The Yellowing of Cotton Cellulose

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Abstract
The differences between the brightness reversion on aging and the yellowing in alkaline solution found for hydrocelluloses and carboxyl-containing celluloses are ex plained by anhydridization of the terminal C1 aldehydes on aging and autohydrolysis caused by the carboxyl groups. The reaction sequence leading to the formation of the yellow substances seems to involve a peeling-off of glucose units from the chain ends, isomerization and fragmentation of the peeled glucose units, and condensation of the fragments to furan derivatives and to carbonyl-groups-containing colored substances. The smaller contribution to yellowing of the aldehydes in NaClO-oxidized cottons, as compared to hydrolyzed cotton, is explained by postulating the existence of "inactive" aldehydes which do not cause peeling. The possible reasons for the lack of yellowing of keto-celluloses are discussed.