Structural characterization of the lignin in the cortex and pith of elephant grass (Pennisetum purpureum) stems
The structure of the lignin in the cortex and pith of elephant grass (Pennisetum purpureum) stems were studied both in situ and in isolated milled ‘wood’ lignins by several analytical methods. The presence of p-coumarate and ferulate in the cortex and pith, as well as in their isolated lignins, was...
| Autores: | , , , , , , , |
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| Formato: | otro |
| Fecha de publicación: | 2012 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/86339 |
| Acesso em linha: | http://hdl.handle.net/10261/86339 |
| Access Level: | acceso abierto |
| Palavra-chave: | Elephant grass Lignin p-Coumarates Ferulates |
| Resumo: | The structure of the lignin in the cortex and pith of elephant grass (Pennisetum purpureum) stems were studied both in situ and in isolated milled ‘wood’ lignins by several analytical methods. The presence of p-coumarate and ferulate in the cortex and pith, as well as in their isolated lignins, was revealed by pyrolysis in the presence of TMAH, and by 2D-NMR, and indicated that ferulate acylates the carbohydrates while p-coumarate acylates the lignin polymer. 2D-NMR showed a predominance of β–O–4alkyl aryl ether linkages (82% of total inter-unit linkages), with low amounts of ‘condensed’ substructures, such as resinols, phenylcoumarans, and spirodienones. Moreover, the NMR also indicated that these lignins are extensively acylated at the γ-carbon of the side-chain. DFRC analyses confirmed that p-coumarate groups acylate the γ-OHs of these lignins, and predominantly on syringyl units. |
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