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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 1623-1633 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Through a study of the selective distribution of substituents introduced into hydrocellulose from reaction with N,N-diethylaziridinium chloride, the change in selective availability of hydroxy groups at C-2, C-3, and C-6 has been followed as a function of duration of hydrolysis to form the hydrocellulose. The hydrocellulose formed at a particular duration of hydrolysis showed maximum selective availability of hydroxyl groups; this was found to coincide with minimum moisture regain and minimum breadth at half height for 101, 101, and 002 peaks in x-ray diffractograms. These points are discussed in terms of the structures of the hydrocelluloses at various stages of hydrolysis and in terms of the sequence of changes which is now associated with the conversion of fibrous cotton to “exemplar hydrocellulose,” i.e., the hydrocellulose having the highest degree of crystalline order, and subsequently, to less highly ordered hydrocelluloses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 1431-1440 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relative accessibilities of the hydroxyl groups of the D-glucopyranosyl units of hydrocellulose have been studied by means of the reaction of N,N-diethylaziridinium chloride, which produces 2-(diethylamino)ethyl cellulose. The deviation in the distribution of substituents among the 2-O-, 3-O-, and 6-O-positions of the D-glucopyranosyl residues in a hydrocellulose from that in a disordered cellulose in which the three types of hydroxyl groups are equally accessible is the basis for estimating the selective accessibilities of the hydroxyl groups in the crystalline cellulose. A particular hydrocellulose, lying within the range of leveling-off degree of polymerization, was studied in detail; this hydrocellulose, designated EHC (“Exemplar Hydrocellulose”), was formed from fibrous cotton by hydrolysis for 0.67 hr in 2.5N hydrochloric acid at reflux. EHC exhibited higher selective accessibility (larger deviation from equal accessibility) of the hydroxyl groups at C-2, C-3, and C-6, than samples of hydrocellulose formed in shorter or longer periods of hydrolysis. This selective accessibility is discussed in terms of intra- and intermolecular hydrogen bonding on the surfaces of crystalline microstructural units in EHC.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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