Polysaccharide derivatives containing aldehyde groups, their preparation from the corresponding acetals and use as paper additives

Abstract

Polysaccharide aldehydes having the general structure ##STR1## such as starch, cellulose and gum aldehydes, are useful for imparting wet, dry, or temporary wet strength to paper. They are prepared by a non-oxidative method which involves reacting the polysaccharide base, in the presence of alkali, with a derivatizing acetal reagent having the general structure ##STR2## and then hydrolyzing the acetal by adjusting the pH to less than 7, preferably 2-4. R is (CH.sub.2).sub.n or a divalent aromatic group and n is 0 or greater; R.sup.1, R.sup.6, and R.sup.7 are hydrogen or an organic group; R.sup.2, R.sup.5, and R.sup.8 are (CH.sub.2).sub.m with m being 1-6; R.sup.3 and R.sup.4 are hydrogen or a lower alkyl; Y is an anion; Z is an organic group capable of reacting with the polysaccharide base to form an ether derivative and selected from the group consisting of an epoxide, ethylenically unsaturated group, halohydrin, and halogen; R.sup.11, if present, is a divalent organic group containing no reactive substiuents; and A and A' are lower alkyls or together form at least a 5-membered cyclic acetal.

Dependencies are inferred from the claim text.