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Carbonyl groups in sulfonated styrene-divinylbenzene macroporous resins / Muhammad Arif Malik in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6961–6965 Titre : Carbonyl groups in sulfonated styrene-divinylbenzene macroporous resins Type de document : texte imprimé Auteurs : Muhammad Arif Malik, Auteur Année de publication : 2009 Article en page(s) : pp. 6961–6965 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbonyl  groups  Porous  styrene−divinylbenzene  copolymers  Sulfonation Résumé : The generation of carbonyl groups during sulfonation of porous styrene−divinylbenzene copolymers is reported. The carbonyl groups and sulfonic acid groups were verified by infrared spectroscopy and quantified by acid−base titrations. A gradual change in sulfonation reaction conditions from 70 °C/30 min to 98 °C/60 min resulted in a gradual increase in sulfonic acid group concentration from ∼1.85 to ∼3.13 mol/kg and in the carboxylic acid group concentration from ∼0 to ∼0.34 mol/kg. Data on the swelling coefficients in water indicate a slight increase in cross-linking during sulfonation. Conversion of ethyl or residual vinyl groups to carboxylic acid groups, followed by conversion of some of the acid groups to cross-links through an acid-catalyzed acylation reaction, is proposed. The proposed reactions also explain the pH-dependent color change of the resins. Sulfonation of copolymers with varied cross-linkages further supports our assertion that, as the concentrations of ethyl and residual vinyl groups increase, the concentration of —COOH groups also increases and the resin color becomes darker. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900681n [article] Carbonyl groups in sulfonated styrene-divinylbenzene macroporous resins [texte imprimé] / Muhammad Arif Malik, Auteur . - 2009 . - pp. 6961–6965. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6961–6965 Mots-clés : Carbonyl  groups  Porous  styrene−divinylbenzene  copolymers  Sulfonation Résumé : The generation of carbonyl groups during sulfonation of porous styrene−divinylbenzene copolymers is reported. The carbonyl groups and sulfonic acid groups were verified by infrared spectroscopy and quantified by acid−base titrations. A gradual change in sulfonation reaction conditions from 70 °C/30 min to 98 °C/60 min resulted in a gradual increase in sulfonic acid group concentration from ∼1.85 to ∼3.13 mol/kg and in the carboxylic acid group concentration from ∼0 to ∼0.34 mol/kg. Data on the swelling coefficients in water indicate a slight increase in cross-linking during sulfonation. Conversion of ethyl or residual vinyl groups to carboxylic acid groups, followed by conversion of some of the acid groups to cross-links through an acid-catalyzed acylation reaction, is proposed. The proposed reactions also explain the pH-dependent color change of the resins. Sulfonation of copolymers with varied cross-linkages further supports our assertion that, as the concentrations of ethyl and residual vinyl groups increase, the concentration of —COOH groups also increases and the resin color becomes darker. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900681n

Sulfonated styrene−divinybenzene resins / Muhammad Arif Malik in Industrial & engineering chemistry research, Vol. 49 N° 6 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2608–2612 Titre : Sulfonated styrene−divinybenzene resins : optimizing synthesis and estimating characteristics of the base copolymers and the resins Type de document : texte imprimé Auteurs : Muhammad Arif Malik, Auteur ; Syed Wasim Ali, Auteur ; Imtiaz Ahmed, Auteur Année de publication : 2010 Article en page(s) : pp. 2608–2612 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Sulfonated  Styrene  Divinybenzene  Resins  Optimizing  Synthesis  Characteristics  Base  Copolymers  Resins Résumé : Maximum sulfonation and minimum carboxylation are desirable in sulfonated styrene−divinylbenzene cation-exchange resins. These characteristics may be achieved with greater control of porosity of the base copolymers. Optimization of the porosity by varying both the nature and amount of porogen, and cross-linking for maximizing sulfonation and minimizing carboxylation, are reported. Predictors of the characteristics obtained by statistical analysis of the data, and the ranges of conditions in which they can be employed, are discussed. The optimum conditions are cross-linking 20% to 23% and pore volume 0.14 mL/g to 0.3 mL/g. The relationship of the particle size with porosity of the base copolymer and capacity of the resins is discussed. The effects of residual porogen/homopolymer on the sulfonation of these copolymers are also discussed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie902057x [article] Sulfonated styrene−divinybenzene resins : optimizing synthesis and estimating characteristics of the base copolymers and the resins [texte imprimé] / Muhammad Arif Malik, Auteur ; Syed Wasim Ali, Auteur ; Imtiaz Ahmed, Auteur . - 2010 . - pp. 2608–2612. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2608–2612 Mots-clés : Sulfonated  Styrene  Divinybenzene  Resins  Optimizing  Synthesis  Characteristics  Base  Copolymers  Resins Résumé : Maximum sulfonation and minimum carboxylation are desirable in sulfonated styrene−divinylbenzene cation-exchange resins. These characteristics may be achieved with greater control of porosity of the base copolymers. Optimization of the porosity by varying both the nature and amount of porogen, and cross-linking for maximizing sulfonation and minimizing carboxylation, are reported. Predictors of the characteristics obtained by statistical analysis of the data, and the ranges of conditions in which they can be employed, are discussed. The optimum conditions are cross-linking 20% to 23% and pore volume 0.14 mL/g to 0.3 mL/g. The relationship of the particle size with porosity of the base copolymer and capacity of the resins is discussed. The effects of residual porogen/homopolymer on the sulfonation of these copolymers are also discussed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie902057x