Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.5/6157
Título: Separação preparativa e caracterização espectroscópica dos principais monómeros da suberina da cortiça
Autor: Santos, Sara Cristina Pereira Guedes Ribeiro
Orientador: Graça, José Afonso
Palavras-chave: suberin
stereochemistry determination by NMR
cis/trans configuration analysis
erythro/threo configuration analysis
Data de Defesa: 2013
Editora: ISA
Citação: Santos, S.C.P.G.R. - Separação preparativa e caracterização espectroscópica dos principais monómeros da suberina da cortiça. Lisboa: ISA, 2013, 134 p.
Resumo: Suberin is a vital biomacromolecule responsible for the protection of plants, and yet its molecular structure remains mostly unknown. Cork is the ideal material for suberin extraction because of its suberin content (≥40%) and availability in industrial quantities. Suberin is a polyester made of glycerol and long-chain α,ω-bifunctional fatty acids, mainly C18 ω-hydroxyacids and α,ω-diacids with mid-chain substituents, either an unsaturation, an epoxide or a vic-diol group. The objective of this work was twofold: to develop techniques to isolate the main suberin acids from cork in preparative quantities and high purity (≥99.5%); and to develop spectroscopic techniques, namely NMR-based, to unambiguously assign the stereochemical configuration of the C18 suberin acids. The multi-step process developed comprised suberin depolymerization and suberin acids separation in solvents of contrasting polarities and tempera-tures, followed by successive purification by normal-phase LC and reversed-phase HPLC. The C18:1 suberin acids were proved to be cis, through the analysis of their olefinic and allylic proton and carbon chemical shifts, and coupling constants extracted by spectra simulation. A NMR technique was developed using the chemical shifts of the benzylidene acetal derivatives of vic-diols, proving that the suberin acids C18 9,10-epoxyacids were cis, and the C18 9,10-diol acids were threo, in both cases present as racemic mixtures. The stereochemistry of these acids will be determinant to understand the macromolecular structure of suberin, and the techniques developed for their preparative isolation can be the basis for their industrial commercialization.
Descrição: Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia
URI: http://hdl.handle.net/10400.5/6157
Aparece nas colecções:BISA - Teses de Doutoramento / Doctoral Thesis

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