References of "Richel, Aurore"
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See detailDiallyl disulfides: comparison between classical and microwave-assisted synthesis
DETHIER, Bérénice ULg; Richel, Aurore ULg; Laurent, Pascal ULg et al

in Ioannou, Efstathia; Roussis, Vassilios (Eds.) Trends in Natural Products Research: Abstracts of the Phytochemical Society of Europe (2011)

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See detailCurrent perspectives on microwave-enhanced reactions of monosaccharides promoted by heterogeneous catalysts.
Richel, Aurore ULg; Laurent, Pascal ULg; Wathelet, Bernard ULg et al

in Catalysis Today (2011), 167

Involvment of heterogeneous catalysts as promoters of carbohydrate conversions, in synergy with microwaves as the heating source, is reported. This paper deals with the application of ion-exchange resins ... [more ▼]

Involvment of heterogeneous catalysts as promoters of carbohydrate conversions, in synergy with microwaves as the heating source, is reported. This paper deals with the application of ion-exchange resins, zeolites, clays and metal oxides as convenient mediators for key transformations of carbohydrates. A special emphasis is placed on the use of (doped) mineral supports, in solventless conditions, as clean promoters in combination with microwave dielectric heating. [less ▲]

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See detailMicrowave-assisted conversion of carbohydrates. State of the art and outlook.
Richel, Aurore ULg; Laurent, Pascal ULg; Wathelet, Bernard ULg et al

in Comptes Rendus Chimie (2011), 14

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast ... [more ▼]

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast, expeditious and cost-effective methodologies for the modification of these naturally occurring compounds is becoming a prerequisite. In this sense, the application of microwaves has gained progressive attention in laboratories for making a range of high-added value sugars derivatives scaffolds. Advantages of microwaves are numerous and include enhancement of reaction rates and yields, combined to improved regio-, chemo- and anomeric selectivities. Summary: 1. Introduction 2. Chemical transformations of monosaccharides Regioselective hydroxyls protections/deprotections Derivatisation at the anomeric position Other derivatisations Microwave-assisted click chemistry Synergy between microwaves and heterogeneous catalysis Enzymatic modifications of monosaccharides 3. Effect of microwave heating on polysaccharides Hydrolysis and pretreatment of cellulose Derivatisation of cellulose 4. Scale-up of microwave-promoted reactions 5. Conclusions [less ▲]

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See detailNew insights into the transformation of carbohydrates into platform chemicals
Richel, Aurore ULg; Wathelet, Jean-Paul ULg; Paquot, Michel ULg

Poster (2010, October 14)

The synthesis of furanic compounds from carbohydrates has become exciting in chemistry and in catalysis studies, because it represents one of the major routes for achieving sustainable energy supply and ... [more ▼]

The synthesis of furanic compounds from carbohydrates has become exciting in chemistry and in catalysis studies, because it represents one of the major routes for achieving sustainable energy supply and chemicals production.1 In particular, 5-hydroxymethylfurfural (5-HMF) and 2-furfural (2-F) occupy a pivotal place and are recognised as versatile and multi-functional starting points for the synthesis of a panel of precursors. Microwaves have readily appeared as a powerfull technique for accelerating reaction rates and increasing selectivities in the field of carbohydrate chemistry.3 In particular, their involvment in combination with heterogeneous catalysts have opened new vistas in the production of bio-oxygenated platform chemicals. The state of the art and main outlook of this strategy are reported here. [less ▲]

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See detailSynthèse assistée par Micro-ondes de dérivés d'acides uroniques
Laurent, Pascal ULg; Richel, Aurore ULg; Wathelet, Bernard ULg et al

Poster (2010, October 14)

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of ... [more ▼]

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of chemicals from the biomass, such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks is therefore an area of outmost interest. In this context, uronic acids such as glucuronic acid (GlcA) or galacturonic acid (GalA) derived from widely available raw material such as hemicellulose or pectins represent important biocompatible and bioresorbable starting material. The quest of highly effective, environmentally friendly and straightforward chemical strategies to transform totally O-unprotected uronic acids into high valuable materials remains actually a particularly challenging task. A new strategy enabling the quantitative “one-pot” production of water-soluble monosubstituted D-glucofuranosidurono-6,3-lactones from unprotected D-glucuronic acid (D-GlcA) involving microwaves and an inexpensive siliceous-based promoter will be described. The use of a heterogeneous acid catalytic systems consisting of sulfuric acid impregnated onto silica (H2SO4/SiG60) or onto carbon (H2SO4/C), offers a green alternative to unrecyclable liquid sulfuric acid and permit the developpment of a truly eco-friendly green process, as these supported acids were readily separated from liquid products, without neutralization, by decantation or filtration, thus minimizing energy consumption and wastes. Faced with environmental concerns, this solventless methodology offers attractive features, including short reaction times, high yields and easy set-up and workup. [less ▲]

Detailed reference viewed: 102 (17 ULg)
See detailCARBOHYDRATE-BASED SURFACTANTS FOR FORMING AND STABILIZING COLLOIDAL SYSTEMS AS EMULSIONS AND FOAMS
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Richel, Aurore ULg et al

in Abstracts book of 5th edition of world congress on emulsions (2010, October 12)

