54 research outputs found
Glycerol as a cheap, safe and sustainable solvent for the catalytic and regioselective ÎČ,ÎČ-diarylation of acrylates over palladium nanoparticles
Herein we show that glycerol can be considered as a promising cheap and green solvent for the regioselective ÎČ,ÎČ-diarylation of alkenes. Whereas this reaction is generally catalyzed under an inert atmosphere by expensive phosphine or carbene-palladium complexes, we show here that the diarylation of alkenes can be conveniently achieved in glycerol in the presence of air-stable palladium nanoparticles. These palladium nanoparticles were stabilized over a sugar-based surfactant derived from biomass. By an adjustment of the reaction temperature, we were able to control the mono- and diarylation step of alkenes, thus offering a convenient route to unsymmetrical diarylated alkenes. At the end of the reaction, the diarylated alkenes were cleanly and selectively extracted from the glycerol-palladium catalytic phase using supercritical carbon dioxide, thus affording a convenient purification work-up. Within the framework of green chemistry, this work combines (i) catalysis in a cheap, safe and sustainable medium, (ii) easily made and air-stable palladium nanoparticles as the catalyst, and (iii) a clean and selective extraction of the reaction products with supercritical carbon dioxide
Les hommes et les femmes sont-ils Ă©gaux face Ă l'illettrisme ?
Delample Armelle. Les hommes et les femmes sont-ils égaux face à l'illettrisme ?. In: DiplÎmées, n°248, 2014. L'illetrisme aujourd hui. pp. 20-21
Edifices supramoléculaires dans le glycérol : Caractérisation et application en catalyse
ThĂšse soutenue publiquement le 3 novembre 2010 DiplĂŽme : Dr. d'UniversitĂ©This PhD work deals with the use of glycerol as a green and sustainable solvent. The main objective is to show that glycerol can be used as a solvent first, to obtain supramolecular buildings (cohesive solvent) and emulsions using an organic phase and then, to develop a catalysis in unconventional conditions (high boiling point and low vapour pressure). The first part consists in the study of aggregation properties using fatty acids as surfactants. By changing the nature of the counter-ion, these molecules allow producing various supramolecular assemblies such as micelles, vesicles and even tubes. In glycerol these aggregates show a smaller size compared to water. Those dispersions were then used in the formation of liquid crystal phases and emulsions with hexadecane as the oil component. In a second part, in order to develop selective catalytic processes in glycerol, we have synthesized new sugar-based surfactants. They are capable to (i) circumvent the low solubility of organic substrates in glycerol and (ii) limit the intrinsic reactivity of glycerol through the formation of hydrophobic domains. In one model reactions studied (Heck coupling), it is possible, by a control of temperature, to change the reaction selectivity. This allows us to envisage the synthesis of more valuable products. The selective extraction of the products formed in glycerol has been studied using supercritical CO2 mainly because the glycerol is poorly soluble in this solvent.Ce travail de thĂšse sâinscrit dans le cadre du dĂ©veloppement durable au travers de lâutilisation du glycĂ©rol en tant que solvant. Lâobjectif est de montrer quâil peut servir de solvant soit, pour lâobtention dâagrĂ©gats de tensioactifs (solvant cohĂ©sif) ainsi que dâĂ©mulsions au contact dâune phase organique, soit pour la rĂ©alisation dâune catalyse dans des conditions peu usuelles (forte tempĂ©rature dâĂ©bullition et faible pression de vapeur saturante). Lâobjectif de la premiĂšre partie consiste en lâĂ©tude des propriĂ©tĂ©s dâagrĂ©gation en utilisant des acides gras comme tensioactifs. En changeant la nature du contre ion, ces molĂ©cules offrent un large polymorphisme dâagrĂ©gats. Ainsi, nous dĂ©crivons dans le glycĂ©rol, lâobtention de micelles, de vĂ©sicules ou encore de tubes. Ces assemblages prĂ©sentent la particularitĂ© dâĂȘtre de plus petite taille comparativement Ă lâeau. Ces systĂšmes ont ensuite Ă©tĂ© utilisĂ©s dans la formation de phases cristal liquide ou dâĂ©mulsions en prĂ©sence dâhexadĂ©cane. Dans une deuxiĂšme partie, de maniĂšre Ă dĂ©velopper des procĂ©dĂ©s catalytiques sĂ©lectifs dans le glycĂ©rol, nous avons synthĂ©tisĂ© des agrotensioactifs dĂ©rivĂ©s de sucres (aminopolysaccharides). Ces derniers sont capables de (i) contourner la faible solubilitĂ© des substrats organiques dans le glycĂ©rol et de (ii) limiter la rĂ©activitĂ© intrinsĂšque du glycĂ©rol, grĂące Ă la formation de domaines hydrophobes. Dans lâune des rĂ©actions modĂšles Ă©tudiĂ©es (couplage de Heck), il est possible, par effet de tempĂ©rature, de contrĂŽler la sĂ©lectivitĂ© de la rĂ©action ce qui permet dâenvisager la synthĂšse de composĂ©s Ă plus haute valeur ajoutĂ©. Lâextraction sĂ©lective des produits formĂ©s dans le glycĂ©rol a ensuite Ă©tĂ© Ă©tudiĂ©e en utilisant le CO2 supercritique puisque la solubilitĂ© du glycĂ©rol dans ce solvant est relativement faible
