Scheme 4.

Reaction of initiation: (a) an intact HA macromolecule reacts with ^●OH radical; (b) formation of an intermediate, i.e., a C-centered HA macroradical. Reactions of propagation and of transfer of the free-radical center; (c) formation of a peroxy-type macroradical; (d,e) generation of a HA hydroperoxide and a highly unstable alkoxy-type macroradical. Reaction yielding fragments: (f) an alkoxy-type macroradical and a HA-like macromolecule bearing a terminal C=O group. Both fragments have reduced molar mass.