199,242 research outputs found
Cleaner Routes for Friedel-Crafts Acylation
No full textFriedel-Crafts acylation is among the most fundamental and useful reactions to yield aromatic ketones but it is one of the less acceptable in terms of unwanted polluting by-products or atom economy because of the overconsumption of catalyst which is used in stoichiometric quantities in the conventional process. This route is nevertheless widely used in the fine chemical industry.In recent years, awareness of the impact of industrial activities on the environment has led chemists to work on new chemical routes, less dangerous and more environmentally friendly.We considered here the acylation of a benzofurane derivative by an acyl chloride, as an intermediary step for a pharmaceutical product. In this study, one of the first alternatives was to replace conventional catalysts (FeCl3 or AlCl3), by reusable solid catalysts. Indeed, a wide variety of new solid catalysts, more efficient and less polluting, has now emerged (zeolites, ion-exchange resins…). In this work, these catalysts were first tested in “conventional” conditions, i.e., using an organic solvent (1,2-dichlorobenzene in our case), to determine the best one, in terms of reactivity, lifetime and reusability. The zeolite Y was found the most appropriate.However, the use of an organic solvent still remains questionable and the use of supercritical carbon dioxide as the solvent was also considered. Its inherent properties include non-flammability, mild critical conditions, tuneable solubility near to the critical point and very low environmental impact. The reaction was operated using a continuous high pressure fixed bed. Results concerning yield and selectivity are presented
Réponse à M. Mügge au sujet des axes ternaires irrationnels
No full textFriedel Georges. Réponse à M. Mügge au sujet des axes ternaires irrationnels. In: Bulletin de la Société française de Minéralogie, volume 30, 1, 1907. pp. 6-17
Notice nécrologique sur M. Adam
No full textFriedel Charles. Notice nécrologique sur M. Adam. In: Bulletin de la Société minéralogique de France, volume 4, 6, 1881. pp. 143-144
Notice nécrologique sur M. Adam
No full textFriedel Charles. Notice nécrologique sur M. Adam. In: Bulletin de la Société minéralogique de France, volume 4, 6, 1881. pp. 143-144
Réponse à M. Georges Friedel
No full textBombicci Luigi. Réponse à M. Georges Friedel. In: Bulletin de la Société française de Minéralogie, volume 15, 5-6, 1892. pp. 144-157
Au sujet de la Communication de M. C. Viola sur les lois d'Haüy et de Curie
No full textFriedel Georges. Au sujet de la Communication de M. C. Viola sur les lois d'Haüy et de Curie. In: Bulletin de la Société française de Minéralogie, volume 41, 8, 1918. pp. 196-198
Notice nécrologique sur M. Henri Sainte-Claire-Deville
No full textFriedel Charles. Notice nécrologique sur M. Henri Sainte-Claire-Deville. In: Bulletin de la Société minéralogique de France, volume 4, 7, 1881. pp. 187-190
2° Rapport oral de M. Georges Friedel
No full text2° Rapport oral de M. Georges Friedel. In: Revue internationale de droit comparé. Vol. 6 N°3, Juillet-septembre 1954. pp. 557-564
2° Rapport oral de M. Georges Friedel
No full text2° Rapport oral de M. Georges Friedel. In: Revue internationale de droit comparé. Vol. 6 N°3, Juillet-septembre 1954. pp. 557-564
Observations sur les « flüssige Kristalle » de M. O. Lehmann
No full textFriedel Georges, Grandjean François. Observations sur les « flüssige Kristalle » de M. O. Lehmann. In: Bulletin de la Société française de Minéralogie, volume 33, 5-6, 1910. pp. 192-239
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