The three cellulosic key chromophores, 2,5-dihydroxy-[1,4]-benzoquinone, 5,8-dihydroxy-[1,4]-naphthoquinone and 2,5-dihydroxy-acetophenone, are nearly ubiquitous in cellulosic materials because of their special structures and resonance stabilization with highly delocalized double bonds that renders them thermodynamically very stable and resistant towards bleaching. All of these compounds possess acidic hydroxyl groups. The current work explores the derivatization of these OH groups by a phosphitylation agent followed by 31P NMR analysis, an approach that is very frequently used for quantitative OH group analysis and differentiation in lignins and lignin derivatives. The chemical shifts are reported and structural peculiarities of the chromophore derivatives are discussed. The 31P NMR approach adds to the toolbox of methods applicable in cellulose chromophore analysis, bleaching and aging studies. Graphical abstract

Lyocell dopes for cellulosic fiber manufacture, i.e., cellulose solutions in N-methylmorpholine-N-oxide monohydrate, are commonly stabilized by propyl gallate, or alternatively by recently proposed gallic acid amide derivatives. In this study, the analysis of the stabilizer and its major degradation products, ellagic acid and ellagoquinone, is investigated. The stabilizer-derived compounds are readily extracted from the dopes with polar aprotic solvents without solvent or cellulose interference. This is followed by the derivatization of the OH groups with a phosphitylation agent and subsequent 31P NMR analysis—an approach frequently used to differentiate and quantify OH groups in lignins. The chemical shifts of the resulting phosphites are reported and structures of the stabilizer derivatives are discussed. The 31P NMR approach offers a straightforward way to analyze the stabilizer chemistry in the Lyocell process. Graphical abstract