Granular hydroxypropylated starch deriv prepn. - from propylene oxide and starch in presence of alkali(ne earth) metal carboxylate salt as catalyst

摘要

Granular, cold water dispersible hydroxyproplated starch ethers are prepd. by reaction of granular starch having a moisture content of 6-20% with 15-50 wt.% propylene oxide for 4.5-24 hrs at 70-100 degrees C and 10-100 psig. The improvement is that the starch is first impregnated with 0.25-5.0% based on wt. of starch of a water soluble alkali(ne earth) metal salt of a carboxylic acid as catalyst. The acid is unsubstd. or hydroxy-substd., contains is not >20C and Al if aliphatic, contains 1-6C in the main chain. The formation of by-products is reduced; the product is free of toxic by-prods and has no off-taste.