H. E. Lerch III T.V. Verheyen Patrick G. Hatcher 1990 <div id="preview-section-abstract"><div id="abstracts" class="Abstracts u-font-serif text-s"><div id="aep-abstract-id4" class="abstract author"><div id="aep-abstract-sec-id5"><p>Organic geochemical investigations of peatified and coalified xylem from gymnosperms have provided useful information on the organic transformational processes collectively known as coalification. The combined use of solid-state<span>&nbsp;</span>¹³C nuclear magnetic resonance (NMR) and pyrolysis/gas chromatography/mass spectrometry (py/gc/ms) has allowed us to examine the organic composition of peatified and coalified xylem on both a bulk (average) compositional basis and on a detailed molecular basis. We conclude from our studies that coalification of gymnospermous xylem involves the following processes1.</p><p>(1) early selective removal of cellulosic materials so that lignin, a primary constituent of xylem, is transformed to macromolecular aromatic components in coal;2.</p><p>(2) modification of gymnospermous lignin by demethylation to form catechol-like structures, and by condensation reactions to induce a high level of cross-linking at an early stage of coalification; and</p><p>(3) dehydroxylation during increasing coalification to subbituminous coal, the resultant xylem becomes more phenolic in character as the catechol-like structures decrease.</p></div></div></div></div><div id="preview-section-references"><br></div> application/pdf 10.1016/0166-5162(89)90090-6 en Elsevier Organic geochemical studies of the transformation of gymnospermous xylem during peatification and coalification to subbituminous coal article