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    Author(s): R.W. Hemingway; G.W. McGraw
    Date: 1978
    Source: Journal of Liquid Chromatography 1(2):163-179
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (2.1 MB)

    Description

    Gel permeation chromatograpy of the condensation products of phenols and formaldehyde proved effective in understanding the reactions of condensed tannins with formaldehyde. Rates of condensation of phloroglucinols, resorcinols, catechols, (+)catechin, and (-)epicatechin were examined to determine if methylol-tannins from southern pine bark could be prepared as resin intermediates. The phloroglucinols (models for the A-ring of pine bark tannins) were so much more reactive than were the resorcinols (models for the A-ring of wattle tannins), that preparation of methylol-tannins from pine bark tannins seems unlikely even though this approach has been applied successfully to synthesis of resins from wattle tannins. The methylol content of catechin-formaldehyde condensation products was very low. The catechol B-ring was unreactive under conditions in which condensations of pine bark tannins could be controlled. Although there is much less steric hindrance of the A-ring of (-)epicatechin than of (+)catechin, differences in the rates of condensati on of these isomers were not detected. GPC and H-NMR spectra of (+)catechin condensation products showed that a dimer formed rapidly and that further condensation occurred more slowly.

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    Citation

    Hemingway, R.W.; McGraw, G.W. 1978. Formaldehyde condensation products of model phenols for conifer bark tannins. Journal of Liquid Chromatography 1(2):163-179

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