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Preparation of Long‐chain Esters of Starch Using Fatty Acid Chlorides in the Absence of an Organic Solvent
Author(s) -
Aburto Jorge,
Alric Isabelle,
Borredon Elisabeth
Publication year - 1999
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/(sici)1521-379x(199904)51:4<132::aid-star132>3.0.co;2-z
Subject(s) - formic acid , chemistry , starch , hydrolysis , chloride , fatty acid , organic chemistry , solvent , long chain fatty acid , yield (engineering) , nuclear chemistry , materials science , metallurgy
An efficient method of synthesizing fatty acid esters of starch without organic solvents is described. The octanoate of starch was prepared by gelatinization of native starch with formic acid, followed by treatment with octanoyl chloride. Esterification was readily carried out under a stream of N 2 at a stirring rate of 500 min ‐1 at 25—130°C for a reaction duration of 20—120 min. Formic acid enabled esterification of starch by long‐chain acyl chlorides with minimum degradation. The major factors affecting the esterification reaction were optimized. The results indicated that the octanoyl degree of substitution (DS 8 ) was increased with increase in fatty acid chloride concentration (from 3—12 eq. per anhydroglucose unit) and rise in temperature (25°C to 130°C). Higher octanoyl chloride concentrations and temperatures led to a reduction in yield due to acid hydrolysis of starch chains. A maximum DS 8 of 1.7 was reached after 40 min of reaction, and high concentrations of formic acid decreased the octanoyl substitution. On the other hand, higher concentration of octanoyl chloride, higher temperatures and longer reaction times increased the substitution of the long acyl chain into starch.