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Fundamentals of wet oxidation of bayer - process liquor / Jackie Dong in Industrial & engineering chemistry research, Vol. 49 N° 11 (Juin 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp. 5347–5352 Titre : Fundamentals of wet oxidation of bayer - process liquor : reactivity of malonates Type de document : texte imprimé Auteurs : Jackie Dong, Auteur ; Greg Power, Auteur ; Joanne Loh, Auteur Année de publication : 2010 Article en page(s) : pp. 5347–5352 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Oxidation Résumé : The application of wet oxidation to the removal of organic impurities from Bayer-process liquors has the potential to deliver major benefits to the alumina industry. Previous work has identified the malonate anion as especially reactive under WO conditions, a property ascribed to its ability to form a carbanion in alkaline conditions. Understanding of the reaction mechanism involved in this effect is of importance to the development of improved WO technology. The current work confirms carbanion formation as the first step in the reaction. Deuterium exchange experiments and 13C NMR spectroscopy are used to demonstrate the weak acidity of the α-hydrogen atoms which leads to carbanion formation. The acidity of the α-hydrogen atoms in malonate is induced by the electron-withdrawing effect of the two adjacent carboxylate groups. Substituting an electron-donating group such as methyl or ethyl at the α-position reduces this effect, resulting in reduced oxidation rates for the substituted malonates. The role of the carbanion in the reaction mechanism is confirmed by analysis of the products and reaction kinetics. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100128k [article] Fundamentals of wet oxidation of bayer - process liquor : reactivity of malonates [texte imprimé] / Jackie Dong, Auteur ; Greg Power, Auteur ; Joanne Loh, Auteur . - 2010 . - pp. 5347–5352. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp. 5347–5352 Mots-clés : Oxidation Résumé : The application of wet oxidation to the removal of organic impurities from Bayer-process liquors has the potential to deliver major benefits to the alumina industry. Previous work has identified the malonate anion as especially reactive under WO conditions, a property ascribed to its ability to form a carbanion in alkaline conditions. Understanding of the reaction mechanism involved in this effect is of importance to the development of improved WO technology. The current work confirms carbanion formation as the first step in the reaction. Deuterium exchange experiments and 13C NMR spectroscopy are used to demonstrate the weak acidity of the α-hydrogen atoms which leads to carbanion formation. The acidity of the α-hydrogen atoms in malonate is induced by the electron-withdrawing effect of the two adjacent carboxylate groups. Substituting an electron-donating group such as methyl or ethyl at the α-position reduces this effect, resulting in reduced oxidation rates for the substituted malonates. The role of the carbanion in the reaction mechanism is confirmed by analysis of the products and reaction kinetics. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100128k