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable ... [more ▼]

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product concept possibilities, and may occur in a large structural range with one or more hydrophilic head groups and hydrophobic chains with various linkers/spacers, thanks to numerous reactive functional groups in their basic structure. It is then possible to design a quasi-unlimited number of new compounds by (bio)-synthesis from various raw materials. This structural diversity can generate a wide range of properties, which could be developed in food and non-food applications. Our challenge is now to find out the most suitable molecular structures for the post-development of CBS, mainly for colloidal systems like emulsion, foam, and suspension. A pre-screening of the dynamic and equilibrium interfacial tensions and interfacial rheology properties of various CBS prepared by chemical, enzymatic, or chemo-enzymatic synthesis routes from the derivatives of bio-renewable substrates is carried out. Then, the characterization of emulsifying and foaming properties of pre-selected molecules is performed. These investigations are completed by the characterization of thermal properties of liquid suspensions and powders. Homologous series of two derivative compounds of glucuronic and galacturonic acids with mono- or bicatenar hydrophobic chains and different linkages (linear or cyclic ester, amide) have been chosen as CBS starting compounds. These were full characterized by spectroscopic techniques (RMN, SM, IR). The effect of the hydrophobic chain length and number, polar head group, and the linker on whole properties investigated is easily deduced. [less ▲]

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See detailMicrowave-assisted conversion of carbohydrates. State of the art and outlook.
Richel, Aurore ULg; Laurent, Pascal ULg; Wathelet, Bernard ULg et al

Conference (2010, May)

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast ... [more ▼]

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast, expeditous and cost-effective methodologies for the modification of these naturally occurring compounds is becoming a prerequisite. In this sense, the application of microwaves has gained progressive attention in laboratories for making a range of high-added value sugars derivatives scaffolds. Its advantages are numerous and include enhacement of reaction rates and yields combined to improved regio-, chemo- and anomeric selectivities. Since the first publications of Gedye et Giguere in 1986, the use of microwave has progressively emerged as a popular non conventional heating source in the field of organic synthesis.1 Nevertheless, its application in the area of carbohydrate chemistry is less documented.2, 3 Although research in this field is still in its infancy, recourse to microwaves often provides, with remarkable yields and atom efficiency, new carbohydrate-based structures that are not easily available by any another means (or only via painstaking multi-step protocols). This communication proposes therefore selected, recent and non exhaustive illustrations of the application of microwaves to promote famous carbohydrates “model” reactions. The scale-up of such microwave-assisted reactions is also presented. [less ▲]

Detailed reference viewed: 71 (12 ULg)
See detailMicrowave – assisted synthesis of carbohydrate compounds, focus on uronic acid derivatives.
Laurent, Pascal ULg; Richel, Aurore ULg; Wathelet, Bernard ULg et al

Poster (2010, May)

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of ... [more ▼]

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of chemicals from the biomass, such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks is therefore an area of outmost interest. In this context, uronic acids such as glucuronic acid (GlcA) or galacturonic acid (GalA) derived from widely available raw material such as hemicellulose or pectins represent important biocompatible and bioresorbable starting material. The quest of highly effective, environmentally friendly and straightforward chemical strategies to transform totally O-unprotected uronic acids into high valuable materials remains actually a particularly challenging task. A new strategy enabling the quantitative “one-pot” production of water-soluble monosubstituted D-glucofuranosidurono-6,3-lactones from unprotected D-glucuronic acid (D-GlcA) involving microwaves and an inexpensive siliceous-based promoter will be described. The use of a heterogeneous acid catalytic systems consisting of sulfuric acid impregnated onto silica (H2SO4/SiG60) or onto carbon (H2SO4/C), offers a green alternative to unrecyclable liquid sulfuric acid and permit the developpment of a truly eco-friendly green process, as these supported acids were readily separated from liquid products, without neutralization, by decantation or filtration, thus minimizing energy consumption and wastes. Faced with environmental concerns, this solventless methodology offers attractive features, including short reaction times, high yields and easy set-up and workup. [less ▲]

Detailed reference viewed: 117 (8 ULg)
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See detailMicrowave-assisted transformations of agroresources: an example of green chemistry
Richel, Aurore ULg

in SciTopics-Research summarises by Experts (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 ▲]

Detailed reference viewed: 29 (4 ULg)
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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 ▲]

Detailed reference viewed: 40 (7 ULg)
See detailMicrowave-assisted transformations of carbohydrates
Richel, Aurore ULg

Report (2010)

This reports deals with the involvment of microwaves for the conversion of renewable feedstocks, and in particlar for the tranfsormation of monosaccharides and cellulose into high added value materials.

Detailed reference viewed: 21 (3 ULg)
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See detailMicrowave-assisted transformations of carbohydrates
Richel, Aurore ULg; Wathelet, Jean-Paul ULg; Paquot, Michel ULg

in SciTopics / Research Summaries by Experts (2010)

Detailed reference viewed: 51 (11 ULg)
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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 ▲]

Detailed reference viewed: 68 (28 ULg)
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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)

Detailed reference viewed: 83 (23 ULg)
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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 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 ▲]

Detailed reference viewed: 58 (9 ULg)