645 research outputs found
Photochemical synthesis of a âcageâ compound in a microreactor: Rigorous comparison with a batch photoreactor
An intramolecular [2 + 2] photocycloaddition is performed in a microphotoreactor (0.81 mL) built by winding FEP tubing around a commercially available Pyrex immersion well in which a medium pressure mercury lamp is inserted. A rigorous comparison with a batch photoreactor (225 mL) is proposed by means of a simple model coupling the reaction kinetics with the mass, momentum and radiative transfer
equations. This serves as a basis to explain why the chemical conversion and the irradiation time are respectively increased and reduced in the microphotoreactor relative to those in the batch photoreactor. Through this simple model reaction, some criteria for transposing photochemical synthesis from a batch photoreactor to a continuous microphotoreactor are defined
La micro-échelle en synthÚse organique : un outil commun chimie/génie chimique
Cet article est une restitution courte de la prĂ©sentation rĂ©alisĂ©e au cours des JIREC 2013 sur lâenseignement de la notion de changement dâĂ©chelle et de passage dâun mode batch Ă un mode continu en synthĂšse organique. Lâenjeu est de faire travailler des Ă©tudiants issus des dĂ©partements chimie et gĂ©nie chimique autour dâun mĂȘme outil, le microrĂ©acteur. Au cours dâune sĂ©ance de travaux pratiques, les Ă©tudiants mettent en oeuvre une synthĂšse organique en continu Ă micro-Ă©chelle et comparent les rĂ©sultats obtenus Ă ceux du procĂ©dĂ© batch. Ils apprĂ©hendent ainsi la notion de synthĂšse en continu et de suivi cinĂ©tique le long du microrĂ©acteur et comprennent lâintĂ©rĂȘt et les difficultĂ©s liĂ©s Ă la petite Ă©chelle. Lâoutil microrĂ©acteur mis en place Ă lâINP-ENSIACET peut ĂȘtre transfĂ©rĂ© vers dâautres formations de type ingĂ©nieurs, mais aussi CPGE, BTS ou IUT, pour accompagner le lien entre les domaines « gĂ©nie de la rĂ©action » et « synthĂšse organique »
Gold(I) complexes bearing phosphole ligands: Synthesis and antimalarial activity
AbstractA series of gold(I)-monophosphole complexes have been synthesized and characterized. The introduction of a nitrogen moiety in the complex structure was envisioned either by choosing the bis(trifluoromethanesulfonyl)imidate ligand as the X-ligand or by preparing a new pyrrolidinophosphole ligand as the L-ligand. All the complexes have been evaluated in vitro for their antimalarial activity. These goldâphosphole complexes showed moderate activities with IC50 values ranging from 9.7 to 24 ΌM against Plasmodium falciparum chloroquine-resistant strains
Retour d'expérience sur un dispositif de Réflexivité et de Contextualisation en formation d'ingénieur par Apprentissage : RéCAp
International audienceRĂ©CAp est un dispositif de problĂ©matisation permettant de mettre en lien les expĂ©riences professionnelles vĂ©cues en entreprise et les savoirs acadĂ©miques dispensĂ©s dans les formations par apprentissage de Toulouse INP-ENSIACET. Lâobjectif de ce dispositif est double : (i) pour les Ă©lĂšves, il sâagit de les initier Ă une analyse rĂ©flexive de leurs activitĂ©s et de leur positionnement en entreprise et de les accompagner dans la co-construction de leurs apprentissages Ă partir de la mise en relation des expĂ©riences en entreprise et des enseignements Ă lâĂ©cole, (ii) pour les enseignants, il sâagit de leur donner lâopportunitĂ© de mieux contextualiser leurs enseignements et de mieux apprĂ©hender la notion de compĂ©tences au travers de situations authentique complexes. Par ailleurs, ce dispositif est suffisamment souple pour ĂȘtre adaptĂ© Ă diffĂ©rents contextes et il permet de relever le dĂ©fi de la coopĂ©ration via sa dimension collaborative tant au niveau des Ă©lĂšves que des enseignants
Microreactors as a Tool for Acquiring Kinetic Data on Photochemical Reactions
For the first time, the application of microreactors as a tool for acquiring kinetic data on a photochemical reaction is demonstrated. For illustration, a T-photochromic system is considered. By using modeling tools and carrying out specific experiments in a spiral-shaped microreactor irradiated by an ultraviolet/light-emitting diode (UV-LED) array, the two kinetic parameters of the reaction, namely, quantum yield and rate of thermal back reaction, are determined. Once these parameters are known, the photochromic reaction is performed in two other microreactors in order to investigate a wider range of operating conditions. It is observed that a critical residence time exists beyond which the conversion into the open form decreases due to a decomposition reaction. The value of the critical residence depends on the microreactor type, which can be predicted by applying the model developed
Photooxygenation in an advanced led-driven flow reactor module: experimental investigations and modelling
The photooxygenation of âŻÎ±-terpinene was investigated as a benchmark reaction in an advanced LED-driven flow reactor module, both from an experimental and modelling point of view. Ethanol was used as a green solvent and rose Bengal was chosen as a cheap sensitizer of industrial importance. Firstly, the kinetic law based on all mechanistic steps was established for the chosen photooxygenation. From this, the set of operating parameters potentially influencing the photoreaction rate were identified. Subsequently, experiments were carried out under continuous-flow conditions to screen these operating parameters, namely concentration of α-terpinene, concentration of photosensitizer, residence time, structure of the segmented gas-liquid flow and nature of the reagent gas phase (air versus pure oxygen). Finally, the conditions enabling minimization of sensitizer bleaching were established. It was also shown that the hydrodynamic characteristics of the gas-liquid flow can have an effect on the conversion levels. From this, a simplified model was proposed to predict the conversion at the reactorâs outlet when pure oxygen was used
Bis(ÎŒ-phenylÂmethanoÂlato)bisÂ({4-[(E)-(4-tert-butylÂphenÂyl)(2-pyridÂylmethylÂimino)methÂyl]-3-methyl-1-phenyl-1H-pyrazol-5-olato}zinc(II))
In the title centrosymmetric dimeric ZnII complex, [Zn2(C27H27N4O)2(C7H7O)2], the ZnII center is coordinated by two N atoms and one O atom of the ketiminate ligand and two bridging O atoms of the benzylÂalkoxy groups. The geometry around the ZnII ions is distorted trigonal-bipyramidal
Study of ligand substituent effects on the rate and stereoselectivity of lactide polymerization using aluminum salen-type initiators.
A series of aluminum salen-type complexes [where salen is N,NâČ-bis(salicylaldimine)-1,2-ethylenediamine] bearing ligands that differ in their steric and electronic properties have been synthesized and investigated for the polymerization of rac-lactide. X-ray crystal structures on key precatalysts reveal metal coordination geometries intermediate between trigonal bipyramidal and square-based pyramidal. Both the phenoxy substituents and the backbone linker have a significant influence over the polymerization. Electron-withdrawing groups attached to the phenoxy donor generally gave an increased polymerization rate, whereas large ortho substituents generally slowed down the polymerization. The vast majority of the initiators afforded polylactide with an isotactic bias; only one exhibited a bias toward heteroselectivity. Isoselectivity generally increases with increased flexibility of the backbone linker, which is presumed to be better able to accommodate any potential steric clashes between the propagating polymer chain, the inserting monomer unit, and the substituents on the phenoxy donor
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