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See detailMicrowave-assisted transformations of agroresources: an example of green chemistry
Richel, Aurore ULg; Laurent, Pascal ULg; Paquot, Michel ULg

Report (2010)

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as a promising renewable alternative. Alongside its traditional involvement in the agro-food, the ... [more ▼]

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as a promising renewable alternative. Alongside its traditional involvement in the agro-food, the biomass has nowadays opened new vistas in the non-food sector. Indeed, original products and structures, potentially biodegradable, are proposed as substitutes for conventional petrochemical derivatives. The steady rise of oil prices, on the one hand, and the implementation of a new European legislation (REACH: Registration, Evaluation and Authorization of Chemicals), on the other hand, have only help to boost the academic and industrial research in this area. In this context, microwave-mediated synthesis has progressively emerged as a green chemistry technology. Application of microwaves (MW) as a non conventional heating source finds a plethora of illustrations in the field of organic synthesis. Microwaves usually accelerate chemical processes, while offering improved yields and selectivities. MW heating enables reactions under solventless conditions, providing unique chemical pathways, with special advantages such as ease of manipulation and reduction (or prevention) of pollution "at source". Various reactions and processes can be applied to transform lignocellulosic raw materials into valuable fuels and chemicals. Selected examples of strategical modifications of renewable biomass feedstocks via activation by microwave irradiation are proposed herein. [less ▲]

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See detailMicrowave-assisted synthesis of D-glucuronic acid derivatives using cost-effective solid acid catalysts
Richel, Aurore ULg; Laurent, Pascal ULg; Wathelet, Bernard ULg et al

in Tetrahedron Letters (2010), 51

Monomode microwave-assisted coupling of D-glucuronic acid with alcohols, in the presence of various impregnated acid catalysts, was successfully performed, affording in almost quantitative yields the ... [more ▼]

Monomode microwave-assisted coupling of D-glucuronic acid with alcohols, in the presence of various impregnated acid catalysts, was successfully performed, affording in almost quantitative yields the corresponding monosubstituted b-D-glucofuranosidurono-6,3-lactones in less than 10 min at 85°C. This study evidences the synergy of microwaves and impregnated acid catalysts as a fast and clean strategy in the field of carbohydrate chemistry. [less ▲]

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See detailCobalt-mediated radical polymerization (CMRP) and coupling reaction (CMRC): mechanistic advances ans synthetic opportunities
Debuigne, Antoine ULg; Poli, Rinaldo; De Winter, Julien et al

Poster (2009, December 14)

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See detailChimie verte et nouvelles molécules issues du Programme d'Excellence Technose
Laurent, Pascal ULg; Richel, Aurore ULg

Scientific conference (2009, October 21)

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See detailChemical and enzymatical modifications of sugar derived from lignocellulose
Richard, Gaetan ULg; Laurent, Pascal ULg; Nott, Katherine ULg et al

Poster (2009, January)

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from ... [more ▼]

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from biomass, with applications such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates from renewable raw materials is currently the subject of numerous researches. In this context, the synthesis of new surfactants derived from the sugars issued from the lignocellulose hydrolysis was undertaken by chemical or enzymatic routes. In this poster, the examples of glucose, cellobiose and uronic acids will be discussed. Whatever the way used, the reaction conditions (use of a catalyst, protection/deprotection steps, type of solvent, presence of co-solvent, reactant concentrations, etc) were optimized to yield a panel of carbohydrate derivatives (some examples of the structures obtained are given above). These differ by the nature of the alkyl chain (in length and in degree of saturation), the type of chemical bond (amide, ester, thioester, acetal), and the position of substitution. The impact of these differences on the techno-functional properties of these modified sugars will be evaluated. [less ▲]

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See detailSynthèse et propriétés tensioactives de nouveaux surfactants provenant de matières premières renouvelables.
Laurent, Pascal ULg; Razafindralambo, Hary ULg; Wathelet, Bernard ULg et al

Poster (2009)

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source ... [more ▼]

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source d'énergie et le développement de produits chimiques issus de la biomasse (végétale principalement) tels que détergents, produits phytopharmaceutiques, dissolvants, matières plastiques, etc. La valorisation de carbohydrates provenant de matières premières renouvelables fait ainsi actuellement l'objet de nombreuses recherches. Dans ce cadre, la synthèse de nouveaux tensioactifs non ioniques dérivés des acides Dglucuronique et D-galacturonique a été effectuée. [less ▲]

