Photooxidation of Chemically Modified Celluloses and Free-Radical Formation

Free-radical and functional-group formations in cotton cellulose and in acetylated, benzhydrylated, benzoylated, benzylated, and cyanoethylated cotton celluloses on irradiation with near-uv light were determined. Modified cotton celluloses with electron withdrawing groups, such as acetyl and benzoyl groups, were more resistant to photooxidation than modified celluloses with structures, such as benzhydryl, benzyl, and cyanoethyl groups. The electron-spin resonance spectra of the photo-irradiated celluloses, in all cases, were singlet spectra; however, the steady-state concentrations of the free radicals in the irradiated celluloses were related to the nature of the pendant groups.