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See detailMicrowave-assisted extraction of pectin from unused pumpkin biomass
Košťálová, Zuzana; Aguedo, Mario ULg; Hromádková, Zdenka

Poster (2014, November)

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See detailMicrowave-assisted extraction of pectin from unutilized pumpkin biomass
Košťálová, Zuzana; Aguedo, Mario ULg; Hromádkováa, Zdenka

in Chemical Engineering and Processing: Process Intensification (2016), 102

Microwave-assisted extraction was employed to extract polysaccharides from pumpkin biomass and compared to the usual extraction by conventional heating. The effect of microwave heating time, liquid/solid ... [more ▼]

Microwave-assisted extraction was employed to extract polysaccharides from pumpkin biomass and compared to the usual extraction by conventional heating. The effect of microwave heating time, liquid/solid (L/S) ratio and extraction temperature on the yield and molecular mass of extracted pectin from the seeded oil pumpkin biomass was investigated. Heating times ranged from 2 to 10 min, L/S ratio from 30/1 to 50/1 and temperature from 80 to 120 °C. The response surface methodology was used to optimize the effects of processing parameters to isolate pectin with medium molecular weight and with the highest yield. The retained conditions were as follows: liquid/solid ratio 50/1, microwave heating time of 10 min and a temperature of 102.2 °C. Among the studied factors, the liquid/solid ratio had the greatest influence on yield and molecular mass, respectively. Application of microwave heating in the extraction of pumpkin biomass gave a pectin with medium Mw and dramatically reduced extraction time in comparison to traditional hot acid extraction. Microwave is an excellent tool for extraction and modification of polysaccharides in one step. [less ▲]

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See detailMicrowave-Assisted Olefin Metathesis
Nicks, François; Borguet, Yannick ULg; Sauvage, Xavier et al

in Dragutan, Valerian; Demonceau, Albert; Dragutan, Ileana (Eds.) et al Green Metathesis Chemistry (2010)

Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers have been published in this field. In most examples, microwave heating has ... [more ▼]

Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers have been published in this field. In most examples, microwave heating has been shown to dramatically reduce reaction times, increase product yields, and enhance product purity by reducing unwanted side reactions compared to conventional heating methods. The present contribution aims at illustrating the advantages of this technology in olefin metathesis and, when data are available, at comparing microwave-heated and conventionally heated experiments. [less ▲]

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See detailMicrowave-assisted ruthenium-catalysed atom transfer radical reactions
Delfosse, Sébastien; Richel, Aurore ULg; Wei, H. et al

Poster (2005, August)

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See detailMicrowave-assisted ruthenium-catalysed atom transfer radical reactions
Delfosse, Sébastien; Richel, Aurore ULg; Wei, H. et al

Conference (2005)

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See detailMicrowave-Assisted Ruthenium-Catalyzed Reactions
Nicks, Francois ULg; Borguet, Yannick ULg; Delfosse, Sebastien et al

in Australian Journal of Chemistry (2009), 62(3), 184-207

Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers has been published in this field. In most examples, microwave heating has ... [more ▼]

Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers has been published in this field. In most examples, microwave heating has been shown to dramatically reduce reaction times, increase product yields, and enhance product purity by reducing unwanted side reactions compared with conventional heating methods. The present contribution aims at illustrating the advantages of this technology in homogeneous catalysis by ruthenium complexes and, when data are available, at comparing microwave-heated and conventionally heated experiments. Selected examples refer to olefin metathesis, isomerization reactions, 1,3-dipolar cycloadditions, atom transfer radical reactions, transfer hydrogenation reactions, and H/D exchange reactions. [less ▲]

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See detailMicrowave-Assisted Synthesis of 1,3-Dimesitylimidazolinium Chloride
Hans, Morgan ULg; Delaude, Lionel ULg

in Wipf, Peter (Ed.) Organic Syntheses. Volume 87 (2010)

A procedure for the microwave-assisted synthesis of 1,3-dimesitylimidazolinium chloride on a preparative scale is described starting from simple, commercially available reagents. Prior to a microwave ... [more ▼]

A procedure for the microwave-assisted synthesis of 1,3-dimesitylimidazolinium chloride on a preparative scale is described starting from simple, commercially available reagents. Prior to a microwave-assisted cyclization, it involves the formation of N,N'-dimesitylethane-1,2-diamine dihydrochloride via condensation of glyoxal with two equivalents of mesitylamine, followed by reduction of the intermediate Schiff base with sodium borohydride under acidic conditions. All three steps proceed readily under normal atmosphere. Laboratory grade solvents and reagents taken straight from the bottles do not require any additional purification. The two intermediates and the final product are isolated in high yield and purity by simple filtration and washing and may be used without any further purification for most applications. [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 detailMicrowave-assisted synthesis of imidazolinium salts
Hans, Morgan; Demonceau, Albert ULg; Delaude, Lionel ULg

in Polymer Preprints (2008), 49(2), 942-943

Imidazolinium salts were prepd. via microwave-assisted cyclocondensation of ethanediamines with triethoxy alkanes or triethoxymethyl benzene. The synthesized imidazolinium salts may be used as NHC ... [more ▼]

Imidazolinium salts were prepd. via microwave-assisted cyclocondensation of ethanediamines with triethoxy alkanes or triethoxymethyl benzene. The synthesized imidazolinium salts may be used as NHC precursors or ionic liqs. [less ▲]

