Acylated starch properties

The limited solubility of starch and its modified products may affect the reversibility of many reactions. This may explain several, apparently unusual, reactions reported in starch chemistry. There are, for example, reports of starch esterification with sodium hydrogenphosphates, acylation of starch with acyl amides (which is equivalent to the transformation of an amide into an ester), and the formation of alkali-metal starchates upon treatment of starch with alkali (a reaction which fails for simple alcohols). A specific property of starch is its ability to form surface sorption and helical inclusion-complexes with many inorganic and organic guest molecules.4... 

Various anhydrides show significant differences in reactivity. For instance, acetic anhydride reacted with starch in the presence of formamide, whereas phthalic anhydride required pyridine to react. This property was utilized in preparation of starch esters carrying two different acyl groups simultaneously.19181919 Mixed starch esters may also be prepared by using a mixture of various anhydrides in... 

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