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Combined influence of fluorinated solvent and base in friedel − crafts reaction of toluene and CO2 / Pradip Munshi in Industrial & engineering chemistry research, Vol. 49 N° 14 (Juillet 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp 6678–6682 Titre : Combined influence of fluorinated solvent and base in friedel − crafts reaction of toluene and CO2 Type de document : texte imprimé Auteurs : Pradip Munshi, Auteur ; Eric J. Beckman, Auteur ; Sudhakar Padmanabhan, Auteur Année de publication : 2010 Article en page(s) : pp 6678–6682 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Reaction  Toluene Résumé : As disclosed in preceding studies [Munshi and Beckman Ind. Eng. Chem. Res. 2009, 48, 1059−1062 and Beckman and Munshi US Patent 7,271,286, 2007], aluminum chloride is superior among Lewis acids in making p-toluic acid from toluene and 6.9 MPa CO2 offering 80% stoichiometric yield, with respect to Al2Cl6, and 98% selectivity at 80 °C in 18 h. Attempts to improve the efficiency resulted in the finding that H+ exchange between HCl and Tol-COOAl2Cl5 is the key step in making the reaction catalytic. Introduction of a base complemented by a fluorinated solvent can only bring Al2Cl6 into catalytic cycle, provided pKa[Tol-COOH] > pKa[BH+] > pKa[HCl]. Efficiency of the reaction depends upon the nature of the fluorinated solvents and reaction parameters employed. Turnover number of 7.87 for p-toluic acid in 6 h is obtained employing 2.68 mmol quinoxaline, 15 mL 1,3,5-tris(trifluoromethyl)benzene, and 2.68 mmol of Al2Cl6 and CO2 at a pressure of 6.9 MPa CO2 and 100 °C. The base and fluorinated solvent could be recyclable and reused. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100533c [article] Combined influence of fluorinated solvent and base in friedel − crafts reaction of toluene and CO2 [texte imprimé] / Pradip Munshi, Auteur ; Eric J. Beckman, Auteur ; Sudhakar Padmanabhan, Auteur . - 2010 . - pp 6678–6682. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp 6678–6682 Mots-clés : Reaction  Toluene Résumé : As disclosed in preceding studies [Munshi and Beckman Ind. Eng. Chem. Res. 2009, 48, 1059−1062 and Beckman and Munshi US Patent 7,271,286, 2007], aluminum chloride is superior among Lewis acids in making p-toluic acid from toluene and 6.9 MPa CO2 offering 80% stoichiometric yield, with respect to Al2Cl6, and 98% selectivity at 80 °C in 18 h. Attempts to improve the efficiency resulted in the finding that H+ exchange between HCl and Tol-COOAl2Cl5 is the key step in making the reaction catalytic. Introduction of a base complemented by a fluorinated solvent can only bring Al2Cl6 into catalytic cycle, provided pKa[Tol-COOH] > pKa[BH+] > pKa[HCl]. Efficiency of the reaction depends upon the nature of the fluorinated solvents and reaction parameters employed. Turnover number of 7.87 for p-toluic acid in 6 h is obtained employing 2.68 mmol quinoxaline, 15 mL 1,3,5-tris(trifluoromethyl)benzene, and 2.68 mmol of Al2Cl6 and CO2 at a pressure of 6.9 MPa CO2 and 100 °C. The base and fluorinated solvent could be recyclable and reused. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100533c

Synthesis of ultrahigh molecular weight polyethylene using traditional heterogeneous ziegler-natta catalyst systems / Sudhakar Padmanabhan in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4866–4871 Titre : Synthesis of ultrahigh molecular weight polyethylene using traditional heterogeneous ziegler-natta catalyst systems Type de document : texte imprimé Auteurs : Sudhakar Padmanabhan, Auteur ; Krishna R. Sarma, Auteur ; Shashikant Sharma, Auteur Année de publication : 2009 Article en page(s) : pp. 4866–4871 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultrahigh  molecular  weight  polyethylene  Ziegler-Natta  catalysts  Oxidation  states  Polymer Résumé : Ultrahigh molecular weight polyethylene was synthesized from traditional Ziegler−Natta type catalysts (ZN), namely, TiCl4 anchored on MgCl2 support. This, upon activation with AlRR′2 (where R, R′ = isoprenyl or isobutyl), gave precatalysts (C-2 to C-5) having 16, 21, 25, and 32% trivalent titanium, respectively. The reduction in oxidation states also accompanies the reduction in particle size of the catalysts, which in turn gets reflected in the resulting polymer properties under specified operating conditions. We have demonstrated the effect of process conditions that can surmount the catalyst dependency over the polymer characteristics, and hence, it can result in polymer with consistent polymer properties, which is an important need of the polymer industries. The polymer characteristics such as particle size distribution, average particle size, bulk density, reduced specific viscosity, and concentration of fine and coarse particles were determined and were dependent on various process parameters. Under identical reaction conditions, the polymerization with larger scale yield polymer with different characteristics. The fine-tuning of process conditions yielded polymer with consistent quality. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie802000n [article] Synthesis of ultrahigh molecular weight polyethylene using traditional heterogeneous ziegler-natta catalyst systems [texte imprimé] / Sudhakar Padmanabhan, Auteur ; Krishna R. Sarma, Auteur ; Shashikant Sharma, Auteur . - 2009 . - pp. 4866–4871. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4866–4871 Mots-clés : Ultrahigh  molecular  weight  polyethylene  Ziegler-Natta  catalysts  Oxidation  states  Polymer Résumé : Ultrahigh molecular weight polyethylene was synthesized from traditional Ziegler−Natta type catalysts (ZN), namely, TiCl4 anchored on MgCl2 support. This, upon activation with AlRR′2 (where R, R′ = isoprenyl or isobutyl), gave precatalysts (C-2 to C-5) having 16, 21, 25, and 32% trivalent titanium, respectively. The reduction in oxidation states also accompanies the reduction in particle size of the catalysts, which in turn gets reflected in the resulting polymer properties under specified operating conditions. We have demonstrated the effect of process conditions that can surmount the catalyst dependency over the polymer characteristics, and hence, it can result in polymer with consistent polymer properties, which is an important need of the polymer industries. The polymer characteristics such as particle size distribution, average particle size, bulk density, reduced specific viscosity, and concentration of fine and coarse particles were determined and were dependent on various process parameters. Under identical reaction conditions, the polymerization with larger scale yield polymer with different characteristics. The fine-tuning of process conditions yielded polymer with consistent quality. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie802000n