La tournée de Forêt Méditerranéenne - Récit d’une 11e tournée à la découverte des Parcs naturels d’Andalousie

Cette année, l’association Forêt Méditerranéenne a choisi d’organiser sa tournée forestière annuelle dans le sud de l’Espagne, en Andalousie. Du 5 au 8 mai 2016, plus de vingt participants sont ainsi partis à la découverte des plus grands Parcs et espaces naturels d’Espagne. Cet article est le compte rendu de ce voyage

On the influence of Si:Al ratio and hierarchical porosity of FAU zeolites in solid acid catalysed esterification pretreatment of bio-oil

A family of faujasite (FAU) zeolites with different Si:Al ratio, and/or hierarchical porosity introduced via post-synthetic alkaline desilication treatment, have been evaluated as solid acid catalysts for esterification pretreatments of pyrolysis bio-oil components. Acetic acid esterification with aliphatic and aromatic alcohols including methanol, anisyl alcohol, benzyl alcohol, p-cresol and n-butanol was first selected as a model reaction to identify the optimum zeolite properties. Materials were fully characterised using N2 porosimetry, ICP, XRD, XPS, FT-IR, pyridine adsorption, NH3 TPD, In-situ ATR and inverse gas chromatography (IGC). IGC demonstrates that the surface polarity and hence hydrophobicity of FAU decreases with increased Si:Al ratio. Despite possessing a higher acid site loading and acetic acid adsorption capacity, high Al-content FAU possess weaker acidity than more siliceous catalysts. Esterification activity increases with acid strength and decreasing surface polarity following the order FAU30>FAU6>FAU2.6. The introduction of mesoporosity through synthesis of a hierarchical HFAU30 material further enhances esterification activity through improved acid site accessibility and hydrophobicity. Methanol was the most reactive alcohol for esterification, and evaluated with HFAU30 for the pretreatment of a real pyrolysis bio-oil, reducing the acid content by 76% under mild conditions

Carbonylative Sonogashira Coupling in the Synthesis of Ynones: A Study of "Boomerang" Phenomena

BIOVERT+MGE:LDJThe behaviour of several organophosphino-palladium complexes immobilized on mesoporous silica during the palladium-catalyzed synthesis of propynone by carbonylative Sonogashira coupling was studied, particularly concerning leaching/redeposition phenomena. The results demonstrated that this cross-coupling reaction is catalyzed by soluble species. Furthermore, it is shown that the palladium leaching is not initiated by the oxidative addition step but rather by palladium-decoordination from grafted ligand. Despite this decoordination, catalyst performance after recycling is adequate. Additionally, several parameters linked either to catalyst preparation or reaction procedures were shown to reduce leaching allowing one to achieve metal contamination levels close to the recommendation of the European Agency for the Evaluation of Medicinal Products. Interestingly, this heterogeneous palladium-catalyzed procedure is fully selective toward the formation of ynones, allowing the preparation of various target compounds

Larock heteroannulation of 2-bromoanilines with internal alkynes via ligand and salt free Pd/C catalysed reaction

16 Batail, Nelly Dufaud, Veronique Djakovitch, LaurentAn alternative to the use of ligands and homogeneous catalysis to promote the synthesis of 2,3-disubstituted indoles starting from 2-bromoanilines is described for the first time. This reaction could be achieved through a Larock heteroannulation via a ligand free heterogeneous catalysis. (C) 2011 Elsevier Ltd. All rights reserved

Matériaux hybrides "complexes de palladium@silice mésoporeuse" pour l'obtention sélective de N-hétérocycles carbolylés

nationa

Selective synthesies of 2 types of N-heterocycles through heterogeneous multi-catalysis.

internationa

Optimised procedures for the one-pot selective syntheses of indoxyls and 4-quinolones by a carbonylative Sonogashira/cyclisation sequence

Genelot, Marie Bendjeriou, Anissa Dufaud, Veronique Djakovitch, LaurentA selective one-pot synthesis of carbonyl-containing N-heterocyclic compounds has been developed using a carbortylative Sonogashira/cyclisation sequence. Various catalytic protocols were studied (CO pressure, temperature, catalyst identity, base and substrate/catalyst ratio) with the objective of obtaining selectively either indoxyl or 4-quinolone products. The origin of the selectivity toward the 5-or 6-membered ring compounds was explained through the respective role of the various catalytic species involved, whether they are organic or metallic. The non-cyclic common intermediate was selectively prepared using [PdCl2(dppp)] as catalyst. By using a two-step multi-catalysis, i.e. {[Pd]+HNEt2}, 4-quinolones were obtained whereas with a tandem catalysis, i.e. {[Pd]/PR3), indoxyls were synthesised. (C) 2009 Elsevier B.V. All rights reserved

Larock indole synthesis using palladium complexes immobilized onto mesoporous silica

Batail, Nelly Bendjeriou, Anissa Djakoyitch, Laurent Dufaud, VeroniqueInternational audienceHeterogeneous palladium catalysts were prepared by covalent immobilization of palladium (II) complexes of the general formula PdCl2L2 (L = P, CN) onto SBA-15 silica using a post-synthetic method. The state of the hybrid materials was characterized using a wide variety of molecular and solid-state techniques. In general, all the palladium modified solids exhibited highly ordered mesostructures while keeping the integrity of the parent molecular precursors. The catalytic performances of the materials were evaluated in the heteroannulation of 2-iodoaniline and 2-bromoaniline with triethyl(phenylethynyl)silane which showed high activities and selectivities with isolated yields in the range of 80-85%. Despite a decrease in the initial activity, quantitative conversion of iodoaniline to the expected product was observed over multiple recyclings, making these materials particularly efficient for such applications. The catalytic process was shown to be homogeneous in nature, the solid apparently serving as a "reservoir" for the metal between cycles. (C) 2010 Elsevier B.V. All rights reserved