Premium
Studies About the Solvent‐Dependent Substitution Pattern of Starch Acetates
Author(s) -
Hampe R.,
Heinze T.
Publication year - 2014
Publication title -
macromolecular materials and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 96
eISSN - 1439-2054
pISSN - 1438-7492
DOI - 10.1002/mame.201400012
Subject(s) - acetic anhydride , starch , dimethyl sulfoxide , imidazole , aqueous solution , hydrolysis , solvent , chemistry , moiety , organic chemistry , nuclear magnetic resonance spectroscopy , acylation , polymer chemistry , nuclear chemistry , medicinal chemistry , catalysis
Starch acetates bearing the ester moiety predominantly at position 2 of the anhydroglucose unit (AGU) could be synthesized by converting starch with acetic anhydride and imidazole in dimethyl sulfoxide (DMSO). Degraded starch (weight average molar mass,M ‾ w < 16 460 g mol −1 ) is additionally acetylated at position 6 exceeding a total degree of substitution (DS) of 0.5. Increasing the concentration of starch up to 50 wt% leads to higher partial DS at position 6 under comparable reaction conditions. Using molten imidazole as solvent, an initial regioselective 6‐ O ‐acylation is achieved. At higher DS values (>0.3), a random distribution of the substituents appears. The substitution pattern can be revealed precisely by means of 13 C and 1 H NMR spectroscopy after perpropionylation. Hydrolytic stability of a selected 2‐ O ‐acetyl starch in aqueous solution is evaluated by time‐dependent capillary viscosimetry.