate Mark-Houwink constants for the chloroform/acetic anhydride mixtures. The dependence of the first-order rate constant on concentration of catalyst, acetic anhydride, and cellulose triacetate, as well as polymer molecular weight and temperature was investigated. An explanation of the results, based on both H+ and Ac+ (acetylium ion) acting as the catalytic degradation species, is given; this is also shown to account for the degradation behaviour in similar cellulose acetate systems observed by previous workers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770109
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  • 2
    Electronic Resource
    Electronic Resource
    Cationic degradation of poly(thio-1,1-dimethylethylene) [poly(isobutylene sulfide)]Dedicated to Prof Dr. T. Tsuruta on the occasion of his 65th birthday (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 317-324 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High molecular weight poly(thio-1,1-dimethylethylene) [poly(isobutylene sulfide)] obtained by anionic polymerization of 2,2-dimethylthiirane (isobutylene sulfide) was degraded to a mixture of low molecular weight compounds when treated with a catalytic amount of methyl trifluoromethanesulfonate. The following degradation products were found: 2,2,5,5-tetramethyl-1,4-dithiane (3), 2,2,6,6-tetramethyl-1,4-dithiane (4), 2-isopropyl-4,4-dimethyl-1,3-dithiolane (2), and an equimolar mixture of 3,3,6,6-tetramethyl-1,2,5-trithiepane (5) and 2-methylpropene (isobutylene). The formation of dithiolane 2 is explained by a hydride transfer to a transient carbenium ion.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860210
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