Synthesis of starch derivatives with labile cationic groups

A new route to starch derivatives bearing hydrolyzable cationic groups was developed. This was based on reacting starch compounds with betaine derivatives in the presence of diisopropylcarbodiimide and 4-dimethylaminopyridine as coupling reagents in an aprotic polar solvent. Water-soluble starches with a perfectly controlled degree of substitution were thus obtained which were fully characterized by infrared, 1H and 13C spectroscopy and viscosity measurements. The cationic groups grafted on the polysaccharides are shown to hydrolyze slowly upon storage at room temperature.