On the nature of carbonyl groups in cellulosic pulps

Apart from the reducing end groups, most celluloses contain small amounts of carbonyl groups in the mumol/g range, which are introduced into the material by a variety of preparation, processing and purification steps. By a combination of carbonyl-selective fluorescence labeling (CCOA method) and UV resonance Raman spectroscopy it was demonstrated that carbonyls in celluloses are not only present as a C=O structure with an SP2-hybridized carbon, but also to a significant extent in sp(3)-hybridized form as hydrates or hemiacetals.