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See detailSynthèse de nouveaux surfactants dérivés des acides D-glucuronique et D-galacturonique.
Laurent, Pascal ULg; Richel, Aurore ULg; Richard, Gaetan ULg et al

Poster (2008)

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source ... [more ▼]

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source d'énergie et le développement de produits chimiques issus de la biomasse (végétale principalement) tels que détergents, produits phytopharmaceutiques, dissolvants, matières plastiques, etc. La valorisation de carbohydrates provenant de matières premières renouvelables [1] fait ainsi actuellement l'objet de nombreuses recherches. Dans ce cadre, la synthèse de nouveaux tensioactifs non ioniques dérivés des acides Dglucuronique et D-galacturonique a été effectuée de manière chimique et/ou enzymatique. [less ▲]

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See detailEthanolic fermentation as a tool for high added value products purification from biomass
Destain, Jacqueline ULg; Laurent, Pascal ULg; Thonart, Philippe ULg et al

Poster (2008)

The biorefinery concept implies the development of processes in order to valorise the whole part of a crop. In this concept, white biotechnologies are usually considered for the production of new ... [more ▼]

The biorefinery concept implies the development of processes in order to valorise the whole part of a crop. In this concept, white biotechnologies are usually considered for the production of new compounds or compounds actually derived from the oil industry. For example, interest in ethanolic fermentation is growing nowadays, mainly for its energetic applications, starting from starch or saccharose. Biorefinery integrating lignocellulosic materials are under development. Whatever the initial substrate may be, wet technologies would produce sugars and other soluble materials from the biomass. Different results could be expected:most of the hydrolysates molecules are used by the microorganisms;some molecules could be inhibitors for the fermentation;some molecules are "indifferent ones" and could be concentrated by the fermentation proccess followed by distillation. In the latest case, these molecules are concentrated in the residual medium and could be more easily recuperated. An example of this exists in the production of ethanol from beet. The different juices (diffusion, clarified, ...) contain molecules such as raffinose, glutamine, betaine, saponins or pectic materials. Some products are used by the yeasts and other are concentrated. Our purpose is to summary the results obtained, allowing the development of the concept in other biorefinery applications. [less ▲]

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See detailBioethanol subproducts as a basis of plant biorefinery
Destain, Jacqueline ULg; Laurent, Pascal ULg; Ndoye, Bassirou et al

Poster (2008)

The philosophy of our research is built on the behaviour of non-sugar compounds from biomass during ethanolic fermentation. Saccharomyces cerevisiae, industrially used to bioconvert sugar into ethanol ... [more ▼]

The philosophy of our research is built on the behaviour of non-sugar compounds from biomass during ethanolic fermentation. Saccharomyces cerevisiae, industrially used to bioconvert sugar into ethanol under anaerobic conditions, assimilates some compounds present in the fermentable juice (proteins, amino acids,...). But others compounds are not used by the yeast. They leave in the vinasse after ethanol distillation and are thus concentrated by the process. Our purpose is to discuss the behaviour of betaine, saponins and raffinose in sugar juices (raw juice, thin juice, thick juice) and in vinasse after ethanolic fermentation. An attention will be given to some high added value products (like betaine) and the potentialities to use fermentation as a tool of purification in white chemistry. [less ▲]

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See detailA new diterpene enone from the soldier beetle Cantharis livida (Coleoptera : Cantharidae)
Durvaux, Christophe; Laurent, Pascal ULg; Daloze, Désiré et al

in ARKIVOC (2007), 10

Cantharenone, a new diterpene structurally related to the prenylbisabolane skeleton, has been isolated from the beetle Cantharis livida (Cantharidae). Its structure has been determined on the basis of its ... [more ▼]

Cantharenone, a new diterpene structurally related to the prenylbisabolane skeleton, has been isolated from the beetle Cantharis livida (Cantharidae). Its structure has been determined on the basis of its spectral properties. This is the first report of such a type of diterpenoid from an insect. [less ▲]

