Cellulose disproportionation reactions

Mino and Kaizerman [12] established that certain. ceric salts such as the nitrate and sulphate form very effective redox systems in the presence of organic reducing agents such as alcohols, thiols, glycols, aldehyde, and amines. Duke and coworkers [14,15] suggested the formation of an intermediate complex between the substrate and ceric ion, which subsequently is disproportionate to a free radical species. Evidence of complex formation between Ce(IV) and cellulose has been studied by several investigators [16-19]. Using alcohol the reaction can be written as follows ... 

It is believed that the above dye monoradicals disproportionate to hydroquinones and quinones. Transfer reactions to solvent lead to formations of homopolymers. This gives high yields of graft copolymers of methyl methacrylate with cellulose. The same is true of acrylonitrile. On the other hand, only small quantities of graft copolymers form with styrene or vinyl acetate monomers. ... 

Photolysis of HABIs as a result of UV-irradiation leads to radicals that abstract an electron from the leucodye salt, which then disproportionates to form at least one dye molecule. Visible light absorbed by the quinone converts it into a reduced derivative, which can react with the imidazolyl radical as the latter is formed. Reaction between these species is very rapid and prevents the radical from interacting with the leucodye salt. Hence, no color is formed. The quinone reduction product also interacts with the cellulosic binder, converting the initially light yellow coating to colorless. Initial studies of a preferred quinone/H-donor combination employed Carbowax. In time amine derivatives were found to be more effective. 

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