22 research outputs found

    Acidic Pretreatment of Wheat Straw in Decanol for the Production of Surfactant, Lignin and Glucose

    Get PDF
    Wheat straw is an abundant residue of agriculture which is increasingly being considered as feedstock for the production of fuels, energy and chemicals. The acidic decanol-based pre-treatment of wheat straw has been investigated in this work. Wheat straw hemicellulose has been efficiently converted during a single step operation into decyl pentoside surfactants and the remaining material has been preserved keeping all its promises as potential feedstock for fuels or value added platform chemicals such as hydroxymethylfurfural (HMF). The enzymatic digestibility of the cellulose contained in the straw residue has been evaluated and the lignin prepared from the material characterized. Wheat-based surfactants thus obtained have exhibited superior surface properties compared to fossil-based polyethoxylates decyl alcohol or alkyl oligoglucosides, some of which are largely used surfactants. In view of the growing importance of renewable resource-based molecules in the chemical industry, this approach may open a new avenue for the conversion of wheat straw into various chemicals

    Additions radicalaires stéréosélectives d'amines tertiaires par photocatalyse homogène et hétérogène

    No full text
    Les radicaux a-aminoalkyles ont permis la synthèse de nombreux composés azotés. Notre laboratoire a développé une méthode efficace et sélective d'addition radicalaire d'amines tertiaires sur des alcènes électrophiles. Lors de cette réaction photosensibilisée en phase homogène, la formation des radicaux a-aminoalkyles s'effectue par transfert mono-électronique. La présence de xanthates conduit à des réactions radicalaires réversibles avec une grande sélectivité faciale et de bons rendements. Cette nouvelle méthode permet d'élargir la gamme des amines tertiaires pouvant être additionnées. En phase hétérogène, les semi-conducteurs permettent l'addition radicalaire d'amines tertiaires sur des alcènes électrophiles. De bons rendements et des excès diastéréoisomériques semblables à ceux en milieu homogène ont été obtenus. Une étude par marquage isotopique a indiqué que la réaction s'effectue à la surface. Les diastéréoisomères de la 5-menthyloxy-2[5H]-furanone ont permis l'étude de la double induction asymétrique constituée par le centre acétalique et la chiralité du menthol. L'encombrement stérique dans les conformations privilégiées des réactifs est à l'origine de l'induction chirale.a-aminoalkyl radicals are used in the synthesis of various nitrogen containing compounds. We described an efficient procedure involving a photochemical electron transfer under homogeneous photocatalysis to initiate the radical addition of tertiary amines to electron deficient alkenes. With the presence of xanthates, reversible radical reactions were observed with good yields and high facial diastereoselectivity. This new procedure enlarge the scope of tertiary amines which can be added to alkenes. Using heterogeneous photocatalysis with semiconductors as sensitisers, the radical addition of tertiary amines with electron deficient alkenes can be performed. Like in homogeneous conditions, high yields and high facial diastereoselectivity were obtained. The mechanism investigated by isotopic labeling shows that the reaction takes place at the surface. Two diastereoisomers of the 5-menthyloxy-2[5H]-furanone were isolated. The double asymmetric induction constituted of the acetalic center and the chirality of menthol was studied. The chiral induction results from the steric hindrance in the favored conformations of the reactant.REIMS-BU Sciences (514542101) / SudocSudocFranceF

    Biosourced lauroyl poly(glycerol-succinate) oligoesters modified by copolymerizable solvents: A wasteless and eco-friendly surfactants properties enhancement

    No full text
    International audienceBiosourced oligomeric surfactants have been synthesized and characterized as potential alternatives to petrobased surfactants. The polar head was a branched oligoester while the hydrophobic part derived from fatty acid or fatty α-monoglyceride ester. Besides the glycerol (G) and succinic acid (S) units, the hydrophilic oligoesters were modified by a third comonomer (X) which was introduced as a copolymerizable solvent in order to improve its grafting with the alkyl chain and facilitate the processability. The investigated comonomers were lactic acid, ethylene glycol, propylene glycol, 1,3-propanediol and 1,4-butanediol. Modified lauroyl oligoesters, C12PGSX, with controllable sizes were thus obtained by polycondensation reactions. They were characterized by their acid values, gas chromatography and size exclusion chromatography. Their surface activity, foamability, wetting power, solubilizing capacity and biodegradation were investigated highlighting the interest of these biosourced surfactants in a wide set of applications

    Acyl Poly(Glycerol-Succinic Acid) Oligoesters: Synthesis, Physicochemical and Functional Properties, and Biodegradability

    No full text
    International audienceBiobased surfactants were synthesized using poly(glycerol-succinate) as the polar head group and variable acyl groups as hydrophobic tails. Acyl chain lengths ranged from 8 to 14 carbon atoms. The resulting oligomeric surfactants were characterized by quantitative 13C nuclear magnetic resonance (NMR), acid values and size exclusion chromatography. Investigation of the physicochemical properties of the acyl poly(glycerol-succinate) surfactants revealed their potential for use in a wide array of applications. The acyl poly(glycerol-succinate) functional properties appeared to be particularly concentration-dependent. This study highlights the relative impact of acyl chain length on the polymeric structure, physicochemical and functional behaviors, and biodegradability of the acyl poly(glycerol-succinate) surfactants

    Selective Depolymerization of Cellulose to Low Molecular Weight Cello-Oligomers Catalyzed by Betaine Hydrochloride

    No full text
    International audienceThis study aims to demonstrate that depolymerization of cellulose can be closely controlled in a reaction media made of betaine hydrochloride (BHC) and [TBMA] Cl opening the route to low molecular weight cello-oligomers that exhibit a high potential for marketing in the production of surfactants and thickener agents. The main advantages of this process rely on (1) the sustainability of BHC, (2) convenient isolation of cello-oligomers, and (3) recyclability of BHC and [TBMA]Cl. On the other hand, we demonstrate that this work can be also considered as an efficient pretreatment process of cellulose. Indeed, whereas in water cellulose is recalcitrant to hydrolysis, we show here that recovered cello-oligomers can be subsequently readily converted in water to glucose

    Acid-Assisted Ball Milling of Cellulose as an Efficient Pretreatment Process for the Production of Butyl Glycosides

    No full text
    Ball milling of cellulose in the presence of a catalytic amount of H2SO4 was found to be a promising pre-treatment process to produce butyl glycosides in high yields. Conversely to the case of water, n-butanol has only a slight effect on the recrystallization of ball-milled cellulose. As a result, thorough depolymerization of cellulose prior the glycosylation step is no longer required, which is a pivotal aspect with respect to energy consumption. This process was successfully transposed to wheat straw from which butyl glycosides and xylosides were produced in good yields. Butyl glycosides and xylosides are important chemicals as they can be used as hydrotropes but also as intermediates in the production of valuable amphiphilic alkyl glycosides
    corecore