Structural Characterization of Wheat Straw Lignin as Revealed by Analytical Pyrolysis, 2D-NMR, and Reductive Cleavage Methods
The structure of the lignin in wheat straw has been investigated by a combination of analytical pyrolysis, 2DNMR, and derivatization followed by reductive cleavage (DFRC). It is a p-hydroxyphenyl-guaiacyl-syringyl lignin (with an H:G:S ratio of 6:64:30) associated with p-coumarates and ferulates. 2D...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2012 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/51774 |
| Acceso en línea: | http://hdl.handle.net/10261/51774 |
| Access Level: | acceso abierto |
| Palabra clave: | wheat straw Py-GC/MS TMAH HSQC DFRC milled wood lignin p-coumarate ferulate Coniferyl acetate tricin |
| Sumario: | The structure of the lignin in wheat straw has been investigated by a combination of analytical pyrolysis, 2DNMR, and derivatization followed by reductive cleavage (DFRC). It is a p-hydroxyphenyl-guaiacyl-syringyl lignin (with an H:G:S ratio of 6:64:30) associated with p-coumarates and ferulates. 2D-NMR indicated that the main substructures present are beta-O-4-ethers (ca. 75%), followed by phenylcoumarans (ca. 11%), with lower amounts of other typical units. A major new finding is that the flavone tricin is apparently incorporated into the lignins. NMR and DFRC indicated that the lignin is partially acylated (ca. 10%) at the gamma-carbon, predominantly with acetates that preferentially acylate guaiacyl (12%) rather than syringyl (1%) units; in dicots, acetylation is predominantly on syringyl units. p-Coumarate esters were barely detectable (<1%) on monomer conjugates released by selectively cleaving beta-ethers in DFRC, indicating that they might be preferentially involved in condensed or terminal structures. |
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