The DFRC method for lignin analysis. 7. Behavior of cinnamyl end groups.
The behavior of cinnamyl end groups of lignins during the derivatization followed by reductive cleavage (DFRC) procedure has been investigated using lignin model compounds. On AcBr treatment, hydroxycinnamyl alcohols give rise mainly to 1-aryl-1, 3-dibromopropanes from which 1-aryl-3-bromopropanes and arylcyclopropanes are formed by zinc reduction. Arylpropene derivatives are also significant among DFRC products of etherified cinnamyl end-group models. Major monomers from DFRC of hydroxycinnamaldehydes are arylcyclopropyl acetates produced by reductive ring closure of 1-acetoxy-3-aryl-1,3-dibromopropanes. Although the reactions are not as clean as the ether-cleaving reactions that form the basis of the DFRC method, end groups produce diagnostic compounds that provide valuable markers for studying end groups in lignins.
Lu
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U.S. Dairy Forage Research Center, Agricultural Research Service, U. S. Department of Agriculture, and Department of Forestry, University of Wisconsin-Madison, 53706, USA.
Ralph
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J
D000438:Alcohols / Q000032:analysis; D002625:Chemistry, Organic / Q000379:methods; D002934:Cinnamates / Q000032:analysis; D007202:Indicators and Reagents; D008031:Lignin / Q000737:chemistry*; D010084:Oxidation-Reduction
D000438:Alcohols; D002934:Cinnamates; D007202:Indicators and Reagents; D008031:Lignin