La dysfonction musculaire périphérique dans la bronchopneumopathie chronique obstructive (mécanismes cellulaires et implication du stress oxydant)
MONTPELLIER-BU MĂ©decine UPM (341722108) / SudocMONTPELLIER-BU MĂ©decine (341722104) / SudocSudocFranceF
Edifices supramoléculaires dans le glycérol (caractérisation et application en catalyse)
Ce travail de thĂšse s'inscrit dans le cadre du dĂ©veloppement durable au travers de l'utilisation du glycĂ©rol en tant que solvant. L'objectif est de montrer qu'il peut servir de solvant soit, pour l'obtention d'agrĂ©gats de tensioactifs (solvant cohĂ©sif) ainsi que d'Ă©mulsions au contact d'une phase organique, soit pour la rĂ©alisation d'une catalyse dans des conditions peu usuelles (forte tempĂ©rature d'Ă©bullition et faible pression de vapeur saturante). L'objectif de la premiĂšre partie consiste en l'Ă©tude des propriĂ©tĂ©s d'agrĂ©gation en utilisant des acides gras comme tensioactifs. En changeant la nature du contre ion, ces molĂ©cules offrent un large polymorphisme d'agrĂ©gats. Ainsi, nous dĂ©crivons dans le glycĂ©rol, l'obtention de micelles, de vĂ©sicules ou encore de tubes. Ces assemblages prĂ©sentent la particularitĂ© d'ĂȘtre de plus petite taille comparativement Ă l'eau. Ces systĂšmes ont ensuite Ă©tĂ© utilisĂ©s dans la formation de phases cristal liquide ou d'Ă©mulsions en prĂ©sence d'hexadĂ©cane. Dans une deuxiĂšme partie, de maniĂšre Ă dĂ©velopper des procĂ©dĂ©s catalytiques sĂ©lectifs dans le glycĂ©rol, nous avons synthĂ©tisĂ© des agrotensioactifs dĂ©rivĂ©s de sucres (aminopolysaccharides). Ces derniers sont capables de (i) contourner la faible solubilitĂ© des substrats organiques dans le glycĂ©rol et de (ii) limiter la rĂ©activitĂ© intrinsĂšque du glycĂ©rol, grĂące Ă la formation de domaines hydrophobes. Dans l'une des rĂ©actions modĂšles Ă©tudiĂ©es (couplage de Heck), il est possible, par effet de tempĂ©rature, de contrĂŽler la sĂ©lectivitĂ© de la rĂ©action ce qui permet d envisager la synthĂšse de composĂ©s Ă plus haute valeur ajoutĂ©. L'extraction sĂ©lective des produits formĂ©s dans le glycĂ©rol a ensuite Ă©tĂ© Ă©tudiĂ©e en utilisant le CO2 supercritique puisque la solubilitĂ© du glycĂ©rol dans ce solvant est relativement faible.This PhD work deals with the use of glycerol as a green and sustainable solvent. The main objective is to show that glycerol can be used as a solvent first, to obtain supramolecular buildings (cohesive solvent) and emulsions using an organic phase and then, to develop a catalysis in unconventional conditions (high boiling point and low vapour pressure). The first part consists in the study of aggregation properties using fatty acids as surfactants. By changing the nature of the counter-ion, these molecules allow producing various supramolecular assemblies such as micelles, vesicles and even tubes. In glycerol these aggregates show a smaller size compared to water. Those dispersions were then used in the formation of liquid crystal phases and emulsions with hexadecane as the oil component. In a second part, in order to develop selective catalytic processes in glycerol, we have synthesized new sugar-based surfactants. They are capable to (i) circumvent the low solubility of organic substrates in glycerol and (ii) limit the intrinsic reactivity of glycerol through the formation of hydrophobic domains. In one model reactions studied (Heck coupling), it is possible, by a control of temperature, to change the reaction selectivity. This allows us to envisage the synthesis of more valuable products. The selective extraction of the products formed in glycerol has been studied using supercritical CO2 mainly because the glycerol is poorly soluble in this solvent.POITIERS-BU Sciences (861942102) / SudocSudocFranceF
Glycerol and supercritical carbon dioxide : towards greener catalytic processes
Here in this communication, we report that combination of glycerol with scCO2 is a convenient tool for designing highly green catalytic processes. Indeed, as water, glycerol is cheap, abundant and non toxic. However, as compared to water, glycerol is poorly miscible and non reactive with scCO2 offering thus an alternative of choice for overcoming a lot of drawbacks encountered with water and scCO2 Key-words. Glycerol, scCO2, catalysis; green process, Heck couplin
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