Mechanistic studies of mineral tanning - Part I : / Anthony D. Covington in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 73 (Année 1989)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 73 (Année 1989) . - p. 1-8 Titre : Mechanistic studies of mineral tanning - Part I : : Solid state aluminium-27 NMR studies and the thermodynamics of shrinking Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; R. A. Hancock, Auteur ; I. A. Ioannidis, Auteur Année de publication : 1989 Article en page(s) : p. 1-8 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Aluminium-27 solid state NMR spectroscopy has been applied to investigate the interactionat the molecular level of various aluminium based tanning salts with leather. High resolution and variable temperature Al-solid state NMR studies, combined with differential scanning calorimetry and kinetic studies of the shrinking of Al-tanned hide powder and sheepskin samples have clearly shown that shrinking is a kinetically controlled process, during which the synthetic crosslinks remain intact. The shrinkage temperature is determined by the size of the formed crosslinked macromolecular moieties which in turn depends on the kinetics stability of the interactions of the tanning agent with collagen. En ligne : https://drive.google.com/file/d/1nWW_-bJbgR1Pfd3BbI_FsAWZj_n39ZNi/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8812 [article]

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Studies of vegetable tannins. Characterisation of commercial chestnut tannin extract / H. R. Tang in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 80, N° 1 (01-02/1996)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 80, N° 1 (01-02/1996) . - p. 15-24 Titre : Studies of vegetable tannins. Characterisation of commercial chestnut tannin extract Type de document : texte imprimé Auteurs : H. R. Tang, Auteur ; R. A. Hancock, Auteur ; Anthony D. Covington Année de publication : 1996 Article en page(s) : p. 15-24 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : A combination of chromatography and spectroscopy has made it possible to reveal the major components of the commercially used chestnut (Castanea Sativa and vesc) tannin extract. Both cellulose and Sephadex LH-20 column were useful although the latter was more successful. Fast atom bombardment mass spectroscopy (FAB-MS) was used to identify individual components. Components of chestnut tannin extract were found having molecular mass range between 170 and 1850 daltons. An HPLC chromatogram showed that at least 17 major components were present in the chestnut extract. All components were derivatives of gallic acid ; no derivatives of catechin were found. En ligne : https://drive.google.com/file/d/1ceCXwlEL6dqtHaEzMTBlaVSrOnbMCWAb/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8195 [article]

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Studies of vegetable tannins. Complete structural determination of two chestnut tannins - vescalagin and castalagin using nuclear magnetic resonance spectroscopic methods / H. R. Tang in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 79, N° 6 (11-12/1995)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 79, N° 6 (11-12/1995) . - p. 181-187 Titre : Studies of vegetable tannins. Complete structural determination of two chestnut tannins - vescalagin and castalagin using nuclear magnetic resonance spectroscopic methods Type de document : texte imprimé Auteurs : H. R. Tang, Auteur ; R. A. Hancock, Auteur Année de publication : 1995 Article en page(s) : p. 181-187 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Current research has focused on studies of commercial tannin extracts from chestnut wood (Castanea Sativa and Castanea vesc). This paper reports the structural determination of two ellagitannins of the extract, vescalagin and castalagin,using nuclear magnetic resonance (NMR) spectroscopy and fast atom bombardment (FAB) mass spectroscopy. En ligne : https://drive.google.com/file/d/1YmpOmOs5wZ_Q8Fp-0TQqugTPt_DTLnTE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8198 [article]

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Studies on the origin of hydrothermal stability : a new theory of tanning / Anthony D. Covington in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCIII, N° 4 (04/1998)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XCIII, N° 4 (04/1998) . - p. 107-120 Titre : Studies on the origin of hydrothermal stability : a new theory of tanning Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; Graham Lampard, Auteur ; R. A. Hancock, Auteur ; I. A. Ioannidis, Auteur Année de publication : 1998 Article en page(s) : p. 107-120 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Research into the thermodynamics of shrinking, the process of heat denaturation of collagen or leather, has demonstrated a relashionship between the activation energy of the reaction and the conventionally measured shrinkage temperature. This reaction is independent of the tannage, concerning instead the breaking of hydrogen bonds. It is postulated that the shrinkage temperature depends on the size of crosslinked macromolecular moieties, or 'cooperating units', formed during tannage. These, in turn, depend on the nature of the tanning agent's interaction with collagen. High hydrothermal stability depends on structure-making crosslinks. These depend on the crosslinking moiety having a 'stiff' structure and there being a non labile reaction between the crosslinking moiety and the collagen. These rules constitute a new theory of tanning. Note de contenu : - The shrinking reaction - Cooperating units - Hydrothermal stability : Multiple interactions - Covalent bonds - Steric considerations - Crystallinity En ligne : https://drive.google.com/file/d/1PYet4SRyRycispwwFrxzyRTZQNg-CrFd/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4520 [article]

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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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Tannage with aluminium salts. Part II. Chemical basis of the reactions with polyphenols / R. L. Sykes in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 64, N° 2 (03-04/1980)  

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