| 摘要 |
PURPOSE:To prepare a cationic starch, having a high substitution degree and useful as a paper strength improver, etc. in high yield, by reacting cyanoethylated starch with NH2OH in an aqueous system, and converting the terminal nitrile groups into amidoxime. CONSTITUTION:Cyanoethylated starch of formula I is reacted with NH2OH or a salt thereof, e.g. sulfate or hydrochloride, in an aqueous solution or slurry or a slurry in a hydrophilic solvent preferably at 50-100 deg.C at neutral - weakly alkaline pH for 3-6hr to give the aimed cationic starch of formula II or III. The cyanoethylated starch of formula I is obtained, e.g. by solubilizing starch of formula IV in water, adding 5-10mol%, based on the starch, NaOH or KOH thereto, and heating the resultant mixture at about 60 deg.C in the presence of acrylonitrile.
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