Abstract
A novel analytical approach based on the fluorescence labelling was developed in the effort to increase the understanding of phenolic group distribution in technical lignins. A selective derivatiza...
Highlights
Lignins are three-dimensional, heterogeneous, and irregular polyphenolic macromolecules and the second most abundant natural polymer after cellulose
Several papers were focused on different fractionation approaches to extract more homogeneous lignin preparation in terms of molecular weight and functional group distribution.[5]
As reported in the Experimental Section, lignin samples were labeled with dansyl chloride (Figure 1) and characterized by 31P NMR in order to study the yield and the selectivity of the reaction
Summary
Lignins are three-dimensional, heterogeneous, and irregular polyphenolic macromolecules and the second most abundant natural polymer after cellulose. The lower the solvent polarity, the lower the average molecular weight of the fraction and the larger the phenolic content.[10−12] Fractionation by successive precipitation, obtained either by a stepwise reduction of the pH value of black liquor or especially by the addition of a nonsolvent to an organic lignin solution, generally results in a high lignin yield and highly monodispersed fractions.[13−15]. The dansylation reaction on model compounds was accomplished using the same conditions described above for lignin except that, after the addition of the reaction mixture to cold acidic water, the pH was adjusted to 3 to optimize the product precipitation, and the dansylated model compounds were extracted in ethyl acetate, anhydrified over sodium sulfate, and rotary evaporated.
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