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See detailMicrowave-assisted synthesis of N-heterocyclic carbene precursors
Aidouni, Adila; Demonceau, Albert ULg; Delaude, Lionel ULg

in Synlett (2006), (3), 493-495

A very simple and efficient procedure is reported for the synthesis of 1,3-diarylimidazolinium chlorides by cyclization of N,N'-diarylethylenediamines dihydrochlorides with triethyl ortho-formate under ... [more ▼]

A very simple and efficient procedure is reported for the synthesis of 1,3-diarylimidazolinium chlorides by cyclization of N,N'-diarylethylenediamines dihydrochlorides with triethyl ortho-formate under microwave irradiation. [less ▲]

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See detailMicrowave-Assisted Synthesis of Vinyl Esters through Ruthenium-Catalyzed Addition of Carboxylic Acids to Alkynes
Nicks, Francois ULg; Libert, Lionel ULg; Delaude, Lionel ULg et al

in Australian Journal of Chemistry (2009), 62(3), 227-231

A rapid and efficient method is described for the selective synthesis of enol esters via the microwave-accelerated addition of carboxylic acids to terminal alkynes. The method employs the readily ... [more ▼]

A rapid and efficient method is described for the selective synthesis of enol esters via the microwave-accelerated addition of carboxylic acids to terminal alkynes. The method employs the readily available [RuCl2(p-cymene)(PPh3)] complex as catalyst without the need of bases, and reactions are complete in 20 min. [less ▲]

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See detailMicrowave-assisted synthesis of vinyl esters through ruthenium-catalyzed addition of carboxylic acids to alkynes
Nicks, Francois ULg; Libert, Lionel ULg; Delaude, Lionel ULg et al

in Polymer Preprints (2008), 49(2), 944-945

1-Hexen-2-yl 4-acetoxybenzoate was regioselectively prepd. via microwave-assisted ruthenium-catalyzed addn. of 4-acetoxybenzoic acid to 1-hexyne. Species of catalysts, reaction time and temp. play roles ... [more ▼]

1-Hexen-2-yl 4-acetoxybenzoate was regioselectively prepd. via microwave-assisted ruthenium-catalyzed addn. of 4-acetoxybenzoic acid to 1-hexyne. Species of catalysts, reaction time and temp. play roles in the reaction respect to yields and selectivity, therefore were examd. Microwave effect was obsd. and preferred to the generation of the Markovnikov-type product compared to traditional heating. [less ▲]

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See detailMicrowave-assisted thermochemical and primary hydrolytic conversions of lignocellulosic resources: a review
Richel, Aurore ULg; Jacquet, Nicolas ULg

in Biomass Conversion and Biorefinery (2015), 5(1), 115-124

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as promising renewable alternatives. Particularly, the conversion of lignocellulosic materials has ... [more ▼]

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as promising renewable alternatives. Particularly, the conversion of lignocellulosic materials has nowadays opened new vistas for the production of energy, biofuels and chemicals. In this literature review, microwave technology is described as an original heating source either for the thermochemical conversions (at temperatures up to 400°C) of lignocellulose into biofuels or the pretreatment (below 400°C) and further hydrolysis of lignocellulose into bioethanol and other valuable chemicals. Advantages of microwave approaches include a commonly observed acceleration in reaction rate and improved selectivities and yields. [less ▲]

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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 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: 40 (6 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: 28 (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: 54 (11 ULg)
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See detailMicrowave-Enhanced Ruthenium Catalysed Atom Transfer Radical Additions
Richel, Aurore ULg; Leclerc, Alain; Demonceau, Albert ULg et al

Poster (2005)

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See detailMicrowave-enhanced ruthenium-catalysed atom transfer radical additions
Borguet, Yannick ULg; Richel, Aurore ULg; Delfosse, Sbastien et al

in Tetrahedron Letters (2007), 48(36), 6334-6338

The first monomode microwave-assisted atom transfer radical additions (ATRA) of carbon tetrachloride to various olefins were successfully performed, affording the adducts with almost quantitative yields ... [more ▼]

The first monomode microwave-assisted atom transfer radical additions (ATRA) of carbon tetrachloride to various olefins were successfully performed, affording the adducts with almost quantitative yields in less than 10 min at 160 'C. (c) 2007 Elsevier Ltd. All rights reserved. [less ▲]

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See detailMicrowave-stimulated superconductivity due to presence of vortices
Lara, Antonio; Aliev, Farkhad; Silhanek, Alejandro ULg et al

in Scientific Reports (2015), 5

The response of superconducting devices to electromagnetic radiation is a core concept implemented in diverse applications, ranging from the currently used voltage standard to single photon detectors in ... [more ▼]

The response of superconducting devices to electromagnetic radiation is a core concept implemented in diverse applications, ranging from the currently used voltage standard to single photon detectors in astronomy. Suprisingly, a sufficiently high power subgap radiation may stimulate superconductivity itself. The possibility of stimulating type II superconductors, in which the radiation may interact also with vortex cores, remains however unclear. Here we report on superconductivity enhanced by GHz radiation in type II superconducting Pb films in the presence of vortices. The stimulation effect is more clearly observed in the upper critical field and less pronounced in the critical temperature. The magnetic field dependence of the vortex related microwave losses in a film with periodic pinning reveals a reduced dissipation of mobile vortices in the stimulated regime due to a reduction of the core size. Results of numerical simulations support the validy of this conclusion. Our findings may have intriguing connections with holographic superconductors in which the possibility of stimulation is under current debate. [less ▲]

Detailed reference viewed: 155 (4 ULg)