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    Author(s): Richard W. Hemingway; Gerald W. McGraw; J.J. Karchesy; L.Y. Foo; L.J. Porter
    Date: 1983
    Source: Journal of Applied PoIymer Science: Applied Polymer Symposium 37(967-977
    Publication Series: Miscellaneous Publication
    PDF: Download Publication  (1.2 MB)


    The presence of the procyanidins epicatechin-(4β-8)-catechin, epicatechin-{4β-6)-catechin, catechin-(4α-8)-catechin, epicatechin-(4β-8)-epicatechin-(4β-8)-catechin, epicatechin-(4β-6)-epicatechin-(4β-8)-catechin, and epicatechin-(4β-8)-epicatechin-(4β-6)catechin in tile phloem of Pinus taeda demonstrated heterogeneity in the location of the interflavanoid bonds in oligomeric procyanidins. Panial acid-catalyzed cleavage of polymeric procyanidins from Pinus taeda and Pinus palustris barks or Photinia glabrescens leaves gave both the epicatechin-(4β-8)-epicatechin- and epicatechin-(4β-6)-epicatechin-benzyl or phenyl sulfides, demonstrating isomerism in tile interflavanoid bond location in these polymers. Comparison of tile rates of acid-catalyzed cleavage of isomeric dimen showed that those compounds with a (4β-6) interflavanoid bond were more stable than compounds with a (4β-8) bond. Also, catechin-(4α-8)-catechin was more resistant to cleavage than either epicatechin-(4β-8)-catechin or epicatechin-(4β-8)-epicatechin when heated in the presence of excess phenylmethanethiol with acetic acid. The structures of condensed tannins and the stability of these polyrnen under acidic conditions are discussed.

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    Hemingway, Richard W.; McGraw, Gerald W.; Karchesy, J.J.; Foo, L.Y.; Porter, L.J. 1983. Recent Advances in the Chemistry of Condensed Tannins. Journal of Applied PoIymer Science: Applied Polymer Symposium 37(967-977

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