The oxidation and thermal transformations of macrooradicals in gamma irradiated cellulose

The secondary reactions of the oxidation and thermal transformations of gamma irradiated (at 77 K) and plasticized (with water) cellulose radicals were studied by 3 cm-and 2 mm-band EPR spectroscopy. The radiolysis of cotton cellulose was found to produce the H-C-center dot=O formyl radical, and heating the irradiated samples to 190-200 K resulted in the formation of the ROO center dot peroxide radical. The EPR spectra of microcrystalline cellulose recorded at room temperature contained an individual triplet (alpha(H)(beta) = 2.5-2.7 mT) with an additional quadruplet structure (splitting 0.5-0.7 mT) from three gamma-hydrogens. This triplet was interpreted as a signal of the primary radical at C4. The main direction of thermal transformations of primary radicals was synchronous reactions of the dehydration of the polycarbohydrate complex accompanied by the dissociation of the C-H, C-OH, and C-C bonds and elimination of H2O, H-2, CO, and CO2 with successive formation of allyl and then polyene radicals, which were a source of the growth of polyconjugated systems in macromolecules.