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Synthesis of Hydrophobic Starch Esters by Reaction of Starch with Various Carboxylic Acid Imidazolides
Author(s) -
Neumann Ulrich,
Wiege Berthold,
Warwel Siegfried
Publication year - 2002
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/1521-379x(200210)54:10<449::aid-star2222449>3.0.co;2-r
Subject(s) - starch , chemistry , organic chemistry , pyridine , imidazole , amylose , hydrolysis , catalysis , fatty acid , chloride , solvent , benzoyl chloride
A novel efficient method of preparing hydrophobic starch esters with a DS = 1.55—2.0 using amylose enriched starch (amylomaize starch) or potato starch and a fatty acid imidazolide in DMSO as solvent is described. The fatty acid imidazolides can be easily prepared by conversion of the corresponding acyl chloride with imidazole in toluene according to a synthesis route developed by Staab et al. [1—4]. The by‐product imidazole hydrochloride could be converted to imidazole by alkaline work up with Na 2 CO 3 . As compared with the direct esterification of starch in presence of a fatty acid chloride the presented synthesis method does not need toxic amines like pyridine as catalyst. Only a catalytic amount of a methanolic KOCH 3 solution is required. Furthermore no hydrolytic degradation of starch could be observed in contrast to the direct esterification reaction with a fatty acid chloride.