Format

Send to

Choose Destination
See comment in PubMed Commons below
J Agric Food Chem. 2016 Jun 15;64(23):4742-50. doi: 10.1021/acs.jafc.6b02234. Epub 2016 Jun 3.

Coupling and Reactions of 5-Hydroxyconiferyl Alcohol in Lignin Formation.

Author information

1
Southern Research Station, USDA-Forest Service , 521 Devall Drive, Auburn, Alabama 36849, United States.
2
National Bioenergy Center, National Renewable Energy Laboratory , 15013 Denver West Parkway, Golden, Colorado 80401, United States.
3
Biosciences Center, National Renewable Energy Laboratory , 15013 Denver West Parkway, Golden, Colorado 80401, United States.

Abstract

The catechol alcohols, caffeyl and 5-hydroxyconiferyl alcohol, may be incorporated into lignin either naturally or through genetic manipulation. Due to the presence of o-OH groups, these compounds form benzodioxanes, a departure from the interunit connections found in lignins derived from the cinnamyl alcohols. In nature, lignins composed of caffeyl and 5-hydroxyconiferyl alcohol are linear homopolymers and, as such, may have properties that make them amenable for use in value-added products, such as lignin-based carbon fibers. In the current work, results from density functional theory calculations for the reactions of 5-hydroxyconiferyl alcohol, taking stereochemistry into account, are reported. Dehydrogenation and quinone methide formation are found to be thermodynamically favored for 5-hydroxyconiferyl alcohol, over coniferyl alcohol. The comparative energetics of the rearomatization reactions suggest that the formation of the benzodioxane linkage is under kinetic control. Ring-opening reactions of the benzodioxane groups show that the bond dissociation enthalpy of the α-O cleavage reaction is lower than that of the β-O reaction. The catechol lignins represent a novel form of the polymer that may offer new opportunities for bioproducts and genetic targets.

KEYWORDS:

5-hydroxyconiferyl alcohol; benzodioxane; coniferyl alcohol; lignin; stereochemistry

PMID:
27236926
DOI:
10.1021/acs.jafc.6b02234
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for American Chemical Society
    Loading ...
    Support Center