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Are Lignins Optically Active?

Authors: J, Ralph; J, Peng; F, Lu; R D, Hatfield; R F, Helm;

Are Lignins Optically Active?

Abstract

The accepted derivation of lignins from non(enzymatically)-controlled radical coupling reactions has been recently challenged, and it is relevant to ascertain unequivocally whether lignins are or are not (as normally assumed) optically active. Two approaches were used. First, DFRC (derivatization followed by reductive cleavage) dimers derived from beta-5- and beta-beta-units in pine lignins, which certainly retain unaltered chiral centers (as well as beta-1- and beta-O-4-units where the intactness may be debated), were shown to be optically inactive by circular dichroism (CD) and chiral high-performance liquid chromatography. CD of beta-5-derived dimers following enantiomeric separation readily demonstrated the sensitivity of the method. Second, no optical activity could be detected (above 250 nm to avoid carbohydrate contributions) by CD of lignin isolates from pine, kenaf, maize, or a CAD-deficient pine mutant. Representative lignins are therefore not, within limits of detection by these methods, optically active.

Keywords

Cycadopsida, Circular Dichroism, Carbohydrate Conformation, Dimerization, Lignin, Trees

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Powered by OpenAIRE graph
Found an issue? Give us feedback
selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
111
Top 10%
Top 1%
Top 10%
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