Chemistry of the Condensed Tannin B-ring

  • Peter E. Laks


The chemistry of the condensed tannin B-ring is closely related to that of the parent phenols — phenol, catechol, and pyrogallol. Many of the same reactions observed for the simple phenols can be reproduced on the tannin B-ring. These include esterification, etherification, and elec­trophilic addition for all the types, and metal chelation, oxidation, free-radical scavenging and ketal formation for the catechol and/or pyro­gallol related B-rings. The latter four characteristics are particularly important, contributing to the biological activity and potential utiliza­tion of the more common types of condensed tannins. The B-ring also has an important effect on the C-2 in the pyran ring. The reactivity of this position is discussed. There is a considerable amount of litera­ture available on the reactions of monomeric flavonoids. Inferences are drawn from this information about comparable reactions being possible for the condensed tannins.


Electron Spin Resonance Condensed Tannin Oxidative Coupling Western Hemlock Coniferyl Alcohol 
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© Plenum Press, New York 1989

Authors and Affiliations

  • Peter E. Laks
    • 1
  1. 1.Institute of Wood ResearchMichigan Technological UniversityHoughtonUSA

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