Acetals useful for the preparation of polysaccharide derivatives

摘要

Polysaccharide aldehydes having the formula Sacch-O-CH2-CH=CH-CHO, Saach-O-CH2-C 3BOND C-CHO, +TR 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 and then hydrolyzing the acetal by adjusting the pH to less than 7, preferably 2-4. In the formulas, n is 1-3; R11 and R12 are independently an alkyl, aryl, aralkyl, or alkaryl group when n is 1, R11 or R12 is one of the groups when n is 2, or R11 and R12 are not present when n is 3; R13 is an alkyl group, optionally containing an ether linkage, or an aralkyl group; R14 and R15 are individually a hydrogen or a methyl group; R16, R17, and R18 are individually an alkyl group; 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; R19, 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.