Synthesis and spectroscopic characterisation of the polygalloyl esters of polyols-models for gallotannins / H. R. Tang in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 87, N° 5 (09-10/2003)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 87, N° 5 (09-10/2003) . - p. 179-188 Titre : Synthesis and spectroscopic characterisation of the polygalloyl esters of polyols-models for gallotannins Type de document : texte imprimé Auteurs : H. R. Tang, Auteur ; Anthony D. Covington, Auteur ; R. A. Hancock, Auteur Année de publication : 2003 Article en page(s) : p. 179-188 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse spectrale Caractérisation Composés organiques -- Synthèse Esters polygalloyliques Gallo-tanins Polyols Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Hydrolysable gallotannins are naturally occurring polygalloyl esters of polyols (e.g., glucose) and are widespread in the plant kingdom. A totally new synthesis is described here for polygalloyl (3,4,5-trihydroxybenzoyl) esters of polyols as structural models for gallotannins, so that the structure-function relationships of this group of phytochemicals can be studied. The new synthesis consists of two steps, condensation of trimethoxybenzoyl chloride with a polyol and demethylation with anhydrous aluminium chloride/thiol. Compared to methods already reported, the new synthesis shortens the total reaction time by up to 30 times and gives high yields. Six polygalloyl esters of polyols were synthesised: di-galloyl-ethylene glycol (DGE), tri-galloyl-glycerol (TGG), tetra-galloyl-meso-erythritol (TGE), penta-galloyl-adonitol (PGA), ß-penta-galloyl-D-glucose (PGG) and hexa-galloyl-dulcitol (HGD). Amongst them, TGE, PGA and HGD are prepared for the first time. The polyphenols and their permethylated derivatives were characterised using a combination of NMR and mass spectroscopic techniques. The effects of galloylation on the NMR properties of polyols are also discussed. Note de contenu : - EXPERIMENTAL : - Materials and methods - Preparation of poly-(3,4,5-trimethoxybenzoyl)-polyols - Demethylation of permethylated polygalloyl polyols - RESULTS AND DISCUSSION : - Synthesis of polygalloyl polyols - Spectroscopic characterisation of permethylated polygalloyl esters - Spectroscopic characterisation of polygalloyl polyols - Table 1 : Data for permethylated polygalloyl esters 2a-7a - Table 2 : H NMR data for permethylated polygalloyl esters 2a - 7a* - Table 3 : 13C NMR data for permethylated polygalloyl esters 2a - 7a* - Table 4 : Data for polygalloyl esters of polyols 2 - 7 - Table 5 : H NMR data for polygalloyl esters (2-7) - Table 6 : 13C NMR Data for polygalloyl esters 2-7 En ligne : https://drive.google.com/file/d/1dJsl5exn-XbLBsFXulD7COfgg5qdqqkQ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39743 [article]

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