Preparation of the Starch Acetates

Starch acetates are the most easUy prepared of the starch esters. They have served frequently for the characterization of starch fractions, for investigations of starch structure and as intermediates - in the preparation of methylated starch. Although most acetylation work has been done on white potato starch, considerable attention has been given to the acetylation of other starches such as those from com, - - - waxy com, wheat, - - - canna, rice, horse chestnut and banana.  

Methods for the preparation of starch acetates may be classified as acetylation (1) in the presence of pyridine, (2) in the presence of specifically added catalysts other than pyridine, and (3) in the absence of a specifically added catalyst. Methods classified in (1) produce little or no degradation of the starch molecules. Those in (2) may or may not produce degradation, depending upon the reagents selected, while methods in (3) almost invariably cause a depolymerization of the starch. 

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