Microwave-assisted transformations of agroresources: an example of green chemistry

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 ▲]

Microwave-assisted synthesis of D-glucuronic acid derivatives using cost-effective solid acid catalysts

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 ▲]

PROCEDE DE FABRICATION DE MONOSACCHARIDES SUBSTITUES ET DE LACTONES SUBSTITUEES.

Patent (2009)

Chemical and enzymatical modifications of sugar derived from lignocellulose

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 ▲]

Synthesis of uronic acid derivatives bearing a single or two alkyl chains as new surfactants

Poster (2008, September)

Ethanolic fermentation as a tool for high added value products purification from biomass

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 ▲]

A new diterpene enone from the soldier beetle Cantharis livida (Coleoptera : Cantharidae)

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 ▲]

Trinervitene diterpenes from soldiers of two Nasutitermes species from French Guyana

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 ▲]

Insect Chemical Defense

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 ▲]

Stenotarsol, a new terpenoid from Stenotarsus subtilis (Coleoptera : Endomychidae)

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 ▲]