13C-N.M.R.-spectral and related studies on the distribution of substituents in O-(2-hydroxypropyl)cellulose
1982; Elsevier BV; Volume: 106; Issue: 1 Linguagem: Inglês
10.1016/s0008-6215(00)80728-4
ISSN1873-426X
AutoresDae‐Sil Lee, Arthur S. Perlin,
Tópico(s)Biofuel production and bioconversion
ResumoInformation about the degree of substitution at individual oxygen atoms of O-(2-hydroxypropyl)cellulose, and the total molar substitution, was obtained from 13C-n.m.r. spectra of the intact polymer and of its hydrolyzate. On the basis of their 13CH3 chemical-shifts, O-(2-hydroxypropyl) (HOPr) substituents occurring singly, or as terminal units of substituent chains, were readily distinguished from inner HOPr units of chains. Differentiation between monomeric HOPr units and longer chains located at O-2 of d-glucosyl residues was effected by the transformation of appropriately substituted sugars in the hydrolyzate into 1,2-cyclic acetals incorporating a 2-O-(2-hydroxypropyl) group. Similarly, the pattern of substitution at O-6 of d-glucosyl residues was determined, through selective degradation, from the identity of HOPr derivatives of ethylene glycol, representing C-5 and C-6 of the residues. Overall, it was found that, although O-2 and O-6 are more readily substituted than O-3, the rate at which each, initially introduced, HOPr substituent is converted into a dimeric structure is not materially affected by its location. Also described are the synthesis and the n.m.r. spectra of several HOPr derivatives of d-glucose, and of simple alkanols that served as model compounds.
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