Starch derivatives of high degree of functionalization. 7. Preparation of cationic 2-hydroxypropyltrimethylammonium chloride starches

Water-soluble starch derivatives containing quarternary ammonium groups of high degree of substitution are prepared by reacting starch with 2,3-epoxypropyltrimethylammonium chloride in different reaction media. The reaction was carried out in aqueous sodium hydroxide under dissolution of the product, in dimethyl sulfoxide homogeneously, and completely heterogeneously in ethanol/water. The DS values of up to 1.1 in an one-step synthesis of the samples can be controlled by adjusting the molar ratio of cationization agent to anhydroglucose unit and are only slightly dependent on the amylose content of the starting starch material. A two-step reaction yields products of a DS of up to 1.5. The structure of the cationic starch derivatives was confirmed by means of elemental analysis, FTIR- and NMR spectroscopy as well as GC-MS.