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See detailOrigine biogénétique des triterpènes pentacycliques présents dans la sécrétion défensive de Platyphora Kollari (Chrysomelidae)
Ghostin, Jean; Laurent, Pascal ULg; Daloze, Désiré et al

Poster (2006)

Les chrysomèles sont des insectes phytophages brillement colorés qui représentent une des famille (Chrysomelidae) les plus importante de l'ordre des coléoptères. Etant aposématiques, ils sont facilement ... [more ▼]

Les chrysomèles sont des insectes phytophages brillement colorés qui représentent une des famille (Chrysomelidae) les plus importante de l'ordre des coléoptères. Etant aposématiques, ils sont facilement repérables par des prédateurs potentiels et ont, au cours de l'évolution, développé des mécanismes de défense chimique élaborés. La découverte de glycosides triterpéniques basés sur le squelette oléanane a soulevé le problème de leur origine biogénétique. En effet, il est bien connu que les insectes ne possèdent pas la squalène synthase, une enzyme indispensable à la formation des stéroïdes et des triterpènes pentacycliques. Dès lors, une biosynthèse de novo de ce type de dérivé est peu probable. Par ailleurs, l'analyse de la plante hôte des chrysomèles a montré que la séquestration des glycosides au départ de cette plante est également exclue. Une troisième possibilité serait que l'insecte utilise un précurseur provenant de son alimentation pour fabriquer ses substances défensives. Un tel précurseur pourrait être la b-amyrine identifiée chez différentes plantes hôtes des chrysomèles ou l'acide oléanolique dont la structure de base se retrouve au niveau des triterpènes défensifs. Enfin, l'analyse des plantes hôtes a montré que celles-ci contiennent à la fois de la b-amyrine et de l'a-amyrine dans un rapport 1,76/1. Cependant aucun glycoside triterpénique basé sur le squelette ursane n'a été isolé jusqu'à présent chez les chrysomèles, ce qui suggère un mécanisme de transport sélectif en faveur de la b-amyrine. Dans le cadre de ce travail, nous présenterons les synthèses d'a-amyrine, de b-amyrine et d'acide oéanolique trideutériés, ainsi que les résultats d'incorporation des deux premiers précurseurs chez Platyphora kollari. [less ▲]

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See detailTrinervitene diterpenes from soldiers of two Nasutitermes species from French Guyana
Laurent, Pascal ULg; Daloze, Désiré; Pasteels, Jacques et al

in Journal of natural products (2005), 68(4), 532-536

Methanolic extracts of soldiers of Nasutitermes guayanae and N. surinamensis have been shown to contain complex mixtures of diterpenes and monoterpenes. Eighteen diterpenes have been isolated and ... [more ▼]

Methanolic extracts of soldiers of Nasutitermes guayanae and N. surinamensis have been shown to contain complex mixtures of diterpenes and monoterpenes. Eighteen diterpenes have been isolated and identified; twelve of them are previously known nasute termite diterpenes, while six are new trinervitene diterpenes. 2 alpha,9 beta-Dihydroxy-3 beta,8 beta-oxido-1(15)-trinervitene (1) has been isolated from N. guayanae, while 3 alpha,14 alpha-diacetoxy-2 beta-hydroxy-1(15),8(19),9-trinervitatriene (3), 14 alpha-acetoxy-2 beta,3 alpha-dihydroxy-1(15),8(19),9-trinervitatriene (4), 2 beta,3 alpha-diacetoxy-11 beta,14 alpha-dihydroxy-1(15),8(19)-trinervitadiene (5), 9 alpha,14 alpha-diacetoxy-2 beta,3 alpha-dihydroxy-1(15),8(19)-trinervitadiene (6), and 2 beta,9 alpha,14 alpha-triacetoxy-3 alpha-hydroxy-1(15),8(19)-trinervitadiene (7) have been isolated from N. surinamensis. Their structures were determined on the basis of their spectroscopic properties. [less ▲]

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See detailSynthèse de la (+/-)-hyperaspine, alcaloïde défensif de la coccinelle Hyperaspis campestris
Dooms, Cédric; Laurent, Pascal ULg; Daloze, Désiré et al

in Chimie Nouvelle (2005), (89), 96

Hyperaspine, isolated from the European Coccinellidae Hyperaspis campestris, is the first representative of a new type of ladybird alkaloids having a 3-oxaquinolizidine skeleton. A new total synthesis of ... [more ▼]

Hyperaspine, isolated from the European Coccinellidae Hyperaspis campestris, is the first representative of a new type of ladybird alkaloids having a 3-oxaquinolizidine skeleton. A new total synthesis of (+/-)-hyperaspine starting from protected piperidin-4-one has been achieved. The absolute configuration of the natural alkaloid was unequivocally established to be 3S,4aS,6R,8S by HPLC analyses on a chiral column. [less ▲]

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See detailInsect Chemical Defense
Laurent, Pascal ULg; Braekman, Jean-Claude; Daloze, Désiré

in Schulz, Stefan (Ed.) The Chemistry of Pheromones and Other Semiochemicals II (2005)

Research on the defensive chemistry of insects during the last decade is reviewed, with special emphasis on non-volatile compounds. The isolation and structure determination of defensive chemicals, of ... [more ▼]

Research on the defensive chemistry of insects during the last decade is reviewed, with special emphasis on non-volatile compounds. The isolation and structure determination of defensive chemicals, of glandular and non-glandular origins, are first discussed, followed by an overview of the synthesis and biological/pharmacological activities of some of them. Biosynthesis has been largely omitted since this topic has been addressed in a recent review. During the period covered, beetles (e.g., coccinellids and chrysomelids) and ants have undoubtedly been the most prolific producers of repellent and/or toxic compounds. This survey also shows that alkaloids are the most frequently encountered defensive compounds in insects. [less ▲]

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See detailInsect chemical defense
Laurent, Pascal ULg; Braekman, Jean-Claude; Daloze, Désiré

in Topics in Current Chemistry (2005), 240

Research on the defensive chemistry of insects during the last decade is reviewed, with special emphasis on non-volatile compounds. The isolation and structure determination of defensive chemicals, of ... [more ▼]

Research on the defensive chemistry of insects during the last decade is reviewed, with special emphasis on non-volatile compounds. The isolation and structure determination of defensive chemicals, of glandular and non-glandular origins, are first discussed, followed by an overview of the synthesis and biological/pharmacological activities of some of them. Biosynthesis has been largely omitted since this topic has been addressed in a recent review. During the period covered, beetles (e.g., coccinellids and chrysomelids) and ants have undoubtedly been the most prolific producers of repellent and/or toxic compounds. This survey also shows that alkaloids are the most frequently encountered defensive compounds in insects. [less ▲]

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See detailStenotarsol, a new terpenoid from Stenotarsus subtilis (Coleoptera : Endomychidae)
Laurent, Pascal ULg; Daloze, Désiré; Braekman, Jean-Claude et al

in Tetrahedron Letters (2005), 46(6), 931-932

Stenotarsol, a new terpenoid alcohol, has been isolated from the beetle Stenotarsus subtilis (Endomychidae). Its structure has been determined on the basis of its spectral properties. Compound 1 ... [more ▼]

Stenotarsol, a new terpenoid alcohol, has been isolated from the beetle Stenotarsus subtilis (Endomychidae). Its structure has been determined on the basis of its spectral properties. Compound 1 represents a new type of terpene skeleton and is the first secondary metabolite reported so far from this family of beetles. [less ▲]

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See detailSynthesis and absolute configuration of hyperaspine, an alkaloid of the ladybird Hyperaspis campestris
Dooms, Cédric; Laurent, Pascal ULg; Daloze, Désiré et al

in European Journal of Organic Chemistry (2005), 7

Hyperaspine, isolated from the European Coccinellidae Hyperaspis campestris, is the first representative of a new type of ladybird alkaloids having a 3-oxaquinolizidine skeleton. A new total synthesis of ... [more ▼]

Hyperaspine, isolated from the European Coccinellidae Hyperaspis campestris, is the first representative of a new type of ladybird alkaloids having a 3-oxaquinolizidine skeleton. A new total synthesis of (+/-)-hyperaspine starting from protected piperidin-4-one has been achieved. The absolute configuration of the natural alkaloid was unequivocally established to be 3S,4aS,6R,8S by HPLC analyses on a chiral column. [less ▲]

Detailed reference viewed: 14 (1 ULg)